Solventless and solvent-minimized sample preparation techniques for determining currently used pesticides in water samples: a review.

PubMed

Tankiewicz, Maciej; Fenik, Jolanta; Biziuk, Marek

2011-10-30

The intensification of agriculture means that increasing amounts of toxic organic and inorganic compounds are entering the environment. The pesticides generally applied nowadays are regarded as some of the most dangerous contaminants of the environment. Their presence in the environment, especially in water, is hazardous because they cause human beings to become more susceptible to disease. For these reasons, it is essential to monitor pesticide residues in the environment with the aid of all accessible analytical methods. The analysis of samples for the presence of pesticides is problematic, because of the laborious and time-consuming operations involved in preparing samples for analysis, which themselves may be a source of additional contaminations and errors. To date, it has been standard practice to use large quantities of organic solvents in the sample preparation process; but as these solvents are themselves hazardous, solventless and solvent-minimized techniques are coming into use. This paper discusses the most commonly used over the last 15 years sample preparation techniques for monitoring organophosphorus and organonitrogen pesticides residue in water samples. Furthermore, a significant trend in sample preparation, in accordance with the principles of 'Green Chemistry' is the simplification, miniaturization and automation of analytical techniques. In view of this aspect, several novel techniques are being developed in order to reduce the analysis step, increase the sample throughput and to improve the quality and the sensitivity of analytical methods. The paper describes extraction techniques requiring the use of solvents - liquid-liquid extraction (LLE) and its modifications, membrane extraction techniques, hollow fibre-protected two-phase solvent microextraction, liquid phase microextraction based on the solidification of a floating organic drop (LPME-SFO), solid-phase extraction (SPE) and single-drop microextraction (SDME) - as well as solvent-free techniques - solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). The advantages and drawbacks of these techniques are also discussed, and some solutions to their limitations are proposed. Copyright © 2011 Elsevier B.V. All rights reserved.

Freeze-thaw method improves the detection of volatile compounds in insects using Headspace Solid-Phase Microextraction (HS-SPME)

USDA-ARS?s Scientific Manuscript database

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS) is commonly used in analyzing insect volatiles. In order to improve the detection of volatiles in insects, a freeze-thaw method was applied to insect samples before the HS-SPME-GC-MS analysis. ...

Determination of volatile organic acids in oriental tobacco by needle-based derivatization headspace liquid-phase microextraction coupled to gas chromatography/mass spectrometry.

PubMed

Sun, Shi-Hao; Xie, Jian-Ping; Xie, Fu-Wei; Zong, Yong-Li

2008-02-01

A method coupling needle-based derivatization headspace liquid-phase microextraction with gas chromatography-mass spectrometry (HS-LPME/GC-MS) was developed to determine volatile organic acids in tobacco. The mixture of N,O-bis(trimethylsilyl)trifluoroacetamide and decane was utilized as the solvent for HS-LPME, resulting that extraction and derivatization were simultaneously completed in one step. The solvent served two purposes. First, it pre-concentrated volatile organic acids in the headspace of tobacco sample. Second, the volatile organic acids extracted were derivatized to form silyl derivatives in the drop. The main parameters affecting needle-based derivatization HS-LPME procedure such as extraction and derivatization reagent, microdrop volume, extraction and derivatization time, and preheating temperature and preheating time were optimized. The standard addition approach was essential to obtain accurate measurements by minimizing matrix effects. Good linearity (R(2)> or =0.9804) and good repeatability (RSDs< or =15.3%, n=5) for 16 analytes in spiked standard analytes sample were achieved. The method has the additional advantages that at the same time it is simple, fast, effective, sensitive, selective, and provides an overall profile of volatile organic acids in the oriental tobacco. This paper does offer an alternative approach to determine volatile organic acids in tobacco.

Gas flow headspace liquid phase microextraction.

PubMed

Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

2009-11-06

There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

Gas-Purged Headspace Liquid Phase Microextraction System for Determination of Volatile and Semivolatile Analytes

PubMed Central

Zhang, Meihua; Bi, Jinhu; Yang, Cui; Li, Donghao; Piao, Xiangfan

2012-01-01

In order to achieve rapid, automatic, and efficient extraction for trace chemicals from samples, a system of gas-purged headspace liquid phase microextraction (GP-HS-LPME) has been researched and developed based on the original HS-LPME technique. In this system, semiconductor condenser and heater, whose refrigerating and heating temperatures were controlled by microcontroller, were designed to cool the extraction solvent and to heat the sample, respectively. Besides, inert gas, whose gas flow rate was adjusted by mass flow controller, was continuously introduced into and discharged from the system. Under optimized parameters, extraction experiments were performed, respectively, using GP-HS-LPME system and original HS-LPME technique for enriching volatile and semivolatile target compounds from the same kind of sample of 15 PAHs standard mixture. GC-MS analysis results for the two experiments indicated that a higher enrichment factor was obtained from GP-HS-LPME. The enrichment results demonstrate that GP-HS-LPME system is potential in determination of volatile and semivolatile analytes from various kinds of samples. PMID:22448341

Headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE): comparison of the performance in classification of ecstasy tablets. Part 2.

PubMed

Bonadio, Federica; Margot, Pierre; Delémont, Olivier; Esseiva, Pierre

2008-11-20

Headspace solid-phase microextraction (HS-SPME) is assessed as an alternative to liquid-liquid extraction (LLE) currently used for 3,4-methylenedioxymethampethamine (MDMA) profiling. Both methods were compared evaluating their performance in discriminating and classifying samples. For this purpose 62 different seizures were analysed using both extraction techniques followed by gas chromatography-mass spectroscopy (GC-MS). A previously validated method provided data for HS-SPME, whereas LLE data were collected applying a harmonized methodology developed and used in the European project CHAMP. After suitable pre-treatment, similarities between sample pairs were studied using the Pearson correlation. Both methods enable to distinguish between samples coming from the same pre-tabletting batches and samples coming from different pre-tabletting batches. This finding emphasizes the use of HS-SPME as an effective alternative to LLE, with additional advantages such as sample preparation and a solvent-free process.

Characterization of Aronia melanocarpa volatiles by headspace-solid-phase microextraction (HS-SPME), simultaneous distillation/extraction (SDE), and gas chromatography-olfactometry (GC-O) methods.

PubMed

Kraujalytė, Vilma; Leitner, Erich; Venskutonis, Petras Rimantas

2013-05-22

The profiles of volatile constituents of berry fruit of two Aronia melanocarpa genotypes were evaluated by headspace-solid-phase microextraction (HS-SPME), simultaneous distillation and extraction (SDE), and gas chromatography-olfactometry (GC-O). In total, 74 volatile compounds were identified in chokeberry juice, 3-penten-2-one, 3,9-epoxy-p-menth-1-ene, and benzaldehyde being the most abundant constituents; however, their percentage concentrations were remarkably different in the HS-SPME and SDE profiles. Twenty two aroma-active compounds were detected and characterized by the trained panelists in HS-SPME using GC-O detection frequency analysis. Olfactometry revealed that ethyl-2-methyl butanoate, ethyl-3-methyl butanoate, ethyl decanoate ("fruity" aroma notes), nonanal ("green" notes), unidentified compound possessing "moldy" odor, and some other volatiles may be very important constituents in formation of chokeberry aroma of both analyzed plant cultivars.

Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

PubMed

Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

2013-01-01

A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

Solid-phase microextraction for the determination of volatile compounds in the spoilage of raw ground beef.

PubMed

Pérez, Rosa Ana; Rojo, Maria Dolores; González, Gema; De Lorenzo, Cristina

2008-01-01

A method using solid-phase microextraction (SPME) and gas chromatography/mass spectrometry was developed and applied to the determination of volatile compounds generated in meat, at different times, from ground beef stored under refrigeration. Selection of the extractive fiber, extraction time, and headspace (HS) or direct extraction was optimized for the determination of volatile compounds from ground meat. Various fibers were investigated, and carboxen/polydimethylsiloxane was selected for these analyses. The HS analysis of the solid sample by HS-SPME produced a higher volatile signal than did direct-SPME. The meat samples were stored under refrigeration and analyzed after 0, 3, and 6 days of storage. These analyses at different times showed important changes in the volatile profile of the evaluated samples. The ketones 3-hydroxy-2-butanone and 2,3-butanedione, and the alcohol 3-methyl-1-butanol were the most representative compounds generated during the meat storage. In general, compounds associated with a butter off-flavor were detected during the storage of raw ground beef.

Rapid and sensitive analysis of polychlorinated biphenyls and acrylamide in food samples using ionic liquid-based in situ dispersive liquid-liquid microextraction coupled to headspace gas chromatography.

PubMed

Zhang, Cheng; Cagliero, Cecilia; Pierson, Stephen A; Anderson, Jared L

2017-01-20

A simple and rapid ionic liquid (IL)-based in situ dispersive liquid-liquid microextraction (DLLME) method was developed and coupled to headspace gas chromatography (HS-GC) employing electron capture (ECD) and mass spectrometry (MS) detection for the analysis of polychlorinated biphenyls (PCBs) and acrylamide at trace levels from milk and coffee samples. The chemical structures of the halide-based ILs were tailored by introducing various functional groups to the cations to evaluate the effect of different structural features on the extraction efficiency of the target analytes. Extraction parameters including the molar ratio of IL to metathesis reagent and IL mass were optimized. The effects of HS oven temperature and the HS sample vial volume on the analyte response were also evaluated. The optimized in situ DLLME method exhibited good analytical precision, good linearity, and provided detection limits down to the low ppt level for PCBs and the low ppb level for acrylamide in aqueous samples. The matrix-compatibility of the developed method was also established by quantifying acrylamide in brewed coffee samples. This method is much simpler and faster compared to previously reported GC-MS methods using solid-phase microextraction (SPME) for the extraction/preconcentration of PCBs and acrylamide from complex food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct synthesis of nitrogen-doped graphene on platinum wire as a new fiber coating method for the solid-phase microextraction of BXes in water samples: Comparison of headspace and cold-fiber headspace modes.

PubMed

Memarian, Elham; Hosseiny Davarani, Saied Saeed; Nojavan, Saeed; Movahed, Siyavash Kazemi

2016-09-07

In this work, a new solid-phase microextraction fiber was prepared based on nitrogen-doped graphene (N-doped G). Moreover, a new strategy was proposed to solve problems dealt in direct coating of N-doped G. For this purpose, first, Graphene oxide (GO) was coated on Pt wire by electrophoretic deposition method. Then, chemical reduction of coated GO to N-doped G was accomplished by hydrazine and NH3. The prepared fiber showed good mechanical and thermal stabilities. The obtained fiber was used in two different modes (conventional headspace solid-phase microextraction and cold-fiber headspace solid-phase microextraction (CF-HS-SPME)). Both modes were optimized and applied for the extraction of benzene and xylenes from different aqueous samples. All effective parameters including extraction time, salt content, stirring rate, and desorption time were optimized. The optimized CF-HS-SPME combined with GC-FID showed good limit of detections (LODs) (0.3-2.3 μg/L), limit of quantifications (LOQs) (1.0-7.0 μg/L) and linear ranges (1.0-5000 μg/L). The developed method was applied for the analysis of benzene and xylenes in rainwater and some wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of furfural and hydroxymethylfurfural from baby formula using headspace solid phase microextraction based on nanostructured polypyrrole fiber coupled with ion mobility spectrometry.

PubMed

Kamalabadi, Mahdie; Ghaemi, Elham; Mohammadi, Abdorreza; Alizadeh, Naader

2015-08-15

Furfural (Fu) and hydroxymethylfurfural (HMFu) are extracted using a dodecylbenzenesulfonate-doped polypyrrole coating as a fiber for headspace solid phase microextraction (HS-SPME) method in baby formula samples and detected using ion mobility spectrometry (IMS). Sample pH, salt effect, extraction time and temperature were investigated and optimized as effective parameters in HS-SPME. The calibration curves were linear in the range of 20-300 ng g(-1) (R(2)>0.99). Limits of detection for Fu and HMFu were 6 ng g(-1) and 5 ng g(-1), respectively. The RSD% of Fu and HMFu for five analyses was 4.4 and 4.9, respectively. The proposed method was successfully applied to determine of Fu and HMFu in the different baby formula samples with satisfactory result. The results were in agreement with those obtained using HPLC analysis. The HS-SPME-IMS is precise, selective and sensitive analytical method for determination of Fu and HMFu in baby formula samples, without any derivatization process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-microg/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method.

PubMed

Cancho, B; Ventur, F; Galceran, M

2000-11-03

A headspace solid-phase microextraction (HS-SPME) procedure has been developed and applied for the determination of cyanogen halides in treated water samples at microg/L concentrations. Several SPME coatings were tested, the divinylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantitation. Experimental parameters such as sample volume, addition of a salt, extraction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protection Agency Method 551.1) for the analysis of spiked ultrapure and granular activated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spain). Cyanogen chloride in treated water was <1.0 microg/L and cyanogen bromide ranged from 3.2 to 6.4 microg/L.

Characterization of aroma compounds in apple cider using solvent-assisted flavor evaporation and headspace solid-phase microextraction.

PubMed

Xu, Yan; Fan, Wenlai; Qian, Michael C

2007-04-18

The aroma-active compounds in two apple ciders were identified using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (MS) techniques. The volatile compounds were extracted using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). On the basis of odor intensity, the most important aroma compounds in the two apple cider samples were 2-phenylethanol, butanoic acid, octanoic acid, 2-methylbutanoic acid, 2-phenylethyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, 4-ethylguaiacol, eugenol, and 4-vinylphenol. Sulfur-containing compounds, terpene derivatives, and lactones were also detected in ciders. Although most of the aroma compounds were common in both ciders, the aroma intensities were different. Comparison of extraction techniques showed that the SAFE technique had a higher recovery for acids and hydroxy-containing compounds, whereas the HS-SPME technique had a higher recovery for esters and highly volatile compounds.

Determination of different recreational drugs in sweat by headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME GC/MS): Application to drugged drivers.

PubMed

Gentili, Stefano; Mortali, Claudia; Mastrobattista, Luisa; Berretta, Paolo; Zaami, Simona

2016-09-10

A procedure based on headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography/mass spectrometry (GC/MS) has been developed for the determination of most commonly used drugs of abuse in sweat of drivers stopped during roadside controls. DrugWipe 5A sweat screening device was used to collect sweat by a specific pad rubbed gently over forehead skin surface. The procedure involved an acid hydrolysis, a HS-SPME extraction for drugs of abuse but Δ(9)-tetrahydrocannabinol, which was directly extracted in alkaline medium HS-SPME conditions, a GC separation of analytes by a capillary column and MS detection by electron impact ionisation. The method was linear from the limit of quantification (LOQ) to 50ng drug per pad (r(2)≥0.99), with an intra- and inter-assay precision and accuracy always less than 15% and an analytical recovery between 95.1% and 102.8%, depending on the considered analyte. Using the validated method, sweat from 60 apparently intoxicated drivers were found positive to one or more drugs of abuse, showing sweat patches testing as a viable economic and simple alternative to conventional (blood and/or urine) and non conventional (oral fluid) testing of drugs of abuse in drugged drivers. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of ionic liquid in liquid phase microextraction technology.

PubMed

Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

2012-11-01

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-conventional solvents in liquid phase microextraction and aqueous biphasic systems.

PubMed

An, Jiwoo; Trujillo-Rodríguez, María J; Pino, Verónica; Anderson, Jared L

2017-06-02

The development of rapid, convenient, and high throughput sample preparation approaches such as liquid phase microextraction techniques have been continuously developed over the last decade. More recently, significant attention has been given to the replacement of conventional organic solvents used in liquid phase microextraction techniques in order to reduce toxic waste and to improve selectivity and/or extraction efficiency. With these objectives, non-conventional solvents have been explored in liquid phase microextraction and aqueous biphasic systems. The utilized non-conventional solvents include ionic liquids, magnetic ionic liquids, and deep eutectic solvents. They have been widely used as extraction solvents or additives in various liquid phase microextraction modes including dispersive liquid-liquid microextraction, single-drop microextraction, hollow fiber-liquid phase microextraction, as well as in aqueous biphasic systems. This review provides an overview into the use of non-conventional solvents in these microextraction techniques in the past 5 years (2012-2016). Analytical applications of the techniques are also discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Lactones in Wines by Headspace Solid-Phase Microextraction and Gas Chromatography Coupled with Mass Spectrometry

PubMed Central

Pérez-Olivero, S. J.; Pérez-Pont, M. L.; Conde, J. E.; Pérez-Trujillo, J. P.

2014-01-01

Application of headspace solid-phase microextraction (HS-SPME) coupled with high-resolution gas chromatographic (HRGC) analysis was studied for determining lactones in wines. Six different SPME fibers were tested, and the influence of different factors such as temperature and time of desorption, ionic strength, time of extraction, content of sugar, ethanol, tannins and anthocyanins, and pH and influence of SO2 were studied. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of γ-butyrolactone, γ-hexalactone, trans-whiskey lactone, γ-octalactone, cis-whiskey lactone, γ-nonalactone, γ-decalactone, δ-decalactone, and γ-undecalactone in wines. Method reproducibility and repeatability ranged between 0.6 and 5.2% for all compounds. Detection limit for γ-butyrolactone was 0.17 mg/L and a few μg/L for the rest of the compounds. The optimized method has been applied to several wine samples. PMID:24782943

Evaluation of a headspace solid-phase microextraction method for the analysis of ignitable liquids in fire debris.

PubMed

Fettig, Ina; Krüger, Simone; Deubel, Jan H; Werrel, Martin; Raspe, Tina; Piechotta, Christian

2014-05-01

The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions--extraction temperature, incubation and exposure time--were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris. © 2013 American Academy of Forensic Sciences.

Determination of organotin compounds by headspace solid-phase microextraction-gas chromatography-pulsed flame-photometric detection (HS-SPME-GC-PFPD).

PubMed

Bravo, Manuel; Lespes, Gaëtane; De Gregori, Ida; Pinochet, Hugo; Gautier, Martine Potin

2005-12-01

A method based on Headspace solid-phase microextraction (HS-SPME, with a 100 mum PDMS-fiber) in combination with gas-chromatography and pulsed flame-photometric detection (GC-PFPD) has been investigated for simultaneous determination of eight organotin compounds. Monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), and the semi-volatile diphenyltin (DPhT), triphenyltin (TPhT), monooctyltin (MOcT), and dioctyltin (DOcT) were determined after derivatization with sodium tetraethylborate. The conditions used for the extraction and preconcentration step were optimised by experimental design methodology. Tripropyltin (TPrT) and diheptyltin (DHepT) were used as internal standards for quantification of volatile and semi-volatile organotin compounds, respectively. The analytical precision (RSD) for ten successive injections of a standard mixture containing all the organic tin compounds ranged between 2 and 11%. The limits of detection for all the organotin compounds were sub ng (Sn) L(-1) in water and close to ng (Sn) kg(-1) in sediments. The accuracy of the method was evaluated by analysis of two certified reference material (CRM) sediment samples. The HS-SPME-GC-PFPD was then applied to the analysis of three harbour sediment samples. The results showed that headspace SPME is an attractive tool for analysis of organotin compounds in solid environmental matrices.

Application of headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography (GC x GC) for the chemical profiling of volatile oils in complex herbal mixtures.

PubMed

Di, Xin; Shellie, Robert A; Marriott, Philip J; Huie, Carmen W

2004-04-01

The coupling of headspace solid-phase microextraction (HS-SPME) with comprehensive two-dimensional gas chromatography (GC x GC) was shown to be a powerful technique for the rapid sampling and analysis of volatile oils in complex herbal materials. When compared to one-dimensional (1-D) GC, the improved analytical capabilities of GC x GC in terms of increased detection sensitivity and separation power were demonstrated by using HS-SPME/GC x GC for the chemical profiling (fingerprinting) of essential/volatile oils contained in herbal materials of increasing analytical complexity. More than 20 marker compounds belonging to Panax quinquefolius (American ginseng) can be observed within the 2-D contour plots of ginseng itself, a mixture of ginseng and another important herb (P. quinquefolius/Radix angelicae sinensis), as well as a mixture of ginseng and three other herbs (P. quinquefolius /R. angelicae sinensis/R. astragali/R. rehmanniae preparata). Such analytical capabilities should be important towards the authentication and quality control of herbal products, which are receiving increasing attention as alternative medicines worldwide. In particular, the presence of Panax in the herb formulation could be readily identified through its specific peak pattern in the 2-D GC x GC plot.

Determination of cannabinoids in hemp food products by use of headspace solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

Lachenmeier, Dirk W; Kroener, Lars; Musshoff, Frank; Madea, Burkhard

2004-01-01

A fully automated procedure using alkaline hydrolysis and headspace solid-phase microextraction (HS-SPME), followed by on-fiber derivatization and gas chromatographic-mass spectrometric (GC-MS) detection has been developed for determination of cannabinoids in hemp food samples. After addition of a deuterated internal standard, the sample was hydrolyzed with sodium hydroxide and submitted to direct HS-SPME. After absorption of analytes for on-fiber derivatization, the fiber was placed directly into the headspace of a second vial containing N-methyl- N-trimethylsilyltrifluoroacetamide (MSTFA), before GC-MS analysis. Linearity was good for Delta(9)-tetrahydrocannabinol (THC), cannabidiol, and cannabinol; regression coefficients were greater than 0.99. Depending on the characteristics of the matrix the detection limits obtained ranged between 0.01 and 0.17 mg kg(-1) and the precision between 0.4 and 11.8%. In comparison with conventional liquid-liquid extraction this automated HS-SPME-GC-MS procedure is substantially faster. It is easy to perform, solvent-free, and sample quantities are minimal, yet it maintains the same sensitivity and reproducibility. The applicability was demonstrated by analysis of 30 hemp food samples. Cannabinoids were detected in all of the samples and it was possible to differentiate between drug-type and fiber-type Cannabis sativa L. In comparison with other studies relatively low THC concentrations between 0.01 and 15.53 mg kg(-1) were determined.

Simple determination of fluoride in biological samples by headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry.

PubMed

Kwon, Sun-Myung; Shin, Ho-Sang

2015-08-14

A simple and convenient method to detect fluoride in biological samples was developed. This method was based on derivatization with 2-(bromomethyl)naphthalene, headspace solid phase microextraction (HS-SPME) in a vial, and gas chromatography-tandem mass spectrometric detection. The HS-SPME parameters were optimized as follows: selection of CAR/PDMS fiber, 0.5% 2-(bromomethyl)naphthalene, 250 mg/L 15-crown-5-ether as a phase transfer catalyst, extraction and derivatization temperature of 95 °C, heating time of 20 min and pH of 7.0. Under the established conditions, the lowest limits of detection were 9 and 11 μg/L in 1.0 ml of plasma and urine, respectively, and the intra- and inter-day relative standard deviation was less than 7.7% at concentrations of 0.1 and 1.0 mg/L. The calibration curve showed good linearity of plasma and urine with r=0.9990 and r=0.9992, respectively. This method is simple, amenable to automation and environmentally friendly. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid detection of atrazine and metolachlor in farm soils: gas chromatography-mass spectrometry-based analysis using the bubble-in-drop single drop microextraction enrichment method.

PubMed

Williams, D Bradley G; George, Mosotho J; Marjanovic, Ljiljana

2014-08-06

Tracking of metolachlor and atrazine herbicides in agricultural soils, from spraying through to harvest, was conducted using our recently reported "bubble-in-drop single-drop microextraction" method. The method showed good linearity (R(2) = 0.999 and 0.999) in the concentration range of 0.01-1.0 ng/mL with LOD values of 0.01 and 0.02 ng/mL for atrazine and metolachlor, respectively. Sonication methods were poor at releasing these herbicides from the soil matrixes, while hot water extraction readily liberated them, providing an efficient accessible alternative to sonication techniques. Good recoveries of 97% and 105% were shown for atrazine and metolachlor, respectively, from the soil. The spiking protocol was also investigated, resulting in a traceless spiking method. We demonstrate a very sensitive technique by which to assess, for example, the length of residence of pesticides in given soils and thus risk of exposure.

Determination of bisphenol A in thermal printing papers treated by alkaline aqueous solution using the combination of single-drop microextraction and HPLC.

PubMed

Gao, Leihong; Zou, Jing; Liu, Haihong; Zeng, Jingbin; Wang, Yiru; Chen, Xi

2013-04-01

A method for the quantitative determination of bisphenol A in thermal printing paper was developed and validated. Bisphenol A was extracted from the paper samples using 2% NaOH solution, then the extracted analyte was enriched using single-drop microextraction followed by HPLC analysis. Several parameters relating to the single-drop microextraction efficiency including extraction solvent, extraction temperature and time, stirring rate, and pH of donor phase were studied and optimized. Spiked recovery of bisphenol A at 20 and 5 mg/g was found to be 95.8 and 108%, and the method detection limit and method quantification limit was 0.03 and 0.01 mg/g, respectively. Under the optimized conditions, the proposed method was applied to the determination of bisphenol A in seven types of thermal printing paper samples, and the concentration of bisphenol A was found in the range of 0.53-20.9 mg/g. The considerably minimum usage of organic solvents (5 μL 1-octanol) and high enrichment factor (189-197) in the sample preparation are the two highlighted advantages in comparison with previously published works. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stirring-controlled solidified floating solid-liquid drop microextraction as a new solid phase-enhanced liquid-phase microextraction method by exploiting magnetic carbon nanotube-nickel hybrid.

PubMed

Ghazaghi, Mehri; Mousavi, Hassan Zavvar; Shirkhanloo, Hamid; Rashidi, Alimorad

2017-01-25

A specific technique is introduced to overcome limitations of classical solidification of floating organic drop microextraction, such as tedious and time-consuming centrifuge step and using disperser solvent, by facile and efficient participation of solid and liquid phases. In this proposed method of stirring-controlled solidified floating solid-liquid drop microextraction (SC-SF-SLDME), magnetic carbon nanotube-nickel hybrid (MNi-CNT) as a solid part of the extractors are dispersed ultrasonically in sample solution, and the procedure followed by dispersion of liquid phase (1-undecanol) through high-rate stirring and easily recollection of MNi-CNT in organic solvent droplets through hydrophobic force. With the reduction in speed of stirring, one solid-liquid drop is formed on top of the solution. MNi-CNT acts as both extractor and the coalescence helper between organic droplets for a facile recollection. MNi-CNT was prepared by spray pyrolysis of nickel oleate/toluene mixture at 1000 °C. Four tyrosine kinase inhibitors were selected as model analytes and the effecting parameters were investigated. The results confirmed that magnetic nanoadsorbent has an important role in the procedure and complete collection of dispersed solvent is not achieved in the absence of the solid phase. Also, short extraction time exhibited success of the proposed method and effect of dispersed solid/liquid phases. The limits of quantification (LOQs) for imatinib, sunitinib, erlotinib, and nilotinib were determined to be as low as 0.7, 1.7, 0.6, and 1.0 μg L -1 , respectively. The intra-day precisions (RSDs) were lower than 4.5%. Method performance was investigated by determination of mentioned tyrosine kinase inhibitors (TKIs) in human serum and cerebrospinal fluid samples with good recoveries in the range of 93-98%. Copyright © 2016 Elsevier B.V. All rights reserved.

Pattern recognition and genetic algorithms for discrimination of orange juices and reduction of significant components from headspace solid-phase microextraction.

PubMed

Rinaldi, Maurizio; Gindro, Roberto; Barbeni, Massimo; Allegrone, Gianna

2009-01-01

Orange (Citrus sinensis L.) juice comprises a complex mixture of volatile components that are difficult to identify and quantify. Classification and discrimination of the varieties on the basis of the volatile composition could help to guarantee the quality of a juice and to detect possible adulteration of the product. To provide information on the amounts of volatile constituents in fresh-squeezed juices from four orange cultivars and to establish suitable discrimination rules to differentiate orange juices using new chemometric approaches. Fresh juices of four orange cultivars were analysed by headspace solid-phase microextraction (HS-SPME) coupled with GC-MS. Principal component analysis, linear discriminant analysis and heuristic methods, such as neural networks, allowed clustering of the data from HS-SPME analysis while genetic algorithms addressed the problem of data reduction. To check the quality of the results the chemometric techniques were also evaluated on a sample. Thirty volatile compounds were identified by HS-SPME and GC-MS analyses and their relative amounts calculated. Differences in composition of orange juice volatile components were observed. The chosen orange cultivars could be discriminated using neural networks, genetic relocation algorithms and linear discriminant analysis. Genetic algorithms applied to the data were also able to detect the most significant compounds. SPME is a useful technique to investigate orange juice volatile composition and a flexible chemometric approach is able to correctly separate the juices.

Application of headspace and direct immersion solid-phase microextraction in the analysis of organothiophosphates related to the Chemical Weapons Convention from water and complex matrices.

PubMed

Althoff, Marc André; Bertsch, Andreas; Metzulat, Manfred; Klapötke, Thomas M; Karaghiosoff, Konstantin L

2017-11-01

The successful application of headspace (HS) and direct immersion (DI) solid phase microextraction (SPME) for the unambiguous identification and characterization of a series of toxic thiophosphate esters, such as Amiton (I), from aqueous phases and complex matrices (e.g. grass and foliage) has been demonstrated. A Thermo Scientific gas chromatograph (GC) - tandem mass spectrometer (MS/MS) system with a TriPlus RSH® autosampler and a SPME tool was used to investigate the effect of different parameters that influence the extraction efficiency: e.g. pH of the sample matrix and extraction temperature. The developed methods were employed for the detection of several Amiton derivatives (Schedule II of the CWC) that are structurally closely related to each other; some of which are new and have not been reported in literature previously. In addition, a novel DI SPME method from complex matrices for the analysis of organophosphates related to the CWC was developed. The studies clearly show that DI SPME for complex matrices is superior to HS extraction and can potentially be applied to other related compounds controlled under the CWC. Copyright © 2017. Published by Elsevier B.V.

Influence of harvest maturity and fruit logistics on pineapple (Ananas comosus [L.] Merr.) volatiles assessed by headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS).

PubMed

Steingass, Christof B; Grauwet, Tara; Carle, Reinhold

2014-05-01

Profiling of volatiles from pineapple fruits was performed at four ripening stages using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS). In total, 142 volatiles were detected, of which 132 were identified. Multivariate data analysis was carried out to assess the effect of post-harvest storage on volatiles composition of green-ripe sea-freighted pineapple in comparison to air-freighted fruits harvested at full maturity. The latter fruits were characterised by volatiles described as potent odorants in pineapples, such as δ-octalactone, γ-lactones, 1-(E,Z)-3,5-undecatriene and 1,3,5,8-undecatetraene, as well as various methyl esters. In contrast, post-harvest storage of green-ripe sea-freighted fruits resulted in an increased formation of ethyl esters, acetates, acetoxy esters and alcohols, thus allowing the authentication of sea- and air-freighted pineapples, respectively. Particularly, compounds presumably derived from methyl-branched amino acid catabolism were identified in the fruits at later post-harvest stages. In addition, physicochemical traits were determined to characterise the fruit maturity stages. Copyright © 2013 Elsevier Ltd. All rights reserved.

An efficient method for the simultaneous determination of furan, 2-methylfuran and 2-pentylfuran in fruit juices by headspace solid phase microextraction and gas chromatography-flame ionisation detector.

PubMed

Hu, Gaofei; Zhu, Yan; Hernandez, Marta; Koutchma, Tatiana; Shao, Suqin

2016-02-01

A headspace solid phase microextraction (HS-SPME) procedure followed by gas chromatography-flame ionisation detector (GC-FID) analysis was developed and validated for the simultaneous analysis of furan, 2-methylfuran and 2-pentylfuran from juice samples. Extraction at 32 °C for 20 min with stirring at 600 rpm and NaCl concentration 15% (W/V) was the optimal HS-SPME condition for all the three compounds by using a carboxen/polydimethylsiloxane fused silica fibre (75 μm). The extracted compounds were base line separated on a SPB-1 GC column within 12 min. The relative standard deviations of all analytes were less than 6.7%. The recovery rates were between 90.2% and 110.1%. The limits of detection and limits of quantification were 0.056-0.23 ng/mL and 0.14-0.76 ng/mL, respectively. The results showed that the developed method was sensitive, precise, accurate and robust for the determination of furan, 2-methylfuran and 2-pentylfuran in complex matrices without interferences from other components. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Determination of polycyclic aromatic hydrocarbons in urine of coke oven workers by headspace solid phase microextraction and gas chromatography-mass spectrometry.

PubMed

Waidyanatha, Suramya; Zheng, Yuxin; Rappaport, Stephen M

2003-05-06

Polycyclic aromatic hydrocarbons (PAHs) represent a complex mixture of toxic compounds that are ubiquitous in the environment. We investigated the utility of head space-solid phase microextraction (HS-SPME) to measure the following surrogate PAHs in urine: naphthalene (NAP), phenanthrene (PHE), pyrene (PYR), and benzo(a)pyrene (BAP), representing classes of 2-, 3-, 4- and 5-ring compounds, respectively. We then applied the method to urine from 28 coke oven workers (median levels (microg/l) were: NAP=3.65, PHE=1.51, PYR=0.003, BAP not detected) and 22 controls (median (microg/l) NAP=0.859, PHE=0.062, PYR=0.001, BAP not detected). Urinary levels of NAP, PHE, and PYR were all associated with exposure category (controls, side- and bottom-workers, and top-workers) but not with smoking status. Strong correlations were observed between urinary levels of NAP, PHE, and PYR in coke-oven workers. Our results indicate that unmetabolized 2-, 3- and 4-ring PAHs can be measured in urine by HS-SPME. Such measurements can be used to investigate the uptake and metabolism of complex PAH mixtures in humans.

Authentication of pineapple (Ananas comosus [L.] Merr.) fruit maturity stages by quantitative analysis of γ- and δ-lactones using headspace solid-phase microextraction and chirospecific gas chromatography-selected ion monitoring mass spectrometry (HS-SPME-GC-SIM-MS).

PubMed

Steingass, Christof B; Langen, Johannes; Carle, Reinhold; Schmarr, Hans-Georg

2015-02-01

Headspace solid phase microextraction and chirospecific gas chromatography-mass spectrometry in selected ion monitoring mode (HS-SPME-GC-SIM-MS) allowed quantitative determination of δ-lactones (δ-C8, δ-C10) and γ-lactones (γ-C6, γ-C8, γ-C10). A stable isotope dilution assay (SIDA) with d7-γ-decalactone as internal standard was used for quantitative analysis of pineapple lactones that was performed at three progressing post-harvest stages of fully ripe air-freighted and green-ripe sea-freighted fruits, covering the relevant shelf-life of the fruits. Fresh pineapples harvested at full maturity were characterised by γ-C6 of high enantiomeric purity remaining stable during the whole post-harvest period. In contrast, the enantiomeric purity of γ-C6 significantly decreased during post-harvest storage of sea-freighted pineapples. The biogenetical background and the potential of chirospecific analysis of lactones for authentication and quality evaluation of fresh pineapple fruits are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry.

PubMed

Shrivas, Kamlesh; Wu, Hui-Fen

2007-11-02

A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

Drop-to-drop solvent microextraction coupled with gas chromatography/mass spectrometry for rapid determination of trimeprazine in urine and blood of rats: application to pharmacokinetic studies.

PubMed

Agrawal, Kavita; Wu, Hui-Fen

2007-01-01

A simple and rapid method based on drop-to-drop solvent microextraction (DDSME) coupled with gas chromatography/mass spectrometry (GC/MS) has been successfully applied for the pharmacokinetic studies of trimeprazine in 8 microL of urine and blood samples of rats. Several factors that influenced the extraction efficiency of DDSME, such as selection of organic solvent, extraction time, exposure volume of organic phase, addition of salt and pH, were optimized. Linearity was obtained over the concentration ranges of 0.2-10, 0.25-7.0 and 0.5-6.0 microg/mL with correlation coefficients of 0.998, 0.996 and 0.993 in deionized water, urine and blood samples of rats, respectively. The limits of detection (LODs) of trimeprazine were 0.05, 0.06 and 0.1 microg/mL in deionized water, urine and blood samples. The concentrations of trimeprazine obtained in urine and blood samples of rats were 0.21-1.25 and 2.72-0.22 microg/mL, respectively, after a single intravenous administration of this drug. The enrichment factors and LOD values obtained by DDSME coupled to GC/MS were compared with those of hollow fiber liquid-phase microextraction (HF-LPME) combined with GC/MS. We believe that this novel approach can be very useful in clinical application since only one microdrop of biological samples was required to perform the pharmacokinetic studies from rats, so the sample pretreatments for animal experiments can be very easy too. Copyright (c) 2007 John Wiley & Sons, Ltd.

Automated headspace solid-phase dynamic extraction to analyse the volatile fraction of food matrices.

PubMed

Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia; Sgorbini, Barbara

2004-01-23

High concentration capacity headspace techniques (headspace solid-phase microextraction (HS-SPME) and headspace sorptive extraction (HSSE)) are a bridge between static and dynamic headspace, since they give high concentration factors as does dynamic headspace (D-HS), and are as easy to apply and as reproducible as static headspace (S-HS). In 2000, Chromtech (Idstein, Germany) introduced an inside-needle technique for vapour and liquid sampling, solid-phase dynamic extraction (SPDE), also known as "the magic needle". In SPDE, analytes are concentrated on a 50 microm film of polydimethylsiloxane (PDMS) and activated carbon (10%) coated onto the inside wall of the stainless steel needle (5 cm) of a 2.5 ml gas tight syringe. When SPDE is used for headspace sampling (HS-SPDE), a fixed volume of the headspace of the sample under investigation is sucked up an appropriate number of times with the gas tight syringe and an analyte amount suitable for a reliable GC or GC-MS analysis accumulates in the polymer coating the needle wall. This article describes the preliminary results of both a study on the optimisation of sampling parameters conditioning HS-SPDE recovery, through the analysis of a standard mixture of highly volatile compounds (beta-pinene, isoamyl acetate and linalool) and of the HS-SPDE-GC-MS analyses of aromatic plants and food matrices. This study shows that HS-SPDE is a successful technique for HS-sampling with high concentration capability, good repeatability and intermediate precision, also when it is compared to HS-SPME.

Comparison of solidification of floating drop and homogenous liquid-liquid microextractions for the extraction of two plasticizers from the water kept in PET-bottles.

PubMed

Yamini, Yadollah; Ghambarian, Mahnaz; Khalili-Zanjani, Mohammad Reza; Faraji, Mohammad; Shariati, Shahab

2009-09-01

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid-liquid microextraction (HLLE) were compared for the extraction and preconcentration of di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1-undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME-GC-FID and HLLE-GC-FID, were ranged from 0.03 to 0.01 microg/L and 0.02 to 0.01 microg/L, respectively. HLLE provided higher preconcentration factors (472.5- and 551.2-fold) within the shorter extraction time as well as better RSDs (4.5-6.9%). While, in SFDME, high preconcentration factors in the range of 162-198 and good RSDs in the range of 5.2-9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.

The effect of surfactant on headspace single drop microextraction for the determination of some volatile aroma compounds in citronella grass and lemongrass leaves by gas chromatography

USDA-ARS?s Scientific Manuscript database

A rapid method for the determination of some volatile aromatic compounds (VACs), including citronellal, citronellol, neral, geranial, geraniol, and eugenol in citronella grass and lemongrass leaves, was developed using surfactant as a surface tension modifier while performing headspace single drop m...

Coupling of headspace solid phase microextraction with ultrasonic extraction for the determination of chlorinated pesticides in bird livers using gas chromatography.

PubMed

Lambropoulou, Dimitra A; Konstantinou, Ioannis K; Albanis, Triantafyllos A

2006-07-28

In the present study a combined analytical method involving ultrasonic extraction (USE), sulfuric acid clean-up and headspace solid-phase microextraction (HS-SPME) was developed for the determination of chlorinated pesticides (CPs) in bird livers. Extraction of CPs from 1g of liver was performed by ultrasonication for 30 min using 20 mL of solvent mixture (n-hexane:acetone (4:1, v/v)). The extract was subsequently subjected to a clean-up step for lipid removal. A comparative study on several clean-up procedures prior to the HS-SPME enrichment step was performed in order to achieve maximum recovery and optimal clean-up efficiency, which would provide suitable limits of detection in the gas chromatographic analysis. For this purpose, destructive (sulfuric acid or sodium hydroxide treatment) and non-destructive (alumina column) clean-up procedures has been assayed. The treatment of the extract with 40% (v/v) H2SO4 prior to HS-SPME process showed the best performance since lower detection limits and higher extraction efficiencies were obtained. The method detection limit ranged from 0.5 to 1.0 ng g(-1) wet weight and peak areas were proportional to analyte concentrations (r2>0.990) in the range of 5-500 ng g(-1) wet wt. The method was found to be reproducible (R.S.D.<10%) and effective under the operational conditions proposed and was applied successfully to the analysis of CPs in liver tissues of various bird species from Greece.

Comparison of direct, headspace and headspace cold fiber modes in solid phase microextraction of polycyclic aromatic hydrocarbons by a new coating based on poly(3,4-ethylenedioxythiophene)/graphene oxide composite.

PubMed

Banitaba, Mohammad Hossein; Hosseiny Davarani, Saied Saeed; Kazemi Movahed, Siyavash

2014-01-17

A novel nanocomposite coating made of poly(3,4-ethylenedioxythiophene) (PEDOT) and graphene oxide was electrochemically prepared on gold wire. The prepared fiber was applied to the solid-phase microextraction (SPME) and gas chromatographic analysis of six polycyclic aromatic hydrocarbons (PAHs). Three modes of extraction i.e. direct immersion (DI), headspace (HS) and headspace cold fiber (HS-CF) in SPME were investigated. The results were compared under optimized conditions of each mode, considering the effects of the three most important parameters which are extraction temperature, extraction time and ionic strength. The comparison showed that HS-CF-SPME results in the best outcome for the extraction of PAHs from water samples. Under the optimized conditions of this mode, the calibration curves were linear within the range of 0.4-600μgL(-1) and the detection limits were between 0.05 and 0.13μgL(-1). The intra-day and inter-day relative standard deviations obtained at 10μgL(-1) (n=5), using a single fiber, were 4.1-6.8% and 4.8-8.4%, respectively. The fiber-to-fiber repeatabilities (n=4), expressed as the relative standard deviations (RSD%), were between 6.5% and 10.7% at a 10μgL(-1) concentration level. The method was successfully applied to the analysis of PAHs in seawater samples showing recoveries from 85% to 107%. Copyright © 2013 Elsevier B.V. All rights reserved.

Emission pattern of semi-volatile organic compounds from recycled styrenic polymers using headspace solid-phase microextraction gas chromatography-mass spectrometry.

PubMed

Vilaplana, Francisco; Martínez-Sanz, Marta; Ribes-Greus, Amparo; Karlsson, Sigbritt

2010-01-15

The emission of low molecular weight compounds from recycled high-impact polystyrene (HIPS) has been investigated using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Four released target analytes (styrene, benzaldehyde, acetophenone, and 2-phenylpropanal) were selected for the optimisation of the HS-SPME sampling procedure, by analysing operating parameters such as type of SPME fibre (polarity and operating mechanism), particle size, extraction temperature and time. 26 different compounds were identified to be released at different temperatures from recycled HIPS, including residues of polymerisation, oxidated derivates of styrene, and additives. The type of SPME fibre employed in the sampling procedure affected the detection of emitted components. An adsorptive fibre such as carbowax/polydimethylsiloxane (CAR/PDMS fibre) offered good selectivity for both non-polar and polar volatile compounds at lower temperatures; higher temperatures result in interferences from less-volatile released compounds. An absorptive fibre as polydimethylsiloxane (PDMS) fibre is suitable for the detection of less-volatile non-polar molecules at higher temperatures. The nature and relative amount of the emitted compounds increased with higher exposure temperature and smaller polymeric particle size. HS-SPME proves to be a suitable technique for screening the emission of semi-volatile organic compounds (SVOCs) from polymeric materials; reliable quantification of the content of target analytes in recycled HIPS is however difficult due to the complex mass-transfer processes involved, matrix effects, and the difficulties in equilibrating the analytical system. 2009 Elsevier B.V. All rights reserved.

Modified application of HS-SPME for quality evaluation of essential oil plant materials.

PubMed

Dawidowicz, Andrzej L; Szewczyk, Joanna; Dybowski, Michal P

2016-01-01

The main limitation in the standard application of head space analysis employing solid phase microextraction (HS-SPME) for the evaluation of plants as sources of essential oils (EOs) are different quantitative relations of EO components from those obtained by direct analysis of EO which was got in the steam distillation (SD) process from the same plant (EO/SD). The results presented in the paper for thyme, mint, sage, basil, savory, and marjoram prove that the quantitative relations of EO components established by HS-SPME procedure and direct analysis of EO/SD are similar when the plant material in the HS-SPME process is replaced by its suspension in oil of the same physicochemical character as that of SPME fiber coating. The observed differences in the thyme EO composition estimated by both procedures are insignificant (F(exp)

Headspace and direct immersion solid phase microextraction procedures for selenite determination in urine, saliva and milk by gas chromatography mass spectrometry.

PubMed

Kapsimali, D C; Zachariadis, G A

2009-10-01

Two solid phase microextraction modes were investigated and compared for their performance on the determination of selenites in various biological liquids like human urine and saliva and various types of milk. Using sodium tetraethylborate (NaBEt(4)) as ethylating reagent, selenites are converted in situ to volatile diethylselenides (DESe) in aqueous medium. The derivative is collected in situ by solid phase microextraction (SPME) using a silica fiber coated with poly(dimethylsiloxane) (PDMS) either from the headspace (HS-SPME) or directly from the liquid phase (LP-SPME) and finally determined by capillary GC/MS. Under optimum conditions of SPME, the GC separation was also optimized. Between the two examined microextraction techniques, direct immersion of the PDMS fiber in the liquid phase was proved less satisfactory. In contrast, the headspace procedure appears to be more efficient. The quantification of selenites was achieved in SIM mode with good analytical performance. A non-fat milk powder certified reference material was analyzed to evaluate the accuracy of the method. The overall precision of the method was ranged between 6.2% and 9.7%. Detection limits achieved were 0.05microgL(-1) for human urine, 0.08microgL(-1) for saliva and 0.03-0.06microgL(-1) in various milk matrices.

Efficacy of head space solid-phase microextraction coupled to gas chromatography-mass spectrometry method for determination of the trace extracellular hydrocarbons of cyanobacteria.

PubMed

Guan, Wenna; Zhu, Tao; Wang, Yuejie; Zhang, Zhongyi; Jin, Zhao; Wang, Cong; Bai, Fali

2016-09-01

Hydrocarbons are widespread in cyanobacteria, and the biochemical synthetic pathways were recently identified. Intracellular fatty alka(e)nes of cyanobacteria have been detected by liquid-liquid extraction (LLE) coupled to gas chromatography-mass spectrometry (GC/MS). However, whether fatty alka(e)nes can be released to cyanobacterial culture media remains to be clarified. This work develops a sensitive method for analyzing the trace level of extracellular hydrocarbons in cyanobacterial culture media by head space solid-phase microextraction (HS-SPME) coupled to GC/MS. Headspace (HS) extraction mode using polydimethylsiloxane fiber to extract for 30min at 50°C was employed as the optimal extraction conditions. Five cyanobacterial fatty alka(e)nes analogs including pentadecene (C15:1), pentadecane (C15:0), heptadecene (C17:1), heptadecane (C17:0), nonadecane (C19:0) were analyzed, and the data obtained from HS-SPME-GC/MS method were quantified using internal standard peak area comparisons. Limits of detection (LOD), limits of quantitation (LOQ), linear dynamic range, precisions (RSD) and recovery for the analysis of extracellular fatty alka(e)nes of cyanobacteria by HS-SPME-GC/MS were evaluated. The LODs limits of detection (S/N = 3) varied from 10 to 21 ng L-1. The correlation coefficients (r) of the calibration curves ranged from 0.9873 to 0.9977 with a linearity from 0.1 to 50 μg L-1. The RSD values were ranging from 7.8 to 14.0% and from 4.0 to 8.8% at 1.0 μg L-1 and 10.0 μg L-1 standard solutions, respectively. Comparative analysis of extracellular fatty alka(e)nes in the culture media of model cyanobacteria Synechocystis sp. PCC 6803 demonstrated that sensitivity of HS-SPME-GC/MS method was significantly higher than LLE method. Finally, we found that heptadecane can be released into the culture media of Synechocystis sp. PCC 6803 at the later growth period. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of Volatile Components of Cape Gooseberry (Physalis peruviana L.) Grown in Turkey by HS-SPME and GC-MS

PubMed Central

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts. PMID:24741358

Analysis of volatile components of cape gooseberry (Physalis peruviana L.) grown in Turkey by HS-SPME and GC-MS.

PubMed

Yilmaztekin, Murat

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts.

Improvement of a headspace solid phase microextraction-gas chromatography/mass spectrometry method for the analysis of wheat bread volatile compounds.

PubMed

Raffo, Antonio; Carcea, Marina; Castagna, Claudia; Magrì, Andrea

2015-08-07

An improved method based on headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was proposed for the semi-quantitative determination of wheat bread volatile compounds isolated from both whole slice and crust samples. A DVB/CAR/PDMS fibre was used to extract volatiles from the headspace of a bread powdered sample dispersed in a sodium chloride (20%) aqueous solution and kept for 60min at 50°C under controlled stirring. Thirty-nine out of all the extracted volatiles were fully identified, whereas for 95 other volatiles a tentative identification was proposed, to give a complete as possible profile of wheat bread volatile compounds. The use of an array of ten structurally and physicochemically similar internal standards allowed to markedly improve method precision with respect to previous HS-SPME/GC-MS methods for bread volatiles. Good linearity of the method was verified for a selection of volatiles from several chemical groups by calibration with matrix-matched extraction solutions. This simple, rapid, precise and sensitive method could represent a valuable tool to obtain semi-quantitative information when investigating the influence of technological factors on volatiles formation in wheat bread and other bakery products. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of glutaraldehyde in water samples by headspace solid-phase microextraction and gas chromatography-mass spectrometry after derivatization with 2,2,2-trifluoroethylhydrazine.

PubMed

Kang, Hye-In; Shin, Ho-Sang

2016-05-27

A simple and convenient headspace solid-phase microextraction (HS-SPME) gas chromatography mass spectrometry (GC-MS) method was described for the determination of glutaraldehyde in water. Glutaraldehyde in water reacted with 2,2,2-trifluoroethylhydrazine (TFEH) in a headspace vial and the formed TFEH derivatives were vaporized and adsorbed onto a fiber. The optimal HS-SPME conditions were achieved with a 50/30μm-divinylbenzene-carboxen-polydimethylsiloxane fiber, 0.06% 2,2,2-TFEH, 25% salt, an extraction/derivatization temperature of 80°C, a heating time of 30min, and a pH of 6.5. The desorption was performed for 1min at 240°C. Under the established conditions, the lowest limits of detection were 0.3μg/L and 0.1μg/L in 6.0mL of surface water and drinking water, respectively, and the intra- and inter-day relative standard deviation was less than 9.1% at concentrations of 50, 100 and 500μg/L. The calibration curve showed good linearity with R=0.9995 and R=0.9993 in surface water and drinking water, respectively. This method is simple, amenable to automation and environmentally friendly. Copyright © 2016 Elsevier B.V. All rights reserved.

Headspace sorptive solid phase microextraction (HS-SPME) combined with a spectrophotometry system: A simple glass devise for extraction and simultaneous determination of cyanide and thiocyanate in environmental and biological samples.

PubMed

Al-Saidi, H M; Al-Harbi, Sami A; Aljuhani, E H; El-Shahawi, M S

2016-10-01

A simple, low cost and efficient headspace sorptive solid phase microextraction (HS-SPME) method for determination of cyanide has been developed. The system comprises of a glass tube with two valves and a moveable glass slide fixed at its centre. It includes an acceptor phase polyurethane foam treated mercury (II) dithizonate [Hg(HDz)2-PUF] complex fixed inside by a septum cap in a cylindrical configuration (5.0cm length and 1.0cm diameter). The extraction is based upon the contact of the acceptor phase to the headspace and subsequently measuring the absorbance of the recovered mercury (II) dithizonate from PUFs sorbent. Unlike other HSSE, extraction and back - extractions was carried out in a closed system, thereby improving the analytical performance by preventing the analyte loss. Under the optimized conditions, a linear calibration plot in the range of 1.0-50.0µmolL(-1) was achieved with limits of detection (LOD) and quantification (LOQ) of 0.34, 1.2µmolL(-1) CN(-), respectively. Simultaneous analysis of cyanide and thiocyanate in saliva was also performed with satisfactory recoveries. Copyright © 2016. Published by Elsevier B.V.

Development of a Δ9-Tetrahydrocannabinol Amino Acid-Dicarboxylate Prodrug With Improved Ocular Bioavailability

PubMed Central

Adelli, Goutham R.; Bhagav, Prakash; Taskar, Pranjal; Hingorani, Tushar; Pettaway, Sara; Gul, Waseem; ElSohly, Mahmoud A.; Repka, Michael A.; Majumdar, Soumyajit

2017-01-01

Purpose The aim of the present study was to evaluate the utility of the relatively hydrophilic Δ9-tetrahydrocannabinol (THC) prodrugs, mono and di-valine esters (THC-Val and THC-Val-Val) and the amino acid (valine)-dicarboxylic acid (hemisuccinate) ester (THC-Val-HS), with respect to ocular penetration and intraocular pressure (IOP) lowering activity. THC, timolol, and pilocarpine eye drops were used as controls. Methods THC-Val, THC-Val-Val, and THC-Val-HS were synthesized and chemically characterized. Aqueous solubility and in vitro transcorneal permeability of THC and the prodrugs, in the presence of various surfactants and cyclodextrins, were determined. Two formulations were evaluated for therapeutic activity in the α-chymotrypsin induced rabbit glaucoma model, and the results were compared against controls comprising of THC emulsion and marketed timolol maleate and pilocarpine eye drops. Results THC-Val-HS demonstrated markedly improved solubility (96-fold) and in vitro permeability compared to THC. Selected formulations containing THC-Val-HS effectively delivered THC to the anterior segment ocular tissues in the anesthetized rabbits: 62.1 ng/100 μL of aqueous humor (AH) and 51.4 ng/50 mg of iris ciliary bodies (IC) (total THC). The duration and extent of IOP lowering induced by THC-Val-HS was 1 hour longer and 10% greater, respectively, than that obtained with THC and was comparable with the pilocarpine eye drops. Timolol ophthalmic drops, however, exhibited a longer duration of activity. Both THC and THC-Val-HS were detected in the ocular tissues following multiple dosing of THC-Val-HS in conscious animals. The concentration of THC in the iris-ciliary bodies at the 60- and 120-minute time points (53 and 57.4 ng/50 mg) were significantly greater than that of THC-Val-HS (24.2 and 11.3 ng/50 mg). Moreover, at the two time points studied, the concentration of THC was observed to increase or stay relatively constant, whereas THC-Val-HS concentration decreased by at least 50%. A similar trend was observed in the retina-choroid tissues. Conclusions A combination of prodrug derivatization and formulation development approaches significantly improved the penetration of THC into the anterior segment of the eye following topical application. Enhanced ocular penetration resulted in significantly improved IOP-lowering activity. PMID:28399267

High-throughput analysis of bergamot essential oil by fast solid-phase microextraction-capillary gas chromatography-flame ionization detection.

PubMed

Tranchida, Peter Quinto; Presti, Maria Lo; Costa, Rosaria; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

2006-01-20

The advantages of using a narrow-bore column in headspace solid-phase microextraction-gas chromatographic (HS-SPME-GC) analysis are investigated. An automated rapid HS-SPME-GC method for the determination of volatile compounds in a complex sample (bergamot essential oil) was developed. A low-capacity (7 microm) SPME fibre was employed, enabling a short equilibration time (15 min). The absorbed volatile compounds were then separated in 12.5 min on a 10 m x 0.1 mm I.D. capillary. The fast GC method was characterized by relatively moderate GC parameters (head pressure: 173 kPa; temperature program rate: 12 degrees C/min). The employment of the low-capacity fibre also suited the reduced sample capacity of the capillary employed, hence column overloading was avoided. Analytical repeatibility was determined in terms of retention times (maximum RSD: 0.32%) and peak areas (maximum RSD: 9.80%). The results obtained were compared to those derived from a conventional HS-SPME-GC (a 30 microm SPME fibre and 0.25 mm I.D. capillary were used) application on the same sample. In this respect, a great reduction of analytical time was obtained both with regard to the conventional SPME equilibration and GC run times, which both required 50 min. Peak resolution was altogether comparable in both applications. Although a slight loss in terms of sensitivity was observed in the rapid approach (generally within the 25-50% range), this did not impair the detection of all peaks of interest. Finally, the selectivities of the 30 and 7 microm fibres were evaluated and, as expected, these were in good agreement.

Rapid screening of methamphetamines in human serum by headspace solid-phase microextraction using a dodecylsulfate-doped polypyrrole film coupled to ion mobility spectrometry.

PubMed

Alizadeh, Naader; Mohammadi, Abdorreza; Tabrizchi, Mahmoud

2008-03-07

A simple, rapid and highly sensitive method for simultaneous analysis of methamphetamine (MA) and 3,4-methylenedioxy methamphetamine (MDMA) in human serum was developed using the solid-phase microextraction (SPME) combined with ion mobility spectrometry (IMS). A dodecylsulfate-doped polypyrrole (PPy-DS) was applied as a new fiber for SPME. Electrochemically polymerized PPy is formed on the surface of a platinum wire and will contain charge-compensating anion (dodecylsulfate) incorporated during synthesis using cyclic voltammetry (CV) technique. The extraction properties of the fiber to MA and MDMA were examined, using a headspace-SPME (HS-SPME) device and thermal desorption in injection port of IMS. The results show that PPy-DS as a SPME fiber coating is suitable for the successful extraction of these compounds. This method is suitable for the identification and determination of MAs, is not time-consuming, requires small quantities of sample and does not require any derivatization. Parameters like pH, extraction time, ionic strength, and temperature of the sample were studied and optimized to obtain the best extraction results. The HS-SPME-IMS method provided good repeatability (RSDs<7.8 %) for spiked serum samples. The calibration graphs were linear in the range of 20-4000 ng ml(-1) (R(2)>0.99) and detection limits for MDMA and MA were 5 and 8 ng ml(-1), respectively. HS-SPME-IMS of non-spiked serum sample provided a spectrum without any peak from the matrix, supporting an effective sample clean-up. Finally, the proposed method was applied for analysis one of the ecstasy tablet.

Stimulus-dependent Maximum Entropy Models of Neural Population Codes

PubMed Central

Segev, Ronen; Schneidman, Elad

2013-01-01

Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME) model—a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population. PMID:23516339

Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

NASA Astrophysics Data System (ADS)

Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

2012-02-01

The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

Identification of volatiles in leaves of Alpinia zerumbet 'Variegata' using headspace solid-phase microextraction-gas chromatography-mass spectrometry.

PubMed

Chen, Jian Yan; Ye, Zheng Mei; Huang, Tian Yi; Chen, Xiao Dan; Li, Yong Yu; Wu, Shao Hua

2014-07-01

Alpinia zerumbet 'Variegata' is an aromatic medicinal plant, its foliage producing an intense, unique fragrant odor. This study identified 46 volatile compounds in the leaf tissue of this plant using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The major compounds included 1, 8-cineole (43.5%), p-cymene (14.7%), humulene (5.5%), camphor (5.3%), linalool (4.7%), (E)-methyl cinnamate (3.8%), gamma-cadinene (3.3%), humulene oxide II (2.1%) and a-terpineol (1.5%). The majority of the volatiles were terpenoids of which oxygenated monoterpenes were the most abundant, accounting for 57.2% of the total volatiles. Alcohols made up the largest (52.8%) and aldehydes the smallest (0.2%) portions of the volatiles. Many bioactive compounds were present in the volatiles.

The current role of on-line extraction approaches in clinical and forensic toxicology.

PubMed

Mueller, Daniel M

2014-08-01

In today's clinical and forensic toxicological laboratories, automation is of interest because of its ability to optimize processes, to reduce manual workload and handling errors and to minimize exposition to potentially infectious samples. Extraction is usually the most time-consuming step; therefore, automation of this step is reasonable. Currently, from the field of clinical and forensic toxicology, methods using the following on-line extraction techniques have been published: on-line solid-phase extraction, turbulent flow chromatography, solid-phase microextraction, microextraction by packed sorbent, single-drop microextraction and on-line desorption of dried blood spots. Most of these published methods are either single-analyte or multicomponent procedures; methods intended for systematic toxicological analysis are relatively scarce. However, the use of on-line extraction will certainly increase in the near future.

[Comparison analysis of muscle enzymes in children with myocarditis and Duchene/Becker muscular dystrophy].

PubMed

Zhang, Yali; Wang, Hong; Yu, Xuexin; Xing, Yanlin; Wang, Ce; He, Rong

2016-09-28

To compare the changes in muscle enzyme between children with myocarditis and Duchene/Becker muscular dystrophy (DMD/BMD), and to seek the explanations for variation.
 The retrospective analysis for 83 myocarditis children (myocarditis group) and 69 DMD/BMD children (DMD/BMD group), who were collected from Department of Pediatric of Shengjing Hospital affiliated to China Medical University since January 2008 to May 2015, was carried out. At the same time, 24 healthy children from the Department of Pediatric Development served as a control group. The examination indexes included creatine kinase (CK), creatine kinase-isoenzyme MB (CK-MB), creatine kinase isoenzyme MB mass (CK-MB mass), cardiac troponin I (cTnI) and high-sensitive-cTnT (hs-cTnT).
 1) In the myocarditis group, the CK increased from 100 to 1 000 U/L, reached a peak after 5 days, which lasted for a week and then dropped to the normal; the CK-MB reached a peak after 5 to 7 days and dropped to the normal a month later; the CK-MB mass reached a peak on the first day and dropped to the normal after 3 weeks; the cTn reached to a peak after 5 days and dropped to the normal after about 17 days; hs-cTnT reached to a peak on the first day and dropped to the normal after about 19 days. 2) In the DMD/BMD group, the CK increased significantly and 27 cases had a CK value of more than 10 000 U/L. After the treatment for 1 to 2 weeks, their enzyme rose again after a slight drop. In terms of cTnI, 6 cases showed a moderate increase, 5 of them couldn't drop to the normal level until more than 3 weeks later; the hs-cTnT increased in the 45 cases, which lasted for more than 3 weeks in the 31 cases of them and showed a tendency of persisting increase.
 The cTnI and hs-cTnT rise significantly and possess wider observation window than CK and CK-MB mass in myocarditis children, with more sensitive and specific changes. The myocardial damage can occur before myasthenia and keep this trend for a long time in the DMD/BMD children. The trend of cTnI change in myocarditis children is similar to hs-cTnT, while hs-cTnT in DMD/BMD children is more sensitive than cTnI.

Development of a Direct Headspace Collection Method from Arabidopsis Seedlings Using HS-SPME-GC-TOF-MS Analysis

PubMed Central

Kusano, Miyako; Iizuka, Yumiko; Kobayashi, Makoto; Fukushima, Atsushi; Saito, Kazuki

2013-01-01

Plants produce various volatile organic compounds (VOCs), which are thought to be a crucial factor in their interactions with harmful insects, plants and animals. Composition of VOCs may differ when plants are grown under different nutrient conditions, i.e., macronutrient-deficient conditions. However, in plants, relationships between macronutrient assimilation and VOC composition remain unclear. In order to identify the kinds of VOCs that can be emitted when plants are grown under various environmental conditions, we established a conventional method for VOC profiling in Arabidopsis thaliana (Arabidopsis) involving headspace-solid-phase microextraction-gas chromatography-time-of-flight-mass spectrometry (HS-SPME-GC-TOF-MS). We grew Arabidopsis seedlings in an HS vial to directly perform HS analysis. To maximize the analytical performance of VOCs, we optimized the extraction method and the analytical conditions of HP-SPME-GC-TOF-MS. Using the optimized method, we conducted VOC profiling of Arabidopsis seedlings, which were grown under two different nutrition conditions, nutrition-rich and nutrition-deficient conditions. The VOC profiles clearly showed a distinct pattern with respect to each condition. This study suggests that HS-SPME-GC-TOF-MS analysis has immense potential to detect changes in the levels of VOCs in not only Arabidopsis, but other plants grown under various environmental conditions. PMID:24957989

Dispersive liquid-liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

NASA Astrophysics Data System (ADS)

Li, Yong; Peng, Guilong; He, Qiang; Zhu, Hui; Al-Hamadani, Sulala M. Z. F.

2015-04-01

In the present work, a dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97-2.18 ng L-1. The relative standard deviations (RSDs) were 2.62-4.51% (n = 7, C = 20 ng L-1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.

A high area, porous and resistant platinized stainless steel fiber coated by nanostructured polypyrrole for direct HS-SPME of nicotine in biological samples prior to GC-FID quantification.

PubMed

Abdolhosseini, Sana; Ghiasvand, Alireza; Heidari, Nahid

2017-09-01

The surface of a stainless steel fiber was made porous, resistant and cohesive using electrophoretic deposition and coated by the nanostructured polypyrrole using an amended in-situ electropolymerization method. The coated fiber was applied for direct extraction of nicotine in biological samples through a headspace solid-phase microextraction (HS-SPME) method followed by GC-FID determination. The effects of the important experimental variables on the efficiency of the developed HS-SPME-GC-FID method, including pH of sample solution, extraction temperature and time, stirring rate, and ionic strength were evaluated and optimized. Under the optimal experimental conditions, the calibration curve was linear over the range of 0.1-20μgmL -1 and the detection limit was obtained 20ngmL -1 . Relative standard deviation (RSD, n=6) was calculated 7.6%. The results demonstrated the superiority of the proposed fiber compared with the most used commercial types. The proposed HS-SPME-GC-FID method was successfully used for the analysis of nicotine in urine and human plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of 76 micropollutants in water samples by headspace solid phase microextraction and gas chromatography-mass spectrometry.

PubMed

Martínez, C; Ramírez, N; Gómez, V; Pocurull, E; Borrull, F

2013-11-15

This study focuses on the development of an analytical method based on headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 76 micropollutants in water samples. The selected micropollutants include volatile organic compounds (VOCs) (e.g. chlorobenzenes, chloroalkanes), endocrine disrupting compounds (EDCs) (e.g. bisphenol A and tributyl phosphate), odour compounds (e.g. limonene, phenol), fragrance allergens (e.g. geraniol, eugenol) and some pesticides (e.g. heptachlor, terbutryn). The experimental conditions affecting their extraction, such as the type of fibre, temperature and time of extraction, sample volume and ionic strength of the samples were optimized using HS-SPME. The method showed good linear range, reproducibility between days, repeatability and low detection limits (at ng L(-1) levels). The validated method has been applied to determine the target organic micropollutants in aqueous samples from different experimental research units of surface water, sea water, waste water and those effluents of advance membrane treatments. The optimized method showed good performance in the different types of samples studied. The analysis revealed the presence of several micropollutants at concentrations between 20 and 5000 μg L(-1), such as ethylbenzene, o-xylene, p-isopropilbenzene, D-limonene, citral and isoeugenol, due to the fact that these species are commonly used in domestic and industrial applications. © 2013 Elsevier B.V. All rights reserved.

Polypyrrole nanowire as an excellent solid phase microextraction fiber for bisphenol A analysis in food samples followed by ion mobility spectrometry.

PubMed

Kamalabadi, Mahdie; Mohammadi, Abdorreza; Alizadeh, Naader

2016-08-15

A polypyrrole nanowire coated fiber was prepared and used in head-space solid phase microextraction coupled with ion mobility spectrometry (HS-SPME-IMS) to the analysis of bisphenol A (BPA) in canned food samples, for the first time. This fiber was synthesized by electrochemical oxidation of the monomer in aqueous solution. The fiber characterization by scanning electron microscopy (SEM) revealed that the new fiber exhibited two-dimensional structures with a nanowire morphology. The effects of important extraction parameters on the efficiency of HS-SPME were investigated and optimized. Under the optimum conditions, the linearity of 10-150ngg(-1) and limit of detection (based on S/N=3) of 1ngg(-1) were obtained in BPA analysis. The repeatability (n=5) expressed as the relative standard deviation (RSD%) was 5.8%. At the end, the proposed method was successfully applied to determine BPA in various canned food samples (peas, corns, beans). Relative recoveries were obtained 93-96%. Method validation was conducted by comparing our results with those obtained through HPLC with fluorescence detection (FLD). Compatible results indicate that the proposed method can be successfully used in BPA analysis. This method is simple and cheaper than chromatographic methods, with no need of extra organic solvent consumption and derivatization prior to sample introduction. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimisation of a simple and reliable method based on headspace solid-phase microextraction for the determination of volatile phenols in beer.

PubMed

Pizarro, C; Pérez-del-Notario, N; González-Sáiz, J M

2010-09-24

A simple, accurate and sensitive method based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the analysis of 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol and 4-vinylphenol in beer. The effect of the presence of CO2 in the sample on the extraction of analytes was examined. The influence on extraction efficiency of different fibre coatings, of salt addition and stirring was also evaluated. Divinylbenzene/carboxen/polydimethylsiloxane was selected as extraction fibre and was used to evaluate the influence of exposure time, extraction temperature and sample volume/total volume ratio (Vs/Vt) by means of a central composite design (CCD). The optimal conditions identified were 80 degrees C for extraction temperature, 55 min for extraction time and 6 mL of beer (Vs/Vt 0.30). Under optimal conditions, the proposed method showed satisfactory linearity (correlation coefficients between 0.993 and 0.999), precision (between 6.3% and 9.7%) and detection limits (lower than those previously reported for volatile phenols in beers). The method was applied successfully to the analysis of beer samples. To our knowledge, this is the first time that a HS-SPME based method has been developed to determine simultaneously these four volatile phenols in beers. Copyright 2010 Elsevier B.V. All rights reserved.

Assessment of dispersive liquid-liquid microextraction conditions for gas chromatography time-of-flight mass spectrometry identification of organic compounds in honey.

PubMed

Moniruzzaman, M; Rodríguez, I; Rodríguez-Cabo, T; Cela, R; Sulaiman, S A; Gan, S H

2014-11-14

The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrasound-Assisted Emulsification Microextraction Based on Solidification Floating Organic Drop Trace Amounts of Manganese Prior to Graphite Furnace Atomic Absorption Spectrometry Determination

PubMed Central

Mohadesi, Alireza; Falahnejad, Masoumeh

2012-01-01

In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn+2 at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50–10.0 ng mL−1 with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL−1 was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

Solid phase microextraction applied to the analysis of organophosphorus insecticides in fruits.

PubMed

Fytianos, K; Raikos, N; Theodoridis, G; Velinova, Z; Tsoukali, H

2006-12-01

Trace amounts of organophosphorus pesticides (OPs) were determined in various fruits by headspace solid phase microextraction (HS-SPME) and gas chromatography-nitrogen phosphorous detection (GC-NPD). Sampling from the headspace enhanced method selectivity, whereas at the same time improved fiber life time and method sensitivity. Diazinon, parathion, methyl parathion, malathion and fenithrothion were determined in various fruits: more than 150 samples of 21 types of fruits were studied. SPME-GC-NPD provided a useful and very efficient analytical tool: method linearity ranged from 1.2 to 700 ng/ml. Limits of detection (LODs) and quantitation (LOQs) ranged from 0.03 to 3 ng/ml and 0.12 to 10 ng/ml respectively, values well below the residue limits set by the EU. Less than 2% of the samples were found positive containing amounts higher than the EU limits. The effect of fruit peeling and washing was also investigated.

Measurement of the isotope ratio of acetic acid in vinegar by HS-SPME-GC-TC/C-IRMS.

PubMed

Hattori, Ryota; Yamada, Keita; Shibata, Hiroki; Hirano, Satoshi; Tajima, Osamu; Yoshida, Naohiro

2010-06-23

Acetic acid is the main ingredient of vinegar, and the worth of vinegar often depends on the fermentation of raw materials. In this study, we have developed a simple and rapid method for discriminating the fermentation of the raw materials of vinegar by measuring the hydrogen and carbon isotope ratio of acetic acid using head space solid-phase microextraction (HS-SPME) combined with gas chromatography-high temperature conversion or combustion-isotope ratio mass spectrometry (GC-TC/C-IRMS). The measurement of acetic acid in vinegar by this method was possible with repeatabilities (1sigma) of +/-5.0 per thousand for hydrogen and +/-0.4 per thousand for carbon, which are sufficient to discriminate the origin of acetic acid. The fermentation of raw materials of several vinegars was evaluated by this method.

Artemisia umbelliformis Lam. and Génépi Liqueur: Volatile Profile as Diagnostic Marker for Geographic Origin and To Predict Liqueur Safety.

PubMed

Boggia, Lorenzo; Pignata, Giuseppe; Sgorbini, Barbara; Colombo, Maria Laura; Marengo, Arianna; Casale, Manuela; Nicola, Silvana; Bicchi, Carlo; Rubiolo, Patrizia

2017-04-05

Artemisia umbelliformis, commonly known as "white génépi", is characterized by a volatile fraction rich in α- and β-thujones, two monoterpenoids; under European Union (EU) regulations these are limited to 35 mg/L in Artemisia-based beverages because of their recognized activity on the human central nervous system. This study reports the results of an investigation to define the geographical origin and thujone content of individual plants of A. umbelliformis from different geographical sites, cultivated experimentally at a single site, and to predict the thujone content in the resulting liqueurs through their volatile fraction. Headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and non-separative HS-SPME-MS were used as analytical platforms to create a database suitable for chemometric description and prediction through linear discriminant analysis (LDA). HS-SPME-MS was applied to shorten analysis time. With both approaches, a diagnostic prediction of (i) plant geographical origin and (ii) thujone content of plant-related liqueurs could be made.

Determination of ochratoxin A in fruit juice by high-performance liquid chromatography after vortex-assisted emulsification microextraction based on solidification of floating organic drop.

PubMed

Asadi, Mohammad

2018-03-01

A rapid, simple, and green vortex-assisted emulsification microextraction method based on solidification of floating organic drop was developed for the extraction and determination of ochratoxin A (OTA) with high-performance liquid chromatography. Some factors influencing the extraction efficiency of OTA such as the type and volume of extraction solvent, sample pH, salt concentration, vortex time, and sample volume were optimized. Under optimized conditions, the calibration curve exhibited linearity in the range of 50.0-500 ng L -1 with a coefficient of determination higher than 0.999. The limit of detection was 15.0 ng L -1 . The inter- and intra-assays relative standard deviations were in a range of 4.7-8.7%. The accuracy of the developed method was investigated through recovery experiments, and it was successfully used for the quantification of OTA in 40 samples of fruit juice.

Solidified Floating Organic Drop Microextraction for the Detection of Trace Amount of Lead in Various Samples by Electrothermal Atomic Absorption Spectrometry.

PubMed

Aydın Urucu, Oya; Dönmez, Şeyda; Kök Yetimoğlu, Ece

2017-01-01

A novel method was developed for determination of trace amounts of lead in water and food samples. Solidified floating organic drop microextraction was used to preconcentrate the lead ion. After the analyte was complexed with 1-(2-pyridylazo)-2-naphthol, undecanol and acetonitrile were added as extraction and dispersive solvent, respectively. Variables such as pH, volumes of extraction and dispersive solvents, and concentration of chelating agent were optimized. Under the optimum conditions, the detection limit of Pb (II) was determined as 0.042  µ g L -1 with an enrichment factor of 300. The relative standard deviation is <10%. Accuracy of the developed procedure was evaluated by the analysis of certified reference material of human hair (NCS DC 73347) and wastewater (SPS-WW2) with satisfactory results. The developed procedure was then successfully applied to biscuit and water samples for detection of Pb (II) ions.

Ionic liquid-based single-drop microextraction/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene and xylene isomers in waters.

PubMed

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2008-08-01

The direct coupling between ionic liquid-based single-drop microextraction and gas chromatography/mass spectrometry is proposed for the rapid and simple determination of benzene, toluene, ethylbenzene and xylenes isomers (BTEX) in water samples. The extraction procedure exploits not only the high affinity of the selected ionic liquid (1-methyl-3-octyl-imidazolium hexaflourophosphate) to these aromatic compounds but also its special properties like viscosity, low vapour pressure and immiscibility with water. All the variables involved in the extraction process have been studied in depth. The developed method allows the determination of these single-ring compounds in water under the reference concentration level fixed by the international legislation. In this case, limits of detection were in the range 20 ng L(-1) (obtained for benzene) and 91 ng L(-1) (for o-xylene). The repeatability of the proposed method, expressed as RSD (n=5), varied between 3.0% (o-xylene) and 5.2% (toluene).

Reversed-phase single drop microextraction followed by high-performance liquid chromatography with fluorescence detection for the quantification of synthetic phenolic antioxidants in edible oil samples.

PubMed

Farajmand, Bahman; Esteki, Mahnaz; Koohpour, Elham; Salmani, Vahid

2017-04-01

The reversed-phase mode of single drop microextraction has been used as a preparation method for the extraction of some phenolic antioxidants from edible oil samples. Butylated hydroxyl anisole, tert-butylhydroquinone and butylated hydroxytoluene were employed as target compounds for this study. High-performance liquid chromatography followed by fluorescence detection was applied for final determination of target compounds. The most interesting feature of this study is the application of a disposable insulin syringe with some modification for microextraction procedure that efficiently improved the volume and stability of the solvent microdrop. Different parameters such as the type and volume of solvent, sample stirring rate, extraction temperature, and time were investigated and optimized. Analytical performances of the method were evaluated under optimized conditions. Under the optimal conditions, relative standard deviations were between 4.4 and 10.2%. Linear dynamic ranges were 20-10 000 to 2-1000 μg/g (depending on the analytes). Detection limits were 5-670 ng/g. Finally, the proposed method was successfully used for quantification of the antioxidants in some edible oil samples prepared from market. Relative recoveries were achieved from 88 to 111%. The proposed method had a simplicity of operation, low cost, and successful application for real samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous extraction and quantification of lamotrigine, phenobarbital, and phenytoin in human plasma and urine samples using solidified floating organic drop microextraction and high-performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Abbasi, Bijan

2015-07-01

A novel and simple method based on solidified floating organic drop microextraction followed by high-performance liquid chromatography with ultraviolet detection has been developed for simultaneous preconcentration and determination of phenobarbital, lamotrigine, and phenytoin in human plasma and urine samples. Factors affecting microextraction efficiency such as the type and volume of the extraction solvent, sample pH, extraction time, stirring rate, extraction temperature, ionic strength, and sample volume were optimized. Under the optimum conditions (i.e. extraction solvent, 1-undecanol (40 μL); sample pH, 8.0; temperature, 25°C; stirring rate, 500 rpm; sample volume, 7 mL; potassium chloride concentration, 5% and extraction time, 50 min), the limits of detection for phenobarbital, lamotrigine, and phenytoin were 1.0, 0.1, and 0.3 μg/L, respectively. Also, the calibration curves for phenobarbital, lamotrigine, and phenytoin were linear in the concentration range of 2.0-300.0, 0.3-200.0, and 1.0-200.0 μg/L, respectively. The relative standard deviations for six replicate extractions and determinations of phenobarbital, lamotrigine, and phenytoin at 50 μg/L level were less than 4.6%. The method was successfully applied to determine phenobarbital, lamotrigine, and phenytoin in plasma and urine samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An alternative method for irones quantification in iris rhizomes using headspace solid-phase microextraction.

PubMed

Roger, B; Fernandez, X; Jeannot, V; Chahboun, J

2010-01-01

The essential oil obtained from iris rhizomes is one of the most precious raw materials for the perfume industry. Its fragrance is due to irones that are gradually formed by oxidative degradation of iridals during rhizome ageing. The development of an alternative method allowing irone quantification in iris rhizomes using HS-SPME-GC. The development of the method using HS-SPME-GC was achieved using the results obtained from a conventional method, i.e. a solid-liquid extraction (SLE) followed by irone quantification by CG. Among several calibration methods tested, internal calibration gave the best results and was the least sensitive to the matrix effect. The proposed method using HS-SPME-GC is as accurate and reproducible as the conventional one using SLE. These two methods were used to monitor and compare irone concentrations in iris rhizomes that had been stored for 6 months to 9 years. Irone quantification in iris rhizome can be achieved using HS-SPME-GC. This method can thus be used for the quality control of the iris rhizomes. It offers the advantage of combining extraction and analysis with an automated device and thus allows a large number of rhizome batches to be analysed and compared in a limited amount of time. Copyright © 2010 John Wiley & Sons, Ltd.

[Determination of flavor compounds in foxtail millet wine by gas chromatography-mass spectrometry coupled with headspace solid phase microextraction].

PubMed

Liu, Jingke; Zhang, Aixia; Li, Shaohui; Zhao, Wei; Zhang, Yuzong; Xing, Guosheng

2017-11-08

To comprehensively understand flavor compounds and aroma characteristics of foxtail millet wine, extraction conditions were optimized with 85 μm polyacrylate (PA), 100 μm polydimethylsiloxane (PDMS), 75 μm carboxen (CAR)/PDMS and 50/30 μm divinylbenzene (DVB)/CAR/PDMS fibers. The flavor compounds in foxtail millet wine were investigated by gas chromatography-mass spectrometry (GC-MS) coupled with headspace solid phase microextraction (HS-SPME), and the odor characteristics and intensity were analyzed by odor active values (OAVs). The samples of 8 mL were placed in headspace vials with 1.5 g NaCl, then the headspace vials were heated at 60℃ for 40 min. Using HS-SPME with different fibers, a total of 55 flavor compounds were identified from the samples, including alcohols, esters, benzene derivatives, hydrocarbons, acids, aldehydes, ketones, terpenes, phenols and heterocycle compounds. The main flavor compounds were alcohols compounds. According to their OAVs, phenylethyl alcohol, styrene, 1-methyl-naphthalene, 2-methyl-naphthalene, benzaldehyde, benzeneacetaldehyde and 2-methoxy-phenol were established to be odor-active compounds. Phenylethyl alcohol and benzeneacetaldehyde were the most prominent odor-active compounds. PA and PDMS fibers had good extraction effect for polar and nonpolar compounds, respectively. CAR/PDMS and DVB/CAR/PDMS provided a similar compounds profile for moderate polar compounds. This research comprehensively determined flavor compounds of foxtail millet wine, and provided theoretical basis for product development and quality control.

Optimization of headspace solid phase microextraction based on nano-structured ZnO combined with gas chromatography-mass spectrometry for preconcentration and determination of ultra-traces of chlorobenzenes in environmental samples.

PubMed

Ghasemi, Ensieh; Sillanpää, Mika

2014-12-01

In this study, a simple, novel and efficient preconcentration method for the determination of some chlorobenzenes (monochlorobenzene (MCB), three isomeric forms of dichlorobenzene (diCB), 1,3,5-trichlorobenzene (triCB) and hexachlorobenze (hexaCB)) has been developed using a headspace solid phase microextraction (HS-SPME) based on nano-structured ZnO combined with capillary gas chromatography-mass spectrometry (GC-MS). ZnO nanorods have been grown on fused silica fibers using a hydrothermal process. The diameter of ZnO nanorods was in the range of 50-80 nm. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-SPME were stirring rate, desorption time and temperature, ionic strength, extraction time and temperature. For this purpose, a multivariate strategy was applied based on an experimental design using a Plackett-Burman design for screening and a Box-Behnken design for optimizing of the significant factors. The detection limit and relative standard deviation (RSD) (n=5) for the target analytes were in the range of 0.01-0.1 ng L(-1) and 4.3-7.6%, respectively. The developed technique was found to be successfully applicable to preconcentration and determination of the target analytes in environmental water and soil samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination of estrogenic odorant alkylphenols, chlorophenols, and their derivatives in water using online headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

PubMed

Yuan, Su-Fen; Liu, Ze-Hua; Lian, Hai-Xian; Yang, Chuangtao; Lin, Qing; Yin, Hua; Dang, Zhi

2016-10-01

A simple online headspace solid-phase microextraction (HS-SPME) coupled with the gas chromatography-mass spectrometry (GC-MS) method was developed for simultaneous determination of trace amounts of nine estrogenic odorant alkylphenols and chlorophenols and their derivatives in water samples. The extraction conditions of HS-SPME were optimized including fiber selection, extraction temperature, extraction time, and salt concentration. Results showed that divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most appropriate one among the three selected commercial fibers, and the optimal extraction temperature, time, and salt concentration were 70 °C, 30 min, and 0.25 g/mL, respectively. The developed method was validated and showed good linearity (R (2) > 0.989), low limit of detection (LOD, 0.002-0.5 μg/L), and excellent recoveries (76-126 %) with low relative standard deviation (RSD, 0.7-12.9 %). The developed method was finally applied to two surface water samples and some of these target compounds were detected. All these detected compounds were below their odor thresholds, except for 2,4,6-TCAS and 2,4,6-TBAS wherein their concentrations were near their odor thresholds. However, in the two surface water samples, these detected compounds contributed to a certain amount of estrogenicity, which seemed to suggest that more attention should be paid to the issue of estrogenicity rather than to the odor problem.

A comparison study on a sulfonated graphene-polyaniline nanocomposite coated fiber for analysis of nicotine in solid samples through the traditional and vacuum-assisted HS-SPME.

PubMed

Ghiasvand, Alireza; Koonani, Samira; Yazdankhah, Fatemeh; Farhadi, Saeid

2018-02-05

A simple, rapid, and reliable headspace solid-phase microextraction (HS-SPME) procedure, reinforced by applying vacuum in the extraction vial, was developed. It was applied for the extraction of nicotine in solid samples prior to determination by gas chromatography-flame ionization detection (GC-FID). First, the surface of a narrow stainless steel wire was made porous and adhesive by platinization to obtain a durable, higher surface area, and resistant fiber. Then, a thin film of sulfonated graphene/polyaniline (Sulf-G/PANI) nanocomposite was synthesized and simultaneously coated on the platinized fiber using the electrophoretic deposition (EPD) method. It was demonstrated that the extraction efficiency remarkably increased by applying the reduced-pressure condition in the extraction vial. To evaluate the conventional HS-SPME and vacuum-assisted HS-SPME (VA-HS-SPME) platforms, all experimental parameters affecting the extraction efficiency including desorption time and temperature, extraction time and temperature and moisture content of sample matrix were optimized. The highest extraction efficiency was obtained at 60°C, 10min (extraction temperature and time) and 280°C, 2min (desorption condition), for VA-HS-SPME strategy, while for conventional HS-SPME the extraction and desorption conditions found to be 100°C, 30min and 280°C, 2min, respectively. The Sulf-G/PANI coated fiber showed high thermal stability, good chemical/mechanical resistance, and long lifetime. For analysis of nicotine in solid samples using VA-HS-SPME-GC-FID, linear dynamic range (LDR) was 0.01-30μgg -1 (R 2 =0.996), the relative standard deviation (RSD%, n=6), for analyses of 1μgg -1 nicotine was calculated 3.4% and limit of detection (LOD) found to be 0.002μgg -1 . The VA-HS-SPME-GC-FID strategy was successfully carried out for quantitation of nicotine in hair and tobacco real samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of a novel cold activated carbon fiber-solid phase microextraction for analysis of organochlorine pesticides in soil.

PubMed

Chai, Xiaolan; Jia, Jinping; Sun, Tonghua; Wang, Yalin; Liao, Liyan

2007-08-01

A novel and simple analytical procedure using cold activated carbon fiber-solid phase microextraction (CACF-SPME) was applied to determine organochlorine pesticides (OCs) in soil samples. The pesticides in this study consist of alpha -, beta -, gamma -, and delta -hexachlorocyclohexane (HCH). By heating the sample while cooling the fiber, the developed method not only provides better performance in terms of sensitivity, linearity and recovery but also offers shorter adsorption procedure than that of traditional headspace-solid phase microextraction (HS-SPME). The experimental conditions such as the amount of water, adsorption time and adsorption temperature were optimized. Matrix effects were investigated with different types of soils. We concluded that using the standard addition method was required for quantification purposes. The limits of detection obtained using the proposed method range from 0.01 to 0.05 ng/g, and the recoveries for CACF-SPME are in the range of 80.01% to 89.68% with relative standard deviation (RSDs) better than 8.60%. The proposed method was further applied to determine OCs in real agricultural soil. The results are in good agreement with those obtained using traditional ultrasonic extraction. The research demonstrates the suitability of the CACF-SPME for the analysis of OCs in soil.

Simultaneous determination of traces of pyrethroids, organochlorines and other main plant protection agents in agricultural soils by headspace solid-phase microextraction-gas chromatography.

PubMed

Fernandez-Alvarez, Maria; Llompart, Maria; Lamas, J Pablo; Lores, Marta; Garcia-Jares, Carmen; Cela, Rafael; Dagnac, Thierry

2008-04-25

A solvent-free and simple method based on headspace solid-phase microextraction (HS-SPME) was developed in order to determine simultaneously 36 common pesticides and breakdown products (mostly pyrethroids and organochlorine compounds) in soil. The analysis was carried out by gas chromatography with micro-electron-capture detection (GC-microECD). As far as we know, this is the first study about the SPME of pyrethroid insecticides from soil. Factors such as extraction temperature, matrix modification by addition of water, salt addition (% NaCl) and fiber coating were considered in the optimization of the HS-SPME. To this end, a 3 x 2(3-1) fractional factorial design was performed. The results showed that temperature and fiber coating were the most significant variables affecting extraction efficiency. A suitable sensitivity for all investigated compounds was achieved at 100 degrees C by extracting soil samples wetted with 0.5 mL of ultrapure water (0% NaCl) employing a polyacrylate (PA) coating fiber. Using the recommended extraction conditions with GC-microECD, a linear calibration could be achieved over a range of two orders of magnitude for both groups of analytes. Limits of detection (LODS) at the sub-ng g(-1) level were attained and relative standard deviations (RSDs) were found to be lower than 14% for both groups of pesticides. Matrix effects were investigated by the analysis of different soil samples fortified with the target compounds. The method accuracy was assessed and good recovery values (>70%, in most cases) were obtained. The method was also validated with a certified reference material (RTC-CRM818-050), which was quantified using a standard addition protocol. Finally, the proposed HS-SPME-GC-microECD methodology was further applied to the screening of environmental soil samples for the presence of the target pesticides.

Determination of N-vinyl-2-pyrrolidone and N-methyl-2-pyrrolidone in drugs using polypyrrole-based headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection.

PubMed

Mehdinia, Ali; Ghassempour, Alireza; Rafati, Hasan; Heydari, Rouhollah

2007-03-21

A headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection (HS-SPME-GC-NPD) method using polypyrrole (PPy) fibers has been introduced to determine two derivatives of pyrrolidone; N-vinyl-2-pyrrolidone (NVP) and N-methyl-2-pyrrolidone (NMP). Two types of PPy fibers, prepared using organic and aqueous media, were compared in terms of extraction efficiency and thermal stability. It was found that PPy film prepared using organic medium (i.e. acetonitrile) had higher extraction efficiency and more thermal stability compared to the film prepared in aqueous medium. To enhance the sensitivity of HS-SPME, the effects of pH, ionic strength, extraction time, extraction temperature and the headspace volume on the extraction efficiency were optimized. Using the results of this research, high sensitivity and selectivity had been achieved due to the combination of the high extraction efficiency of PPy film prepared in organic medium and the high sensitivity and selectivity of nitrogen-phosphorous detection. Linear range of the analytes was found to be between 1.0 and 1000 microg L(-1) with regression coefficients (R(2)) of 0.998 and 0.997 for NVP and NMP, consequently. Limits of detection (LODs) were 0.074 and 0.081 microg L(-1) for NVP and NMP, respectively. Relative standard deviation (R.S.D.) for five replications of analyses was found to be less than 6.0%. In real samples the mean recoveries were 94.81% and 94.15% for NVP and NMP, respectively. The results demonstrated the suitability of the HS-SPME technique for analyzing NVP and NMP in two different pharmaceutical matrices. In addition, the method was used for simultaneous detection of NVP, 2-pyrrolidone (2-Pyr), gamma-butyrolactone (GBL) and ethanolamine (EA) compounds.

Analysis of fatty acid ethyl esters in hair as possible markers of chronically elevated alcohol consumption by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Pragst, F; Auwaerter, V; Sporkert, F; Spiegel, K

2001-09-15

Fatty acid ethyl esters (FAEE) are products of the nonoxidative ethanol metabolism, which are known to be detectable in blood only about 24h after the last alcohol intake. After deposition in hair they should be suitable long-term markers of chronically elevated alcohol consumption. Therefore, a method for the analysis of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate from hair was developed based on the extraction of the hair sample by a dimethylsulphoxide (DMSO)/n-hexane mixture, separation and evaporation of the n-hexane phase and application of headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography-mass spectrometry (GC-MS) to the extract. For use as internal standards, the corresponding D(5)-ethyl esters were prepared. The HS-SPME/GC-MS measurements were automatically performed using a multi-purpose sampler. The detection limits of the FAEE were between 0.01 and 0.04ng/mg and the reproducibility was between 3.5 and 16%. By application of the method to hair samples of 21 fatalities with known heavy alcohol abuse 0.045-2.4ng/mg ethyl myristate, 0.35-13.5ng/mg ethyl palmitate, 0.25-7.7ng/mg ethyl oleate and 0.05-3.85ng/mg ethyl stearate were measured. For social drinkers (30-60g ethanol per week), the concentrations were about one order of magnitude smaller. For 10 teetotalers negative results or traces of ethyl palmitate were found. It was shown by supplementary investigations in single cases that FAEE are also present in sebum, that there is no strong difference in their concentrations between pubic, chest and scalp hair, and that they are detectable in hair segments after a 2 months period of abstinence. From the results follows that the measurement of FAEE concentrations in hair is a useful way for a retrospective detection of alcohol abuse.

Comparative evaluation of liquid-liquid extraction, solid-phase extraction and solid-phase microextraction for the gas chromatography-mass spectrometry determination of multiclass priority organic contaminants in wastewater.

PubMed

Robles-Molina, José; Gilbert-López, Bienvenida; García-Reyes, Juan F; Molina-Díaz, Antonio

2013-12-15

The European Water Framework Directive (WFD) 2000/60/EC establishes guidelines to control the pollution of surface water by sorting out a list of priority substances that involves a significant risk to or via the aquatic systems. In this article, the analytical performance of three different sample preparation methodologies for the GC-MS/MS determination of multiclass organic contaminants-including priority comprounds from the WFD-in wastewater samples using gas chromatography-mass spectrometry was evaluated. The methodologies tested were: (a) liquid-liquid extraction (LLE) with n-hexane; (b) solid-phase extraction (SPE) with C18 cartridges and elution with ethyl acetate:dichloromethane (1:1 (v/v)), and (c) headspace solid-phase microextraction (HS-SPME) using two different fibers: polyacrylate and polydimethylsiloxane/carboxen/divinilbenzene. Identification and confirmation of the selected 57 compounds included in the study (comprising polycyclic aromatic hydrocarbons (PAHs), pesticides and other contaminants) were accomplished using gas chromatography tandem mass spectrometry (GC-MS/MS) with a triple quadrupole instrument operated in the multiple reaction monitoring (MRM) mode. Three MS/MS transitions were selected for unambiguous confirmation of the target chemicals. The different advantages and pitfalls of each method were discussed. In the case of both LLE and SPE procedures, the method was validated at two different concentration levels (15 and 150 ng L(-1)) obtaining recovery rates in the range 70-120% for most of the target compounds. In terms of analyte coverage, results with HS-SPME were not satisfactory, since 14 of the compounds tested were not properly recovered and the overall performance was worse than the other two methods tested. LLE, SPE and HS-SPME (using polyacrylate fiber) procedures also showed good linearity and precision. Using any of the three methodologies tested, limits of quantitation obtained for most of the detected compounds were in the low nanogram per liter range. © 2013 Elsevier B.V. All rights reserved.

Optimization, validation and application of headspace solid-phase microextraction gas chromatography for the determination of 1-nitro-2-phenylethane and methyleugenol from Aniba canelilla (H.B.K.) Mez essential oil in skin permeation samples.

PubMed

Kreutz, Tainá; Lucca, Letícia G; Loureiro-Paes, Orlando A R; Teixeira, Helder F; Veiga, Valdir F; Limberger, Renata P; Ortega, George G; Koester, Letícia S

2018-06-02

Aniba canelilla (H.B.K.) Mez is an aromatic plant from the Amazon region whose essential oil has 1-nitro-2-phenylethane (NP) and methyleugenol (ME) as major compounds. Despite of the scientifically proven antifungal and anti-inflammatory activities for these compounds, there is no report up to date about the topical permeation or quantification of NP and ME on skin samples. The aim of this study was the validation of an optimized bioanalytical method by solid-phase microextraction in headspace mode in gas chromatograph with flame ionization detector (HS-SPME-GC-FID) for the determination of NP and ME from the oil in different samples from permeation study, such as porcine ear skin (PES) layers (stratum corneum, epidermis and dermis) and receptor fluid (RF). For this propose polydimethylsiloxane fibers (100 μm) were used and HS-SPME extraction condition consisted of 53 °C, 21 min, and 5% w.v -1 NaCl addition. The wide range of the calibration curve (2.08-207.87 μg mL -1 for NP and 0.40-40.41 μg mL -1 for ME), the presence of matrix interferences and the intrinsic characteristics of HS-SPME required a data linearization using Log 10 . Thereby, data and the gained results presented homoscedasticity, normalization of residues and adequate linearity (r 2  > 0.99) and accuracy for both compounds. In order to verify the applicability of the validated method, the HS-SPME-GC-FID procedure was performed to determine the amount of NP and ME permeated and retained in samples after Franz diffusion cell study from different dosages (20, 100 and 200 μL) of A. canelilla oil. Compounds permeation showed a progressive increase and penetration dependence based on the dosage applied. Furthermore, retention was in order receptor fluid > dermis > epidermis > stratum corneum for both compounds, suggesting NP and ME could penetrate deep tissue, probably due to the partition coefficient, mass, size, and solubility of these compounds. In conclusion, the proposed method by HS-SPME-GC-FID to quantify 1-nitro-2-phenylethane and methyleugenol from Aniba canelilla essential oil was able to determine selectively, precisely and accurately these main compounds in skin permeation samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Optimization of HS-SPME/GC-MS analysis and its use in the profiling of illicit ecstasy tablets (Part 1).

PubMed

Bonadio, Federica; Margot, Pierre; Delémont, Olivier; Esseiva, Pierre

2009-05-30

A headspace solid-phase microextraction procedure (HS-SPME) was developed for the profiling of traces present in 3,4-methylenedioxymethylampethamine (MDMA). Traces were first extracted using HS-SPME and then analyzed by gas chromatography-mass spectroscopy (GC-MS). The HS-SPME conditions were optimized using varying conditions. Optimal results were obtained when 40 mg of crushed MDMA sample was heated at 80 degrees C for 15 min, followed by extraction at 80 degrees C for 15 min with a polydimethylsiloxane/divinylbenzene coated fibre. A total of 31 compounds were identified as traces related to MDMA synthesis, namely precursors, intermediates or by-products. In addition some fatty acids used as tabletting materials and caffeine used as adulterant, were also detected. The use of a restricted set of 10 target compounds was also proposed for developing a screening tool for clustering samples having close profile. 114 seizures were analyzed using an SPME auto-sampler (MultiPurpose Samples MPS2), purchased from Gerstel GMBH & Co. (Germany), and coupled to GC-MS. The data was handled using various pre-treatment methods, followed by the study of similarities between sample pairs based on the Pearson correlation. The results show that HS-SPME, coupled with the suitable statistical method is a powerful tool for distinguishing specimens coming from the same seizure and specimens coming from different seizures. This information can be used by law enforcement personnel to visualize the ecstasy distribution network as well as the clandestine tablet manufacturing.

Comparison of the atmospheric- and reduced-pressure HS-SPME strategies for analysis of residual solvents in commercial antibiotics using a steel fiber coated with a multiwalled carbon nanotube/polyaniline nanocomposite.

PubMed

Ghiasvand, Ali Reza; Nouriasl, Kolsoum; Yazdankhah, Fatemeh

2018-01-01

A low-cost, sensitive and reliable reduced-pressure headspace solid-phase microextraction (HS-SPME) setup was developed and evaluated for direct extraction of residual solvents in commercial antibiotics, followed by determination by gas chromatography with flame ionization detection (GC-FID). A stainless steel narrow wire was made porous and adhesive by platinization by a modified electrophoretic deposition method and coated with a polyaniline/multiwalled carbon nanotube nanocomposite. All experimental variables affecting the extraction efficiency were investigated for both atmospheric-pressure and reduced-pressure conditions. Comparison of the optimal experimental conditions and the results demonstrated that the reduced-pressure strategy leads to a remarkable increase in the extraction efficiency and reduction of the extraction time and temperature (10 min, 25 °Ϲ vs 20 min, 40 °Ϲ). Additionally, the reduced-pressure strategy showed better analytical performances compared with those obtained by the conventional HS-SPME-GC-FID method. Limit of detections, linear dynamic ranges, and relative standard deviations of the reduced-pressure HS-SPME procedure for benzene, toluene, ethylbenzene, and xylene (BTEX) in injectable solid drugs were obtained over the ranges of 20-100 pg g -1 , 0.02-40 μg g -1 , and 2.8-10.2%, respectively. The procedure developed was successful for the analysis of BTEX in commercial containers of penicillin, ampicillin, ceftriaxone, and cefazolin. Graphical abstract Schematic representation of the developed RP-HS-SPME setup.

Differentiation of Commercial PDO Wines Produced in Istria (Croatia) According to Variety and Harvest Year Based on HS-SPME-GC/MS Volatile Aroma Compound Profiling.

PubMed

Lukić, Igor; Horvat, Ivana

2017-03-01

To differentiate monovarietal wines made from native and introduced varieties in Istria (Croatia), samples of Malvazija istarska, Chardonnay and Muscat yellow from two harvest years (2013 and 2014) were subjected to headspace solid-phase microextraction and gas chromatographic/mass spectrometric analysis (HS-SPME-GC/MS) of volatile aroma compounds. Significant effects of variety and harvest year were determined, but their interaction complicated the differentiation. Particular compounds were consistent as markers of variety in both years: nerol for Malvazija, ethyl cinnamate and a tentatively identified isomer of dimethylbenzaldehyde for Chardonnay, and terpenes for Muscat yellow. Wines from 2013 contained higher concentrations of the majority of important volatiles. A 100% correct differentiation of Malvazija istarska and Chardonnay wines according to both variety and harvest year was achieved by stepwise linear discriminant analysis.

[Analyze on volatile compounds of Antrodia camphorata using HS-SPME-GC-MS].

PubMed

He, Zhe; Lu, Zhen-Ming; Xu, Hong-Yu; Shi, Jing-Song; Xu, Zheng-Hong

2011-11-01

To analyze the volatile compounds of Antrodia camphorata in solid-state and submerged cultures. A headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry(GC-MS) were used to evaluate the profile of the volatile compounds. 49 volatile compounds were identified in A. camphorata mycelia in submerged culture, while 43 volatile compounds were identified in mycelia in solid-state culture. 1-octen-3-ol, 3-octanone, 1-octen-3-ylacetate, acetic acid octyl ester and ethanol were the main volatile compounds in A. camphorata mycelia in submerged culture, while 1-octen-3-ol, 3-octanone, 3-methyl-butyraldenhyde, gamma-podecalactone and methyl 2-furozte were the most potent key volatile compounds in mycelia in solid-state culture. The volatile compounds in the mycelia of A. camphorata in solid-state and submerged cultures are similar but their relative contents are different.

Optimization of headspace solid-phase microextraction by means of an experimental design for the determination of methyl tert.-butyl ether in water by gas chromatography-flame ionization detection.

PubMed

Dron, Julien; Garcia, Rosa; Millán, Esmeralda

2002-07-19

A procedure for determination of methyl tert.-butyl ether (MTBE) in water by headspace solid-phase microextraction (HS-SPME) has been developed. The analysis was carried out by gas chromatography with flame ionization detection. The extraction procedure, using a 65-microm poly(dimethylsiloxane)-divinylbenzene SPME fiber, was optimized following experimental design. A fractional factorial design for screening and a central composite design for optimizing the significant variables were applied. Extraction temperature and sodium chloride concentration were significant variables, and 20 degrees C and 300 g/l were, respectively chosen for the best extraction response. With these conditions, an extraction time of 5 min was sufficient to extract MTBE. The calibration linear range for MTBE was 5-500 microg/l and the detection limit 0.45 microg/l. The relative standard deviation, for seven replicates of 250 microg/l MTBE in water, was 6.3%.

Analysis of potassium formate in airport storm water runoff by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

Fries, Elke; Klasmeier, Jörg

2009-01-30

Potassium formate was extracted from airport storm water runoff by headspace solid-phase microextraction (HS-SPME) and analyzed by GC-MS. Formate was transformed to formic acid by adding phosphoric acid. Subsequently, formic acid was derivatized to methyl formate by adding methanol. Using sodium [(2)H]formate (formate-d) as an internal standard, the relative standard deviation of the peak area ratio of formate (m/z 60) and formate-d (m/z 61) was 0.6% at a concentration of 208.5 mg L(-1). Calibration was linear in the range of 0.5-208.5 mg L(-1). The detection limit calculated considering the blank value was 0.176 mg L(-1). The mean concentration of potassium formate in airport storm water runoff collected after surface de-icing operations was 86.9 mg L(-1) (n=11) with concentrations ranging from 15.1 mg L(-1) to 228.6 mg L(-1).

Application of Microextraction Techniques Including SPME and MESI to the Thermal Degradation of Polymers: A Review.

PubMed

Kaykhaii, Massoud; Linford, Matthew R

2017-03-04

Here, we discuss the newly developed micro and solventless sample preparation techniques SPME (Solid Phase Microextraction) and MESI (Membrane Extraction with a Sorbent Interface) as applied to the qualitative and quantitative analysis of thermal oxidative degradation products of polymers and their stabilizers. The coupling of these systems to analytical instruments is also described. Our comprehensive literature search revealed that there is no previously published review article on this topic. It is shown that these extraction techniques are valuable sample preparation tools for identifying complex series of degradation products in polymers. In general, the number of products identified by traditional headspace (HS-GC-MS) is much lower than with SPME-GC-MS. MESI is particularly well suited for the detection of non-polar compounds, therefore number of products identified by this technique is not also to the same degree of SPME. Its main advantage, however, is its ability of (semi-) continuous monitoring, but it is more expensive and not yet commercialized.

Determination of roasted pistachio (Pistacia vera L.) key odorants by headspace solid-phase microextraction and gas chromatography-olfactometry.

PubMed

Aceña, Laura; Vera, Luciano; Guasch, Josep; Busto, Olga; Mestres, Montserrat

2011-03-23

Key odorants in roasted pistachio nuts have been determined for the first time. Two different pistachio varieties (Fandooghi and Kerman) have been analyzed by means of headspace solid-phase microextraction (HS-SPME) and gas chromatography-olfactometry (GCO). The aroma extract dilution analyses (AEDA) applied have revealed 46 and 41 odor-active regions with a flavor dilution (FD) factor≥64 for the Fandooghi and the Kerman varieties, respectively, and 39 of them were related to precisely identified compounds. These included esters, pyrazines, aldehydes, acids, furans, and phenols. The results show that the Fandooghi variety presents, not only more odor-active regions but also higher FD factors than the Kerman variety that can lead to the conclusion that the first variety has a richer aromatic profile than the second one. The descriptive sensory analysis (DSA) showed that the roasted, chocolate/coffee, and nutty attributes were rated significantly higher in the Fandooghi variety, whereas the green attribute was significantly higher in the Kerman one.

Quantitative analysis of 2-furfural and 5-methylfurfural in different Italian vinegars by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry using isotope dilution.

PubMed

Giordano, Lucia; Calabrese, Roberto; Davoli, Enrico; Rotilio, Domenico

2003-10-31

A new method was developed for the determination of 2-furfural (2-F) and 5-methylfurfural (5-MF), two products of Maillard reaction in vinegar, with head-space solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). A divinylbenzene (DVB)/carboxen (CAR)/polydimethylsiloxane (PDMS) fibre was used and SPME conditions were optimised, studying ionic strength effect, temperature effect and adsorption time. Both analytes were determined by calibration established on 2-furfural-d4 (2-F-d4). The method showed good linearity in the range studied (from 16 to 0.12 mg/l), with a regression coefficient r2 of 0.9999. Inter-batch precision and accuracy were found between 14.9 and 6.0% and between -11.7 and 0.2%, respectively. Detection limit was 15 microg/l. The method is simple and accurate and it has been applied to a series of balsamic and non-balsamic vinegars.

Furanic compounds and furfural in different coffee products by headspace liquid-phase micro-extraction followed by gas chromatography-mass spectrometry: survey and effect of brewing procedures.

PubMed

Chaichi, Maryam; Ghasemzadeh-Mohammadi, Vahid; Hashemi, Maryam; Mohammadi, Abdorreza

2015-01-01

In this study, the levels of furan, 2-methylfuran, 2,5-dimethylfuran, vinyl furan, 2-methoxymethyl-furan and furfural in different coffee products were evaluated. Simultaneous determination of these six furanic compounds was performed by a head space liquid-phase micro-extraction (HS-LPME) method. A total of 67 coffee powder samples were analysed. The effects of boiling and espresso-making procedures on the levels of furanic compounds were investigated. The results showed that different types of coffee samples contained different concentrations of furanic compounds, due to the various processing conditions such as temperature, degree of roasting and fineness of grind. Among the different coffee samples, the highest level of furan (6320 µg kg⁻¹) was detected in ground coffee, while coffee-mix samples showed the lowest furan concentration (10 µg kg⁻¹). Levels in brewed coffees indicated that, except for furfural, brewing by an espresso machine caused significant loss of furanic compounds.

Global volatile profile of virgin olive oils flavoured by aromatic/medicinal plants.

PubMed

Perestrelo, R; Silva, C; Silva, P; Câmara, J S

2017-07-15

The global volatile profile of commercial virgin olive oils and flavoured olive oils with aromatic/medicinal plants, was established using liquid-liquid microextraction (LLME) and headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS). More than 60 volatile organic compounds (VOCs belonging to different groups were identified using both methods. Olive oils volatile profile was slightly influenced by maceration process, which occurred at room temperature (20±2°C) for 15days. The predominant differences were observed in terpenoids group, since some of them were only identified in the flavoured olive oils, while others showed an increase with the maceration process. VOCs mass transfer from plants to olive oils could explain the observed results. Principal components analysis (PCA) applied to LLME/GC-qMS data allowed to distinguish the olive oils. The flavoured oils would increase the use of olive oil among consumers as consequence of the improvement of its aromatic profile and healthy properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous extraction and determination of albendazole and triclabendazole by a novel syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop combined with high performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

2016-08-17

A syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop was introduced and used for the simultaneous extraction of trace amounts of albendazole and triclabendazole from different matrices. The extracted analytes were determined by high performance liquid chromatography along with fluorescence detection. The analytical parameters affecting the microextraction efficiency including the nature and volume of the extraction solvent, sample volume, sample pH, ionic strength and the cycles of extraction were optimized. The calibration curves were linear in the range of 0.1-30.0 μg L(-1) and 0.2-30.0 μg L(-1) with determination coefficients of 0.9999 and 0.9998 for albendazole and triclabendazole respectively. The detection limits defined as three folds of the signal to noise ratio were found to be 0.02 μg L(-1) for albendazole and 0.06 μg L(-1) for triclabendazole. The inter-day and intra-day precision (RSD%) for both analytes at three concentration levels (0.5, 2.0 and 10.0 μg L(-1)) were in the range of 6.3-10.1% and 5.0-7.5% respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, cow milk, honey, and urine samples. Copyright © 2016. Published by Elsevier B.V.

A hollow sphere soft lithography approach for long-term hanging drop methods.

PubMed

Lee, Won Gu; Ortmann, Daniel; Hancock, Matthew J; Bae, Hojae; Khademhosseini, Ali

2010-04-01

In conventional hanging drop (HD) methods, embryonic stem cell aggregates or embryoid bodies (EBs) are often maintained in small inverted droplets. Gravity limits the volumes of these droplets to less than 50 microL, and hence such cell cultures can only be sustained for a few days without frequent media changes. Here we present a new approach to performing long-term HD methods (10-15 days) that can provide larger media reservoirs in a HD format to maintain more consistent culture media conditions. To implement this approach, we fabricated hollow sphere (HS) structures by injecting liquid drops into noncured poly(dimethylsiloxane) mixtures. These structures served as cell culture chambers with large media volumes (500 microL in each sphere) where EBs could grow without media depletion. The results showed that the sizes of the EBs cultured in the HS structures in a long-term HD format were approximately twice those of conventional HD methods after 10 days in culture. Further, HS cultures showed multilineage differentiation, similar to EBs cultured in the HD method. Due to its ease of fabrication and enhanced features, this approach may be of potential benefit as a stem cell culture method for regenerative medicine.

A Hollow Sphere Soft Lithography Approach for Long-Term Hanging Drop Methods

PubMed Central

Lee, Won Gu; Ortmann, Daniel; Hancock, Matthew J.; Bae, Hojae

2010-01-01

In conventional hanging drop (HD) methods, embryonic stem cell aggregates or embryoid bodies (EBs) are often maintained in small inverted droplets. Gravity limits the volumes of these droplets to less than 50 μL, and hence such cell cultures can only be sustained for a few days without frequent media changes. Here we present a new approach to performing long-term HD methods (10–15 days) that can provide larger media reservoirs in a HD format to maintain more consistent culture media conditions. To implement this approach, we fabricated hollow sphere (HS) structures by injecting liquid drops into noncured poly(dimethylsiloxane) mixtures. These structures served as cell culture chambers with large media volumes (500 μL in each sphere) where EBs could grow without media depletion. The results showed that the sizes of the EBs cultured in the HS structures in a long-term HD format were approximately twice those of conventional HD methods after 10 days in culture. Further, HS cultures showed multilineage differentiation, similar to EBs cultured in the HD method. Due to its ease of fabrication and enhanced features, this approach may be of potential benefit as a stem cell culture method for regenerative medicine. PMID:19505251

Analysis of volatile secondary metabolites from Colombian Xylopia aromatica (Lamarck) by different extraction and headspace methods and gas chromatography.

PubMed

Stashenko, Elena E; Jaramillo, Beatriz E; Martínez, Jairo René

2004-01-30

Hydrodistillation (HD), simultaneous distillation-solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE), were employed to isolate volatile secondary metabolites from Colombian Xylopia aromatica (Lamarck) fruits. Static headspace (S-HS), simultaneous purge and trap (P&T) in solvent (CH2Cl2), and headspace (HS) solid-phase microextraction (SPME) were utilised to obtain volatile fractions from fruits of X. aromatica trees, which grow wild in Central and South America, and are abundant in Colombia. Kováts indices, mass spectra or standard compounds, were used to identify more than 50 individual components in the various volatile fractions. beta-Phellandrene was the main component found in the HD and MWHD essential oils, SDE and SFE extracts (61, 65, 57, and ca. 40%, respectively), followed by beta-myrcene (9.1, 9.3, 8.2 and 5.1%), and alpha-pinene (8.1, 7.3, 8.1 and 5.9%). The main components present in the volatile fractions of the X. aromatica fruits, isolated by S-HS, P&T and HS-SPME were beta-phellandrene (53.8, 35.7 and 39%), beta-myrcene (13.3, 12.3 and 10.1%), p-mentha-1(7),8-diene (7.1, 10.6 and 10.4%), alpha-phellandrene (2.2, 5.0 and 6.4%), and p-cymene (2.2,4.7 and 4.4%), respectively.

Sensitive determination of cadmium using solidified floating organic drop microextraction-slotted quartz tube-flame atomic absorption spectroscopy.

PubMed

Akkaya, Erhan; Chormey, Dotse Selali; Bakırdere, Sezgin

2017-09-20

In this study, solidified floating organic drop microextraction (SFODME) by 1-undecanol was combined with slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) for the determination of cadmium at trace levels. Formation of a complex with 4,4'-dimethyl-2,2'-bipyridine facilitated the extraction of cadmium from aqueous solutions. Several chemical variables were optimized in order to obtain high extraction outputs. Parameters such as concentration of the ligand, pH, and amount of buffer solution were optimized to enhance the formation of cadmium complex. The SFODME method was assisted by dispersion of extractor solvent into aqueous solutions using 2-propanol. Under the optimum extraction and instrumental conditions, the limit of detection and limit of quantitation values obtained for cadmium using the combined methods (SFODME-SQT-FAAS) were found to be 0.4 and 1.3 μg L -1 , respectively. Matrix effects on the method were also examined for tap water and wastewater, and spiked recovery results were found to be very satisfactory. Graphical Abstract SFODME-SQT-FAAS system for sensitive determination of cadmium.

Preconcentration of valsartan by dispersive liquid-liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design.

PubMed

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayesteh; Talebianpoor, Mohammad Sharif; Khodadoust, Saeid

2016-05-01

In this work, a fast, easy, and efficient dispersive liquid-liquid microextraction method based on solidification of floating organic drop followed by high-performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1-dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min(-1) . The linear response (r(2) = 0.997) was obtained in the range of 0.013-10.0 μg mL(-1) with a limit of detection of 4.0 ng mL(-1) and relative standard deviations of less than 5.0 % (n = 6). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HS-SPME determination of volatile carbonyl and carboxylic compounds in different matrices.

PubMed

Stashenko, Elena E; Mora, Amanda L; Cervantes, Martha E; Martínez, Jairo R

2006-07-01

Specific chromatographic methodologies are developed for the analysis of carboxylic acids (C(2)-C(6), benzoic) and aldehydes (C(2)-C(10)) of low molecular weight in diverse matrices, such as air, automotive exhaust gases, human breath, and aqueous matrices. For carboxylic acids, the method is based on their reaction with pentafluorobenzyl bromide in aqueous solution, followed by the separation and identification of the resultant pentafluorobenzyl esters by means of headspace (HS)-solid-phase microextraction (SPME) combined with gas chromatography (GC) and electron capture detection (ECD). Detection limits in the microg/m(3) range are reached, with relative standard deviation (RSD) less than 10% and linear response (R(2) > 0.99) over two orders of magnitude. The analytical methodology for aldehydes is based on SPME with simultaneous derivatization of the analytes on the fiber, by reaction with pentafluorophenylhydrazine. The derivatization reagent is previously deposited on the SPME fiber, which is then exposed to the gaseous matrix or the HS of the sample solution. The pentafluorophenyl hydrazones formed on the fiber are analyzed selectively by means of GC-ECD, with detection limits in the ng/m(3) range, RSD less than 10%, and linear response (R(2) > 0.99) over two orders of magnitude.

Ionic Liquid-Mediated Multi-Walled Carbon Nanotube-Polydimethylsiloxane Fiber for Headspace Solid-Phase Microextraction of Phenolic Compounds in Aqueous Samples by Gas Chromatography Coupled to Flame Ionization Detector.

PubMed

Sadri, Minoo; Vatani, Hossein

2017-02-01

An ionic liquid-mediated multi-walled carbon nanotube (MWCNT)-polydimethylsiloxane (PDMS) sorbent was developed for headspace solid-phase microextraction (HS-SPME) of phenolic compounds from human urine samples. Sol-gel method was used to prepare this sorbent. For this purpose, MWCNTs were functionalized covalently and were attached chemically to the hydroxyl-terminated PDMS. Prepared fiber showed high thermal stability (over than 320°C) and good lifespan (>210 times). These good performances can be attributed to the performance of carbon nanotubes and sol-gel method. Affecting parameters on the efficiency of HS-SPME were investigated and optimized. Under the optimal conditions, linear dynamic ranges were observed over a range of 0.002-200 ng mL -1 with limits of detection from 0.0005 to 0.005 ng mL -1 and limits of quantitation between 0.002 and 0.02 ng mL -1 The relative standard deviations for one fiber (repeatability) (n = 5) at three different concentrations (0.05, 2 and 100 ng mL -1 ) were obtained from 4.6 up to 6.7% and between fibers or batch to batch (n = 3) (reproducibility) in the range of 5.7-7.8%. Urine samples were used as real samples. All real samples were spiked at 0.5 ng mL -1 of understudy analytes and the relative recovery percentages obtained from 90.7 to 102.1%. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rapid method for the simultaneous detection of boar taint compounds by means of solid phase microextraction coupled to gas chromatography/mass spectrometry.

PubMed

Verplanken, Kaat; Wauters, Jella; Van Durme, Jim; Claus, Dirk; Vercammen, Joeri; De Saeger, Sarah; Vanhaecke, Lynn

2016-09-02

Because of animal welfare issues, the voluntary ban on surgical castration of male piglets, starting January 2018 was announced in a European Treaty. One viable alternative is the fattening of entire male pigs. However, this can cause negative consumer reactions due to the occurrence of boar taint and possibly lead to severe economic losses in pig husbandry. In this study, headspace solid phase microextraction (HS-SPME) coupled to GC-MS was used in the development and optimization of a candidate method for fast and accurate detection of the boar taint compounds. Remarkably fast extraction (45s) of the boar taint compounds from adipose tissue was achieved by singeing the fat with a soldering iron while released volatiles were extracted in-situ using HS-SPME. The obtained method showed good performance characteristics after validation according to CD 2002/657/EC and ISO/IEC 17025 guidelines. Moreover, cross-validation with an in-house UHPLC-HR-Orbitrap-MS method showed good agreement between an in-laboratory method and the new candidate method for the fast extraction and detection of skatole and androstenone, which emphasizes the accuracy of this new SPME-GC-MS method. Threshold detection of the boar taint compounds on a portable GC-MS could not be achieved. However, despite the lack of sensitivity obtained on the latter instrument, a very fast method with run-to-run time of 3.5min for the detection of the boar taint compounds was developed. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of the aroma formation and transformation during the manufacturing process of oolong tea by solid-phase micro-extraction and gas chromatography-mass spectrometry combined with chemometrics.

PubMed

Ma, Chengying; Li, Junxing; Chen, Wei; Wang, Wenwen; Qi, Dandan; Pang, Shi; Miao, Aiqing

2018-06-01

Oolong tea is a typical semi-fermented tea and is famous for its unique aroma. The aim of this study was to compare the volatile compounds during manufacturing process to reveal the formation of aroma. In this paper, a method was developed based on head-space solid phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) combined with chemometrics to assess volatile profiles during manufacturing process (fresh leaves, sun-withered leaves, rocked leaves and leaves after de-enzyming). A total of 24 aroma compounds showing significant differences during manufacturing process were identified. Subsequently, according to these aroma compounds, principal component analysis and hierarchical cluster analysis showed that the four samples were clearly distinguished from each other, which suggested that the 24 identified volatile compounds can represent the changes of volatile compounds during the four steps. Additionally, sun-withering, rocking and de-enzyming can influence the variations of volatile compounds in different degree, and we found the changes of volatile compounds in withering step were less than other two manufacturing process, indicating that the characteristic volatile compounds of oolong tea might be mainly formed in rocking stage by biological reactions and de-enzyming stage through thermal chemical transformations rather than withering stage. This study suggested that HS-SPME/GC-MS combined with chemometrics methods is accurate, sensitive, fast and ideal for rapid routine analysis of the aroma compounds changes in oolong teas during manufacturing processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of chemical stability of lemon oil components in sodium caseinate-lactose glycoconjugate-stabilized oil-in-water emulsions using solid-phase microextraction-gas chromatography.

PubMed

Sabik, Hassan; Achouri, Allaoua; Alfaro, Maria; Pelletier, Marylène; Belanger, Denis; Britten, Michel; Fustier, Patrick

2014-07-25

A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC/MS) method was developed to quantify lemon oil components and their degradation products in oil-in-water (O/W) emulsions prepared with sodium caseinate-heated-lactose (NaC-T + Lact) glycoconjugates as wall materials at two pH values (3.0 and 6.8). NaC-T + Lact conjugates had a significantly lower solubility at both pHs. Hydrolysis prior to glycation enhanced the solubility of glycoconjugates. Glycation with lactose did not improve the emulsion activity of NaC, while caseinate glycoconjugates showed much stronger antioxidant activity than the NaC-control sample. This might be due to the presence of melanoidins formed between the sugar and amino acid compounds as supported by the increase in browning intensity. Among the SPME-fibres tested, carboxen/polydimethylsiloxane (CAR/PDMS) provided better results in terms of sensitivity and selectivity for oil lemon components and their degradation products. Storage studies of these emulsions demonstrated that glycated NaC-T + Lact showed protection against peroxidation compared to the control. However, acidic pH conditions altered their stability over storage time. The major off-flavor components (α-terpineol and carvone) were inhibited in emulsions stabilized with glycated NaC, particularly at pH 6.8. The use of NaC-T + Lact conjugates showed improved encapsulation efficiency and stability and could be used as potential food ingredient-emulsifiers for stabilising citrus oils against oxidative degradation in food and beverage applications.

An improved ionic liquid-based headspace single-drop microextraction-liquid chromatography method for the analysis of camphor and trans-anethole in compound liquorice tablets.

PubMed

He, Xiaowen; Zhang, Fucheng; Jiang, Ye

2012-07-01

A simple, accurate and sensitive ionic liquid-based headspace single-drop microextraction procedure followed by high-performance liquid chromatography was developed and validated for the determination of camphor and trans-anethole in compound liquorice tablets. The volume of the ionic liquid microdrop was increased to 12 µL by modifying the device of the suspended drop. The stability of the microdrop and the sensitivity of the method were improved. Under the optimum experimental conditions, the calculated calibration curves gave acceptable linearity for camphor and trans-anethole with correlation coefficients of 0.9990 and 0.9998, respectively. The repeatability of the proposed method, expressed as relative standard deviation, was below 4.5% (n = 5). The limits of detection for the two target analytes were found to be 9.77 and 1.95 × 10(-2) μg/mL, respectively. In this study, the separation, purification and enrichment were achieved in one step in an airtight system, which reduced the interferences caused by other complicated constituents, increased the signal-to-noise of the method and ensured the accuracy of the results because there was no loss of volatile components. It is expected to be widely applied for sample pretreatment of volatile components with high boiling points in samples with complicated matrices such as the extractions of plants or Chinese traditional drugs.

Serum levels of organochlorine pesticides in the general population of Thessaly, Greece, determined by HS-SPME GC-MS method.

PubMed

Koureas, Michalis; Karagkouni, Foteini; Rakitskii, Valerii; Hadjichristodoulou, Christos; Tsatsakis, Aristidis; Tsakalof, Andreas

2016-07-01

In this study, exposure levels of organochlorine pesticides (OCs) were determined in general population residing in Larissa, central Greece. Serum samples from 103 volunteers were analyzed by optimized headspace solid-phase microextraction gas chromatography-mass spectrometry, to detect and quantify OC levels. The most frequently detected analytes were p,p'-DDE (frequency 99%, median:1.25ng/ml) and Hexachlorobenzene (HCB) (frequency 69%, median: 0.13ng/ml). Statistical analysis revealed a significant relationship of p,p'-DDE and HCB levels with age. Copyright © 2016 Elsevier Inc. All rights reserved.

Pinot noir wine volatile and anthocyanin composition under different levels of vine fruit zone leaf removal.

PubMed

Feng, Hui; Skinkis, Patricia A; Qian, Michael C

2017-01-01

The impacts of fruit zone leaf removal on volatile and anthocyanin compositions of Pinot noir wine were investigated over two growing seasons. Wine volatiles were analyzed by multiple techniques, including headspace solid phase microextraction-GC-MS (HS-SPME-GC-MS), headspace-GC-FID (HS-GC-FID) and stir bar sorptive extraction-GC-MS (SBSE-GC-MS). Fruit zone leaf removal affected the concentration of many grape-derived volatile compounds such as terpene alcohols and C13-norisoprenoids in wine, although the degree of impact depended on the vintage year and severity of leaf removal. Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol and β-damascenone but had no impact on other terpene alcohols or β-ionone. Fruit zone leaf removal had no consistent impact on C6 alcohols, volatile phenols, lactones, fermentation-derived alcohols, acids, or most esters. Fruit zone leaf removal increased anthocyanins in final wine. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lichenysin, a cyclooctapeptide occurring in Chinese liquor jiannanchun reduced the headspace concentration of phenolic off-flavors via hydrogen-bond interactions.

PubMed

Zhang, Rong; Wu, Qun; Xu, Yan

2014-08-20

Nonvolatile compounds play important roles in the quality of alcoholic beverages. In our previous work, a type of cyclooctapeptide lichenysin was newly identified in Chinese strong-aroma type liquor. In this work, it was found that lichenysin could selectively affect aroma volatility in strong-aroma type (Jiannanchun) liquor. Interaction of lichenysin and volatile phenolic compounds (off-odors in strong-aroma type liquor) was characterized using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). HS-SPME results indicated that lichenysin very efficiently suppressed the volatility of phenolic compounds by 36-48% (P < 0.05). Thermodynamic analysis showed that the binding process was mainly mediated by hydrogen bonding. Furthermore, the mixture of lichenysin and 4-ethylguaiacol revealed intermolecular cross peaks between the aH (Val) of lichenysin and the 1H of 4-ethylguaiacol, by using nuclear Overhauser effect spectroscopy. This study will help to further understand the interaction mechanisms between flavor and nonvolatile matrix components in Chinese liquors.

NMR, HS-SPME-GC/MS, and HPLC/MSn Analyses of Phytoconstituents and Aroma Profile of Rosmarinus eriocalyx.

PubMed

Bendif, Hamdi; Miara, Mohamed Djamel; Peron, Gregorio; Sut, Stefania; Dall'Acqua, Stefano; Flamini, Guido; Maggi, Filippo

2017-10-01

In this work, a comprehensive study on the chemical constituents of the aerial parts of Rosmarinus eriocalyx (Lamiaceae), an aromatic shrub traditionally consumed as a food and herbal remedy in Algeria, is presented. The aroma profile was analysed by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC/MS), whereas the crude extract constituents were analyzed by 1 H-NMR and by high performance liquid chromatography coupled with mass spectrometry (HPLC/MS n ). Thirty-nine volatile compounds, most of them being monoterpenes, have been identified, with camphor, camphene, and α-pinene as the most abundant constituents. 1 H-NMR analysis revealed the presence of phenolic compounds and betulinic acid while HPLC/MS n allowed the identification of glycosilated and aglyconic flavonoids as well as phenylpropanoid derivatives. Some of these constituents, namely as betulinic acid, rosmanol, and cirsimaritin were reported for the first time in R. eriocalyx. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Speciation analysis of organotin compounds in human urine by headspace solid-phase micro-extraction and gas chromatography with pulsed flame photometric detection.

PubMed

Valenzuela, Aníbal; Lespes, Gaëtane; Quiroz, Waldo; Aguilar, Luis F; Bravo, Manuel A

2014-07-01

A new headspace solid-phase micro-extraction (HS-SPME) method followed by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis has been developed for the simultaneous determination of 11 organotin compounds, including methyl-, butyl-, phenyl- and octyltin derivates, in human urine. The methodology has been validated by the analysis of urine samples fortified with all analytes at different concentration levels, and recovery rates above 87% and relative precisions between 2% and 7% were obtained. Additionally, an experimental-design approach has been used to model the storage stability of organotin compounds in human urine, demonstrating that organotins are highly degraded in this medium, although their stability is satisfactory during the first 4 days of storage at 4 °C and pH=4. Finally, this methodology was applied to urine samples collected from harbor workers exposed to antifouling paints; methyl- and butyltins were detected, confirming human exposure in this type of work environment. Copyright © 2014 Elsevier B.V. All rights reserved.

Headspace solid-phase microextraction (HS-SPME) combined with GC-MS as a process analytical technology (PAT) tool for monitoring the cultivation of C. tetani.

PubMed

Ghader, Masoud; Shokoufi, Nader; Es-Haghi, Ali; Kargosha, Kazem

2018-04-15

Vaccine production is a biological process in which variation in time and output is inevitable. Thus, the application of Process Analytical Technologies (PAT) will be important in this regard. Headspace solid - phase microextraction (HS-SPME) coupled with GC-MS can be used as a PAT for process monitoring. This method is suitable to chemical profiling of volatile organic compounds (VOCs) emitted from microorganisms. Tetanus is a lethal disease caused by Clostridium tetani (C. tetani) bacterium and vaccination is an ultimate way to prevent this disease. In this paper, SPME fiber was used for the investigation of VOCs emerging from C. tetani during cultivation. Different types of VOCs such as sulfur-containing compounds were identified and some of them were selected as biomarkers for bioreactor monitoring during vaccine production. In the second step, the portable dynamic air sampling (PDAS) device was used as an interface for sampling VOCs by SPME fibers. The sampling procedure was optimized by face-centered central composite design (FC-CCD). The optimized sampling time and inlet gas flow rates were 10 min and 2 m L s -1 , respectively. PDAS was mounted in exhausted gas line of bioreactor and 42 samples of VOCs were prepared by SPME fibers in 7 days during incubation. Simultaneously, pH and optical density (OD) were evaluated to cultivation process which showed good correlations with the identified VOCs (>80%). This method could be used for VOCs sampling from off-gas of a bioreactor to monitoring of the cultivation process. Copyright © 2018. Published by Elsevier B.V.

Evaluation of volatile metabolites as markers in Lycopersicon esculentum L. cultivars discrimination by multivariate analysis of headspace solid phase microextraction and mass spectrometry data.

PubMed

Figueira, José; Câmara, Hugo; Pereira, Jorge; Câmara, José S

2014-02-15

To gain insights on the effects of cultivar on the volatile metabolomic expression of different tomato (Lycopersicon esculentum L.) cultivars--Plum, Campari, Grape, Cherry and Regional, cultivated under similar edafoclimatic conditions, and to identify the most discriminate volatile marker metabolites related to the cultivar, the chromatographic profiles resulting from headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-qMS) analysis, combined with multivariate analysis were investigated. The data set composed by the 77 volatile metabolites identified in the target tomato cultivars, 5 of which (2,2,6-trimethylcyclohexanone, 2-methyl-6-methyleneoctan-2-ol, 4-octadecyl-morpholine, (Z)-methyl-3-hexenoate and 3-octanone) are reported for the first time in tomato volatile metabolomic composition, was evaluated by chemometrics. Firstly, principal component analysis was carried out in order to visualise data trends and clusters, and then, linear discriminant analysis in order to detect the set of volatile metabolites able to differentiate groups according to tomato cultivars. The results obtained revealed a perfect discrimination between the different Lycopersicon esculentum L. cultivars considered. The assignment success rate was 100% in classification and 80% in prediction ability by using "leave-one-out" cross-validation procedure. The volatile profile was able to differentiate all five cultivars and revealed complex interactions between them including the participation in the same biosynthetic pathway. The volatile metabolomic platform for tomato samples obtained by HS-SPME/GC-qMS here described, and the interrelationship detected among the volatile metabolites can be used as a roadmap for biotechnological applications, namely to improve tomato aroma and their acceptance in the final consumer, and for traceability studies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantification of selected volatile organic compounds in human urine by gas chromatography selective reagent ionization time of flight mass spectrometry (GC-SRI-TOF-MS) coupled with head-space solid-phase microextraction (HS-SPME).

PubMed

Mochalski, Paweł; Unterkofler, Karl

2016-08-07

Selective reagent ionization time of flight mass spectrometry with NO(+) as the reagent ion (SRI-TOF-MS(NO(+))) in conjunction with gas chromatography (GC) and head-space solid-phase microextraction (HS-SPME) was used to determine selected volatile organic compounds in human urine. A total of 16 volatiles exhibiting high incidence rates were quantified in the urine of 19 healthy volunteers. Amongst them there were ten ketones (acetone, 2-butanone, 3-methyl-2-butanone, 2-pentanone, 3-methyl-2-pentanone, 4-methyl-2-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, and 4-heptanone), three volatile sulphur compounds (dimethyl sulfide, allyl methyl sulfide, and methyl propyl sulfide), and three heterocyclic compounds (furan, 2-methylfuran, 3-methylfuran). The concentrations of the species under study varied between 0.55 nmol L(-1) (0.05 nmol mmol(-1)creatinine) for allyl methyl sulfide and 11.6 μmol L(-1) (1.54 μmol mmol(-1)creatinine) for acetone considering medians. Limits of detection (LODs) ranged from 0.08 nmol L(-1) for allyl methyl sulfide to 1.0 nmol L(-1) for acetone and furan (with RSDs ranging from 5 to 9%). The presented experimental setup assists both real-time and GC analyses of volatile organic compounds, which can be performed consecutively using the same analytical system. Such an approach supports the novel concept of hybrid volatolomics, an approach which combines VOC profiles obtained from two or more body fluids to improve and complement the chemical information on the physiological status of an individual.

Determination of phthalate esters in drinking water and edible vegetable oil samples by headspace solid phase microextraction using graphene/polyvinylchloride nanocomposite coated fiber coupled to gas chromatography-flame ionization detector.

PubMed

Amanzadeh, Hatam; Yamini, Yadollah; Moradi, Morteza; Asl, Yousef Abdossalmi

2016-09-23

In the current study, a graphene/polyvinylchloride nanocomposite was successfully coated on a stainless steel substrate by a simple dip coating process and used as a novel headspace solid phase microextraction (HS-SPME) fiber for the extraction of phthalate esters (PEs) from drinking water and edible vegetable oil samples. The prepared SPME fibers exhibited high extractability for PEs (due to the dominant role of π-π stacking interactions and hydrophobic effects) yielding good sensitivity and precision when followed by a gas chromatograph with a flame ionization detector (GC-FID). The optimization strategy of the extraction process was carried out using the response surface method based on a central composite design. The developed method gave a low limit of detection (0.06-0.08μgL(-1)) and good linearity (0.2-100μgL(-1)) for the determination of the PEs under the optimized conditions (extraction temperature, 70±1°C; extraction time, 35min; salt concentration, 30% w/v; stirring rate, 900rpm; desorption temperature, 230°C; and desorption time, 4min) whereas the repeatability and fiber-to-fiber reproducibility were in the range 6.1-7.8% and 8.9-10.2%, respectively. Finally, the proposed method was successfully applied to the analysis of PEs in drinking water and edible oil samples with good recoveries (87-112%) and satisfactory precisions (RSDs<8.3%), indicating the absence of matrix effects in the proposed HS-SPME method. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct determination of acrylamide in potato chips by using headspace solid-phase microextraction coupled with gas chromatography-flame ionization detection.

PubMed

Ghiasvand, Ali Reza; Hajipour, Somayeh

2016-01-01

Acrylamide is a potentially toxic and carcinogenic substance present in many high-consumption foods. Recently, this matter has been placed in category of "reasonably anticipated to be a human carcinogen" by National Toxicology Program (NTP). Therefore, simple and cost-effective determination of acrylamide in food samples has attracted intense interest. The most reported techniques for this purpose are GC-MS and LC-MS, which are very expensive and available in few laboratories. In this research, for the first time, a rapid, easy and low-cost method is introduced for sensitive and precise determination of acrylamide in foodstuffs, using gas chromatography-flame ionization detection (GC-FID) system after its direct trapping in the upper atmosphere of samples by headspace solid-phase microextraction (HS-SPME). The effects of main experimental variables were studied and the optimized parameters were obtained as the type of fiber, carboxen/divinylbenzene/polydimethylsiloxane (CAR/DVB/PDMS); extraction time, 30 min; extraction temperature, 60°C; moisture content, 10 µL water per 1g of sample; desorption time, 2 min; and desorption temperature, 230°C. The linear calibration graph was obtained in the range of 0.77-50 µg g(-1), with regression coefficient of 0.998. The detection and quantification limits of the proposed method were 0.22 and 0.77 µg g(-1), respectively. The recoveries, for different food samples, were 79.6-95.7%. The repeatability of measurements, expressed as relative standard deviation (RSD), were found to be 4.1-8.0% (n=9). The proposed HS-SPME-GC-FID method was successfully carried out for quantifying of trace levels of acrylamide in some processed food products (chips and French fries), sold in open local markets. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of water-phase derivatization followed by solid-phase microextraction and gas chromatography/mass spectrometry for fast determination of valproic acid in human plasma.

PubMed

Deng, Chunhui; Li, Ning; Ji, Jie; Yang, Bei; Duan, Gengli; Zhang, Xiangmin

2006-01-01

In this study, a simple, rapid, and sensitive method was developed and validated for the quantification of valproic acid (VPA), an antiepileptic drug, in human plasma, which was based on water-phase derivatization followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS). In the proposed method, VPA in plasma was rapidly derivatized with a mixture of isobutyl chloroformate, ethanol and pyridine under mild conditions (room temperature, aqueous medium), and the VPA ethyl ester formed was headspace-extracted and simultaneously concentrated using the SPME technique. Finally, the analyte extracted on SPME fiber was analyzed by GC/MS. The experimental parameters and method validations were studied. The optimal conditions were obtained: PDMS fiber, stirring rate of 1100 rpm, sample temperature of 80 degrees C, extraction time of 20 min, NaCl concentration of 30%. The proposed method had a limit of quantification (0.3 microg/mL), good recovery (89-97%) and precision (RSD value less than 10%). Because the proposed method combined a rapid water-phase derivatization with a fast, simple and solvent-free sample extraction and concentration technique of SPME, the sample preparation time was less than 25 min. This much shortens the whole analysis time of VPA in plasma. The validated method has been successfully used to analyze VPA in human plasma samples for application in pharmacokinetic studies. All these results show that water-phase derivatization followed by HS-SPME and GC/MS is an alternative and powerful method for fast determination of VPA in biological fluids. Copyright 2006 John Wiley & Sons, Ltd.

[Rapid determination of volatile flavor compounds in soy sauce using head space solid-phase microextraction and gas chromatography-mass spectrometry].

PubMed

Yan, Liujun; Zhang, Yanfang; Tao, Wenyi; Wang, Liping; Wu, Shengfang

2008-05-01

A rapid and simple method was developed for the determination of volatile flavor compounds (VFCs) in soy sauce by head space solid-phase microextraction (HS-SPME) coupled to capillary gas chromatography-mass spectrometry (GC-MS). Five types of SPME fibers, including 85 microm PA, 100 microm PDMS, 75 microm CAR/PDMS, 65 microm PDMS/DVB, 50 microm DVB/CAR/PDMS were investigated. Three parameters for HS-SPME in terms of adsorption time, salt concentration, and extraction temperature were optimized. Adsorption time tested in this study were 20, 40 and 60 minutes; the salt concentrations were 180, 210, 250, 270 and 300 g/L; and extraction temperatures were 25, 35, 45, 55 and 65 degrees C. The concentrations of the compounds were calculated based on their relative peak areas to the internal standard of 2-octanol. An 85 microm PA fiber, adsorption time of 40 min, a temperature of 45 degrees C and NaCl concentration of 250 g/L were selected as th optimum conditions. This optimized method was applied to evaluate a real sample. As a result, 97 compounds in a soy sauce sample were isolated and identified successfully. The results showed that alcohols, carboxylic acids, esters and phenols were the major VFCs of soy sauce. The most important groups of volatile compounds in the soy sauce sample were ethanol, hexadecanoic acid, phenylethyl alcohol and 2,3-butanediol. In addition, some oxo-compounds and heterocyclic compounds were also found. The average relative standard deviation of the relative peak area was 12.1%, and the recoveries were 79.9% - 109.6%. The method is simple, fast and accurate with high reproducibility, high sensitivity and low cost.

Simultaneous determination of perfluoroalkyl iodides, perfluoroalkane sulfonamides, fluorotelomer alcohols, fluorotelomer iodides and fluorotelomer acrylates and methacrylates in water and sediments using solid-phase microextraction-gas chromatography/mass spectrometry.

PubMed

Bach, Cristina; Boiteux, Virginie; Hemard, Jessica; Colin, Adeline; Rosin, Christophe; Munoz, Jean-François; Dauchy, Xavier

2016-05-27

Here, we developed and validated a headspace-solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS) method for the determination of 14 volatile perfluorinated alkylated substances (PFASs) in water and sediment samples according to SANTE 11945/2015 guidelines. Three fluorotelomer alcohols (FTOHs), two perfluoroalkyl iodides (PFIs), three fluorotelomer iodides (FTIs), four fluorotelomer acrylates and methacrylates (FTACs and FTMACs) and two perfluoroalkyl sulfonamides (FASAs) were analysed simultaneously to assess the occurrence of these compounds from their emission sources to the outlets in water treatment plants. Several SPME parameters were optimised for both water and sediment to maximise responses and keep analysis time to a minimum. In tap water, the limits of quantification (LOQs) were found to be between 20ng/L and 100ng/L depending on the analyte, with mean recoveries ranging from 76 to 126%. For sediments, LOQs ranged from 1 to 3ng/g dry weight depending on the target compound, with mean recoveries ranging from 74 to 125%. SPME considerably reduced sample preparation time and its use provided a sensitive, fast and simple technique. We then used this HS-SPME-GC/MS method to investigate the presence of volatile PFASs in the vicinity of an industrial facility. Only 8:2 FTOH and 10:2 FTOH were detected in a few water and sediment samples at sub-ppb concentration levels. Moreover, several non-target fluorotelomers (12:2 FTOH, 14:2 FTOH and 10:2 FTI) were identified in raw effluent samples. These long-chain fluorotelomers have high bioaccumulative potential in the aquatic environment compared with short-chain fluorotelomers such as 6:2 FTOH and 6:2 FTI. Copyright © 2016 Elsevier B.V. All rights reserved.

Dispersive liquid-liquid microextraction based on solidification of floating organic drop for preconcentration and determination of trace amounts of copper by flame atomic absorption spectrometry.

PubMed

Karadaş, Cennet; Kara, Derya

2017-04-01

A novel, simple, rapid, sensitive, inexpensive and environmentally friendly dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) was developed for the determination of copper by flame atomic absorption spectrometry (FAAS). N-o-Vanillidine-2-amino-p-cresol was used as a chelating ligand and 1-undecanol was selected as an extraction solvent. The main parameters affecting the performance of DLLME-SFO, such as sample pH, volume of extraction solvent, extraction time, concentration of the chelating ligand, salt effect, centrifugation time and sample volume were investigated and optimized. The effect of interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.93μgL -1 for Cu using a sample volume of 20mL, yielding a preconcentration factor of 20. The proposed method was successfully applied to the determination of Cu in tap, river and seawater, rice flour and black tea samples as well as certified reference materials. Copyright © 2016. Published by Elsevier Ltd.

Optimization of dispersive liquid-phase microextraction based on solidified floating organic drop combined with high-performance liquid chromatography for the analysis of glucocorticoid residues in food.

PubMed

Huang, Yuan; Zheng, Zhiqun; Huang, Liying; Yao, Hong; Wu, Xiao Shan; Li, Shaoguang; Lin, Dandan

2017-05-10

A rapid, simple, cost-effective dispersive liquid-phase microextraction based on solidified floating organic drop (SFOD-LPME) was developed in this study. Along with high-performance liquid chromatography, we used the developed approach to determine and enrich trace amounts of four glucocorticoids, namely, prednisone, betamethasone, dexamethasone, and cortisone acetate, in animal-derived food. We also investigated and optimized several important parameters that influenced the extraction efficiency of SFOD-LPME. These parameters include the extractant species, volumes of extraction and dispersant solvents, sodium chloride addition, sample pH, extraction time and temperature, and stirring rate. Under optimum experimental conditions, the calibration graph exhibited linearity over the range of 1.2-200.0ng/ml for the four analytes, with a reasonable linearity(r 2 : 0.9990-0.9999). The enrichment factor was 142-276, and the detection limits was 0.39-0.46ng/ml (0.078-0.23μg/kg). This method was successfully applied to analyze actual food samples, and good spiked recoveries of over 81.5%-114.3% were obtained. Copyright © 2017. Published by Elsevier B.V.

Indirect spectrophotometric determination of ultra trace amounts of selenium based on dispersive liquid-liquid microextraction-solidified floating organic drop.

PubMed

Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh; Nozohor, Mahnaz

2013-12-01

A novel dispersive liquid-liquid microextraction-solidified floating organic drop (DLLME-SFOD) method combined with fiber optic-linear array detection spectrophotometry has been developed for the indirect determination of selenium. The method is based on the oxidation of the I(-) to iodine by inorganic Se(IV). The produced I2 reacts with the excess of I(-) ions in acidic media to give triiodide ions. The I3(-) is then extracted into 1-undecanol by DLLME-SFOD upon the formation of an ion pair with cetyltrimethylammonium cation. The extracted ion pair is determined by measuring its absorption at 360 nm. The absorbance signal is proportional to the selenium concentration in the aqueous phase. Under optimum conditions, the method provided an enrichment factor of 250 with a detection limit of 16.0 μg L(-1) and a linear dynamic range of 40.0-1000.0 μg L(-1). The relative standard deviation was found to be 2.1% (n=7) at 100.0 μg L(-1) concentration level. The method was successfully applied to th e determination of selenium in water samples and selenium plus tablet. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

PubMed

Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

2010-06-30

A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. Copyright 2010 Elsevier B.V. All rights reserved.

Characterization of the volatile components in green tea by IRAE-HS-SPME/GC-MS combined with multivariate analysis.

PubMed

Yang, Yan-Qin; Yin, Hong-Xu; Yuan, Hai-Bo; Jiang, Yong-Wen; Dong, Chun-Wang; Deng, Yu-Liang

2018-01-01

In the present work, a novel infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of the volatile components in green tea. The extraction parameters such as fiber type, sample amount, infrared power, extraction time, and infrared lamp distance were optimized by orthogonal experimental design. Under optimum conditions, a total of 82 volatile compounds in 21 green tea samples from different geographical origins were identified. Compared with classical water-bath heating, the proposed technique has remarkable advantages of considerably reducing the analytical time and high efficiency. In addition, an effective classification of green teas based on their volatile profiles was achieved by partial least square-discriminant analysis (PLS-DA) and hierarchical clustering analysis (HCA). Furthermore, the application of a dual criterion based on the variable importance in the projection (VIP) values of the PLS-DA models and on the category from one-way univariate analysis (ANOVA) allowed the identification of 12 potential volatile markers, which were considered to make the most important contribution to the discrimination of the samples. The results suggest that IRAE-HS-SPME/GC-MS technique combined with multivariate analysis offers a valuable tool to assess geographical traceability of different tea varieties.

Volatile profile analysis and quality prediction of Longjing tea (Camellia sinensis) by HS-SPME/GC-MS

PubMed Central

Lin, Jie; Dai, Yi; Guo, Ya-nan; Xu, Hai-rong; Wang, Xiao-chang

2012-01-01

This study aimed to analyze the volatile chemical profile of Longjing tea, and further develop a prediction model for aroma quality of Longjing tea based on potent odorants. A total of 21 Longjing samples were analyzed by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Pearson’s linear correlation analysis and partial least square (PLS) regression were applied to investigate the relationship between sensory aroma scores and the volatile compounds. Results showed that 60 volatile compounds could be commonly detected in this famous green tea. Terpenes and esters were two major groups characterized, representing 33.89% and 15.53% of the total peak area respectively. Ten compounds were determined to contribute significantly to the perceived aroma quality of Longjing tea, especially linalool (0.701), nonanal (0.738), (Z)-3-hexenyl hexanoate (−0.785), and β-ionone (−0.763). On the basis of these 10 compounds, a model (correlation coefficient of 89.4% and cross-validated correlation coefficient of 80.4%) was constructed to predict the aroma quality of Longjing tea. Summarily, this study has provided a novel option for quality prediction of green tea based on HS-SPME/GC-MS technique. PMID:23225852

Characterization of the volatile components in green tea by IRAE-HS-SPME/GC-MS combined with multivariate analysis

PubMed Central

Yin, Hong-Xu; Yuan, Hai-Bo; Jiang, Yong-Wen; Dong, Chun-Wang; Deng, Yu-Liang

2018-01-01

In the present work, a novel infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of the volatile components in green tea. The extraction parameters such as fiber type, sample amount, infrared power, extraction time, and infrared lamp distance were optimized by orthogonal experimental design. Under optimum conditions, a total of 82 volatile compounds in 21 green tea samples from different geographical origins were identified. Compared with classical water-bath heating, the proposed technique has remarkable advantages of considerably reducing the analytical time and high efficiency. In addition, an effective classification of green teas based on their volatile profiles was achieved by partial least square-discriminant analysis (PLS-DA) and hierarchical clustering analysis (HCA). Furthermore, the application of a dual criterion based on the variable importance in the projection (VIP) values of the PLS-DA models and on the category from one-way univariate analysis (ANOVA) allowed the identification of 12 potential volatile markers, which were considered to make the most important contribution to the discrimination of the samples. The results suggest that IRAE-HS-SPME/GC-MS technique combined with multivariate analysis offers a valuable tool to assess geographical traceability of different tea varieties. PMID:29494626

Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

PubMed

Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

2014-10-01

A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mannitol versus hypertonic saline: Safety and efficacy of mannitol and hypertonic saline in sputum induction and bronchial hyperreactivity assessment.

PubMed

Alvarez-Puebla, M J; Olaguibel, J M; Almudevar, E; Echegoyen, A A; Vela, C; de Esteban, B

2015-08-01

Eosinophilic asthma phenotype predicts good response to corticosteroids and associates to asthmatic exacerbations. Sputum induction by hypertonic saline (HS) inhalation is technically demanding. Bronchial hyperresponsiveness (BHR) to osmotic agents indirectly mirrors active airway inflammation. We compared the safety and ability of HS and mannitol to induce sputum and measure BHR. We evaluated the stability of inflammatory phenotypes. We studied 35 non-smoking asthmatics randomized to undergo HS and mannitol challenges on 2 days 1 week apart. Sputum was sampled for cell analysis and phenotyped as eosinophilic (≥3% eosinophils) and non-eosinophilic (<3%) asthma. Nineteen subjects had BHR to mannitol and nine of them also had BHR to HS. Drops in forced expiratory volume in 1 s were higher from HS challenge than from mannitol challenge. Adequate sputum samples were obtained from 80% subjects (68% mannitol and 71% HS). Eosinophils and macrophages from both challenges correlated. Neutrophils were higher in sputum from HS. Ninety percent samples were equally phenotyped with HS and mannitol. Fractional exhaled nitric oxide, sputum eosinophils and BHR correlated in both challenges. HS and mannitol showed similar capacity to produce valuable sputum samples. BHR to both osmotic stimuli partially resembled airway eosinophilic inflammation but mannitol was more sensitive than HS to assess BHR. Eosinophilic phenotype remained stable in most patients with both stimuli. © The Author(s) 2015.

Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples.

PubMed

Yilmaz, Erkan; Soylak, Mustafa

2015-07-30

A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO2 (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L(-1) (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A MODEL OF THE HELIOSPHERE WITH JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drake, J. F.; Swisdak, M.; Opher, M., E-mail: drake@umd.edu, E-mail: swisdak@umd.edu, E-mail: mopher@bu.edu

2015-08-01

An analytic model of the heliosheath (HS) between the termination shock (TS) and the heliopause (HP) is developed in the limit in which the interstellar flow and magnetic field are neglected. The heliosphere in this limit is axisymmetric and the overall structure of the HS and HP is controlled by the solar magnetic field even in the limit in which the ratio of the plasma to magnetic field pressure, β = 8πP/B{sup 2}, in the HS is large. The tension of the solar magnetic field produces a drop in the total pressure between the TS and the HP. This samemore » pressure drop accelerates the plasma flow downstream of the TS into the north and south directions to form two collimated jets. The radii of these jets are controlled by the flow through the TS and the acceleration of this flow by the magnetic field—a stronger solar magnetic field boosts the velocity of the jets and reduces the radii of the jets and the HP. MHD simulations of the global heliosphere embedded in a stationary interstellar medium match well with the analytic model. The results suggest that mechanisms that reduce the HS plasma pressure downstream of the TS can enhance the jet outflow velocity and reduce the HP radius to values more consistent with the Voyager 1 observations than in current global models.« less

The Muslim Headscarf and Face Perception: “They All Look the Same, Don't They?”

PubMed Central

Toseeb, Umar; Bryant, Eleanor J.; Keeble, David R. T.

2014-01-01

The headscarf conceals hair and other external features of a head (such as the ears). It therefore may have implications for the way in which such faces are perceived. Images of faces with hair (H) or alternatively, covered by a headscarf (HS) were used in three experiments. In Experiment 1 participants saw both H and HS faces in a yes/no recognition task in which the external features either remained the same between learning and test (Same) or switched (Switch). Performance was similar for H and HS faces in both the Same and Switch condition, but in the Switch condition it dropped substantially compared to the Same condition. This implies that the mere presence of the headscarf does not reduce performance, rather, the change between the type of external feature (hair or headscarf) causes the drop in performance. In Experiment 2, which used eye-tracking methodology, it was found that almost all fixations were to internal regions, and that there was no difference in the proportion of fixations to external features between the Same and Switch conditions, implying that the headscarf influenced processing by virtue of extrafoveal viewing. In Experiment 3, similarity ratings of the internal features of pairs of HS faces were higher than pairs of H faces, confirming that the internal and external features of a face are perceived as a whole rather than as separate components. PMID:24520313

Headspace-Solid-Phase Microextraction-Gas Chromatography as Analytical Methodology for the Determination of Volatiles in Wild Mushrooms and Evaluation of Modifications Occurring during Storage

PubMed Central

Costa, Rosaria; De Grazia, Selenia; Grasso, Elisa; Trozzi, Alessandra

2015-01-01

Mushrooms are sources of food, medicines, and agricultural means. Not much is reported in the literature about wild species of the Mediterranean flora, although many of them are traditionally collected for human consumption. The knowledge of their chemical constituents could represent a valid tool for both taxonomic and physiological characterizations. In this work, a headspace-solid-phase microextraction (HS-SPME) method coupled with GC-MS and GC-FID was developed to evaluate the volatile profiles of ten wild mushroom species collected in South Italy. In addition, in order to evaluate the potential of this analytical methodology for true quantitation of volatiles, samples of the cultivated species Agaricus bisporus were analyzed. The choice of this mushroom was dictated by its ease of availability in the food market, due to the consistent amounts required for SPME method development. For calibration of the main volatile compounds, the standard addition method was chosen. Finally, the assessed volatile composition of A. bisporus was monitored in order to evaluate compositional changes occurring during storage, which represents a relevant issue for such a wide consumption edible product. PMID:25945282

Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop combined with high performance liquid chromatography for determination of naproxen and nabumetone.

PubMed

Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh; Abbasi, Bijan

2015-12-18

A novel, rapid, simple and green vortex-assisted surfactant-enhanced emulsification microextraction method based on solidification of floating organic drop was developed for simultaneous separation/preconcentration and determination of ultra trace amounts of naproxen and nabumetone with high performance liquid chromatography-fluorescence detection. Some parameters influencing the extraction efficiency of analytes such as type and volume of extractant, type and concentration of surfactant, sample pH, KCl concentration, sample volume, and vortex time were investigated and optimized. Under optimal conditions, the calibration graph exhibited linearity in the range of 3.0-300.0ngL(-1) for naproxen and 7.0-300.0ngL(-1) for nabumetone with a good coefficient of determination (R(2)>0.999). The limits of detection were 0.9 and 2.1ngL(-1). The relative standard deviations for inter- and intra-day assays were in the range of 5.8-10.1% and 3.8-6.1%, respectively. The method was applied to the determination of naproxen and nabumetone in urine, water, wastewater and milk samples and the accuracy was evaluated through recovery experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Stable isotope dilution assay (SIDA) and HS-SPME-GCMS quantification of key aroma volatiles for fruit and sap of Australian mango cultivars.

PubMed

San, Anh T; Joyce, Daryl C; Hofman, Peter J; Macnish, Andrew J; Webb, Richard I; Matovic, Nicolas J; Williams, Craig M; De Voss, James J; Wong, Siew H; Smyth, Heather E

2017-04-15

Reported herein is a high throughput method to quantify in a single analysis the key volatiles that contribute to the aroma of commercially significant mango cultivars grown in Australia. The method constitutes stable isotope dilution analysis (SIDA) in conjunction with headspace (HS) solid-phase microextraction (SPME) coupled with gas-chromatography mass spectrometry (GCMS). Deuterium labelled analogues of the target analytes were either purchased commercially or synthesised for use as internal standards. Seven volatiles, hexanal, 3-carene, α-terpinene, p-cymene, limonene, α-terpinolene and ethyl octanoate, were targeted. The resulting calibration functions had determination coefficients (R 2 ) ranging from 0.93775 to 0.99741. High recovery efficiencies for spiked mango samples were also achieved. The method was applied to identify the key aroma volatile compounds produced by 'Kensington Pride' and 'B74' mango fruit and by 'Honey Gold' mango sap. This method represents a marked improvement over current methods for detecting and measuring concentrations of mango fruit and sap volatiles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Volatile aroma compounds in various brewed green teas.

PubMed

Lee, Jeehyun; Chambers, Delores H; Chambers, Edgar; Adhikari, Koushik; Yoon, Youngmo

2013-08-20

This study identifies and semi-quantifies aroma volatiles in brewed green tea samples. The objectives of this study were to identify using a gas chromatograph-mass spectrometer (GC-MS) paired with a headspace solid-phase micro-extraction (HS-SPME) the common volatile compounds that may be responsible for aroma/flavor of the brewed liquor of a range of green tea samples from various countries as consumed and to determine if green teas from the same region have similarities in volatile composition when green tea samples are prepared for consumption. Twenty-four green tea samples from eight different countries were brewed as recommended for consumer brewing. The aroma volatiles were extracted by HS-SPME, separated on a gas chromatograph and identified using a mass spectrometer. Thirty-eight compounds were identified and the concentrations were semi-quantified. The concentrations were lower than those reported by other researchers, probably because this research examined headspace volatiles from brewed tea rather than solvent extraction of leaves. No relationship to country of origin was found, which indicates that other factors have a greater influence than country of origin on aroma.

Characterization of volatile profile from ten different varieties of Chinese jujubes by HS-SPME/GC-MS coupled with E-nose.

PubMed

Chen, Qinqin; Song, Jianxin; Bi, Jinfeng; Meng, Xianjun; Wu, Xinye

2018-03-01

Volatile profile of ten different varieties of fresh jujubes was characterized by HS-SPME/GC-MS (headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry) and E-nose (electronic nose). GC-MS results showed that a total of 51 aroma compounds were identified in jujubes, hexanoic acid, hexanal, (E)-2-hexenal, (Z)-2-heptenal, benzaldehyde and (E)-2-nonenal were the main aroma components with contributions that over 70%. Differentiation of jujube varieties was conducted by cluster analysis of GC-MS data and principal component analysis & linear discriminant analysis of E-nose data. Both results showed that jujubes could be mainly divided into two groups: group A (JZ, PDDZ, JSXZ and LWZZ) and group B (BZ, YZ, MZ, XZ and DZ). There were significant differences in contents of alcohols, acids and aromatic compounds between group A and B. GC-MS coupled with E-nose could be a fast and accurate method to identify the general flavor difference in different varieties of jujubes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Volatile Compounds with HS-SPME from Oxidized n-3 PUFA Rich Oils via Rancimat Tests.

PubMed

Yang, Kai-Min; Cheng, Ming-Ching; Chen, Chih-Wei; Tseng, Chin-Yin; Lin, Li-Yun; Chiang, Po-Yuan

2017-02-01

Algae oil and fish oil are n-3 PUFA mainstream commercial products. The various sources for the stability of n-3 PUFA oxidation are influenced by the fatty acid composition, extraction and refined processing. In this study, the oil stability index (OSI) occurs within 2.3 to 7.6 hours with three different n-3 PUFA rich oil. To set the OSI in the Rancimat test as the oil stability limit and observed various degrees of oxidation (0, 25, 50, 75, 100 and 125%). The volatile oxidation compounds were analyzed via headspace-solid phase microextraction (HS-SPME) and GC/MS. We detected 51 volatile compound variations during the oxidation, which were composed of aldehydes, hydrocarbons, cyclic compounds, alcohols, benzene compounds, ketones, furans, ester and pyrrolidine. The off-flavor characteristics can be strongly influenced by the synergy effects of volatile oxidation compounds. Chemometric analysis (PCA and AHC) was applied to identify the sensitive oxidation marker compounds, which included a (E,E)-2,4-heptadienal appropriate marker, via lipid oxidation in the n-3 PUFA rich oil.

Effect of hot air drying on volatile compounds of Flammulina velutipes detected by HS-SPME-GC-MS and electronic nose.

PubMed

Yang, Wenjian; Yu, Jie; Pei, Fei; Mariga, Alfred Mugambi; Ma, Ning; Fang, Yong; Hu, Qiuhui

2016-04-01

Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modified HS-SPME for determination of quantitative relations between low-molecular oxygen compounds in various matrices.

PubMed

Dawidowicz, Andrzej L; Szewczyk, Joanna; Dybowski, Michal P

2016-09-07

Similar quantitative relations between individual constituents of the liquid sample established by its direct injection can be obtained applying Polydimethylsiloxane (PDMS) fiber in the headspace solid phase microextraction (HS-SPME) system containing the examined sample suspended in methyl silica oil. This paper proves that the analogous system composed of sample suspension/emulsion in polyethylene glycol (PEG) and Carbowax fiber allows to get similar quantitative relations between components of the mixture as those established by its direct analysis, but only for polar constituents. It is demonstrated for essential oil (EO) components of savory, sage, mint and thyme, and of artificial liquid mixture of polar constituents. The observed differences in quantitative relations between polar constituents estimated by both applied procedures are insignificant (Fexp < Fcrit). The presented results indicates that wider applicability of the system composed of a sample suspended in the oil of the same physicochemical character as that of used SPME fiber coating strongly depends on the character of interactions between analytes-suspending liquid and analytes-fiber coating. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of aroma formation and transformation during the manufacturing process of Biluochun green tea in Yunnan Province by HS-SPME and GC-MS.

PubMed

Wang, Chen; Lv, Shidong; Wu, Yuanshuang; Lian, Ming; Gao, Xuemei; Meng, Qingxiong

2016-10-01

Biluochun is a typical non-fermented tea and is also famous for its unique aroma in China. Few studies have been performed to evaluate the effect of the manufacturing process on the formation and content of its aroma. The volatile components were extracted at different manufacturing process steps of Biluochun green tea using fully automated headspace solid-phase microextraction (HS-SPME) and further characterised by gas chromatography-mass spectrometry (GC-MS). Among 67 volatile components collected, the fractions of linalool oxides, β-ionone, phenylacetaldehyde, aldehydes, ketones, and nitrogen compounds were increased while alcohols and hydrocarbons declined during the manufacturing process. The aroma compounds decreased the most during the drying steps. We identified a number of significantly changed components that can be used as markers and quality control during the producing process of Biluochun. The drying step played a major role in the aroma formation of green tea products and should be the most important step for quality control. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

HS-SPME/GC analysis reveals the population variability of terpene contents in Juniperus communis needles.

PubMed

Filipowicz, Natalia; Madanecki, Piotr; Gołebiowski, Marek; Stepnowski, Piotr; Ochocka, J Renata

2009-12-01

Juniperus communis var. communis L. is an aromatic plant - typical boreal element of flora. In the extensive literature concerning J. communis, there is much data on the composition and the content of essential oil of needles and coneberries, but a detailed analysis of terpene distribution within and between populations is missing. A representative pool of 74 J. communis individuals originating from ten populations of Northern Poland was investigated in order to evaluate the intra- and interpopulational variability of the terpene pattern. Headspace solid-phase microextraction (HS-SPME) coupled with GC/MS and GC/FID was applied in achiral and enantioselective analysis. The majority of the samples (85%), despite different origin, were similar in the terpene pattern. High diversity of terpenes was observed within the populations and low diversity between them. High variation of enantiomeric composition was in accordance with large variation of individual compounds in general (achiral analysis). J. communis samples from Northern Poland could be distinguished by the alpha-pinene/sabinene ratio, and they were divided into three chemical races.

Rapid evaluation technique to differentiate mushroom disease-related moulds by detecting microbial volatile organic compounds using HS-SPME-GC-MS.

PubMed

Radványi, Dalma; Gere, Attila; Jókai, Zsuzsa; Fodor, Péter

2015-01-01

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to analyse microbial volatile organic compounds (MVOCs) of mushroom disease-related microorganisms. Mycogone perniciosa, Lecanicillum fungicola var. fungicola, and Trichoderma aggressivum f. europaeum species, which are typically harmful in mushroom cultivation, were examined, and Agaricus bisporus (bisporic button mushroom) was also examined as a control. For internal standard, a mixture of alkanes was used; these were introduced as the memory effect of primed septa in the vial seal. Several different marker compounds were found in each sample, which enabled us to distinguish the different moulds and the mushroom mycelium from each other. Monitoring of marker compounds enabled us to investigate the behaviour of moulds. The records of the temporal pattern changes were used to produce partial least squares regression (PLS-R) models that enabled determination of the exact time of contamination (the infection time of the media). Using these evaluation techniques, the presence of mushroom disease-related fungi can be easily detected and monitored via their emitted MVOCs.

Characterization of volatiles and identification of odor-active compounds of rocket leaves.

PubMed

Raffo, Antonio; Masci, Maurizio; Moneta, Elisabetta; Nicoli, Stefano; Sánchez Del Pulgar, José; Paoletti, Flavio

2018-02-01

The volatile profile of crushed rocket leaves (Eruca sativa and Diplotaxis tenuifolia) was investigated by applying Headspace Solid-Phase MicroExtraction (HS-SPME), combined with GC-MS, to an aqueous extract obtained by homogenization of rocket leaves, and stabilized by addition of CaCl 2 . A detailed picture of volatile products of the lipoxygenase pathway (mainly C6-aldehydes) and of glucosinolate hydrolysis (mainly isothiocyanates), and their dynamics of formation after tissue disruption was given. Odor-active compounds of leaves were characterized by GC-Olfactometry (GC-O) and Aroma Extract Dilution Analysis (AEDA): volatile isolates obtained by HS-SPME from an aqueous extract and by Stir-Bar Sorptive Extraction (SBSE) from an ethanolic extract were analyzed. The most potent odor-active compounds fully or tentatively identified were (Z)- and (E)-3-hexenal, (Z)-1,5-octadien-3-one, responsible for green olfactory notes, along with 4-mercaptobutyl and 4-(methylthio)butyl isothiocyanate, associated with typical rocket and radish aroma. Relatively high odor potency was observed for 1-octen-3-one, (E)-2-octenal and 1-penten-3-one. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantification of furanic compounds in coated deep-fried products simulating normal preparation and consumption: optimisation of HS-SPME analytical conditions by response surface methodology.

PubMed

Pérez-Palacios, T; Petisca, C; Melo, A; Ferreira, I M P L V O

2012-12-01

The validation of a method for the simultaneous quantification of furanic compounds in coated deep-fried samples processed and handled as usually consumed is presented. The deep-fried food was grinded using a device that simulates the mastication, and immediately analysed by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry. Parameters affecting the efficiency of HS-SPME procedure were selected by response surface methodology, using a 2(3) full-factorial central composite design. Optimal conditions were achieved using 2g of sample, 3g of NaCl and 40min of absorption time at 37°C. Consistency between predicted and experimented values was observed and quality parameters of the method were established. As a result, furan, 2-furfural, furfuryl alcohol and 2-pentylfuran were, for the first time, simultaneously detected and quantified (5.59, 0.27, 10.48 and 1.77μgg(-1) sample, respectively) in coated deep-fried fish, contributing to a better understanding of the amounts of these compounds in food. Copyright © 2012 Elsevier Ltd. All rights reserved.

Herbs and spices: characterization and quantitation of biologically-active markers for routine quality control by multiple headspace solid-phase microextraction combined with separative or non-separative analysis.

PubMed

Sgorbini, Barbara; Bicchi, Carlo; Cagliero, Cecilia; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia

2015-01-09

Herbs and spices are used worldwide as food flavoring, thus determination of their identity, origin, and quality is mandatory for safe human consumption. An analysis strategy based on separative (HS-SPME-GC-MS) and non-separative (HS-SPME-MS) approaches is proposed for the volatile fraction of herbs and spices, for quality control and to quantify the aromatic markers with a single analysis directly on the plant material as such. Eight-to-ten lots of each of the following herbs/spices were considered: cloves (Syzygium aromaticum (L.) Merr. & Perry), American peppertree (Schinus molle L.), black pepper and white pepper (Piper nigrum L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.). Homogeneity, origin, and chemotypes of the investigated lots of each herb/spice were defined by fingerprinting, through statistical elaboration with principal component analysis (PCA). Characterizing aromatic markers were directly quantified on the solid matrix through multiple headspace extraction-HS-SPME (MHS-SPME). Reliable results were obtained with both separative and non-separative methods (where the latter were applicable); the two were in full agreement, RSD% ranging from 1.8 to 7.7% for eugenol in cloves, 2.2-18.4% for carvacrol+thymol in thyme, and 3.1-16.8% for thujones in sage. Copyright © 2014 Elsevier B.V. All rights reserved.

Differential cross sections and spin density matrix elements for gamma p -> phi p from CLAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biplab Dey, Curtis A. Meyer

2011-10-01

Preliminary differential cross-sections and the {rho}{sub MM'}{sup 0} spin density matrix elements (SDME) for the reaction {gamma}p {yields} {phi} for both charged- ({phi} {yields} K{sup +}K{sup -}) and neutral-mode ({phi} {yields} K{sub L}{sup 0}K{sub S}{sup 0}) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold ({radical}s {approx} 1.97more » $$ GeV) to {radical}s = 2.84$$ GeV, with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized 'bump' between {radical}s {approx} 2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K{sup +} {Lambda}(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.« less

Optimization of the HS-SPME-GC-IT/MS method using a central composite design for volatile carbonyl compounds determination in beers.

PubMed

Moreira, Nathalie; Meireles, Sónia; Brandão, Tiago; de Pinho, Paula Guedes

2013-12-15

An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography and ion trap mass spectrometry detection (GC-IT/MS) was developed in order to quantify a large number of carbonyl compounds in beers. Carbonyl compounds were previously derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). Volatile carbonyl compounds associated with staling beer aroma includes alkanals, alkenals, alkadienals, dicarbonyl compounds, Strecker aldehydes, ketones and furans. The HS-SPME was performed using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber. The procedures were optimized for HS-SPME pre-incubation temperature and time, extraction temperature and time, and PFBHA addition. A central composite design was used in the optimization of extraction conditions and PFBHA addition. The volatile compounds showed optimal extraction incubating 5 ml of beer with 700 mg l(-1) of PFBHA for 7 min and extracted for more 20 min at 45 °C. The method was validated with regard to the linearity, repeatability, inter and intra-day precision and accuracy. The method achieved detection limits ranging from 0.003 to 0.510 µg l(-1), except for furans (1.54-3.44 µg l(-1)). The quantification limits varied from 0.010 to 1.55 µg l(-1), except for 2-furfural (4.68 µg l(-1)), 5-methyl-2-furfural (5.82 µg l(-1)) and 5-hyfroxymethylfurfural (10.4 µg l(-1)). Repeatability values of all compounds were lower than 17%. The method accuracy was satisfactory with recoveries ranging from 88% to 114%. The validated method showed to be suitable for a fast and reliable determination of main carbonyl compounds in beers. © 2013 Published by Elsevier B.V.

Highly porous nanostructured copper foam fiber impregnated with an organic solvent for headspace liquid-phase microextraction.

PubMed

Saraji, Mohammad; Ghani, Milad; Rezaei, Behzad; Mokhtarianpour, Maryam

2016-10-21

A new headspace liquid-phase microextraction technique based on using a copper foam nanostructure substrate followed by gas chromatography-flame ionization detection was developed for the determination of volatile organic compounds in water and wastewater samples. The copper foam with highly porous nanostructured walls was fabricated on the surface of a copper wire by a rapid and facile electrochemical process and used as the extractant solvent holder. Propyl benzoate was immobilized in the pores of the copper foam coating and used for the microextraction of benzene, toluene, ethylbenzene and xylenes. The experimental parameters such as the type of organic solvent, desorption temperature, desorption time, salt concentration, sample temperature, equilibrium time and extraction time, were investigated and optimized. Under the optimum conditions, the method detection limit was between 0.06 and 0.25μgL -1 . The relative standard deviation of the method for the analytes at 4-8μgL -1 concentration level ranged from 7.9 to 11%. The fiber-to-fiber reproducibility for three fibers prepared under the same condition was 9.3-12%. The enrichment factor was in the range of 615-744. Different water samples were analyzed for the evaluation of the method in real sample analysis. Relative recoveries for spiked tap, river and wastewater samples were in the range of 85-94%. Finally, the extraction efficiency of the method was compared with those of headspace single drop microextraction and headspace SPME with the commercial fibers. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimal design of experiments applied to headspace solid phase microextraction for the quantification of vicinal diketones in beer through gas chromatography-mass spectrometric detection.

PubMed

Leça, João M; Pereira, Ana C; Vieira, Ana C; Reis, Marco S; Marques, José C

2015-08-05

Vicinal diketones, namely diacetyl (DC) and pentanedione (PN), are compounds naturally found in beer that play a key role in the definition of its aroma. In lager beer, they are responsible for off-flavors (buttery flavor) and therefore their presence and quantification is of paramount importance to beer producers. Aiming at developing an accurate quantitative monitoring scheme to follow these off-flavor compounds during beer production and in the final product, the head space solid-phase microextraction (HS-SPME) analytical procedure was tuned through experiments planned in an optimal way and the final settings were fully validated. Optimal design of experiments (O-DOE) is a computational, statistically-oriented approach for designing experiences that are most informative according to a well-defined criterion. This methodology was applied for HS-SPME optimization, leading to the following optimal extraction conditions for the quantification of VDK: use a CAR/PDMS fiber, 5 ml of samples in 20 ml vial, 5 min of pre-incubation time followed by 25 min of extraction at 30 °C, with agitation. The validation of the final analytical methodology was performed using a matrix-matched calibration, in order to minimize matrix effects. The following key features were obtained: linearity (R(2) > 0.999, both for diacetyl and 2,3-pentanedione), high sensitivity (LOD of 0.92 μg L(-1) and 2.80 μg L(-1), and LOQ of 3.30 μg L(-1) and 10.01 μg L(-1), for diacetyl and 2,3-pentanedione, respectively), recoveries of approximately 100% and suitable precision (repeatability and reproducibility lower than 3% and 7.5%, respectively). The applicability of the methodology was fully confirmed through an independent analysis of several beer samples, with analyte concentrations ranging from 4 to 200 g L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

A molybdenum disulfide/reduced graphene oxide fiber coating coupled with gas chromatography-mass spectrometry for the saponification-headspace solid-phase microextraction of polychlorinated biphenyls in food.

PubMed

Lv, Fangying; Gan, Ning; Cao, Yuting; Zhou, You; Zuo, Rongjie; Dong, Youren

2017-11-24

In this work, the molybdenum disulfide/reduced graphene oxide (MoS 2 /RGO) composite material was synthesized as a fiber coating to extract seven indicator polychlorinated biphenyls (PCBs; PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) present in food via a saponification-headspace solid-phase microextraction assay (saponification-HS-SPME). The MoS 2 /RGO coating was prepared and deposited on a stainless steel wire with the help of a silicone sealant and used as an SPME fiber. The alkali solution dissolved the fat and helped in releasing the PCBs present in milk to the headspace for extraction under 100°C. Following desorption in the inlet, the targets were quantified by gas chromatography-mass spectrometry. The effects of sorbent dosage, extraction time, added salts, and stirring rate on the extraction efficiency were investigated. The new coating was able to adsorb a higher amount of analytes, which was about 1.1-2.9 times in comparison with the commercially available SPME fiber (coated with divinylbenzene/carboxen/polydimethylsiloxane). It also showed the highest adsorption capability toward PCBs, which was 1.5-2.7 times that of the prepared RGO modified fiber. Moreover, MoS 2 also showed a strong affinity toward PCBs in a manner similar to its affinity for graphene. The developed method is simple and environmentally friendly as it does not require any organic solvents. Furthermore, it exhibits good sensitivity with detection limits less than 0.1ngmL -1 , linearity (0.25-100ngmL -1 ), and reproducibility (relative standard deviation below 10% for n=3). The novel SPME fibers are inexpensive, reusable, and can be easily prepared and manipulated. In addition, the saponification-HS-SPME assay was also found to be suitable for screening persistent organic pollutants in dairy products. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of microextraction by packed sorbent directly coupled to an electron ionization single quadrupole mass spectrometer as an alternative for non-separative determinations.

PubMed

Casas Ferreira, Ana María; Moreno Cordero, Bernardo; Pérez Pavón, José Luis

2017-02-01

Sometimes it is not necessary to separate the individual compounds of a sample to resolve an analytical problem, it is enough to obtain a signal profile of the sample formed by all the components integrating it. Within this strategy, electronic noses based on the direct coupling of a headspace sampler with a mass spectrometer (HS-MS) have been proposed. Nevertheless, this coupling is not suitable for the analysis of non-volatile compounds. In order to propose an alternative to HS-MS determinations for non-volatile compounds, here we present the first 'proof of concept' use of the direct coupling of microextraction by packed sorbents (MEPS) to a mass spectrometer device using an electron ionization (EI) and a single quadrupole as ionization source and analyzer, respectively. As target compounds, a set of analytes with different physic-chemical properties were evaluated (2-ethyl-1-hexanol, styrene, 2-heptanone, among others). The use of MEPS extraction present many advantages, such as it is fast, simple, easy to automate and requires small volumes of sample and organic solvents. Moreover, MEPS cartridges are re-usable as samples can be extracted more than 100 times using the same syringe. In order to introduce into the system all the elution volume from the MEPS extraction, a programmable temperature vaporizer (PTV) is proposed as the injector device. Results obtained with the proposed methodology (MEPS-PTV/MS) were compared with the ones obtained based on the separative scheme, i.e. using gas chromatography separation (MEPS-PTV-GC/MS), and both methods provided similar results. Limits of detection were found to be between 3.26 and 146.6μgL -1 in the non-separative scheme and between 0.02 and 1.72μgL -1 when the separative methodology was used. Repeatability and reproducibility were evaluated with values below 17% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

PubMed

Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

2014-04-01

The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Application of the experimental design of experiments (DoE) for the determination of organotin compounds in water samples using HS-SPME and GC-MS/MS.

PubMed

Coscollà, Clara; Navarro-Olivares, Santiago; Martí, Pedro; Yusà, Vicent

2014-02-01

When attempting to discover the important factors and then optimise a response by tuning these factors, experimental design (design of experiments, DoE) gives a powerful suite of statistical methodology. DoE identify significant factors and then optimise a response with respect to them in method development. In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography tandem mass spectrometry (GC-MS/MS) methodology for the simultaneous determination of six important organotin compounds namely monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT) has been optimized using a statistical design of experiments (DOE). The analytical method is based on the ethylation with NaBEt4 and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency selected for optimization were pre-incubation time, incubation temperature, agitator speed, extraction time, desorption temperature, buffer (pH, concentration and volume), headspace volume, sample salinity, preparation of standards, ultrasonic time and desorption time in the injector. The main factors (excitation voltage, excitation time, ion source temperature, isolation time and electron energy) affecting the GC-IT-MS/MS response were also optimized using the same statistical design of experiments. The proposed method presented good linearity (coefficient of determination R(2)>0.99) and repeatibilty (1-25%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked surface and marine waters was higher than 70% for all compounds studied. Finally, the optimized methodology was applied to real aqueous samples enabled the simultaneous determination of all compounds under study in surface and marine water samples obtained from Valencia region (Spain). © 2013 Elsevier B.V. All rights reserved.

A paper-based analytical device for the determination of hydrogen sulfide in fuel oils based on headspace liquid-phase microextraction and cyclic voltammetry.

PubMed

Nechaeva, Daria; Shishov, Andrey; Ermakov, Sergey; Bulatov, Andrey

2018-06-01

An easily performed miniaturized, cheap, selective and sensitive procedure for the determination of H 2 S in fuel oil samples based on a headspace liquid-phase microextraction followed by a cyclic voltammetry detection using a paper-based analytical device (PAD) was developed. A modified wax dipping method was applied to fabricate the PAD. The PAD included hydrophobic zones of sample and supporting electrolyte connecting by hydrophilic channel. The zones of sample and supporting electrolyte were connected with nickel working, platinum auxiliary and Ag/AgCl reference electrodes. The analytical procedure included separation of H 2 S from fuel oil sample based on the headspace liquid-phase microextraction in alkaline solution. Then, sulfide ions solution obtained and supporting electrolyte were dropped on the zones followed by analyte detection at + 0.45 V. Under the optimized conditions, H 2 S concentration in the range from 2 to 20 mg kg -1 had a good linear relation with the peak current. The limit of detection (3σ) was 0.6 mg kg -1 . The procedure was successfully applied to the analysis of fuel oil samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Electromembrane Surrounded Solid Phase Microextraction Followed by Injection Port Derivatization and Gas Chromatography-Flame Ionization Detector Analysis for Determination of Acidic Herbicides in Plant Tissue.

PubMed

Rezazadeh, Maryam; Yamini, Yadollah; Seidi, Shahram; Tahmasebi, Elham; Rezaei, Fatemeh

2014-04-09

Electromembrane surrounded solid phase microextraction (EM-SPME) of acidic herbicides was studied for the first time. In order to investigate the capability of this new microextraction technique to analyze acidic targets, chlorophenoxy acid (CPA) herbicides were quantified in plant tissue. 1-Octanol, was sustained in the pores of the wall of a hollow fiber and served as supported liquid membrane (SLM). Other EM-SPME related parameters, including extraction time, applied voltage, and pHs of the sample solution and the acceptor phase, were optimized using experimental design. A 20 min time frame was needed to reach the highest extraction efficiency of the analytes from a 24 mL alkaline sample solution across the organic liquid membrane and into the aqueous acceptor phase through a 50 V electrical field, and to their final adsorption on a carbonaceous anode. In addition to high sample cleanup, which made the proposed method appropriate for analysis of acidic compounds in a complicated media (plant tissue), 4.8% of 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 0.6% of 2,4-dichlorophenoxyacetic acid (2,4-D) were adsorbed on the anode, resulting in suitable detection limits (less than 5 ng mL -1 ), and admissible repeatability and reproducibility (intra- and interassay precision were in the ranges of 5.2-8.5% and 8.8-12.0%, respectively). Linearity of the method was scrutinized within the ranges of 1.0-500.0 and 10.0-500.0 ng mL -1 for MCPA and 2,4-D, respectively, and coefficients of determination greater than 0.9958 were obtained. Optimal conditions of EM-SPME of the herbicides were employed for analysis of CPAs in whole wheat tissue.

Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS.

PubMed

Ye, Qing

2013-06-01

In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

PubMed

Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

2015-05-22

Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

HS-SPME analysis of volatile organic compounds of coniferous needle litter

NASA Astrophysics Data System (ADS)

Isidorov, V. A.; Vinogorova, V. T.; Rafałowski, K.

The composition of volatile emission of Scots pine ( Pinus sylvestris) and spruce ( Picea exelsa) litter was studied by gas chromatography-mass spectrometry (GC-MS) and samples were collected by solid-phase microextraction (SPME) method. The list of identified compounds includes over 60 organic substances of different classes. It was established that volatile emission contain not only components of essential oils of pine and spruce needles but also a large number of organic compounds which are probably secondary metabolites of litter-decomposing fungi. They include lower carbonyl compounds and alcohols as well as products of terpene dehydration and oxidation. These data show that the processes of litter decomposition are an important source of reactive organic compounds under canopy of coniferous forests.

Volatile compounds of dry beans (Phaseolus vulgaris L.).

PubMed

Oomah, B Dave; Liang, Lisa S Y; Balasubramanian, Parthiba

2007-12-01

Volatile compounds of uncooked dry bean (Phaseolus vulgaris L.) cultivars representing three market classes (black, dark red kidney and pinto) grown in 2005 were isolated with headspace solid phase microextraction (HS-SPME), and analyzed with gas chromatography mass spectrometry (GC-MS). A total of 62 volatiles consisting of aromatic hydrocarbons, aldehydes, alkanes, alcohols and ketones represented on average 62, 38, 21, 12, and 9 x 10(6) total area counts, respectively. Bean cultivars differed in abundance and profile of volatiles. The combination of 18 compounds comprising a common profile explained 79% of the variance among cultivars based on principal component analysis (PCA). The SPME technique proved to be a rapid and effective method for routine evaluation of dry bean volatile profile.

Quantitation of zolpidem in biological fluids by electro-driven microextraction combined with HPLC-UV analysis.

PubMed

Yaripour, Saeid; Mohammadi, Ali; Esfanjani, Isa; Walker, Roderick B; Nojavan, Saeed

2018-01-01

In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R 2 >0.9991) with repeatability ( %RSD) between 0.3 % and 7.3 % ( n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %.

Quantitation of zolpidem in biological fluids by electro-driven microextraction combined with HPLC-UV analysis

PubMed Central

Yaripour, Saeid; Mohammadi, Ali; Esfanjani, Isa; Walker, Roderick B.; Nojavan, Saeed

2018-01-01

In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R2 >0.9991) with repeatability ( %RSD) between 0.3 % and 7.3 % (n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %. PMID:29805344

Development and application of a new solid-phase microextraction fiber by sol-gel technology on titanium wire.

PubMed

Es-haghi, Ali; Hosseini, Seyed Maryam; Khoshhesab, Zahra Monsef

2012-09-12

Novel solid-phase microextraction fibers were prepared based on sol-gel technique. Commonly used fused silica substrate was replaced by titanium wire which provided high strength and longer fiber life cycle. Titanium isopropoxide was employed as the precursor which provides a sol solution containing Ti-OH groups and shows more tendencies to the molecularly similar group on the substrate. Three different polymers, poly (dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol)-monobutyl ether (Ucon) and polyethylene glycol (PEG) were employed as coating polymer in preparing three different fibers. The applicability of these fibers was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water sample followed by gas chromatography-mass spectrometry (GC-MS). Effects of different parameters such as fiber coating type, extraction condition, desorption condition were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.75-10 μg L(-1) (S/N=3) and 1-20 μg L(-1) (S/N=10) were respectively obtained. The method showed linearity in the range of 10-25,000 μg L(-1) with correlation coefficient of >0.99. The relative standard deviation was less than 8%. Copyright © 2012 Elsevier B.V. All rights reserved.

Headspace Solid-Phase Microextraction and Ultrasonic Extraction with the Solvent Sequences in Chemical Profiling of Allium ursinum L. Honey.

PubMed

Jerković, Igor; Kuś, Piotr M

2017-11-06

A volatile profile of ramson (wild garlic, Allium ursinum L.) honey was investigated by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) followed by gas chromatography and mass spectrometry (GC-FID/GC-MS) analyses. The headspace was dominated by linalool derivatives: cis - and trans -linalool oxides (25.3%; 9.2%), hotrienol (12.7%), and linalool (5.8%). Besides direct extraction with dichloromethane and pentane/diethyl ether mixture (1:2, v / v ), two solvent sequences (I: pentane → diethyl ether; II: pentane → pentane/diethyl ether (1:2, v / v ) → dichloromethane) were applied. Striking differences were noted among the obtained chemical profiles. The extracts with diethyl ether contained hydroquinone (25.8-36.8%) and 4-hydroxybenzoic acid (11.6-16.6%) as the major compounds, while ( E )-4-(r-1',t-2',c-4'-trihydroxy-2',6',6'-trimethylcyclohexyl)but-3-en-2-one predominated in dichloromethane extracts (18.3-49.1%). Therefore, combination of different solvents was crucial for the comprehensive investigation of volatile organic compounds in this honey type. This particular magastigmane was previously reported only in thymus honey and hydroquinone in vipers bugloss honey, while a combination of the mentioned predominant compounds is unique for A. ursinum honey.

Graphene oxide based sol-gel stainless steel fiber for the headspace solid-phase microextraction of organophosphate ester flame retardants in water samples.

PubMed

Jin, Tingting; Cheng, Jing; Cai, Cuicui; Cheng, Min; Wu, Shiju; Zhou, Hongbin

2016-07-29

In this paper, graphene oxide was coated onto a stainless steel wire through sol-gel technique and it was used as a solid phase microextraction (SPME) fiber. The prepared fiber was characterized by scanning electron microscopy (SEM), which displayed that the fiber had crinkled surface and porous structure The application of the fiber was evaluated through the headspace SPME of nine organophosphate ester flame retardants (OPFRs) with different characteristics in water samples followed by gas chromatography and nitrogen-phosphorous detector (GC/NPD). The major factors influencing the extraction efficiency, including the extraction and desorption conditions, were studied and optimized. Under the optimum conditions, the proposed method was evaluated, and applied to the analysis of organophosphate ester flame retardants in real environmental water samples. The results demonstrated the HS-SPME method based on GO sol-gel fiber had good linearity (R>0.9928), and limits of detection (1.4-135.6ngL(-1)), high repeatability (RSD<9.8%) and good recovery (76.4-112.4%). The GO based sol-gel fiber displayed bigger extraction capability than the commercial PDMS fiber and the pure sol-gel fiber for both polar and apolar organophosphate esters, especially for the OPFRs containing benzene rings. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of in vivo solid phase microextraction for minimally invasive analysis of nonvolatile phytochemicals in Amazonian plants.

PubMed

Musteata, Florin Marcel; Sandoval, Manuel; Ruiz-Macedo, Juan C; Harrison, Kathleen; McKenna, Dennis; Millington, William

2016-08-24

Although solid phase microextraction (SPME) has been used extensively for fingerprinting volatile compounds emitted by plants, there are very few such reports for direct insertion SPME. In this research, direct contact of SPME probes with the interstitial fluid of plants was investigated as a method for phytochemical analysis. Medicinal plants from the Amazon have been the source of numerous drugs used in western medicine. However, a large number of species used in traditional medicine have not been characterized chemically, partly due to the difficulty of field work. In this project, the phytochemical composition of plants from several genera was fingerprinted by combining convenient field sampling by solid phase microextraction (SPME) with laboratory analysis by LC-MS. The new method was compared with classical sampling followed by liquid extraction (LE). SPME probes were prepared by coating stainless steel wires with a mixture of polyacrylonitrile and either RP-amide or HS-F5 silica particles. Sampling was performed by inserting the microextraction probes into various tissues of living plants in their natural environment. After in vivo extraction, the probes were sealed under vacuum and refrigerated until analyzed. The probes were desorbed in mobile phase and analyzed on a Waters Acquity UPLC with triple quadrupole mass spectrometer in positive ion mode. Twenty Amazonian plant species were sampled and unique metabolomic fingerprints were obtained. In addition, quantitative analysis was performed for previously identified compounds in three species. Comparison of the fingerprints obtained by in vivo SPME with those obtained by LE showed that 27% of the chromatographic features were unique to SPME, 57% were unique to LE, and 16% were common to both methods. In vivo SPME caused minimal damage to the plants, was much faster than traditional liquid extraction, and provided unique fingerprints for all investigated plants. SPME revealed unique chromatographic features, undetected by traditional extraction, although it produced only half as many peaks as ethanol extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

Approaches of aroma extraction dilution analysis (AEDA) for headspace solid phase microextraction and gas chromatography-olfactometry (HS-SPME-GC-O): Altering sample amount, diluting the sample or adjusting split ratio?

PubMed

Feng, Yunzi; Cai, Yu; Sun-Waterhouse, Dongxiao; Cui, Chun; Su, Guowan; Lin, Lianzhu; Zhao, Mouming

2015-11-15

Aroma extract dilution analysis (AEDA) is widely used for the screening of aroma-active compounds in gas chromatography-olfactometry (GC-O). In this study, three aroma dilution methods, (I) using different test sample volumes, (II) diluting samples, and (III) adjusting the GC injector split ratio, were compared for the analysis of volatiles by using HS-SPME-AEDA. Results showed that adjusting the GC injector split ratio (III) was the most desirable approach, based on the linearity relationships between Ln (normalised peak area) and Ln (normalised flavour dilution factors). Thereafter this dilution method was applied in the analysis of aroma-active compounds in Japanese soy sauce and 36 key odorants were found in this study. The most intense aroma-active components in Japanese soy sauce were: ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl 4-methylpentanoate, 3-(methylthio)propanal, 1-octen-3-ol, 2-methoxyphenol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol, 2-phenylethanol, and 4-hydroxy-5-ethyl-2-methyl-3(2H)-furanone. Copyright © 2015. Published by Elsevier Ltd.

A new method for the determination of short-chain fatty acids from the aliphatic series in wines by headspace solid-phase microextraction-gas chromatography-ion trap mass spectrometry.

PubMed

Olivero, Sergio J Pérez; Trujillo, Juan P Pérez

2011-06-24

A new analytical method for the determination of nine short-chain fatty acids (acetic, propionic, isobutyric, butyric, isovaleric, 2-methylbutyric, hexanoic, octanoic and decanoic acids) in wines using the automated HS/SPME-GC-ITMS technique was developed and optimised. Five different SPME fibers were tested and the influence of different factors such as temperature and time of extraction, temperature and time of desorption, pH, strength ionic, tannins, anthocyans, SO(2), sugar and ethanol content were studied and optimised using model solutions. Some analytes showed matrix effect so a study of recoveries was performed. The proposed HS/SPME-GC-ITMS method, that covers the concentration range of the different analytes in wines, showed wide linear ranges, values of repeatability and reproducibility lower than 4.0% of RSD and detection limits between 3 and 257 μgL(-1), lower than the olfactory thresholds. The optimised method is a suitable technique for the quantitative analysis of short-chain fatty acids from the aliphatic series in real samples of white, rose and red wines. Copyright © 2011 Elsevier B.V. All rights reserved.

HS-SPME-GC-MS/MS Method for the Rapid and Sensitive Quantitation of 2-Acetyl-1-pyrroline in Single Rice Kernels.

PubMed

Hopfer, Helene; Jodari, Farman; Negre-Zakharov, Florence; Wylie, Phillip L; Ebeler, Susan E

2016-05-25

Demand for aromatic rice varieties (e.g., Basmati) is increasing in the US. Aromatic varieties typically have elevated levels of the aroma compound 2-acetyl-1-pyrroline (2AP). Due to its very low aroma threshold, analysis of 2AP provides a useful screening tool for rice breeders. Methods for 2AP analysis in rice should quantitate 2AP at or below sensory threshold level, avoid artifactual 2AP generation, and be able to analyze single rice kernels in cases where only small sample quantities are available (e.g., breeding trials). We combined headspace solid phase microextraction with gas chromatography tandem mass spectrometry (HS-SPME-GC-MS/MS) for analysis of 2AP, using an extraction temperature of 40 °C and a stable isotopologue as internal standard. 2AP calibrations were linear between the concentrations of 53 and 5380 pg/g, with detection limits below the sensory threshold of 2AP. Forty-eight aromatic and nonaromatic, milled rice samples from three harvest years were screened with the method for their 2AP content, and overall reproducibility, observed for all samples, ranged from 5% for experimental aromatic lines to 33% for nonaromatic lines.

Measurement of natural carbon isotopic composition of acetone in human urine.

PubMed

Yamada, Keita; Ohishi, Kazuki; Gilbert, Alexis; Akasaka, Mai; Yoshida, Naohiro; Yoshimura, Ryoko

2016-02-01

The natural carbon isotopic composition of acetone in urine was measured in healthy subjects using gas chromatography-combustion-isotope ratio mass spectrometry combined with headspace solid-phase microextraction (HS-SPME-GC-C-IRMS). Before applying the technique to a urine sample, we optimized the measurement conditions of HS-SPME-GC-C-IRMS using aqueous solutions of commercial acetone reagents. The optimization enabled us to determine the carbon isotopic compositions within ±0.2 ‰ of precision and ±0.3‰ of error using 0.05 or 0.2 mL of aqueous solutions with acetone concentrations of 0.3-121 mg/L. For several days, we monitored the carbon isotopic compositions and concentrations of acetone in urine from three subjects who lived a daily life with no restrictions. We also monitored one subject for 3 days including a fasting period of 24 h. These results suggest that changes in the availability of glucose in the liver are reflected in changes in the carbon isotopic compositions of urine acetone. Results demonstrate that carbon isotopic measurement of metabolites in human biological samples at natural abundance levels has great potential as a tool for detecting metabolic changes caused by changes in physiological states and disease.

Application of HS-SPME and GC-MS to characterization of volatile compounds emitted from Osmanthus flowers.

PubMed

Deng, Chunhui; Song, Guoxin; Hu, Yaoming

2004-12-01

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was developed for characterization of volatile compounds emitted from two varieties Osmanthus flowers of O. fragrans var. latifolius and O. fragrans var. thunbergii. The SPME parameters were studied, the optimum conditions of a 65 microm carbowax/divinylbenzene (CW/DVB), extraction temperature of 22 degrees C and extraction time of 10 min were obtained and applied to extraction of the volatile emissions. Fourteen compounds released from both varieties of Osmanthus flowers were separated and identified by GC-MS, which mainly included alpha-linalool, beta-linalool, trans-linalool oxide, cis-linalool oxide, alpha-lonone, beta-lonone, capraldehyde and decalactone. By comparing their peak areas, we found that the sums of the fourteen compounds from the two Osmanthus flowers were very close, while the relative contents of individual volatile compounds in the two emissions were very different. The relative content of alpha-linalool and beta-linalool in O. fragrans var. latifolius were 39.46% and 0.51%, while in O. fragrans var. thunbergii were 9.53% and 27.71%. Due to their different relative contents, the two varieties of flower have different fragrances.

The effect of short-term cardiac rehabilitation after acute myocardial infarction on high-sensitivity C-reactive protein.

PubMed

Mlakar, Polona; Salobir, Barbara; Cobo, Nusret; Jug, Borut; Terčelj, Marjeta; Sabovič, Mišo

2014-03-01

High-sensitivity C-reactive protein (hsCRP) is an important biomarker of risk for coronary heart disease morbidity and mortality. We investigated the influence of short-term cardiac rehabilitation (CR) after acute myocardial infarction (AMI) on values of hsCRP and classical risk factors, including metabolic syndrome. hsCRP and classical risk factors were measured before and after completed 2-week CR program in 30 men after AMI. The comparison group comprised 30 age-balanced healthy men, with no risk factors for coronary heart disease. As expected, in comparison to healthy individuals, patients had higher values of hsCRP; furthermore, smokers had significantly higher hsCRP values than nonsmokers. Patients had more expressed markers of metabolic syndrome and due to pharmacological therapy lower blood pressure, total cholesterol and low-density lipoprotein cholesterol (LDL-C). After CR was completed, a significant drop in hsCRP (P=0.006) and improvement of metabolic syndrome parameters (lower body mass index, blood pressure, LDL-C, triglycerides) was observed in nonsmokers, whereas no such changes occurred in smokers. Our study revealed that hsCRP and metabolic syndrome parameters can be substantially reduced by a 2-week CR program; however, this effect is present only in nonsmokers. Thus, all patients entering the CR program after AMI should be advised to quit smoking before entering the program to achieve optimal benefits.

Damage-Associated Molecular Patterns (DAMPs) in Resuscitated Hemorrhagic Shock Are Mitigated by Peritoneal Fluid Administration.

PubMed

Matheson, Paul J; Eid, Mark A; Wilson, Matthew A; Graham, Victoria S; Matheson, Samuel A; Weaver, Jessica Lee; Downard, Cynthia D; Smith, Jason W

2018-05-03

Conventional resuscitation (CR) of hemorrhagic shock (HS), a significant cause of trauma mortality, is I.V. blood and fluids. CR restores central hemodynamics, but vital organ flow can drop causing hypoperfusion, hypoxia, Damage-Associated Molecular Patterns (DAMPs), and remote organ dysfunction (i.e., lung). CR plus Direct Peritoneal Resuscitation (DPR) prevents intestinal and hepatic hypoperfusion. We hypothesized that DPR prevents lung injury in HS/CR by altering DAMPs. Anesthetized male SD rats were randomized to groups (n=8/group) in one of two sets: 1) Sham (no HS, CR, or DPR); 2) HS/CR (HS=40% MAP for 60min, CR=shed blood + 2 volumes NS); or 3) HS/CR+DPR. First set underwent whole lung blood flow by colorimetric microspheres. Second set underwent tissue collection for Luminex, ELISAs, and histopathology. Lipopolysaccharide (LPS) and DAMPs were measured in serum and/or lung including cytokines, hyaluronic acid (HA), high mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), MYD88, and TRIF. Statistics were by ANOVA and Tukey-Kramer test with a priori P<0.05. HS/CR increased serum LPS, HA, HMGB1 and some cytokines (IL-1α, IL-1β, IL-6, and interferon-γ). Lung TLR4 and MYD88 were increased but not TRIF compared to Shams. HS/CR+DPR decreased LPS, HA, cytokines, HMGB1, TLR4, and MYD88 levels but did not alter TRIF compared to HS/CR. Data suggest that gut-derived DAMPs can be modulated by adjunctive DPR to prevent activation of lung TLR-4-mediated processes. Also, DPR improved lung blood flow and reduced lung tissue injury. Adjunctive DPR in HS/CR potentially improves morbidity/mortality by down-regulating the systemic DAMP response.

Suitable conditions for liquid-phase microextraction using solidification of a floating drop for extraction of fat-soluble vitamins established using an orthogonal array experimental design.

PubMed

Sobhi, Hamid Reza; Yamini, Yadollah; Esrafili, Ali; Abadi, Reza Haji Hosseini Baghdad

2008-07-04

A simple, rapid and efficient microextraction method for the extraction and determination of some fat-soluble vitamins (A, D2, D3) in aqueous samples was developed. For the first time orthogonal array designs (OADs) were employed to screen the liquid-phase microextraction (LPME) method in which few microliters of 1-undecanol were delivered to the surface of the aqueous sample and it was agitated for a selected time. Then sample vial was cooled by inserting it into an ice bath for 5 min. The solidified solvent was transferred into a suitable vial and immediately melted. Then, the extract was directly injected into a high-performance liquid chromatography (HPLC) for analysis. Several factors affecting the microextraction efficiency such as sample solution temperature, stirring speed, volume of the organic solvent, ionic strength and extraction time were investigated and screened using an OA16 (4(5)) matrix. Under the best conditions (temperature, 55 degrees C; stirring speed, 1000 rpm; the volume of extracting solvent, 15.0 microL; no salt addition and extraction time, 60 min), detection limits of the method were in the range of 1.0-3.5 microgL(-1). The relative standard deviations (RSDs) to determine the vitamins at microg L(-1) levels by applying the proposed method varied in the range of 5.1-10.7%. Dynamic linear ranges of 5-500 mugL(-1) with good correlation coefficients (0.9984

Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry.

PubMed

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2008-10-31

A simple, rapid, solventless method for the determination of trihalomethanes (THMs) (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in water samples is presented. The analytes are extracted from the headspace of the aqueous matrix into a 2 microL drop of the ionic liquid 1-octyl-3-methyl-imidazolium hexafluorophosphate working at 30 degrees C for 30 min. The separation and detection of the target compounds is accomplished by gas chromatography/mass spectrometry owing to the use of an interface that efficiently transfers the analytes extracted in the ionic liquid drop to the gas chromatograph while preventing the ionic liquid from entering the column. The detection limits obtained are below the values compelled by the legislation, ranging from 0.5 microg L(-1) for chloroform and bromodichloromethane to 0.9 microg L(-1) for dibromochloromethane. The use of ionic liquid in the extraction procedure avoids the use of organic solvents and leads to relative standard deviations that range from 3.1% to 4.8%.

Characterisation of volatile profiles in 50 native Peruvian chili pepper using solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS).

PubMed

Patel, Kirti; Ruiz, Candy; Calderon, Rosa; Marcelo, Mavel; Rojas, Rosario

2016-11-01

The volatiles were characterised by headspace solid phase micro extraction (HS-SPME), gas chromatography mass spectrometry (GC-FID/MS). A total of 127 compounds were identified with terpenes (including mono terpenes and sesquiterpenes - a total of 45 compounds), esters (31 compounds) and hydrocarbons (20 compounds) were the predominant volatile compounds. Principal component analysis (PCA) of the volatile compounds yielded 2 significant PC's, which together accounted for 90.3% of the total variance in the data set and the scatter plot generated between PC1 and PC2 successfully segregated the 50 chili pepper samples into 7 groups. Clusters of hydrocarbons, esters, terpenes, aldehyde and ketones formed the major determinants of the difference. Copyright © 2016 Elsevier Ltd. All rights reserved.

A modified multiscale peak alignment method combined with trilinear decomposition to study the volatile/heat-labile components in Ligusticum chuanxiong Hort - Cyperus rotundus rhizomes by HS-SPME-GC/MS.

PubMed

He, Min; Yan, Pan; Yang, Zhi-Yu; Zhang, Zhi-Min; Yang, Tian-Biao; Hong, Liang

2018-03-15

Head Space/Solid Phase Micro-Extraction (HS-SPME) coupled with Gas Chromatography/Mass Spectrometer (GC/MS) was used to determine the volatile/heat-labile components in Ligusticum chuanxiong Hort - Cyperus rotundus rhizomes. Facing co-eluting peaks in k samples, a trilinear structure was reconstructed to obtain the second-order advantage. The retention time (RT) shift with multi-channel detection signals for different samples has been vital in maintaining the trilinear structure, thus a modified multiscale peak alignment (mMSPA) method was proposed in this paper. The peak position and peak width of representative ion profile were firstly detected by mMSPA using Continuous Wavelet Transform with Haar wavelet as the mother wavelet (Haar CWT). Then, the raw shift was confirmed by Fast Fourier Transform (FFT) cross correlation calculation. To obtain the optimal shift, Haar CWT was again used to detect the subtle deviations and be amalgamated in calculation. Here, to ensure there is no peaks shape alternation, the alignment was performed in local domains of data matrices, and all data points in the peak zone were moved via linear interpolation in non-peak parts. Finally, chemical components of interest in Ligusticum chuanxiong Hort - Cyperus rotundus rhizomes were analyzed by HS-SPME-GCMS and mMSPA-alternating trilinear decomposition (ATLD) resolution. As a result, the concentration variation between herbs and their pharmaceutical products can provide a scientific basic for the quality standard establishment of traditional Chinese medicines. Copyright © 2018 Elsevier B.V. All rights reserved.

Why do Ladybugs Smell Bad? In-vivo Quantification of Odorous Insect Kairomones with SPME and Multidimensional GC-MS-Olfactometry

NASA Astrophysics Data System (ADS)

Cai, Lingshuang; Koziel, Jacek A.; O'Neal, Matthew E.

2009-05-01

Winemakers, small fruit growers, and homeowners are concerned with noxious compounds released by multicolored Asian ladybird beetles (Harmonia axyridis, Coleoptera: Coccinellidae). New method based on headspace solid phase microextraction (HS-SPME) coupled with multidimensional gas chromatography mass spectrometry—olfactometry (MDGC-MS-O) system was developed for extraction, isolation and simultaneous identification of compounds responsible for the characteristic odor of live H. axyridis. Four methoxypyrazines (MPs) were identified in headspace volatiles of live H. axyridis as those responsible for the characteristic odor: 2, 5-dimethy1-3-methoxypyrazine (DMMP), 2-isopropy1-3-methoxypyrazine (IPMP), 2-sec-buty1-3-methoxypyrazine (SBMP), and 2-isobuty1-3-methoxypyrazine (IBMP). To the best of our knowledge this is the first report of H. axyridis releasing DMMP and the first report of this compound being a component of the H. axyridis characteristic odor. Quantification of three MPs (IPMP, SBMP and IBMP) emitted from live H. axyridis were performed using external calibration with HS-SPME and direct injections. A linear relationship (R2>0.9958 for all 3 MPs) between MS response and concentration of standard was observed over a concentration range from 0.1 ng L-1 to 0.05 μg L-1 for HS-SPME-GC-MS. The method detection limits (MDL) based on multidimensional GC-MS approach for three MPs were estimated to be between 0.020 ng L-1. to 0.022 ng L-1. This methodology is applicable for in vivo determination of odor-causing chemicals associated with emissions of volatiles from insects.

Anti-malarial activity and HS-SPME-GC-MS chemical profiling of Plinia cerrocampanensis leaf essential oil

PubMed Central

2014-01-01

Background Plinia cerrocampanensis is an endemic plant of Panama. The leaf essential oil of this plant has shown antibacterial activity. However, anti-malarial activity and chemical profiling by HS-SPME-GC-MS of this essential oil have not been reported before. Methods Anti-malarial activity of the essential oil (EO) was evaluated in vitro against chloroquine-sensitive HB3 and chloroquine-resistant W2 strains of Plasmodium falciparum. Synergistic effect of chloroquine and the EO on parasite growth was evaluated by calculating the combination index. A methodology involving headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) was developed to investigate the composition of Plinia cerrocampanensis EO. Results Plinia cerrocampanensis EO showed a high anti-malarial activity and a synergistic interaction with chloroquine. The Plinia cerrocampanensis EO inhibited P. falciparum growth in vitro at an IC50 of 7.3 μg/mL. Chloroquine together with the EO decreased the IC50 of chloroquine from 0.1 μg/mL to 0.05 μg/mL, and of the EO from 7.3 μg/mL to 1.1 μg/mL. The measured combination index was 0.58, which clearly indicates that the EO acts synergistically with chloroquine. Since the EO maintained its inhibitory activity on the chloroquine-sensitive strain of the parasite, it could be acting by a different mechanism of action than chloroquine. The best HS-SPME-GC-MS analytical conditions were obtained when the temperature of extraction was 49°C, incubation time 14 min, and the time of extraction 10 min. This method allowed for the identification of 53 volatile constituents in the EO, including new compounds not reported earlier. Conclusions The anti-malarial activity exhibited by the Plinia cerrocampanensis EO may lend support for its possible use as an alternative for anti-malarial therapy. PMID:24410874

Direct screening of ground water samples for fuel oxygenates by headspace liquid phase microextraction-gas chromatography.

PubMed

Kaykhaii, Massoud; Mirbaloochzahi, Mohammad Reza

2008-12-01

The applicability of the headspace liquid phase microextraction and gas chromatography (HS-LPME/GC) for the expeditious and reliable screening of 68 well water samples for selected fuel oxygenates compounds, viz. methyl tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), ethyl tertiary-butyl ether (ETBE) and n-butyl ethyl ether (n-BEE) has been evaluated. The method used 3 microl of 1:1 benzyl alcohol/1-octanol as extraction solvent, 20 min extraction time with stirring at 1,250 rpm, at 20 degrees C and salt addition of a mixture of 0.3 g ml(-1) sodium sulphate/0.1 g ml(-1) sodium chloride. The enrichment factors of this method were from 171 to 571. Limits of detection were in the range of 77-110 ng l(-1). The relative standard deviations (RSDs) at 0.05, 0.50 and 10.0 mg l(-1) of spiking levels were in the range of 1.28-6.80% with recoveries between 96.2 and 106.0%. Sixty-eight groundwater wells that were located near different gasoline reservoirs in eight largest cities of the Sistan and Balouchestan province were screened by the method. Eight contaminated wells were identified contained MTBE at levels between 0.3 and 1.7 mg l(-1). In all cases, other target analytes were at low concentrations or not detected.

Head space solid phase microextraction based on nano-structured lead dioxide: application to the speciation of volatile organoselenium in environmental and biological samples.

PubMed

Ghasemi, Ensieh; Farahani, Hadi

2012-10-05

A novel and efficient speciation method based on the nano-structured lead dioxide as stationary phase of head space solid phase microextraction combined with gas chromatography mass spectrometry (GC-MS) was developed for the determination of volatile organoselenium compounds (dimethylselenide (DMSe) and dimethyldiselenide (DMDSe)) in different biological and environmental samples. PbO(2) particles with a diameter in the range of 50-70 nm have been grown on platinum wire via elechtrochemical deposition. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-SPME were condition of coating preparation, desorption time, stirring rate, desorption temperature, ionic strength, time and temperature of extraction. A Plackett-Burman design was performed for screening in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by a Box-Behnken design (BBD) and the response surface equations were derived. The detection limit and relative standard deviation (RSD) (n=5, c=50 μgL(-1)) for DMSe were 16 ngL(-1) and 4.3%, respectively. They were also obtained for DMDSe as 11ngL(-1) and 4.6%, respectively. The developed technique was found to be applicable to spiked environmental and biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

A platinized stainless steel fiber with in-situ coated polyaniline/polypyrrole/graphene oxide nanocomposite sorbent for headspace solid-phase microextraction of aliphatic aldehydes in rice samples.

PubMed

Ghiasvand, Alireza; Nasirian, Afagh; Koonani, Samira; Nouriasl, Kolsoum

2017-12-01

The surface of a stainless steel fiber was made larger, porous and cohesive by platinizing for tight attachment of its coating. Then it was coated by a polyaniline/polypyrrole/graphene oxide (PANI/PP/GO) nanocomposite film using electrochemical polymerization. The prepared PANI/PP/GO fiber was used for headspace solid-phase microextraction (HS-SPME) of linear aliphatic aldehydes in rice samples followed by GC-FID determination. To achieve the highest extraction efficiency, various experimental parameters including extraction time and temperature, matrix modifier and desorption condition were studied. The linear calibration curves were obtained over the range of 0.05-20 μg g -1 (R 2  > 0.99) for C 4 -C 11 aldehydes. The limits of detection were found to be in the range of 0.01-0.04 μg g -1 . RSD values were calculated to be <7.4 and 10.7% for intra- and inter-day, respectively. The superiority of the prepared nanocomposite SPME fiber was established by comparison of its results with those obtained by polydimethylsiloxane, carbowax-divinylbenzene, divinylbenzene-carboxen-polydimethylsiloxane and polyacrylate commercial ones. Finally, the nanocomposite fiber was used to extract and determine linear aliphatic aldehydes in 18 rice samples. Copyright © 2017 John Wiley & Sons, Ltd.

Development of the HS-SPME-GC-MS/MS method for analysis of chemical warfare agent and their degradation products in environmental samples.

PubMed

Nawała, Jakub; Czupryński, Krzysztof; Popiel, Stanisław; Dziedzic, Daniel; Bełdowski, Jacek

2016-08-24

After World War II approximately 50,000 tons of chemical weapons were dumped in the Baltic Sea by the Soviet Union under the provisions of the Potsdam Conference on Disarmament. These dumped chemical warfare agents still possess a major threat to the marine environment and to human life. Therefore, continue monitoring of these munitions is essential. In this work, we present the application of new solid phase microextraction fibers in analysis of chemical warfare agents and their degradation products. It can be concluded that the best fiber for analysis of sulfur mustard and its degradation products is butyl acrylate (BA), whereas for analysis of organoarsenic compounds and chloroacetophenone, the best fiber is a co-polymer of methyl acrylate and methyl methacrylate (MA/MMA). In order to achieve the lowest LOD and LOQ the samples should be divided into two subsamples. One of them should be analyzed using a BA fiber, and the second one using a MA/MMA fiber. When the fast analysis is required, the microextraction should be performed by use of a butyl acrylate fiber because the extraction efficiency of organoarsenic compounds for this fiber is acceptable. Next, we have elaborated of the HS-SPME-GC-MS/MS method for analysis of CWA degradation products in environmental samples using laboratory obtained fibers The analytical method for analysis of organosulfur and organoarsenic compounds was optimized and validated. The LOD's for all target chemicals were between 0.03 and 0.65 ppb. Then, the analytical method developed by us, was used for the analysis of sediment and pore water samples from the Baltic Sea. During these studies, 80 samples were analyzed. It was found that 25 sediments and 5 pore water samples contained CWA degradation products such as 1,4-dithiane, 1,4-oxathiane or triphenylarsine, the latter being a component of arsine oil. The obtained data is evidence that the CWAs present in the Baltic Sea have leaked into the general marine environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Analytical Determination of KDOC-Values of Polycyclic Musk Compounds with HS-SPME and GC/MS/MS

NASA Astrophysics Data System (ADS)

Böhm, L.; Düring, R.-A.

2009-04-01

Polycyclic musk compounds, used as fragrances in cosmetics and detergents, get into rivers via domestic wastewater and sewage treatment plants and with sewage sludge as fertilizer into soils. Because of their persistence and lipophilic character they accumulate in biota, so they are pollutants with environmental relevance. The coefficient KDOC is used to quantify the distribution of substances between aqueous phase and dissolved organic matter (DOM) which is quantified by the determination of dissolved organic carbon (DOC). DOM is of specific relevance for the transport and fate of persistent and lipophilic compounds in the environment. The affinity to DOM increases, the more lipophilic a substance is. So the environmental mobility is enhanced with increasing binding on DOM. For that reason, measured KDOC-values are important to predict the fate and behaviour of chemicals in the environment and should be used for environmental fate modelling purposes. LITZ ET AL. (2007) state that, to carry out a risk-assessment for polycyclic musk compounds, further research on their sorption-behaviour is necessary. For the determination of KDOC-values, different concentrations of humic acid were spiked with a multi-component stock solution. The samples were analysed with headspace solid-phase microextraction in combination with gas chromatography coupled with mass spectrometry (HS-SPME GC/MS/MS). The KDOC-values were calculated according to YABUTA ET AL. (2004). The method was validated with single substance stock solutions and with polycyclic aromatic hydrocarbons (PAHs). The results show that the method is applicable, repeatable and suitable to get KDOC-values for many substances very fast, cheap and solvent-free. With our results KDOC-values for polycyclic musk compounds were determined for the first time. Literature LITZ, N. TH., MüLLER, J. AND BöHMER, W. (2007): Occurrence of Polycyclic Musks in Sewage Sludge and their Behaviour in Soils and Plants. Part 2: Investigation of Polycyclic Musks in Soils and Plants. J Soils Sediments 7: 36-44 YABUTA, H., FUKUSHIMA, M., TANAKA, F., ICHIKAWA, H. AND TATSUMI, K. (2004): Solid-phase Microextraction for the Evaluation of Partition Coefficients of a Chlorinated Dioxin and Hexachlorobenzene into Humic Substances. Anal. Sci. 20: 787-791

Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting.

PubMed

Altaki, M S; Santos, F J; Galceran, M T

2011-06-15

In this work, we evaluated the occurrence of furan in brews obtained from regular, decaffeinated, and instant coffee and commercial packed capsules. For this purpose, a previously developed automated headspace solid-phase microextraction method coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used. Initially, the influence of HS-SPME conditions on furan formation was evaluated. In addition, the effect of roasting conditions (temperature and time) used for coffee beans on furan formation was also studied. We found that low temperature and long roasting time (140°C and 20min) decreases the final furan content. Furan concentrations in regular ground coffee brews from an espresso coffee machine were higher (43-146ng/ml) than those obtained from a home drip coffee maker (20 and 78ng/ml), while decaffeinated coffee brews from a home drip coffee maker (14-65ng/ml) showed a furan concentration similar to that obtained from regular coffee. Relatively low concentrations of this compound (12-35ng/ml) were found in instant coffee brews, while commercial packed coffee capsules showed the highest concentrations (117-244ng/ml). Finally, the daily intake of furan through coffee consumption in Barcelona (Spain) (0.03-0.38μg/kg of body weight) was estimated. Copyright © 2010 Elsevier Ltd. All rights reserved.

Sol-gel-based SPME fiber as a reliable sampling technique for studying biogenic volatile organic compounds released from Clostridium tetani.

PubMed

Ghader, Masoud; Shokoufi, Nader; Es-Haghi, Ali; Kargosha, Kazem

2017-11-01

A novel and efficient headspace solid-phase microextraction (HS-SPME) method, followed by gas chromatography mass spectrometry (GC-MS), was developed to study volatile organic compounds (VOCs) emerging from microorganisms. Two homemade SPME fibers, a semi-polar poly (dimethylsiloxane) (PDMS) fiber, and a polar polyethylene glycol (PEG) fiber, along with two commercial fibers (PDMS and PDMS/DVB) were used to collect VOCs emerging from Clostridium tetani which was cultured in different media. The adsorbed VOCs were desorbed and identified, in vitro, using GC-MS. The adsorption efficiency was improved by optimizing the time duration of adsorption and desorption. About 50 components were identified by the proposed method. The main detected compounds appeared to be sulfur containing compounds such as butanethioic acid S-methyl ester, dimethyl trisulfide, and dimethyl tetrasulfide. These volatile sulfur containing compounds are derived from amino acids containing the sulfur element, which probably coexist in the mentioned bacterium or are added to the culture media. The developed HS-SPME-GC-MS method allowed the determination of the chemical fingerprint of Clostridium tetani volatile constituents, and thus provides a new, simple, and reliable tool for studying the growth of microorganisms. Graphical abstract Investigation of biogenic VOCs released from Clostridium tetani using SPME-GC-MS.

Volatile profiles of Italian monovarietal extra virgin olive oils via HS-SPME-GC-MS: newly identified compounds, flavors molecular markers, and terpenic profile.

PubMed

Cecchi, Teresa; Alfei, Barbara

2013-12-01

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from Italy (Marche region), renowned since ancient times. Headspace solid-phase micro-extraction (HS-SPME) was applied for the very first time to the sampling of volatile compounds of eleven typical Italian monocultivar EVOOs. Forty-eight compounds were characterised by GC-MS, some of them were only occasionally found in other EVOOs and some other were never detected before in any EVOO. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles. The main volatile compounds detected in the EVOOs were the C6 compounds derived from polyunsaturated fatty acids, through the lipoxygenase pathway, in different proportion according to the specific cultivar. The results suggest that genetic factors strongly influence volatile formation and terpene hydrocarbons are claimed to be suitable markers of the geographic origin and genotype of the EVOO. Correlations among sensory attributes evaluated by a panel test and the presence of specific volatile compounds were highlighted for the very first time. The significance of the presence of some newly identified volatile compounds was discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of the volatile and semi-volatile secondary metabolites, and aristolochic acids in Aristolochia ringens Vahl.

PubMed

Stashenko, Elena E; Andrés Ordóñez, Sergio; Marín, Néstor Armando; Martínez, Jairo René

2009-10-01

Volatile and semi-volatile secondary metabolites, as well as aristolochic acids (AA), present in leaves, stems, and flowers of Aristolochia ringens were determined by gas chromatography (GC)-mass spectrometry (MS) and high-performance liquid chromatography (HPLC) methods, respectively. Metabolite isolation was performed using different extraction techniques: microwave-assisted hydrodistillation (MWHD), supercritical fluid extraction, and headspace solid-phase microextraction (HS-SPME). The chemical composition of the extracts and oils was established by GC-MS. The determinations of AAI and AAII were conducted by methanolic extraction of different plant parts followed by HPLC analysis. Essential oil yields from leaves and stems were 0.008 +/- 0.0022% and 0.047 +/- 0.0026%, respectively. Aristolochia ringens flowers did not yield essential oil under MWHD. Sesquiterpene hydrocarbons (66%) were the main compounds in the essential oil isolated from leaves whereas monoterpene hydrocarbons (73%) predominated in the stems essential oil. Yields of extracts isolated by SFE from leaves, stems, and flowers were 4 +/- 1.8%, 1.2 +/- 0.25%, and 4 +/- 1.8%, respectively. In vivo HS-SPME of flowers isolated compounds with known unpleasant smells such as volatile aldehydes and short-chain carboxylic acids. HPLC analysis detected the presence of AAII in the flowers of Aristolochia ringens at a concentration of 610 +/- 47 mg/kg of dried flower.

Collins Center Update. Volume 14, Issue 2, January-March 2012

DTIC Science & Technology

2012-03-01

forces in Afghanistan, the Romanian Armed Forces General Staff requested a traveling contact team (TCT) from the Commander, U.S. European Command...THIS ISSUE • Strategic Decision Making Exercise (SDME) 2012 • The Romanian Armed Forces and Joint Staff Planning • The Senior Leader Seminar (SLS...military decision-making exercise is designed as a capstone event which provides students the opportunity to role-play as strategic leaders and staffs

Equation of state and spin crossover of (Mg,Fe)O at high pressure, with implications for explaining topographic relief at the core-mantle boundary

DOE PAGES

Solomatova, Natalia V.; Jackson, Jennifer M.; Sturhahn, Wolfgang; ...

2016-05-01

Iron-bearing periclase is thought to represent a significant fraction of Earth’s lower mantle. However, the concentration of iron in (Mg,Fe)O is not well constrained at all mantle depths. Therefore, understanding the effect of iron on the density and elastic properties of this phase plays a major role in interpreting seismically observed complexity in the deep Earth. Here in this paper, we examine the high-pressure behavior of polycrystalline (Mg,Fe)O containing 48 mol% FeO, loaded hydrostatically with neon as a pressure medium. Using X-ray diffraction and synchrotron Mössbauer spectroscopy, we measure the equation of state to about 83 GPa and hyperfine parametersmore » to 107 GPa at 300 K. A gradual volume drop corresponding to a high-spin (HS) to low-spin (LS) crossover is observed between ~45 and 83 GPa with a volume drop of 1.85% at 68.8(2.7) GPa, the calculated spin transition pressure. Using a newly formulated spin crossover equation of state, the resulting zero-pressure isothermal bulk modulus K 0T,HS for the HS state is 160(2) GPa with a K' 0T,HS of 4.12(14) and a V 0,HS of 77.29(0) Å 3. For the LS state, the K 0T,LS is 173(13) GPa with a K' 0T,LS fixed to 4 and a V 0,LS of 73.64(94) Å 3. To confirm that the observed volume drop is due to a spin crossover, the quadrupole splitting (QS) and isomer shift (IS) are determined as a function of pressure. At low pressures, the Mössbauer spectra are well explained with two Fe 2+-like sites. At pressure between 44 and 84, two additional Fe 2+-like sites with a QS of 0 are required, indicative of low-spin iron. Above 84 GPa, two low-spin Fe 2+-like sites with increasing weight fraction explain the data well, signifying the completion of the spin crossover. To systematically compare the effect of iron on the equation of state parameters for (Mg,Fe)O, a spin crossover equation of state was fitted to the pressure-volume data of previous measurements. Our results show that K 0,HS is insensitive to iron concentration between 10 to 60 mol% FeO, while the spin transition pressure and width generally increases from about 50–80 and 2–25 GPa, respectively. A key implication is that iron-rich (Mg,Fe)O at the core-mantle boundary would likely contain a significant fraction of high-spin (less dense) iron, contributing a positive buoyancy to promote observable topographic relief in tomographic images of the lowermost mantle.« less

Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

PubMed

Enteshari Najafabadi, Marzieh; Bagheri, Habib

2017-12-26

This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10 ng.L -1 . The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

An Analysis of Hispanic Students' Drop Out Rates.

ERIC Educational Resources Information Center

Egemba, Maria Olivia; Crawford, James R.

This study examined factors associated with Hispanic students' high dropout rates, considering not only demographic factors but also the role of family background, early school experiences, and social influences in the high Hispanic student dropout rate. Data came from students in the High School and Beyond (HS&B) longitudinal study of the…

Development of a rapid screening technique for organochlorine pesticides using solvent microextraction (SME) and fast gas chromatography (GC).

PubMed

de Jager, L S; Andrews, A R

2000-11-01

A novel, fast screening method for organochlorine pesticides (OCPs) in water samples has been developed. Total analysis time was less than 9 min, allowing 11 samples to be screened per hour. The relatively new technique of solvent microextraction (SME) was used to extract and preconcentrate the pesticides into a single drop of hexane. The use of a conventional carbon dioxide cryotrap was investigated for introduction of the extract onto a micro-bore (0.1 mm) capillary column for fast GC analysis. A pulsed-discharge electron capture detector was used which yielded selective and sensitive measurement of the pesticide peaks. Fast GC conditions were optimised and tested with the previously developed SME procedure. Calibration curves yielded good linearity and concentrations down to 0.25 ng mL-1 were detectable with RSD values ranging from 12.0 to 28% and LOD for most OCPs at 0.25 ng mL-1. Spiked river water samples were tested and using the developed screen we were able to differentiate between spiked samples and samples containing no OCPs.

Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection.

PubMed

Chen, Chen-Wen; Hsu, Wen-Chan; Lu, Ya-Chen; Weng, Jing-Ru; Feng, Chia-Hsien

2018-02-15

Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r 2 =0.998, 0.1-10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Increased Amazon freshwater discharge during late Heinrich Stadial 1

NASA Astrophysics Data System (ADS)

Crivellari, Stefano; Chiessi, Cristiano Mazur; Kuhnert, Henning; Häggi, Christoph; da Costa Portilho-Ramos, Rodrigo; Zeng, Jing-Ying; Zhang, Yancheng; Schefuß, Enno; Mollenhauer, Gesine; Hefter, Jens; Alexandre, Felipe; Sampaio, Gilvan; Mulitza, Stefan

2018-02-01

The temporal succession of changes in Amazonian hydroclimate during Heinrich Stadial 1 (HS1) (ca. 18-14.7 cal ka BP) is currently poorly resolved. Here we present HS1 records based on isotope, inorganic and organic geochemistry from a marine sediment core influenced by the Amazon River discharge. Our records offer a detailed reconstruction of the changes in Amazonian hydroclimate during HS1, integrated over the basin. We reconstructed surface water hydrography using stable oxygen isotopes (δ18O) and Mg/Ca-derived paleotemperatures from the planktonic foraminifera Globigerinoides ruber, as well as salinity changes based on stable hydrogen isotope (δD) of palmitic acid. We also analyzed branched and isoprenoid tetraether concentrations, and compared them to existing bulk sediment ln(Fe/Ca) data and vegetation reconstruction based on stable carbon isotopes from n-alkanes, in order to understand the relationship between continental precipitation, vegetation and sediment production. Our results indicate a two-phased HS1 (HS1a and HS1b). During HS1a (18-16.9 cal ka BP), a first sudden increase of sea surface temperatures (SST) in the western equatorial Atlantic correlated with the slowdown of the Atlantic Meridional Overturning Circulation (AMOC) and the associated southern hemisphere warming phase of the bipolar seesaw. This phase was also characterized by an increased delivery of terrestrial material. During HS1b (16.9-14.8 cal ka BP), a decrease in terrestrial input was, however, associated with a marked decline of seawater δ18O and palmitic acid δD. Both isotopic proxies independently indicate a drop in sea surface salinity (SSS). A number of records under the influence of the North Brazil Current, in contrast, indicate increases in SST and SSS resulting from a weakened AMOC during HS1. Our records thus suggest that the expected increase in SSS due to the AMOC slowdown was overridden by a two-phased positive precipitation anomaly in Amazonian hydroclimate.

Development of a novel ultrasound-assisted headspace liquid-phase microextraction and its application to the analysis of chlorophenols in real aqueous samples.

PubMed

Xu, Hui; Liao, Ying; Yao, Jinrong

2007-10-05

A new sample pretreatment technique, ultrasound-assisted headspace liquid-phase microextraction was developed as mentioned in this paper. In the technique, the volatile analytes were headspace extracted into a small drop of solvent, which suspended on the bottom of a cone-shaped PCR tube instead of the needle tip of a microsyringe. More solvent could be suspended in the PCR tube than microsyringe due to the larger interfacial tension, thus the analysis sensitivity was significantly improved with the increase of the extractant volume. Moreover, ultrasound-assisted extraction and independent controlling temperature of the extractant and the sample were performed to enhance the extraction efficiency. Following the extraction, the solvent-loaded sample was analyzed by high-performance liquid chromatography. Chlorophenols (2-chlorophenol, 2,4-dichlorophenol and 2,6-dichlorophenol) were chosen as model analytes to investigate the feasibility of the method. The experimental conditions related to the extraction efficiency were systematically studied. Under the optimum experimental conditions, the detection limit (S/N=3), intra- and inter-day RSD were 6 ng mL(-1), 4.6%, 3.9% for 2-chlorophenol, 12 ng mL(-1), 2.4%, 8.8% for 2,4-dichlorophenol and 23 ng mL(-1), 3.3%, 5.3% for 2,6-dichlorophenol, respectively. The proposed method was successfully applied to determine chlorophenols in real aqueous samples. Good recoveries ranging from 84.6% to 100.7% were obtained. In addition, the extraction efficiency of our method and the conventional headspace liquid-phase microextraction were compared; the extraction efficiency of the former was about 21 times higher than that of the latter. The results demonstrated that the proposed method is a promising sample pretreatment approach, its advantages over the conventional headspace liquid-phase microextraction include simple setup, ease of operation, rapidness, sensitivity, precision and no cross-contamination. The method is very suitable for the analysis of trace volatile and semivolatile pollutants in real aqueous sample.

A comparison of sample preparation methods for extracting volatile organic compounds (VOCs) from equine faeces using HS-SPME.

PubMed

Hough, Rachael; Archer, Debra; Probert, Christopher

2018-01-01

Disturbance to the hindgut microbiota can be detrimental to equine health. Metabolomics provides a robust approach to studying the functional aspect of hindgut microorganisms. Sample preparation is an important step towards achieving optimal results in the later stages of analysis. The preparation of samples is unique depending on the technique employed and the sample matrix to be analysed. Gas chromatography mass spectrometry (GCMS) is one of the most widely used platforms for the study of metabolomics and until now an optimised method has not been developed for equine faeces. To compare a sample preparation method for extracting volatile organic compounds (VOCs) from equine faeces. Volatile organic compounds were determined by headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GCMS). Factors investigated were the mass of equine faeces, type of SPME fibre coating, vial volume and storage conditions. The resultant method was unique to those developed for other species. Aliquots of 1000 or 2000 mg in 10 ml or 20 ml SPME headspace were optimal. From those tested, the extraction of VOCs should ideally be performed using a divinylbenzene-carboxen-polydimethysiloxane (DVB-CAR-PDMS) SPME fibre. Storage of faeces for up to 12 months at - 80 °C shared a greater percentage of VOCs with a fresh sample than the equivalent stored at - 20 °C. An optimised method for extracting VOCs from equine faeces using HS-SPME-GCMS has been developed and will act as a standard to enable comparisons between studies. This work has also highlighted storage conditions as an important factor to consider in experimental design for faecal metabolomics studies.

An Innovative Rapid Method for Analysis of 10 Organophosphorus Pesticide Residues in Wheat by HS-SPME-GC-FPD/MSD.

PubMed

Du, Xin; Ren, YongLin; Beckett, Stephen J

2016-01-01

The rapid detection of pesticide residues in wheat has become a top food security priority. A solvent-free headspace solid-phase microextraction (HS-SPME) has been evaluated for rapid screening of organophosphorus pesticide (OPP) residues in wheat with high sensitivity. Individual wheat samples (1.7 g), spiked with 10 OPPs, were placed in a 4 mL sealed amber glass vial and heated at 60°C for 45 min. During this time, the OPP residues were extracted with a 50 μm/30 μm divinylbenzene (DVB)/carboxen (CAR)/plasma desorption mass spectroscopy polydimethylsiloxane (PDMS) fiber from the headspace above the sample. The fiber was then removed and injected into the GC injection port at 250°C for desorption of the extracted chemicals. The multiple residues were identified by a GC mass spectrometer detector (GC-MSD) and quantified with a GC flame photometric detector (GC-FPD). Seven spiked levels of 10 OPPs on wheat were analyzed. The GC responses for a 50 μm/30 μm DVB/CAR/PDMS fiber increased with increasing spiking levels, yielding significant (R(2) > 0.98) linear regressions. The lowest LODs of the multiple pesticide standards were evaluated under the conditions of the validation study in a range of levels from 0 (control) to 100 ng of pesticide residue per g of wheat that separated on a low-polar GC capillary column (Agilent DB-35UI). The results of the HS-SPME method were compared with the QuEChERS AOAC 2007.01 method and they showed several advantages over the latter. These included improved sensitivity, selectivity, and simplicity.

Why do Ladybugs Smell Bad? In-vivo Quantification of Odorous Insect Kairomones with SPME and Multidimensional GC-MS-Olfactometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai Lingshuang; Koziel, Jacek A.; O'Neal, Matthew E.

2009-05-23

Winemakers, small fruit growers, and homeowners are concerned with noxious compounds released by multicolored Asian ladybird beetles (Harmonia axyridis, Coleoptera: Coccinellidae). New method based on headspace solid phase microextraction (HS-SPME) coupled with multidimensional gas chromatography mass spectrometry--olfactometry (MDGC-MS-O) system was developed for extraction, isolation and simultaneous identification of compounds responsible for the characteristic odor of live H. axyridis. Four methoxypyrazines (MPs) were identified in headspace volatiles of live H. axyridis as those responsible for the characteristic odor: 2, 5-dimethy1-3-methoxypyrazine (DMMP), 2-isopropy1-3-methoxypyrazine (IPMP), 2-sec-buty1-3-methoxypyrazine (SBMP), and 2-isobuty1-3-methoxypyrazine (IBMP). To the best of our knowledge this is the first report of H.more » axyridis releasing DMMP and the first report of this compound being a component of the H. axyridis characteristic odor. Quantification of three MPs (IPMP, SBMP and IBMP) emitted from live H. axyridis were performed using external calibration with HS-SPME and direct injections. A linear relationship (R{sup 2}>0.9958 for all 3 MPs) between MS response and concentration of standard was observed over a concentration range from 0.1 ng L{sup -1} to 0.05 {mu}g L{sup -1} for HS-SPME-GC-MS. The method detection limits (MDL) based on multidimensional GC-MS approach for three MPs were estimated to be between 0.020 ng L{sup -1}. to 0.022 ng L{sup -1}. This methodology is applicable for in vivo determination of odor-causing chemicals associated with emissions of volatiles from insects.« less

Hepatic thyroid signaling of heat-stressed late pregnant and early lactating cows

PubMed Central

Weitzel, Joachim M; Viergutz, Torsten; Albrecht, Dirk; Bruckmaier, Rupert; Schmicke, Marion; Tuchscherer, Armin; Koch, Franziska

2017-01-01

During the transition between late gestation and early lactation, dairy cows experience severe metabolic stress due to the high energy and nutrient requirements of the fetus and the mammary gland. Additional thermal stress that occurs with rising temperatures during the ongoing climate change has further adverse implications on energy intake, metabolism and welfare. The thyroid hormone (TH)-mediated cellular signaling has a pivotal role in regulation of body temperature, energy intake and metabolic adaptation to heat. To distinguish between energy intake and heat stress-related effects, Holstein cows were first kept at thermoneutrality at 15°C followed by exposure to heat stress (HS) at 28°C or pair-feeding (PF) at 15°C for 6 days, in late pregnancy and again in early lactation. Herein, we focused on hepatic metabolic changes associated with alterations in the hypothalamic–pituitary–thyroid axis in HS and PF animals. T3 and T4 levels dropped with HS or PF; however, in HS animals, this decline was more pronounced. Thyroid-stimulating hormone (TSH) levels remain unaffected, while plasma cholesterol concentrations were lower in HS than PF animals. Hepatic marker genes for TH action (THRA, DIO1 and PPARGC1) decreased after HS and were lower compared to PF cows but only post-partum. Proteomics data revealed reduced hepatic amino acid catabolism ante-partum and a shift toward activated beta-oxidation and gluconeogenesis but declined oxidative stress defense post-partum. Thus, liver metabolism of HS and PF cows adapts differently to diminished energy intake both ante-partum and post-partum, and a different TH sensitivity is involved in the regulation of catabolic processes. PMID:28500083

Multivariate analysis of volatile compounds detected by headspace solid-phase microextraction/gas chromatography: A tool for sensory classification of cork stoppers.

PubMed

Prat, Chantal; Besalú, Emili; Bañeras, Lluís; Anticó, Enriqueta

2011-06-15

The volatile fraction of aqueous cork macerates of tainted and non-tainted agglomerate cork stoppers was analysed by headspace solid-phase microextraction (HS-SPME)/gas chromatography. Twenty compounds containing terpenoids, aliphatic alcohols, lignin-related compounds and others were selected and analysed in individual corks. Cork stoppers were previously classified in six different classes according to sensory descriptions including, 2,4,6-trichloroanisole taint and other frequent, non-characteristic odours found in cork. A multivariate analysis of the chromatographic data of 20 selected chemical compounds using linear discriminant analysis models helped in the differentiation of the a priori made groups. The discriminant model selected five compounds as the best combination. Selected compounds appear in the model in the following order; 2,4,6 TCA, fenchyl alcohol, 1-octen-3-ol, benzyl alcohol and benzothiazole. Unfortunately, not all six a priori differentiated sensory classes were clearly discriminated in the model, probably indicating that no measurable differences exist in the chromatographic data for some categories. The predictive analyses of a refined model in which two sensory classes were fused together resulted in a good classification. Prediction rates of control (non-tainted), TCA, musty-earthy-vegetative, vegetative and chemical descriptions were 100%, 100%, 85%, 67.3% and 100%, respectively, when the modified model was used. The multivariate analysis of chromatographic data will help in the classification of stoppers and provide a perfect complement to sensory analyses. Copyright © 2010 Elsevier Ltd. All rights reserved.

Analysis of volatile human urinary metabolome by solid-phase microextraction in combination with gas chromatography-mass spectrometry for biomarker discovery: application in a pilot study to discriminate patients with renal cell carcinoma.

PubMed

Monteiro, Márcia; Carvalho, Márcia; Henrique, Rui; Jerónimo, Carmen; Moreira, Nathalie; de Lourdes Bastos, Maria; de Pinho, Paula Guedes

2014-07-01

A new and simple analytical approach consisting of headspace-solid phase microextraction (HS-SPME) sampling coupled with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed to study the volatile human urinary metabolome. A central composite design (CCD) was used in the optimisation of extraction conditions. Fibre selection and evaluation of pH influence were performed using an univariate mode and the influence of other parameters, such as the time and temperature of extraction, time of incubation and salt addition, that affect the efficiency of the SPME sampling, was carried out using a CCD. With a sample volume of 2 mL, the optimal conditions in terms of total response values and reproducibility were achieved by performing analyses with a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre, in an acidic pH (pH 2) with the addition of 0.59 g of NaCl, allowing the sample to equilibrate for 9 min and extracting at 68 °C for 24 min. The applicability of the optimised method was then tested in a pilot non-target analysis of urine samples obtained from patients with renal cell carcinoma (RCC) and healthy individuals. Chemometric unsupervised analyses performed on the volatile pattern acquired for these samples clearly showed the potential of volatile urinary metabolome to discriminate between RCC and control patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol–Gel Technique

PubMed Central

Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

2016-01-01

A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography–flame ionization detector (GC–FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol–gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic–inorganic sol–gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol–gel active organic component for sol–gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001–0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3–10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%. PMID:26759488

Characterization of Volatile Sulfur Compounds in Moutai Liquors by Headspace Solid-Phase Microextraction Gas Chromatography-Pulsed Flame Photometric Detection and Odor Activity Value.

PubMed

Chen, Shuang; Sha, Sha; Qian, Michael; Xu, Yan

2017-12-01

This study investigated the aroma contribution of volatile sulfur compounds (VSCs) in Moutai liquors. The VSCs were analyzed using headspace solid-phase microextraction-gas chromatography-pulsed flame photometric detection (HS-SPME-GC-PFPD). The influences of SPME fibers, ethanol content in the sample, pre-incubation time, and extraction temperature and time on the extraction of VSCs were optimized. The VSCs were optimally extracted using a divinylbenzene/carboxen/polydimethylsiloxane fiber, by incubating 10 mL diluted Chinese liquor (5% vol.) with 3 g NaCl at 30 °C for 15 min, followed by a subsequent extraction for 40 min at 30 °C. The optimized method was further validated. A total of 13 VSCs were identified and quantified in Moutai liquors. The aroma contribution of these VSCs were evaluated by their odor activity values (OAVs), with the result that 7 of 13 VSCs had OAVs > 1. In particular, 2-furfurylthiol, methanethiol, dimethyl trisulfide, ethanethiol, and methional had relatively high OAVs and could be the key aroma contributors to Moutai liquors. In this study, a method for analyzing volatile sulfur compounds in Chinese liquors has been developed. This method will allow an in-depth study the aroma contribution of volatile sulfur compounds in Chinese liquors. Seven volatile sulfur compounds were identified as potential key aroma contributors for Moutai liquors, which can help to the quality control of Moutai liquors. © 2017 Institute of Food Technologists®.

Determination of triazine herbicides in juice samples by microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography.

PubMed

Su, Rui; Li, Dan; Wu, Lijie; Han, Jing; Lian, Wenhui; Wang, Keren; Yang, Hongmei

2017-07-01

A novel microextraction method, termed microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high-performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1-hexyl-3-methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1-butyl-3-methylimidazolium tetrafluoroborate. In addition, an ion-pairing agent (NH 4 PF 6 ) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00-250.00 μg/L, with the correlation coefficients of 0.9982-0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7-105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Profiles of Volatile Compounds in Black Currant (Ribes nigrum) Cultivars with Special Focus on Influence of Growth Latitude and Weather Conditions.

PubMed

Marsol-Vall, Alexis; Kortesniemi, Maaria Katariina; Karhu, Saila; Kallio, Heikki; Yang, Baoru

2018-06-25

The volatile profile of three blackcurrant (Ribes nigrum L.) cultivars grown in Finland and their response to growth latitude and weather conditions were studied over an eight-year period by headspace solid-phase microextraction (HS-SPME) followed by gas chromatographic-mass spectrometric (GC-MS) analysis. Monoterpene hydrocarbons and oxygenated monoterpenes were the major classes of volatiles. The cultivar 'Melalahti' presented lower content of volatiles compared with 'Ola' and 'Mortti', the two latter showing a very similar composition. Higher contents of volatiles were found in berries cultivated at higher latitude (66° 34' N) than in those from the southern location (60° 23' N). Among the meteorological variables, radiation and temperature during the last month before harvest were negatively linked with the volatile content. Storage time had a negative impact on the amount of blackcurrant volatiles.

Pedologic Factors Affecting Virgin Olive Oil Quality of "Chemlali" Olive Trees (Olea europaea L.).

PubMed

Rached, Mouna Ben; Galaverna, Gianni; Cirlini, Martina; Boujneh, Dalenda; Zarrouk, Mokhtar; Guerfel, Mokhtar

2017-08-01

The aim of this study examined the characterization of extra virgin olive oil samples from the main cultivar Chemlali, grown in five olive orchards with different soil type (Sandy, Clay, Stony, Brown, Limestone and Gypsum). Volatile compounds were studied using headspace-solid phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) technics. Moreover, the sterol profile was established using gas chromatography-mass spectrometry. 35 different volatile compounds were identified: alcohols, esters, aldehydes, ketones and hydrocarbons. The chemical composition of the volatile fraction was characterized by the preeminence of 2-hexenal (32.75%) and 1-hexanol (31.88%). Three sterols were identified and characterized. For all olive oil samples, ß-sitosterol (302.25 mg/kg) was the most abundant sterol. Interestingly, our results showed significant qualitative and quantitative differences in the levels of the volatile compounds and sterols from oils obtained from olive trees grown in different soil type.

Aroma Characterization and Safety Assessment of a Beverage Fermented by Trametes versicolor.

PubMed

Zhang, Yanyan; Fraatz, Marco Alexander; Müller, Julia; Schmitz, Hans-Joachim; Birk, Florian; Schrenk, Dieter; Zorn, Holger

2015-08-12

A cereal-based beverage was developed by fermentation of wort with the basidiomycete Trametes versicolor. The beverage possessed a fruity, fresh, and slightly floral aroma. The volatiles of the beverage were isolated by liquid-liquid extraction (LLE) and additionally by headspace solid phase microextraction (HS-SPME). The aroma compounds were analyzed by a gas chromatography system equipped with a tandem mass spectrometer and an olfactory detection port (GC-MS/MS-O) followed by aroma (extract) dilution analysis. Thirty-four different odor impressions were perceived, and 27 corresponding compounds were identified. Fifteen key odorants with flavor dilution (FD) factors ranging from 8 to 128 were quantitated, and their respective odor activity values (OAVs) were calculated. Six key odorants were synthesized de novo by T. versicolor. Furthermore, quantitative changes during the fermentation process were analyzed. To prepare for the market introduction of the beverage, a comprehensive safety assessment was performed.

Microencapsulation, Chemical Characterization, and Antimicrobial Activity of Mexican (Lippia graveolens H.B.K.) and European (Origanum vulgare L.) Oregano Essential Oils

PubMed Central

Regalado-González, Carlos; Vázquez-Landaverde, Pedro; Guerrero-Legarreta, Isabel; García-Almendárez, Blanca E.

2014-01-01

The effect of solvent polarity (methanol and pentane) on the chemical composition of hydrodistilled essential oils (EO's) of Lippia graveolens H.B.K. (MXO) and Origanum vulgare L. (EUO) was studied by GC-MS. Composition of modified starch microencapsulated EO's was conducted by headspace-solid-phase microextraction (HS-SPME). The antimicrobial activity of free and microencapsulated EO's was evaluated. They were tested against Salmonella sp., Brochothrix thermosphacta, Pseudomonas fragi, Lactobacillus plantarum, and Micrococcus luteus. Thymol and carvacrol were among the main components of EO's and their free and microencapsulated inhibitory activity was tested against M. luteus, showing an additive combined effect. Chemical composition of EO's varied according to the solvent used for GC analysis and to volatile fraction as evaluated by HS-SPME. Thymol (both solvents) was the main component in essential oil of MXO, while carvacrol was the main component of the volatile fraction. EUO showed α-pinene (methanol) and γ-terpinene (pentane) as major constituents, the latter being the main component of the volatile fraction. EO's showed good stability after 3 months storage at 4°C, where antimicrobial activity of microencapsulated EO's remained the same, while free EO's decreased 41% (MXO) and 67% (EUO) from initial activity. Microencapsulation retains most antimicrobial activity and improves stability of EO's from oregano. PMID:25177730

Comprehensive quality evaluation of medical Cannabis sativa L. inflorescence and macerated oils based on HS-SPME coupled to GC-MS and LC-HRMS (q-exactive orbitrap®) approach.

PubMed

Calvi, Lorenzo; Pentimalli, Daniela; Panseri, Sara; Giupponi, Luca; Gelmini, Fabrizio; Beretta, Giangiacomo; Vitali, Davide; Bruno, Massimo; Zilio, Emanuela; Pavlovic, Radmila; Giorgi, Annamaria

2018-02-20

There are at least 554 identified compounds in C. sativa L., among them 113 phytocannabinoids and 120 terpenes. Phytocomplex composition differences between the pharmaceutical properties of different medical cannabis chemotype have been attributed to strict interactions, defined as 'entourage effect', between cannabinoids and terpenes as a result of synergic action. The chemical complexity of its bioactive constituents highlight the need for standardised and well-defined analytical approaches able to characterise the plant chemotype, the herbal drug quality as well as to monitor the quality of pharmaceutical cannabis extracts and preparations. Hence, in the first part of this study an analytical procedures involving the combination of headspace-solid-phase microextraction (HS-SPME) coupled to GC-MS and High Resolution Mass-Spectrometry LC-HRMS (Orbitrap ® ) were set up, validated and applied for the in-depth profiling and fingerprinting of cannabinoids and terpenes in two authorised medical grade varieties of Cannabis sativa L. inflorescences (Bedrocan ® and Bediol ® ) and in obtained macerated oils. To better understand the trend of all volatile compounds and cannabinoids during oil storage a new procedure for cannabis macerated oil preparation without any thermal step was tested and compared with the existing conventional methods to assess the potentially detrimental effect of heating on overall product quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-destructive profiling of volatile organic compounds using HS-SPME/GC-MS and its application for the geographical discrimination of white rice.

PubMed

Lim, Dong Kyu; Mo, Changyeun; Lee, Dong-Kyu; Long, Nguyen Phuoc; Lim, Jongguk; Kwon, Sung Won

2018-01-01

The authenticity determination of white rice is crucial to prevent deceptive origin labeling and dishonest trading. However, a non-destructive and comprehensive method for rapidly discriminating the geographical origins of white rice between countries is still lacking. In the current study, we developed a volatile organic compound based geographical discrimination method using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS) to discriminate rice samples from Korea and China. A partial least squares discriminant analysis (PLS-DA) model exhibited a good classification of white rice between Korea and China (accuracy = 0.958, goodness of fit = 0.937, goodness of prediction = 0.831, and permutation test p-value = 0.043). Combining the PLS-DA based feature selection with the differentially expressed features from the unpaired t-test and significance analysis of microarrays, 12 discriminatory biomarkers were found. Among them, hexanal and 1-hexanol have been previously known to be associated with the cultivation environment and storage conditions. Other hydrocarbon biomarkers are novel, and their impact on rice production and storage remains to be elucidated. In conclusion, our findings highlight the ability to rapidly discriminate white rice from Korea and China. The developed method maybe useful for the authenticity and quality control of white rice. Copyright © 2017. Published by Elsevier B.V.

Aroma volatiles obtained at harvest by HS-SPME/GC-MS and INDEX/MS-E-nose fingerprint discriminate climacteric behaviour in melon fruit.

PubMed

Chaparro-Torres, Libia A; Bueso, María C; Fernández-Trujillo, Juan P

2016-05-01

Melon aroma volatiles were extracted at harvest from juice of a climacteric near-isogenic line (NIL) SC3-5-1 with two quantitative trait loci (QTLs) introgressed which produced climacteric behaviour and its non-climacteric parental (PS) using two methodologies of analysis: static headspace solid phase micro-extraction (HS-SPME) by gas chromatography-mass spectrometry (GC-MS) and inside needle dynamic extraction (INDEX) by MS-based electronic nose (MS-E-nose). Of the 137 volatiles compounds identified, most were found at significantly higher concentrations in SC3-5-1 than in PS in both seasons. These volatiles were mostly esters, alcohols, sulfur-derived esters and even some aldehydes and others. The number of variables with high correlation values was reduced by using correlation network analysis. Partial least squares-discriminant analysis (PLS-DA) achieved the correct classification of PS and SC3-5-1. The ions m/z 74, 91, 104, 105, 106 and 108, mainly volatile derivatives precursor phenylalanine, were the most discriminant in SC3-5-1 and PS. As many as 104 QTLs were mapped in season 1 and at least 78 QTLs in each season with an effect above the PS mean. GC-MS gave better discrimination than E-nose. Most of the QTLs that mapped in both seasons enhanced aroma volatiles associated with climacteric behaviour. © 2015 Society of Chemical Industry.

A Study on the Reliability of an On-Site Oral Fluid Drug Test in a Recreational Context

PubMed Central

Gentili, Stefano; Tittarelli, Roberta; Mannocchi, Giulio

2016-01-01

The reliability of DrugWipe 5A on site test for principal drugs of abuse (cannabis, amphetamines, cocaine, and opiates) detection in oral fluid was assessed by comparing the on-site results with headspace solid-phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS) analysis on samples extracted by the device collection pad. Oral fluid samples were collected at recreational settings (e.g., discos, pubs, and music bars) of Rome metropolitan area. Eighty-three club goers underwent the on-site drug screening test with one device. Independently from the result obtained, a second device was used just to collect another oral fluid sample subsequently extracted and analyzed in the laboratory following HS-SPME procedure, gas chromatographic separation by a capillary column, and MS detection by electron impact ionization. DrugWipe 5A on-site test showed 54 samples (65.1%) positive to one or more drugs of abuse, whereas 75 samples (90.4%) tested positive for one or more substances following GC-MS assay. Comparing the obtained results, the device showed sensitivity, specificity, and accuracy around 80% for amphetamines class. Sensitivity (67 and 50%) was obtained for cocaine and opiates, while both sensitivity and accuracy were unsuccessful (29 and 53%, resp.) for cannabis, underlying the limitation of the device for this latter drug class. PMID:27610266

Gas chromatographic-mass spectrometric analysis of urinary volatile organic metabolites: Optimization of the HS-SPME procedure and sample storage conditions.

PubMed

Živković Semren, Tanja; Brčić Karačonji, Irena; Safner, Toni; Brajenović, Nataša; Tariba Lovaković, Blanka; Pizent, Alica

2018-01-01

Non-targeted metabolomics research of human volatile urinary metabolome can be used to identify potential biomarkers associated with the changes in metabolism related to various health disorders. To ensure reliable analysis of urinary volatile organic metabolites (VOMs) by gas chromatography-mass spectrometry (GC-MS), parameters affecting the headspace-solid phase microextraction (HS-SPME) procedure have been evaluated and optimized. The influence of incubation and extraction temperatures and times, coating fibre material and salt addition on SPME efficiency was investigated by multivariate optimization methods using reduced factorial and Doehlert matrix designs. The results showed optimum values for temperature to be 60°C, extraction time 50min, and incubation time 35min. The proposed conditions were applied to investigate urine samples' stability regarding different storage conditions and freeze-thaw processes. The sum of peak areas of urine samples stored at 4°C, -20°C, and -80°C up to six months showed a time dependent decrease over time although storage at -80°C resulted in a slight non-significant reduction comparing to the fresh sample. However, due to the volatile nature of the analysed compounds, more than two cycles of freezing/thawing of the sample stored for six months at -80°C should be avoided whenever possible. Copyright © 2017 Elsevier B.V. All rights reserved.

Biodegradation testing of chemicals with high Henry's constants - Separating mass and effective concentration reveals higher rate constants.

PubMed

Birch, Heidi; Andersen, Henrik R; Comber, Mike; Mayer, Philipp

2017-05-01

During simulation-type biodegradation tests, volatile chemicals will continuously partition between water phase and headspace. This study addressed how (1) this partitioning affects test results and (2) can be accounted for by combining equilibrium partition and dynamic biodegradation models. An aqueous mixture of 9 (semi)volatile chemicals was first generated using passive dosing and then diluted with environmental surface water producing concentrations in the ng/L to μg/L range. After incubation for 2 h to 4 weeks, automated Headspace Solid Phase Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relatively to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Biodegradation rate constants relating to the chemical in the water phase, k water , were generally a factor 1 to 11 times higher than biodegradation rate constants relating to the total mass of chemical in the test system, k system , with one exceptional factor of 72 times for a long chain alkane. True water phase degradation rate constants were found (i) more appropriate for risk assessment than test system rate constants, (ii) to facilitate extrapolation to other air-water systems and (iii) to be better defined input parameters for aquatic exposure and fate models. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microencapsulation, chemical characterization, and antimicrobial activity of Mexican (Lippia graveolens H.B.K.) and European (Origanum vulgare L.) oregano essential oils.

PubMed

Hernández-Hernández, Elvia; Regalado-González, Carlos; Vázquez-Landaverde, Pedro; Guerrero-Legarreta, Isabel; García-Almendárez, Blanca E

2014-01-01

The effect of solvent polarity (methanol and pentane) on the chemical composition of hydrodistilled essential oils (EO's) of Lippia graveolens H.B.K. (MXO) and Origanum vulgare L. (EUO) was studied by GC-MS. Composition of modified starch microencapsulated EO's was conducted by headspace-solid-phase microextraction (HS-SPME). The antimicrobial activity of free and microencapsulated EO's was evaluated. They were tested against Salmonella sp., Brochothrix thermosphacta, Pseudomonas fragi, Lactobacillus plantarum, and Micrococcus luteus. Thymol and carvacrol were among the main components of EO's and their free and microencapsulated inhibitory activity was tested against M. luteus, showing an additive combined effect. Chemical composition of EO's varied according to the solvent used for GC analysis and to volatile fraction as evaluated by HS-SPME. Thymol (both solvents) was the main component in essential oil of MXO, while carvacrol was the main component of the volatile fraction. EUO showed α-pinene (methanol) and γ-terpinene (pentane) as major constituents, the latter being the main component of the volatile fraction. EO's showed good stability after 3 months storage at 4°C, where antimicrobial activity of microencapsulated EO's remained the same, while free EO's decreased 41% (MXO) and 67% (EUO) from initial activity. Microencapsulation retains most antimicrobial activity and improves stability of EO's from oregano.

Analysis of honeybush tea (Cyclopia spp.) volatiles by comprehensive two-dimensional gas chromatography using a single-stage thermal modulator.

PubMed

Ntlhokwe, Gaalebalwe; Tredoux, Andreas G J; Górecki, Tadeusz; Edwards, Matthew; Vestner, Jochen; Muller, Magdalena; Erasmus, Lené; Joubert, Elizabeth; Christel Cronje, J; de Villiers, André

2017-07-01

The applicability of comprehensive two-dimensional gas chromatography (GC×GC) using a single-stage thermal modulator was explored for the analysis of honeybush tea (Cyclopia spp.) volatile compounds. Headspace solid phase micro-extraction (HS-SPME) was used in combination with GC×GC separation on a non-polar × polar column set with flame ionisation (FID) detection for the analysis of fermented Cyclopia maculata, Cyclopia subternata and Cyclopia genistoides tea infusions of a single harvest season. Method optimisation entailed evaluation of the effects of several experimental parameters on the performance of the modulator, the choice of columns in both dimensions, as well as the HS-SPME extraction fibre. Eighty-four volatile compounds were identified by co-injection of reference standards. Principal component analysis (PCA) showed clear differentiation between the species based on their volatile profiles. Due to the highly reproducible separations obtained using the single-stage thermal modulator, multivariate data analysis was simplified. The results demonstrate both the complexity of honeybush volatile profiles and the potential of GC×GC separation in combination with suitable data analysis techniques for the investigation of the relationship between sensory properties and volatile composition of these products. The developed method therefore offers a fast and inexpensive methodology for the profiling of honeybush tea volatiles. Graphical abstract Surface plot obtained for the GC×GC-FID analysis of honeybush tea volatiles.

Characterisation of the volatile profile of coconut water from five varieties using an optimised HS-SPME-GC analysis.

PubMed

Prades, Alexia; Assa, Rebecca Rachel Ablan; Dornier, Manuel; Pain, Jean-Pierre; Boulanger, Renaud

2012-09-01

Coconut (Cocos nucifera L.) water is a refreshing tropical drink whose international market has recently been growing. However, little is yet known about its physicochemical composition, particularly its aroma. This study set out to characterise the volatile profile of water from five coconut varieties. Aroma compounds were characterised by headspace solid phase microextraction gas chromatography (HS-SPME-GC) analysis. An experimental design was established to optimise SPME conditions, leading to an equilibration time of 10 min followed by an extraction time of 60 min at 50 °C. Accordingly, immature coconut water from WAT (West African Tall), PB121 (MYD × WAT Hybrid), MYD (Malayan Yellow Dwarf), EGD (Equatorial Guinea Green Dwarf) and THD (Thailand Aromatic Green Dwarf) palms was analysed and described. Ketones were mainly present in the Tall and Hybrid varieties, whereas aldehydes were most abundant in the Dwarf palms. Tall coconut water was characterised by a high lactone content. THD exhibited a high ethyl octanoate level. The cluster analysis of the volatile fraction from the five coconut cultivars was found to be related to their genetic classification. The volatile compounds of immature coconut water from five varieties were characterised for the first time. Volatile profile analysis could be a useful tool for the selection of Dwarf coconut varieties, which are mainly consumed as a beverage. Copyright © 2012 Society of Chemical Industry.

Automation of static and dynamic non-dispersive liquid phase microextraction. Part 1: Approaches based on extractant drop-, plug-, film- and microflow-formation.

PubMed

Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

2016-02-04

Simplicity, effectiveness, swiftness, and environmental friendliness - these are the typical requirements for the state of the art development of green analytical techniques. Liquid phase microextraction (LPME) stands for a family of elegant sample pretreatment and analyte preconcentration techniques preserving these principles in numerous applications. By using only fractions of solvent and sample compared to classical liquid-liquid extraction, the extraction kinetics, the preconcentration factor, and the cost efficiency can be increased. Moreover, significant improvements can be made by automation, which is still a hot topic in analytical chemistry. This review surveys comprehensively and in two parts the developments of automation of non-dispersive LPME methodologies performed in static and dynamic modes. Their advantages and limitations and the reported analytical performances are discussed and put into perspective with the corresponding manual procedures. The automation strategies, techniques, and their operation advantages as well as their potentials are further described and discussed. In this first part, an introduction to LPME and their static and dynamic operation modes as well as their automation methodologies is given. The LPME techniques are classified according to the different approaches of protection of the extraction solvent using either a tip-like (needle/tube/rod) support (drop-based approaches), a wall support (film-based approaches), or microfluidic devices. In the second part, the LPME techniques based on porous supports for the extraction solvent such as membranes and porous media are overviewed. An outlook on future demands and perspectives in this promising area of analytical chemistry is finally given. Copyright © 2015 Elsevier B.V. All rights reserved.

Capabilities and limitations of dispersive liquid-liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples.

PubMed

Vera-Avila, Luz E; Rojo-Portillo, Tania; Covarrubias-Herrera, Rosario; Peña-Alvarez, Araceli

2013-12-17

Dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (LogKow 0-7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with LogKow 3-7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD<12%) and linear behavior was observed in the studied concentration range (r(2)>0.995). Extraction recoveries for pollutants with LogKow 1.46-2.8 were in the range 13-62%, directly depending on individual LogKow values; however, good linearity (r(2)>0.993) and precision (RSD<6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with LogKow≤1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol-Gel Technique.

PubMed

Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

2016-04-01

A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography-flame ionization detector (GC-FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol-gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic-inorganic sol-gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol-gel active organic component for sol-gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001-0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3-10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of caffeine, myosmine, and nicotine in chocolate by headspace solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry.

PubMed

Müller, Christoph; Vetter, Florian; Richter, Elmar; Bracher, Franz

2014-02-01

The occurrence of the bioactive components caffeine (xanthine alkaloid), myosmine and nicotine (pyridine alkaloids) in different edibles and plants is well known, but the content of myosmine and nicotine is still ambiguous in milk/dark chocolate. Therefore, a sensitive method for determination of these components was established, a simple separation of the dissolved analytes from the matrix, followed by headspace solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry (HS-SPME-GC-MS/MS). This is the first approach for simultaneous determination of caffeine, myosmine, and nicotine with a convenient SPME technique. Calibration curves were linear for the xanthine alkaloid (250 to 3000 mg/kg) and the pyridine alkaloids (0.000125 to 0.003000 mg/kg). Residuals of the calibration curves were lower than 15%, hence the limits of detection were set as the lowest points of the calibration curves. The limits of detection calculated from linearity data were for caffeine 216 mg/kg, for myosmine 0.000110 mg/kg, and for nicotine 0.000120 mg/kg. Thirty samples of 5 chocolate brands with varying cocoa contents (30% to 99%) were analyzed in triplicate. Caffeine and nicotine were detected in all samples of chocolate, whereas myosmine was not present in any sample. The caffeine content ranged from 420 to 2780 mg/kg (relative standard deviation 0.1 to 11.5%) and nicotine from 0.000230 to 0.001590 mg/kg (RSD 2.0 to 22.1%). © 2014 Institute of Food Technologists®

Photodegradation of crude oil: liquid injection and headspace solid-phase microextraction for crude oil analysis by gas chromatography with mass spectrometer detector.

PubMed

D'Auria, Maurizio; Racioppi, Rocco; Velluzzi, Vincenzina

2008-04-01

The fate of crude oil under irradiation is studied. After UV irradiation, the fraction present in the highest percentage shifts from the C8-C9 fractions to C13, using gas chromatography-mass spectrometry (GC-MS) analysis in solution. An increase of the relative amount of the C13-C25 fraction is observed, while a decrease in the relative amount of the C7-C12 fractions is present. In headspace solid-phase microextraction (HS-SPME) analysis, the C8-C10 fractions represent 53% of all the compounds detected. A decrease in the relative amount of the C8-C10 fractions is observed, while C11-C15 fractions increase. The irradiation of crude oil with a solar simulator gives a mixture the analysis of which using GC-MS in solution furnishes the same type of results: the relative amounts of linear alkanes and aromatic compounds increase, while a sharp decrease in the relative amounts of branched and cyclic alkanes is observed. In the SPME analysis, a decreased relative amount of branched alkanes and alkenes, and an increase in the relative amounts of cyclic alkanes and aromatic compounds are observed. Analysis of the distribution of the compounds in all the types of compound shows that a dynamic equilibrium between different compounds and different types of compounds is present. To confirm the presence of a dynamic equilibrium, the irradiation of methylcyclohexane in the presence of 2-methylnaphthalene shows the presence in the reaction mixture of a small amount of tetradecane.

Headspace solid-phase microextraction for the determination of volatile and semi-volatile pollutants in water and air.

PubMed

Llompart, M; Li, K; Fingas, M

1998-10-16

In this work we report the use of solid-phase microextraction (SPME) to extract and concentrate water-soluble volatile as well as semi-volatile pollutants. Both methods of exposing the SPME fibre were utilised: immersion in the aqueous solution (SPME) and in the headspace over the solution (HSSPME). The proposed HSSPME procedure was compared to conventional static headspace (HS) analysis for artificially spiked water as well as real water samples, which had been, equilibrated with various oil and petroleum products. Both techniques gave similar results but HSSPME was much more sensitive and exhibited better precision. Detection limits were found to be in the sub-ng/ml level, with precision better than 5% R.S.D. in most cases. To evaluate the suitability of SPME for relatively high contamination level analysis, the proposed HSSPME method was applied to the screening of run-off water samples that had heavy oil suspended in them from a tire fire incident. HSSPME results were compared with liquid--liquid extraction. Library searches were conducted on the resulting GC-MS total ion chromatograms to determine the types of compounds found in such samples. Both techniques found similar composition in the water samples with the exception of alkylnaphthalenes that were detected only by HSSPME. A brief study was carried out to assess using SPME for air monitoring. By sampling and concentrating the volatile organic compounds in the coating of the SPME fibre without any other equipment, this new technique is useful as an alternative to active air monitoring by means of sampling pumps and sorbent tubes.

Octadecyltrimethoxysilane functionalized ZnO nanorods as a novel coating for solid-phase microextraction with strong hydrophobic surface.

PubMed

Zeng, Jingbin; Liu, Haihong; Chen, Jinmei; Huang, Jianli; Yu, Jianfeng; Wang, Yiru; Chen, Xi

2012-09-21

In this paper, we have, for the first time, proposed an approach by combining self-assembled monolayers (SAMs) and nanomaterials (NMs) for the preparation of novel solid-phase microextraction (SPME) coatings. The self-assembly of octadecyltrimethoxysilane (OTMS) on the surface of ZnO nanorods (ZNRs) was selected as a model system to demonstrate the feasibility of this approach. The functionalization of OTMS on the surface of ZNRs was characterized and confirmed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The OTMS-ZNRs coated fiber exhibited stronger hydrophobicity after functionalization, and its extraction efficiency for non-polar benzene homologues was increased by a factor of 1.5-3.6 when compared to a ZNRs fiber with almost identical thickness and façade. In contrast, the extraction efficiency of the OTMS-ZNRs coated fiber for polar aldehydes was 1.6-4.0-fold lower than that of the ZNRs coated fiber, further indicating its enhanced surface hydrophobicity. The OTMS-ZNRs coated fiber revealed a much higher capacity upon increasing the OTMS layer thickness to 5 μm, leading to a factor of 12.0-13.4 and 1.8-2.5 increase in extraction efficiency for the benzene homologues relative to a ZNRs coated fiber and a commercial PDMS fiber, respectively. The developed HS-SPME-GC method using the OTMS-ZNRs coated fiber was successfully applied to the determination of the benzene homologues in limnetic water samples with recovery ranging from 83 to 113% and relative standard deviations (RSDs) of less than 8%.

Changes in monsoon-driven upwelling in the South China Sea over glacial Terminations I and II: a multi-proxy record

NASA Astrophysics Data System (ADS)

Sadatzki, Henrik; Sarnthein, Michael; Andersen, Nils

2016-06-01

Upwelling intensity in the South China Sea has changed over glacial-interglacial cycles in response to orbital-scale changes in the East Asian Monsoon. Here, we evaluate new multi-proxy records of two sediment cores from the north-eastern South China Sea to uncover millennial-scale changes in winter monsoon-driven upwelling over glacial Terminations I and II. On the basis of U/Th-based speleothem chronology, we compare these changes with sediment records of summer monsoon-driven upwelling east of South Vietnam. Ocean upwelling is traced by reduced (UK'37-based) temperature and increased nutrient and productivity estimates of sea surface waters (δ13C on planktic foraminifera, accumulation rates of alkenones, chlorins, and total organic carbon). Accordingly, strong winter upwelling occurred north-west of Luzon (Philippines) during late Marine Isotope Stage 6.2, Heinrich (HS) and Greenland stadials (GS) HS-11, GS-26, GS-25, HS-1, and the Younger Dryas. During these stadials, summer upwelling decreased off South Vietnam and sea surface salinity reached a maximum suggesting a drop in monsoon rains, concurrent with speleothem records of aridity in China. In harmony with a stadial-to-interstadial see-saw pattern, winter upwelling off Luzon in turn was weak during interstadials, in particular those of glacial Terminations I and II, when summer upwelling culminated east of South Vietnam. Most likely, this upwelling terminated widespread deep-water stratification, coeval with the deglacial rise in atmospheric CO2. Yet, a synchronous maximum in precipitation fostered estuarine overturning circulation in the South China Sea, in particular as long as the Borneo Strait was closed when sea level dropped below -40 m.

Screening of salivary volatiles for putative breast cancer discrimination: an exploratory study involving geographically distant populations.

PubMed

Cavaco, Carina; Pereira, Jorge A M; Taunk, Khushman; Taware, Ravindra; Rapole, Srikanth; Nagarajaram, Hampapathalu; Câmara, José S

2018-05-07

Saliva is possibly the easiest biofluid to analyse and, despite its simple composition, contains relevant metabolic information. In this work, we explored the potential of the volatile composition of saliva samples as biosignatures for breast cancer (BC) non-invasive diagnosis. To achieve this, 106 saliva samples of BC patients and controls in two distinct geographic regions in Portugal and India were extracted and analysed using optimised headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME/GC-MS, 2 mL acidified saliva containing 10% NaCl, stirred (800 rpm) for 45 min at 38 °C and using the CAR/PDMS SPME fibre) followed by multivariate statistical analysis (MVSA). Over 120 volatiles from distinct chemical classes, with significant variations among the groups, were identified. MVSA retrieved a limited number of volatiles, viz. 3-methyl-pentanoic acid, 4-methyl-pentanoic acid, phenol and p-tert-butyl-phenol (Portuguese samples) and acetic, propanoic, benzoic acids, 1,2-decanediol, 2-decanone, and decanal (Indian samples), statistically relevant for the discrimination of BC patients in the populations analysed. This work defines an experimental layout, HS-SPME/GC-MS followed by MVSA, suitable to characterise volatile fingerprints for saliva as putative biosignatures for BC non-invasive diagnosis. Here, it was applied to BC samples from geographically distant populations and good disease separation was obtained. Further studies using larger cohorts are therefore very pertinent to challenge and strengthen this proof-of-concept study. Graphical abstract ᅟ.

Comparison of different extraction methods for the analysis of volatile secondary metabolites of Lippia alba (Mill.) N.E. Brown, grown in Colombia, and evaluation of its in vitro antioxidant activity.

PubMed

Stashenko, Elena E; Jaramillo, Beatriz E; Martínez, Jairo René

2004-01-30

Hydrodistillation (HD), simultaneous distillation solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE) were employed to isolate volatile secondary metabolites from fresh leaves and stems of Colombian Lippia alba (Mill.) N.E. Brown. Kovàts indices, mass spectra or standard compounds were used to identify around 40 components in the various volatile fractions. Carvone (40-57%) was the most abundant component, followed by limonene (24-37%), bicyclosesquiphellandrene (5-22%), piperitenone (1-2%), piperitone (ca. 1.0%), and beta-bourbonene (0.6-1.5%), in the HD, SDE, MWHD, and SFE volatile fractions. Static headspace (S-HS), simultaneous purge and trap in solvent (CH2Cl2) (P&T), and headspace solid-phase microextraction (HS-SPME) were used to sample volatiles from fresh L. alba stems and leaves. The main components isolated from the headspace of the fresh plant material were limonene (27-77%), carvone (14-30%), piperitone (0.3-0.5%), piperitenone (ca. 0.4%), and beta-bourbonene (0.5-6.5%). The in vitro antioxidant activity of L. alba essential oil, obtained by hydrodistillation was evaluated by determination of hexanal, the main carbonyl compound released by linoleic acid subjected to peroxidation (1 mm Fe2+, 37 degrees C, 12 h), and by quantification of this acid as its methyl ester. Under the same conditions, L. alba HD-essential oil and Vitamin E exhibited similar antioxidant effects.

A comparison of the thermal and hydraulic performances between miniature pin fin heat sink and microchannel heat sink with zigzag flow channel together with using nanofluids

NASA Astrophysics Data System (ADS)

Duangthongsuk, Weerapun; Wongwises, Somchai

2018-05-01

In this study, a comparison of the convective heat transfer, pressure drop, and performance index characteristics of heat sinks with a miniature circular pin-fin inline arrangement (MCFHS) and a zigzag flow channel with single cross-cut structures (CCZ-HS) is presented. SiO2-water nanofluids with different particle concentrations are used as the coolant. The effects of the heat sink type, particle concentration and fluid flow rate on the thermal and hydraulic performances are evaluated. The testing conditions are performed at the wall heat fluxes of 10 to 60 kW/m2 and at a mass flow rate ranging from 0.18 to 0.6 kg/s. The dimension of heat sinks is equally designed at 28 × 33 mm. The heat transfer area of MCFHS and of CCZ-HS is 1430 and 1238 mm2, respectively. Similarly, the hydraulic diameter of the flow channel of MCFHS and of CCZ-HS is 1.2 and 1.0 mm, respectively. The measured data indicate that the cooling performances of CCZ-HS are about 24-55% greater than that of MCFHS. The effects of the channel diameter and single cross-cut of the flow channel are more dominant than the effects of the fin structure and heat transfer area.

Sampling methods for the study of volatile profile of PDO wine vinegars. A comparison using multivariate data analysis.

PubMed

Ríos-Reina, Rocío; Morales, M Lourdes; García-González, Diego L; Amigo, José M; Callejón, Raquel M

2018-03-01

High-quality wine vinegars have been registered in Spain under protected designation of origin (PDO): "Vinagre de Jerez", "Vinagre de Condado de Huelva" and "Vinagre de Montilla-Moriles". The raw material, production and aging processes determine their quality and their aromatic composition. Vinegar volatile profile is usually analyzed by gas chromatography-mass spectrometry (GC-MS), being necessary a previous extraction step. Thus, three different sampling methods (Headspace solid phase microextraction "HS-SPME", Headspace stir bar sorptive extraction "HSSE" and Dynamic headspace extraction "DHS") were studied for the analysis of the volatile composition of Spanish PDO wine vinegars. Multivariate curve resolution (MCR) was used to solve chromatographic problems, improving the results obtained. Principal component analysis (PCA) showed that not all the sampling methods were equally suitable for the characterization and differentiation between PDOs and categories, being HSSE the technique that made able the best vinegar characterization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of Urinary Btex, Nicotine, and Cotinine as Biomarkers of Airborne Pollutants in Nonsmokers and Smokers.

PubMed

Brajenović, Nataša; Karačonji, Irena Brčić; Bulog, Aleksandar

2015-01-01

Benzene, toluene, ethylbenzene, and isomeric xylenes (BTEX) are by-products of tobacco smoke and traffic emissions. The aim of this study was to determine the contribution of cigarette smoking to urinary levels of BTEX present in humans. Nicotine and cotinine, biomarkers of exposure to tobacco smoke, as well as BTEX, were measured in urine of smokers (n = 70) and nonsmokers (n = 65) using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). In smokers, a significant correlation was found between urinary BTEX levels and nicotine and cotinine. In addition, significant regression models with nicotine and cotinine as predictors showed that BTEX in smokers' urine was predominantly derived from exposure to tobacco smoke. In nonsmokers a weak correlation between BTEX and nicotine and cotinine was found in urine. Further, there was a lack of significant contribution of BTEX to urinary nicotine and cotinine concentrations in nonsmokers. Thus, it was presumed that vehicle exhaust was the main source of exposure to BTEX in nonsmokers.

Three-way principal component analysis of the volatile fraction by HS-SPME/GC of aceto balsamico tradizionale of modena.

PubMed

Cocchi, Marina; Durante, Caterina; Grandi, Margherita; Manzini, Daniela; Marchetti, Andrea

2008-01-15

The present research is aimed at monitoring the evolution of the volatile organic compounds of different samples of aceto balsamico tradizionale of modena (ABTM) during ageing. The flavouring compounds, headspace fraction, of the vinegars of four batterie were sampled by solid phase microextraction technique (SPME), and successively analysed by gas chromatography. Obtaining a data set characterized by different sources of variability such as, different producers, samples of different age and chromatographic profile. The gas chromatographic signals were processed by a three-way data analysis method (Tucker3), which allows an easy visualisation of the data by furnishing a distinct set of graphs for each source of variability. The obtained results indicate that the samples can be separated according to their age highlighting the chemical constituents, which play a major role for their differentiation. The present study represents an example of how the application of Tucker3 models, on gas chromatographic signals may help to follow the transformation processes of food products.

Occurrence of furan in commercial processed foods in Brazil.

PubMed

Arisseto, A P; Vicente, E; Furlani, R P Z; Ueno, M S; Pereira, A L D; Toledo, M C F

2012-01-01

Selected commercial processed foods available in the Brazilian market (306 samples) were analysed for furan content using a validated gas chromatography-mass spectrometry method preceded by headspace solid phase micro-extraction (HS-SPME-GC/MS). Canned and jarred foods, including vegetable, meat, fruit and sweet products, showed levels up to 32.8 µg kg⁻¹, with the highest concentrations observed in vegetables and meats. For coffee, furan content ranged from 253.0 to 5021.4 µg kg⁻¹ in the roasted ground coffee and from not detected to 156.6 µg kg⁻¹ in the beverage. For sauces, levels up to 138.1 µg kg⁻¹ were found. In cereal-based products, the highest concentrations (up to 191.3 µg kg⁻¹) were observed in breakfast cereal (corn flakes), cracker (cream crackers) and biscuit (wafer). In general, these results are comparable with those reported in other countries and will be useful for a preliminary estimate of the furan dietary intake in Brazil.

The effect of cryogenic grinding and hammer milling on the flavour quality of ground pepper (Piper nigrum L.).

PubMed

Liu, Hong; Zeng, Fankui; Wang, Qinghuang; Ou, Shiyi; Tan, Lehe; Gu, Fenglin

2013-12-15

In this study, we compared the effects of cryogenic grinding and hammer milling on the flavour attributes of black, white, and green pepper. The flavour attributes were analysed using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS), sensory evaluation and electronic nose (e-nose) analysis. Cryogenic grinding resulted in minimal damage to the colour, flavour, and sensory attributes of the spices. Cryogenic grinding was also better than hammer milling at preserving the main potent aroma constituents, but the concentrations of the main aroma constituents were dramatically reduced after storing the samples at 4 °C for 6 months. Pattern matching performed by the e-nose further supported our sensory and instrumental findings. Overall, cryogenic grinding was superior to hammer milling for preserving the sensory properties and flavour attributes of pepper without significantly affecting its quality. However, we found that the flavour quality of ground pepper was reduced during storage. Copyright © 2013 Elsevier Ltd. All rights reserved.

Static headspace analysis using polyurethane phases--application to roasted coffee volatiles characterization.

PubMed

Rodrigues, C; Portugal, F C M; Nogueira, J M F

2012-01-30

Static headspace sorptive extraction using polyurethane foams (HSSE(PU)) followed by gas chromatography coupled to mass spectrometry is proposed for volatile analysis. The application of this novel analytical approach to characterize the volatiles profile from roasted coffee samples, selected as model system, revealed remarkable advantages under convenient experimental conditions. The comparison of HSSE(PU) with other well-established procedures, such as headspace sorptive extraction using polydimethylsiloxane (HSSE(PDMS)) and headspace solid phase microextraction using carboxen/polydimethylsiloxane fibers (HS-SPME(CAR/PDMS)), showed that the former presented much higher capacity, sensitivity and even selectivity, where larger abundance and number of roasted coffee volatile compounds (e.g. furans, pyrazines, ketones, acids and pyrroles) could be achieved, under similar experimental conditions. The data presented herein proved, for the first time, that PU foams present great performance for static headspace sorption-based procedures, showing to be an alternative polymeric phase for volatile analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of some packaging materials and of natural tocopherols on the sensory properties of breakfast cereals.

PubMed

Paradiso, Vito M; Caponio, Francesco; Summo, Carmine; Gomes, Tommaso

2014-04-01

The combined effect of natural antioxidants and packaging materials on the quality decay of breakfast cereals during storage was evaluated. Corn flakes were produced on industrial scale, using different packages and adding natural tocopherols to the ingredients, and stored for 1 year. The samples were then submitted to sensory analysis and HS-solid phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS) analysis. The packaging had a significant influence on the sensory profile of the aged product: metallized polypropylene gave the highest levels of oxidation compounds and sensory defects. The sensory profile was improved using polypropylene and especially high-density polyethylene. Natural tocopherols reduced the sensory decay of the flakes and the oxidative evolution of the volatile profile. They gave the most remarkable improvement in polypropylene (either metallized or not) packs. Polypropylene showed a barrier effect on the scalping of volatiles outside of the pack. This led to higher levels of oxidation volatiles and faster rates of the further oxidative processes involving the volatiles.

Influence of enzymatic extrusion liquefaction pretreatment for Chinese rice wine on the volatiles generated from extruded rice.

PubMed

Xu, Enbo; Li, Hongyan; Wu, Zhengzong; Wang, Fang; Xu, Xueming; Jin, Zhengyu; Jiao, Aiquan

2015-01-01

Volatile compounds in enzymatic extruded rice, produced under different conditions of varying barrel temperature (BT), α-amylase concentration (AC) and moisture content (MC), were extracted and identified by headspace solid phase microextraction (HS-SPME) and gas chromatography-linked mass spectrometry (GC-MS). Statistical analyses reflected that the Maillard reaction could be inhibited both by the mild extrusion conditions and the enhanced hydrolysis caused by thermostable α-amylase. Relative amounts of total volatiles in enzymatic extruded rice were far less than those in severe processed extruded rice. Reverse-phase high-performance liquid chromatography (RP-HPLC) showed that the amino acids (AAs) involved in Maillrad reaction were utmostly preserved in extruded rice with highest amylase concentration by comparison of total AA content of different extrudates. These results suggest that enzymatic extrusion liquefaction is an effective way to control the generation of volatiles from extruded rice for Chinese rice wine production. © 2014 Institute of Food Technologists®

Ripening-dependent metabolic changes in the volatiles of pineapple (Ananas comosus (L.) Merr.) fruit: I. Characterization of pineapple aroma compounds by comprehensive two-dimensional gas chromatography-mass spectrometry.

PubMed

Steingass, Christof Björn; Carle, Reinhold; Schmarr, Hans-Georg

2015-03-01

Qualitative ripening-dependent changes of pineapple volatiles were studied via headspace solid-phase microextraction and analyzed by comprehensive two-dimensional gas chromatography quadrupole mass spectrometry (HS-SPME-GC×GC-qMS). Early green-ripe stage, post-harvest ripened, and green-ripe fruits at the end of their commercial shelf-life were compared to air-freighted pineapples harvested at full maturity. In total, more than 290 volatiles could be identified by mass spectrometry and their linear retention indices. The majority of compounds comprise esters (methyl and ethyl esters of saturated and unsaturated fatty acids, acetates), terpenes, alcohols, aldehydes, 2-ketones, free fatty acids, and miscellaneous γ- and δ-lactones. The structured separation space obtained by GC×GC allowed revealing various homologous series of compound classes as well as clustering of sesquiterpenes. Post-harvest ripening increased the diversity of the volatile profile compared to both early green-ripe maturity stages and on-plant ripened fruits.

Metabolite profiling on apple volatile content based on solid phase microextraction and gas-chromatography time of flight mass spectrometry.

PubMed

Aprea, Eugenio; Gika, Helen; Carlin, Silvia; Theodoridis, Georgios; Vrhovsek, Urska; Mattivi, Fulvio

2011-07-15

A headspace SPME GC-TOF-MS method was developed for the acquisition of metabolite profiles of apple volatiles. As a first step, an experimental design was applied to find out the most appropriate conditions for the extraction of apple volatile compounds by SPME. The selected SPME method was applied in profiling of four different apple varieties by GC-EI-TOF-MS. Full scan GC-MS data were processed by MarkerLynx software for peak picking, normalisation, alignment and feature extraction. Advanced chemometric/statistical techniques (PCA and PLS-DA) were used to explore data and extract useful information. Characteristic markers of each variety were successively identified using the NIST library thus providing useful information for variety classification. The developed HS-SPME sampling method is fully automated and proved useful in obtaining the fingerprint of the volatile content of the fruit. The described analytical protocol can aid in further studies of the apple metabolome. Copyright © 2011 Elsevier B.V. All rights reserved.

Rapid determination of floral aroma compounds of lilac blossom by fast gas chromatography combined with surface acoustic wave sensor.

PubMed

Oh, Se Yeon; Shin, Hyun Du; Kim, Sung Jean; Hong, Jongki

2008-03-07

A novel analytical method using fast gas chromatography combined with surface acoustic wave sensor (GC/SAW) has been developed for the detection of volatile aroma compounds emanated from lilac blossom (Syringa species: Syringa vulgaris variginata and Syringa dilatata). GC/SAW could detect and quantify various fragrance emitted from lilac blossom, enabling to provide fragrance pattern analysis results. The fragrance pattern analysis could easily characterize the delicate differences in aromas caused by the substantial difference of chemical composition according to different color and shape of petals. Moreover, the method validation of GC/SAW was performed for the purpose of volatile floral actual aroma analysis, achieving a high reproducibility and excellent sensitivity. From the validation results, GC/SAW could serve as an alternative analytical technique for the analysis of volatile floral actual aroma of lilac. In addition, headspace solid-phase microextraction (HS-SPME) GC-MS was employed to further confirm the identification of fragrances emitted from lilac blossom and compared to GC/SAW.

Gold nanorods for in-drop colorimetric determination of thiomersal after photochemical decomposition.

PubMed

Martín-Alonso, Manuel; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

2018-03-13

This work reports on the implementation of gold nanorods (AuNRs) in headspace solvent microextraction for colorimetric determination of volatile analyte derivatives in a single drop. The exposure of AuNRs to both H 2 Se and elemental mercury (Hg 0 ) results in a shift of the longitudinal plasmonic band, unlike a number of volatiles. Accordingly, a method is reported for the determination of Hg 0 with potential applicability to the determination of thiomersal (sodium ethylmercurithiosalicylate). It is based on the photochemical decomposition of thiomersal into Hg(II) and subsequent exposure of AuNRs-containing microdrop to in situ generated Hg 0 . Colorimetric analysis of the enriched drop was carried out without dilution by means of a cuvetteless microvolume UV-vis spectrometer. Under optimal conditions, the limit of detection was 0.5 ng mL -1 (as Hg). The repeatability, expressed as relative standard deviation, was 8.4% (for n = 10). AuNRs exposed to increasing concentrations of the analyte were characterized by means of transmission electron microscopy and UV-vis spectrophotometry to ascertain the mechanism of detection. The method was finally applied to the determination of thiomersal in various pharmaceutical samples and showed quantitative recoveries. Graphical abstract Schematic illustration of a miniaturized colorimetric method based on the use of a microdrop of gold nanorods (AuNRs) for thiomersal determination in pharmaceuticals. It is based on the photochemical decomposition of thiomersal and subsequent Hg 0 generation with in-drop amalgamation.

Determination of fluoroquinolone antibiotics via ionic-liquid-based, salt-induced, dual microextraction in swine feed.

PubMed

Wang, Huili; Gao, Ming; Gao, Jiajia; Yu, Nana; Huang, Hong; Yu, Qing; Wang, Xuedong

2016-09-01

In conventional microextraction procedures, the disperser (organic solvent or ionic liquid) is left in the aqueous phase and discarded after finishing the microextraction process. Because the disperser is water-soluble, it results in low extraction recovery for polar compounds. In this investigation, an ionic-liquid-based microextraction (ILBME) was integrated with salting-out assisted liquid-liquid microextraction (SALLME) to build an ionic-liquid-based, salt-induced, dual microextraction (ILSDME) for isolation of five fluoroquinolone antibiotics (FQs) with high polarity (log P, -1.0 to 1.0). The proposed ILSDME method incorporates a dual microextraction by converting the disperser in the ILBME to the extractor in the SALLME. Optimization of key factors was conducted by integrating single-factor experiments and central composite design. The optimized experimental parameters were 80 μL [C8MIM][PF6] as extractor, 505 μL acetone as disperser, pH = 2.0, 4.1 min extraction time, and 4.2 g of Na2SO4. Under optimized conditions, high ERs (90.6-103.2 %) and low LODs (0.07-0.61 μg kg(-1)) were determined for five FQs in swine feed. Experimental precision based on RSDs was 1.4-5.2 % for intra-day and 2.4-6.9 % for inter-day analyses. The combination of ILBME with SALLME increased FQ recoveries by 15-20 % as compared with SALLME, demonstrating that the ILSDME method can enhance extraction efficiency for polar compounds compared to single-step microextraction. Therefore, the ILSDME method developed in this study has wide application for pretreatment of moderately to highly polar pollutants in complex matrices. Graphical Abstract A dual microextraction was developed by integrating ionic-liquid-based microextraction with salting-out assisted liquid-liquid microextraction for isolation of five fluoroquinolone antibiotics (FQs) with high polarity (log P = -1.0 to 1.0). The principle of dual microextraction is based on converting the remaining disperser from the first microextraction into an extractor in the second microextraction. Single-factor experiment and central composite design were applied for optimizing operational parameters using 3D response surfaces and contour lines. Under optimized conditions, the method provided high extraction recoveries and low LODs for five FQs in swine feed. The prominent advantage of the dual microextraction is rapid and highly efficient extraction of moderately to highly polar fluoroquinolones from complex matrices.

Nanoporous array anodic titanium-supported co-polymeric ionic liquids as high performance solid-phase microextraction sorbents for hydrogen bonding compounds.

PubMed

Jia, Jing; Liang, Xiaojing; Wang, Licheng; Guo, Yong; Liu, Xia; Jiang, Shengxiang

2013-12-13

A nanoporous array anodic titanium-supported co-polymeric ionic liquids (NAAT/PILs) solid-phase microextraction (SPME) fiber was prepared in situ on the titanium wire. NAAT was selected as the substrate, in view of its high surface-to-volume ratio, easy preparation, mechanical stability, and rich titanol groups on its surface which can anchor silica coupling agent containing vinyl and then introduce ionic liquid copolymers as sorbents. In this work, 1-vinyl-3-nonanol imidazolium bromide ([C9OHVIm]Br) and 1,4-di(3-vinylimidazolium) butane dibromide ([(VIM)2C4]2[Br]) were synthesized and used as monomer and crosslinker, respectively. Extraction properties of the NAAT/PILs fiber for polar alcohols and volatile fatty acids (VFAs) in aqueous matrix were examined using gaseous sampling-SPME (GS-SPME) and headspace SPME (HS-SPME) mode, respectively. Combining the superior properties of NAAT substrate and the strong hydrogen bond interaction of PILs to polar compounds, the NAAT/PILs SPME fiber showed much higher adsorption affinity to aliphatic alcohols than bare NAAT and pure PILs fibers. The detection limits (LOD) of established GS-SPME-GC-FID method are in the range of 0.35-17.30ngL(-1) with a linear range from 0.01 to 500ngmL(-1). Also, it showed high extraction performance toward volatile fatty acids (VFAs) compounds from aqueous matrix. Under the optimized SPME conditions, wide linear ranges were obtained with correlation coefficients (R(2)) greater than 0.99 and limits of detection were in the range of 0.85-8.74ngL(-1). Moreover, real-world samples were analyzed and good results were obtained. Copyright © 2013. Published by Elsevier B.V.

Characterization of the aroma profile of novel Brazilian wines by solid-phase microextraction using polymeric ionic liquid sorbent coatings.

PubMed

Crucello, Juliana; Miron, Luiz F O; Ferreira, Victor H C; Nan, He; Marques, Marcia O M; Ritschel, Patricia S; Zanus, Mauro C; Anderson, Jared L; Poppi, Ronei J; Hantao, Leandro W

2018-05-28

In this study, a series of polymeric ionic liquid (PIL) sorbent coatings is evaluated for the extraction of polar volatile organic compounds (VOCs) from Brazilian wines using headspace solid-phase microextraction (HS-SPME), including samples from 'Isabella' and 'BRS Magna' cultivars-the latter was recently introduced by the Brazilian Agricultural Research Corporation - National Grape & Wine Research Center. The structurally tuned SPME coatings were compared to the commercial SPME phases, namely poly(acrylate) (PA) and divinylbenzene/carboxen/poly(dimethylsiloxane) (DVB/CAR/PDMS). The separation, detection and identification of the aroma profiles were obtained using comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS). The best performing PIL-based SPME fiber, namely 1-hexadecyl-3-vinylimidazolium bis[(trifluoromethyl)sulfonyl]imide with 1,12-di(3-vinylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide incorporated cross-linker supported on an elastic nitinol wire, exhibited superior performance to DVB/CAR/PDMS regarding the average number of extracted peaks and extracted more polar analytes providing additional insight into the aroma profile of 'BRS Magna' wines. Four batches of wine were evaluated, namely 'Isabella' and 'BRS Magna' vintages 2015 and 2016, using highly selective PIL-based SPME coatings and enabled the detection of 350+ peaks. Furthermore, this is the first report evaluating the aroma of 'BRS Magna' wines. A hybrid approach that combined pixel-based Fisher ratio and peak table-based data comparison was used for data handling. This proof-of-concept experiment provided reliable and statistically valid distinction of wines that may guide regulation agencies to create high sample throughput protocols to screen wines exported by Brazilian vintners. Graphical abstract Highly selective extraction of wine aroma using polymeric ionic liquid.

Rapid screening procedure based on headspace solid-phase microextraction and gas chromatography-mass spectrometry for the detection of many recreational drugs in hair.

PubMed

Gentili, Stefano; Cornetta, Maria; Macchia, Teodora

2004-03-05

An increasing number of synthetic drugs are appearing on the illicit market and on the scene of drug use by youngsters. Official figures are underestimated. In addition, immunochemical tests are blind to many of these drugs and appropriate analytical procedures for routine clinical and epidemiological purposes are lacking. Therefore, the perceived increasing abuse of recreational drugs has not been proved yet. In a previous paper, we proposed a procedure for the preliminary screening of several recreational substances in hair and other biological matrices. Unfortunately, this procedure cannot apply to cocaine. Consequently, we performed a new headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) procedure for the simultaneous detection of cocaine, amphetamine (A), methamphetamine (MA), methylen-dioxyamphetamine (MDA), methylen-dioxymethamphetamine (MDMA), methylen-dioxyethamphetamine (MDE), N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine (MBDB), ketamine, and methadone in human hair. Hair was washed with water and acetone in an ultrasonic bath. A short acid extraction with 1M hydrochloric acid was needed; the fiber was exposed to a 5 min absorption at 90 degrees C and thermal desorption was performed at 250 degrees C for 3 min. The procedure was simple, rapid, required small quantities of sample and no derivatization. Good linearity was obtained over the 0.1-20.0 ng/mg range for the target compounds. Sensitivity was good enough: limits of detection (LOD) were 0.7 ng/mg of hair for the majority of substances. The intra-day precision ranged between 7 and 20%. This paper deals with the analytical performance of this procedure and its preliminary application to hair samples obtained on a voluntary basis from 183 young people (138 males and 45 females) in the Rome area.

An improved method for the analysis of 2-aminoacetophenone in wine based on headspace solid-phase microextraction and heart-cut multidimensional gas chromatography with selective detection by tandem mass spectrometry.

PubMed

Schmarr, Hans-Georg; Keiser, Jutta; Krautwald, Susann

2016-12-16

Heart-cut multidimensional gas chromatography coupled to selective mass spectrometric detection (H/C MDGC-MS-MS) was shown to be a suitable combination for analysis of the key component for the wine off-flavor named "atypical aging off-flavor" (german: "Untypische Alterungsnote", UTA), 2-aminoacetophenone (2-AAP). Headspace solid phase microextraction (HS-SPME) was applied as an easy to automate sample preparation step suiting routine control situations. During method development two critical aspects were found, of which one is the chemical degradation of the neat substance, leading to signal reduction and a false response behavior. A second aspect is the pH stability of the deuterated isotopologue 1-(2-aminophenyl)-2,2,2-trideuterio-ethanone (2-AAP-d3) used for quantification via a stable isotope dilution assay. Despite an earlier suggestion to increase the extractable amount of 2-AAP and its isotopic standard in the headspace, alkalization of 2-AAP-d3 containing aqueous samples were found to be critical. In such a milieu a deuterium exchange can then cause erroneous quantitative results. The method proposed in our study thus uses native wine pH conditions and proved to be suitable for routine control with respect to the detection of the "atypical aging off-flavor" in wine at concentration levels below its sensory threshold of about 1μgL -1 . Good linearity was obtained in the calibrated range from 0.1-8μgL -1 (y=1,2338x+0,1029, R=0,9985) with limits of detection or quantification being 0.01 and 0.14μg/L, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Headspace solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the analysis of aerosol from tobacco heating product.

PubMed

Savareear, Benjamin; Lizak, Radoslaw; Brokl, Michał; Wright, Chris; Liu, Chuan; Focant, Jean-Francois

2017-10-20

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was developed and optimised to elucidate the volatile composition of the particulate phase fraction of aerosol produced by tobacco heating products (THPs). Three SPME fiber types were studied in terms of extraction capacity and precision measurements. Divinylbenzene polydimethylsiloxane appeared as the most efficient coating for these measurements. A central composite design of experiment was utilised for the optimization of the extraction conditions. Qualitative and semi-quantitative analysis of the headspace above THP aerosol condensate was carried out using optimised extraction conditions. Semi-quantitative analyses of detected constituents were performed by assuming that their relative response factors to the closest internal standard ( i t R ) were equal to 1. Using deconvoluted mass spectral data (library similarity and reverse match >750) and linear retention indices (match window of ±15 index units), 205 peaks were assigned to individual compounds, 82 of which (including 43 substances previously reported to be present in tobacco) have not been reported previously in tobacco aerosol. The major volatile fraction of the headspace contained ketones, alcohols, aldehydes, alicyclic hydrocarbons alkenes, and alkanes. The method was further applied to compare the volatiles from the particulate phase of aerosol composition of THP with that of reference cigarette smoke and showed that the THP produced a less complex chemical mixture. This new method showed good efficiency and precision for the peak areas and peak numbers from the volatile fraction of aerosol particulate phase for both THP and reference cigarettes. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigations on the emission of fragrance allergens from scented toys by means of headspace solid-phase microextraction gas chromatography-mass spectrometry.

PubMed

Masuck, Ines; Hutzler, Christoph; Luch, Andreas

2010-04-30

In the revised European toy safety directive 2009/48/EC the application of fragrance allergens in children's toys is restricted. The focus of the present work lies on the instrumental analytics of 13 banned fragrance allergens, as well as on 11 fragrance allergens that require declaration when concentrations surpass 100 microg per gram material. Applying a mixture of ethyl acetate and toluene solid/liquid extraction was performed prior to quantitative analysis of mass contents of fragrances in scented toys. In addition, an easy-to-perform method for the determination of emitted fragrances at 23 degrees C (handling conditions) or at 40 degrees C (worst case scenario) has been worked out to allow for the evaluation of potential risks originating from inhalation of these compounds during handling of or playing with toys. For this purpose a headspace solid-phase microextraction (HS-SPME) technique was developed and coupled to subsequent gas chromatography-mass spectrometry (GC-MS) analysis. Fragrance allergens were adsorbed (extracted) from the gas phase onto an 85 microm polyacrylate fiber while incubating pieces of the scented toys in sealed headspace vials at 23 degrees C and 40 degrees C. Quantification of compounds was performed via external calibration. The newly developed headspace method was subsequently applied to five perfumed toys. As expected, the emission of fragrance allergens from scented toys depends on the temperature and on the content of fragrance allergens present in those samples. In particular at conditions mimicking worst case (40 degrees C), fragrance allergens in toys may pose a risk to children since considerable amounts of compound might be absorbed by lung tissue via breathing of contaminated air. 2010 Elsevier B.V. All rights reserved.

A salting out system for improving the efficiency of the headspace solid-phase microextraction of short and medium chain free fatty acids.

PubMed

Fiorini, Dennis; Pacetti, Deborah; Gabbianelli, Rosita; Gabrielli, Serena; Ballini, Roberto

2015-08-28

Given the importance of short and medium chain free fatty acids (FFAs) in several fields, this study sought to improve the extraction efficiency of the solid-phase microextraction (SPME) of FFAs by evaluating salting out agents that appear promising for this application. The salts ammonium sulfate ((NH4)2SO4) and sodium dihydrogen phosphate (NaH2PO4) were tried on their own and in combination (3.7/1), in four different total amounts, as salting out agents in the headspace-SPME-gas chromatographic (HS-SPME-GC) analysis of the FFAs from acetic acid (C2) to decanoic acid (C10). Their performance in a model system of an aqueous standard mixture of FFAs at a pH of 3.5 was compared to that of the more commonly used sodium chloride (NaCl) and sodium sulfate (Na2SO4). All of the salts and salt systems evaluated, in proper amount, gave improved results compared to NaCl (saturated), which instead gave interesting results only for the least volatile FFAs C8 and C10. For C2-C6, the salt system that gave the best results compared to NaCl was (NH4)2SO4/NaH2PO4, in the highest of the four amounts evaluated, with factor increases between 1.2 and 4.1-fold, and NaH2PO4, between 1.0 and 4.3-fold. The SPME extraction efficiency given by the mixture (NH4)2SO4/NaH2PO4 was also assessed on biological and food samples, confirming that overall it performed better than NaCl. Copyright © 2015 Elsevier B.V. All rights reserved.

Use of different sample temperatures in a single extraction procedure for the screening of the aroma profile of plant matrices by headspace solid-phase microextraction.

PubMed

Martendal, Edmar; de Souza Silveira, Cristine Durante; Nardini, Giuliana Stael; Carasek, Eduardo

2011-06-17

This study proposes a new approach to the optimization of the extraction of the volatile fraction of plant matrices using the headspace solid-phase microextraction (HS-SPME) technique. The optimization focused on the extraction time and temperature using a CAR/DVB/PDMS 50/30 μm SPME fiber and 100mg of a mixture of plants as the sample in a 15-mL vial. The extraction time (10-60 min) and temperature (5-60 °C) were optimized by means of a central composite design. The chromatogram was divided into four groups of peaks based on the elution temperature to provide a better understanding of the influence of the extraction parameters on the extraction efficiency considering compounds with different volatilities/polarities. In view of the different optimum extraction time and temperature conditions obtained for each group, a new approach based on the use of two extraction temperatures in the same procedure is proposed. The optimum conditions were achieved by extracting for 30 min with a sample temperature of 60 °C followed by a further 15 min at 5 °C. The proposed method was compared with the optimized conventional method based on a single extraction temperature (45 min of extraction at 50 °C) by submitting five samples to both procedures. The proposed method led to better results in all cases, considering as the response both peak area and the number of identified peaks. The newly proposed optimization approach provided an excellent alternative procedure to extract analytes with quite different volatilities in the same procedure. Copyright © 2011 Elsevier B.V. All rights reserved.

Optimisation of solid-phase microextraction combined with gas chromatography-mass spectrometry based methodology to establish the global volatile signature in pulp and skin of Vitis vinifera L. grape varieties.

PubMed

Perestrelo, Rosa; Barros, António S; Rocha, Sílvia M; Câmara, José S

2011-09-15

The volatiles (VOCs) and semi-volatile organic compounds (SVOCs) responsible for aroma are mainly present in skin of grape varieties. Thus, the present investigation is directed towards the optimisation of a solvent free methodology based on headspace-solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS) in order to establish the global volatile composition in pulp and skin of Bual and Bastardo Vitis vinifera L. varieties. A deep study on the extraction-influencing parameters was performed, and the best results, expressed as GC peak area, number of identified compounds and reproducibility, were obtained using 4 g of sample homogenised in 5 mL of ultra-pure Milli-Q water in a 20 mL glass vial with addition of 2g of sodium chloride (NaCl). A divinylbenzene/carboxen/polydimethylsiloxane fibre was selected for extraction at 60°C for 45 min under continuous stirring at 800 rpm. More than 100 VOCs and SVOCs, including 27 monoterpenoids, 27 sesquiterpenoids, 21 carbonyl compounds, 17 alcohols (from which 2 aromatics), 10 C(13) norisoprenoids and 5 acids were identified. The results showed that, for both grape varieties, the levels and number of volatiles in skin were considerably higher than those observed in pulp. According to the data obtained by principal component analysis (PCA), the establishment of the global volatile signature of grape and the relationship between different part of grapes-pulp and skin, may be an useful tool to winemaker decision to define the vinification procedures that improves the organoleptic characteristics of the corresponding wines and consequently contributed to an economic valorization and consumer acceptance. Copyright © 2011 Elsevier B.V. All rights reserved.

Headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry for the determination of haloanisoles in sparkling (cava and cider) and non-sparkling (wine) alcoholic beverages.

PubMed

Ruiz-Delgado, Ana; Arrebola-Liébanas, Francisco Javier; Romero-González, Roberto; López-Ruiz, Rosalía; Garrido Frenich, Antonia

2016-10-01

A highly sensitive analytical method was developed to determine 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA) and 2,3,4,5,6-pentachloroanisole (PCA) in sparkling alcoholic beverages. The method was based on the use of headspace solid-phase microextraction (HS-SPME) using a polydimethylsiloxane (PDMS) fibre. It was coupled to gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) for the detection and quantification of the target haloanisoles. The method was fully automated and no sample preparation was needed. The method was validated for alcoholic beverages. The influence of CO 2 on the extraction efficiency was also evaluated for the studied sparkling drinks (cava and cider). All the calibration curves showed good linearity (R 2  > 0.98) within the tested range (1-50 ng l -1 ). Recoveries were evaluated at three different levels (1, 5 and 50 ng l -1 ) and were always between 71% and 119%. Precision was expressed as relative standard deviation (RSD), and was evaluated as intra- and inter-day precisions, with values ≤ 22% in both cases. Limits of quantitation (LOQs) were ≤ 0.91 ng l -1 , which are below the sensory threshold levels for such compounds in humans. The validated method was applied to commercial samples, 10 cavas and 10 ciders, but it was also used for the analysis of nine red wines and four white wines, demonstrating the further applicability of the proposed method to non-sparkling beverages. TCA was detected in most samples at up to 0.45 ng l -1 .

Layer-by-layer fabrication of chemical-bonded graphene coating for solid-phase microextraction.

PubMed

Zhang, Suling; Du, Zhuo; Li, Gongke

2011-10-01

A new fabrication strategy of the graphene-coated solid-phase microextraction (SPME) fiber is developed. Graphite oxide was first used as starting coating material that covalently bonded to the fused-silica substrate using 3-aminopropyltriethoxysilane (APTES) as cross-linking agent and subsequently deoxidized by hydrazine to give the graphene coating in situ. The chemical bonding between graphene and the silica fiber improve its chemical stability, and the obtained fiber was stable enough for more than 150 replicate extraction cycles. The graphene coating was wrinkled and folded, like the morphology of the rough tree bark. Its performance is tested by headspace (HS) SPME of polycyclic aromatic hydrocarbons (PAHs) followed by GC/MS analysis. The results showed that the graphene-coated fiber exhibited higher enrichment factors (EFs) from 2-fold for naphthalene to 17-fold for B(b)FL as compared to the commercial polydimethylsioxane (PDMS) fiber, and the EFs increased with the number of condensed rings of PAHs. The strong adsorption affinity was believed to be mostly due to the dominant role of π-π stacking interaction and hydrophobic effect, according to the results of selectivity study for a variety of organic compounds including PAHs, the aromatic compounds with different substituent groups, and some aliphatic hydrocarbons. For PAHs analysis, the graphene-coated fiber showed good precision (<11%), low detection limits (1.52-2.72 ng/L), and wide linearity (5-500 ng/L) under the optimized conditions. The repeatability of fiber-to-fiber was 4.0-10.8%. The method was applied to simultaneous analysis of eight PAHs with satisfactory recoveries, which were 84-102% for water samples and 72-95% for soil samples, respectively.

Speciation of As(III) and As(V) in water samples by graphite furnace atomic absorption spectrometry after solid phase extraction combined with dispersive liquid-liquid microextraction based on the solidification of floating organic drop.

PubMed

Shamsipur, Mojtaba; Fattahi, Nazir; Assadi, Yaghoub; Sadeghi, Marzieh; Sharafi, Kiomars

2014-12-01

A solid phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) method, using diethyldithiphosphate (DDTP) as a proper chelating agent, has been developed as an ultra preconcentration technique for the determination of inorganic arsenic in water samples prior to graphite furnace atomic absorption spectrometry (GFAAS). Variables affecting the performance of both steps were thoroughly investigated. Under optimized conditions, 100mL of As(ΙΙΙ) solution was first concentrated using a solid phase sorbent. The extract was collected in 2.0 mL of acetone and 60.0 µL of 1-undecanol was added into the collecting solvent. The mixture was then injected rapidly into 5.0 mL of pure water for further DLLME-SFO. Total inorganic As(III, V) was extracted similarly after reduction of As(V) to As(III) with potassium iodide and sodium thiosulfate and As(V) concentration was calculated by difference. A mixture of Pd(NO3)2 and Mg(NO3)2 was used as a chemical modifier in GFAAS. The analytical characteristics of the method were determined. The calibration graph was linear in the rage of 10-100 ng L(-1) with detection limit of 2.5 ng L(-1). Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 80 ng L(-1) of As(ΙΙΙ) were 6.8% and 7.5%, respectively. The method was successfully applied to speciation of As(III), As(V) and determination of the total amount of As in water samples and in a certified reference material (NIST RSM 1643e). Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of residual 1,4-dioxane in surfactants and cleaning agents using headspace single-drop microextraction followed by gas chromatography-flame ionization detection.

PubMed

Saraji, M; Shirvani, N

2017-02-01

Polyethoxylated surfactants are widely used in the formulation of different cleaning agents such as shampoo, dish washing and hand washing products and lotion formulation. During the production of polyethoxylated surfactants, 1,4-dioxane as a toxic and carcinogenic by-product is formed. A simple low-cost method based on headspace single-drop microextraction combined with gas chromatography-flame ionization detection was developed for the determination of 1,4-dioxane in surfactants and cleaning agents. In this method, 1,4-dioxane was extracted from 8.0 mL sample solution into a microdrop of an organic solvent, and then, it was injected to gas chromatography. The effects of such parameters as the solvent type, salt addition, microdrop volume, stirring rate, equilibrium time, extraction time and the temperature of sample solution on the extraction performance were studied and optimized. An ethoxylated surfactant containing 1,4-dioxane was used as the sample for the optimization of the extraction parameters. The linear range, determination coefficient, limit of detection and relative standard deviation of the method were 0.5-100 μg g -1 , 0.9977, 0.4 μg g -1 and 7.2% (n = 5), respectively. Different real samples including sodium lauryl ether sulphate, sodium lauryl sulphate (SLS), four brands of shampoo, and hand washing and dish washing liquids were analysed by the method. 1,4-Dioxane was detected at the concentration range of 2.4-201 μg g -1 in the samples, except dish washing liquid and SLS. A new method with the merits of simplicity, low cost, low organic solvent consumption, short analysis time, good repeatability and suitable detection limit was developed for the analysis of 1,4-dioxane in surfactants and cleaning agents. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

A comprehensive comparison between thermodynamic perturbation theory and first-order mean spherical approximation: Based on discrete potentials with hard core

NASA Astrophysics Data System (ADS)

Zhou, Shiqi; Zhou, Run

2017-08-01

Using the TL (Tang and Lu, 1993) method, Ornstein-Zernike integral equation is solved perturbatively under the mean spherical approximation (MSA) for fluid with potential consisting of a hard sphere plus square-well plus square-shoulder (HS + SW + SS) to obtain first-order analytic expressions of radial distribution function (RDF), second-order direct correlation function, and semi-analytic expressions for common thermodynamic properties. A comprehensive comparison between the first-order MSA and high temperature series expansion (HTSE) to third-, fifth- and seventh-order is performed over a wide parameter range for both a HS + SW and the HS + SW + SS model fluids by using corresponding ;exact; Monte Carlo results as a reference; although the HTSE is carried out up to seventh-order, and not to the first order as the first-order MSA the comparison is considered fair from a calculation complexity perspective. It is found that the performance of the first-order MSA is dramatically model-dependent: as target potentials go from the HS + SW to the HS + SW + SS, (i) there is a dramatic dropping of performance of the first-order MSA expressions in calculating the thermodynamic properties, especially both the excess internal energy and constant volume excess heat capacity of the HS + SW + SS model cannot be predicted even qualitatively correctly. (ii) One tendency is noticed that the first-order MSA gets more reliable with increasing temperatures in dealing with the pressure, excess Helmholtz free energy, excess enthalpy and excess chemical potential. (iii) Concerning the RDF, the first-order MSA is not as disappointing as it displays in the cases of thermodynamics. (iv) In the case of the HS + SW model, the first-order MSA solution is shown to be quantitatively correct in calculating the pressure and excess chemical potential even if the reduced temperatures are as low as 0.8. On the other hand, the seventh-order HTSE is less model-dependent; in most cases of the HS + SW and the HS + SW + SS models, the seventh-order HTSE improves the fifth- and third-order HTSE in both thermodynamic properties and RDF, and the improvements are very demonstrable in both the excess internal energy and constant volume excess heat capacity; for very limited cases, the seventh-order HTSE improves the fifth-order HTSE only within lower density domain and even shows a bit of inadaptation over higher density domain.

Volatile Compound Profiling by HS-SPME/GC-MS-FID of a Core Olive Cultivar Collection as a Tool for Aroma Improvement of Virgin Olive Oil.

PubMed

García-Vico, Lourdes; Belaj, Angjelina; Sánchez-Ortiz, Araceli; Martínez-Rivas, José M; Pérez, Ana G; Sanz, Carlos

2017-01-14

Virgin olive oil (VOO) is the only food product requiring official sensory analysis to be classified in commercial categories, in which the evaluation of the aroma plays a very important role. The selection of parents, with the aim of obtaining new cultivars with improved oil aroma, is of paramount importance in olive breeding programs. We have assessed the volatile fraction by headspace-solid-phase microextraction/gas chromatography-mass spectrometry-flame ionization detection (HS-SPME/GC-MS-FID) and the deduced aroma properties of VOO from a core set of olive cultivars (Core-36) which possesses most of the genetic diversity found in the World Olive Germplasm Collection (IFAPA Alameda del Obispo) located in Cordoba, Spain. The VOO volatile fractions of Core-36 cultivars display a high level of variability. It is mostly made of compounds produced from polyunsaturated fatty acids through the lipoxygenase pathway, which confirms to be a general characteristic of the olive species ( Olea europaea L.). The main group of volatile compounds in the oils was six straight-chain carbon compounds derived from linolenic acid, some of them being the main contributors to the aroma of the olive oils according to their odor activity values (OAV). The high level of variability found for the volatile fraction of the oils from Core-36 and, therefore, for the aroma odor notes, suggest that this core set may be a very useful tool for the choice of optimal parents in olive breeding programs in order to raise new cultivars with improved VOO aroma.

Headspace-Solid Phase Microextraction Approach for Dimethylsulfoniopropionate Quantification in Solanum lycopersicum Plants Subjected to Water Stress

PubMed Central

Catola, Stefano; Kaidala Ganesha, Srikanta Dani; Calamai, Luca; Loreto, Francesco; Ranieri, Annamaria; Centritto, Mauro

2016-01-01

Dimethylsulfoniopropionate (DMSP) and dimethyl sulphide (DMS) are compounds found mainly in marine phytoplankton and in some halophytic plants. DMS is a globally important biogenic volatile in regulating of global sulfur cycle and planetary albedo, whereas DMSP is involved in the maintenance of plant-environment homeostasis. Plants emit minute amounts of DMS compared to marine phytoplankton and there is a need for hypersensitive analytic techniques to enable its quantification in plants. Solid Phase Micro Extraction from Head Space (HS-SPME) is a simple, rapid, solvent-free and cost-effective extraction mode, which can be easily hyphenated with GC-MS for the analysis of volatile organic compounds. Using tomato (Solanum lycopersicum) plants subjected to water stress as a model system, we standardized a sensitive and accurate protocol for detecting and quantifying DMSP pool sizes, and potential DMS emissions, in cryoextracted leaves. The method relies on the determination of DMS free and from DMSP pools before and after the alkaline hydrolysis via Headspace-Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS). We found a significant (2.5 time) increase of DMSP content in water-stressed leaves reflecting clear stress to the photosynthetic apparatus. We hypothesize that increased DMSP, and in turn DMS, in water-stressed leaves are produced by carbon sources other than direct photosynthesis, and function to protect plants either osmotically or as antioxidants. Finally, our results suggest that SPME is a powerful and suitable technique for the detection and quantification of biogenic gasses in trace amounts. PMID:27602039

Glyoxal and methylglyoxal as urinary markers of diabetes. Determination using a dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry.

PubMed

Pastor-Belda, M; Fernández-García, A J; Campillo, N; Pérez-Cárceles, M D; Motas, M; Hernández-Córdoba, M; Viñas, P

2017-08-04

Glyoxal (GO) and methylglyoxal (MGO) are α-oxoaldehydes that can be used as urinary diabetes markers. In this study, their levels were measured using a sample preparation procedure based on salting-out assisted liquid-liquid extraction (SALLE) and dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-mass spectrometry (GC-MS). The effect of the derivatization reaction with 2,3-diaminonaphthalene, the addition of acetonitrile and sodium chloride to urine, and the DLLME step using the acetonitrile extract as dispersant solvent and carbon tetrachloride as extractant solvent were carefully optimized. Quantification was performed by the internal standard method, using 5-bromo-2-chloroanisole. The intraday and interday precisions were lower than 6%. Limits of detection were 0.12 and 0.06ngmL -1 , and enrichment factors 140 and 130 for GO and MGO, respectively. The concentrations of these α-oxoaldehydes in urine were between 0.9 and 35.8ngg -1 levels (creatinine adjusted). A statistical comparison of the analyte contents of urine samples from non-diabetic and diabetic patients pointed to significant differences (P=0.046, 24 subjects investigated), particularly regarding MGO, which was higher in diabetic patients. The novelty of this study compared with previous procedures lies in the treatment of the urine sample by SALLE based on the addition of acetonitrile and sodium chloride to the urine. The DLLME procedure is performed with a sedimented drop of the extractant solvent, without a surfactant reagent, and using acetonitrile as dispersant solvent. Separation of the analytes was performed using GC-MS detection, being the analytes unequivocal identified. The proposed procedure is the first microextraction method applied to the analysis of urine samples from diabetic and non-diabetic patients that allows a clear differentiation between both groups using a simple analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

PubMed

Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

2016-09-01

A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of three different dispersive liquid-liquid microextraction modes performed on their most usual configurations for the extraction of phenolic, neutral aromatic, and amino compounds from waters.

PubMed

Saraji, Mohammad; Ghambari, Hoda

2018-06-21

In this work we seek clues to select the appropriate dispersive liquid-liquid microextraction mode for extracting three categories of compounds. For this purpose, three common dispersive liquid-liquid microextraction modes were compared under optimized conditions. Traditional dispersive liquid-liquid microextraction, in situ ionic liquid dispersive liquid-liquid microextraction and conventional ionic liquid dispersive liquid-liquid microextraction using chloroform, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-hexyl-3-methylimidazolium hexafluorophosphate as the extraction solvent, respectively, were considered in this work. Phenolic, neutral aromatic and amino compounds (each category included six members) were studied as analytes. The analytes in the extracts were determined by high-performance liquid chromatography with UV detection. For the analytes with polar functionalities, the in situ ionic liquid dispersive liquid-liquid microextraction mode mostly led to better results. In contrast, for neutral hydrocarbons without polar functionalities, traditional dispersive liquid-liquid microextraction using chloroform produced better results. In this case, where dispersion forces were the dominant interactions in the extraction, the refractive index of solvent and analyte predicted the extraction performance better than the octanol-water partition coefficient. It was also revealed that none of the methods were successful in extracting very hydrophilic analytes (compounds with the log octanol-water partition coefficient < 2). The results of this study could be helpful in selecting a dispersive liquid-liquid microextraction mode for the extraction of various groups of compounds. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Mortality predictors in a 60-year follow-up of adolescent males: exploring delinquency, socioeconomic status, IQ, high-school drop-out status, and personality.

PubMed

Trumbetta, Susan L; Seltzer, Benjamin K; Gottesman, Irving I; McIntyre, Kathleen M

2010-01-01

To examine whether socioeconomic status (SES), high school (HS) completion, IQ, and personality traits that predict delinquency in adolescence also could explain men's delinquency-related (Dq-r) mortality risk across the life span. Through a 60-year Social Security Death Index (SSDI) follow-up of 1812 men from Hathaway's adolescent normative Minnesota Multiphasic Personality Inventory (MMPI) sample, we examined mortality risk at various ages and at various levels of prior delinquency severity. We examined SES (using family rent level), HS completion, IQ, and MMPI indicators simultaneously as mortality predictors and tested for SES (rent level) interactions with IQ and personality. We ascertained 418 decedents. Dq-r mortality peaked between ages 45 years to 64 years and continued through age 75 years, with high delinquency severity showing earlier and higher mortality risk. IQ and rent level failed to explain Dq-r mortality. HS completion robustly conferred mortality protection through ages 55 years and 75 years, explained IQ and rent level-related risk, but did not fully explain Dq-r risk. Dq-r MMPI scales, Psychopathic Deviate, and Social Introversion, respectively, predicted risk for and protection from mortality by age 75 years, explaining mortality risk otherwise attributable to delinquency. Wiggins' scales also explained Dq-r mortality risk, as Authority Conflict conferred risk for and Social Maladjustment and Hypomania conferred protection from mortality by age 75 years. HS completion robustly predicts mortality by ages 55 years and 75 years. Dq-r personality traits predict mortality by age 75 years, accounting, in part, for Dq-r mortality.

Effect of Extra Virgin Olive Oil on Biomarkers of Inflammation in HIV-Infected Patients: A Randomized, Crossover, Controlled Clinical Trial

PubMed Central

Dokmanović, Sanja Kozić; Kolovrat, Krunoslava; Laškaj, Renata; Jukić, Vedrana; Vrkić, Nada; Begovac, Josip

2015-01-01

Background Premature atherosclerosis in HIV-infected patients is associated with chronic infection by itself and adverse effects of antiretroviral treatment (ART). Extra virgin olive oil (EVOO) has a beneficial effect on the cardiovascular system because of its anti-inflammatory properties. The objective of this study was to determine whether the consumption of EVOO improves inflammation and atherosclerosis biomarkers in HIV-infected patients receiving ART. Material/Methods This randomized, crossover, controlled trial included 39 HIV-positive male participants who consumed 50 mL of EVOO or refined olive oil (ROO) daily. Four participants dropped out of the study. Leukocyte count, erythrocyte sedimentation rate (ESR), high-sensitivity C-reactive protein (hsCRP), interleukin-6, fibrinogen, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, malondialdehyde, glutathione-peroxidase, superoxide dismutase, oxidized LDL and von Willebrand factor were determined before the first and after each of the 2 intervention periods. Intervention and washout periods lasted for 20 and 14 days, respectively. Results In participants with >90% compliance (N=30), hsCRP concentrations were lower after EVOO intervention (geometric mean [GM], 1.70 mg/L; 95% confidence interval [CI], 1.15–2.52) compared to ROO administration (GM, 2.92 mg/L; 95% CI, 1.95–4.37) (p=0.035). In participants using lopinavir/ritonavir, ESR and hsCRP concentrations decreased 62% and 151%, respectively, after EVOO administration. In the whole study population (N=35) we found no difference in analyzed biomarkers after EVOO administration. Conclusions Our exploratory study suggests that EVOO consumption could lower hsCRP in patients on ART. PMID:26280823

Development of a HS-SPME-GC/MS protocol assisted by chemometric tools to study herbivore-induced volatiles in Myrcia splendens.

PubMed

Souza Silva, Érica A; Saboia, Giovanni; Jorge, Nina C; Hoffmann, Camila; Dos Santos Isaias, Rosy Mary; Soares, Geraldo L G; Zini, Claudia A

2017-12-01

A headspace solid phase microextraction (HS-SPME) method combined with gas chromatography-mass spectrometry (GC/MS) was developed and optimized for extraction and analysis of volatile organic compounds (VOC) of leaves and galls of Myrcia splendens. Through a process of optimization of main factors affecting HS-SPME efficiency, the coating divivnilbenzene-carboxen-polydimethylsiloxane (DVB/Car/PDMS) was chosen as the optimum extraction phase, not only in terms of extraction efficiency, but also for its broader analyte coverage. Optimum extraction temperature was 30°C, while an extraction time of 15min provided the best compromise between extraction efficiencies of lower and higher molecular weight compounds. The optimized protocol was demonstrated to be capable of sampling plant material with high reproducibility, considering that most classes of analytes met the 20% RSD FDA criterion. The optimized method was employed for the analysis of three classes of M. splendens samples, generating a final list of 65 tentatively identified VOC, including alcohols, aldehydes, esters, ketones, phenol derivatives, as well as mono and sesquiterpenes. Significant differences were evident amongst the volatile profiles obtained from non-galled leaves (NGL) and leaf-folding galls (LFG) of M. splendens. Several differences pertaining to amounts of alcohols and aldehydes were detected between samples, particularly regarding quantities of green leaf volatiles (GLV). Alcohols represented about 14% of compounds detected in gall samples, whereas in non-galled samples, alcohol content was below 5%. Phenolic derived compounds were virtually absent in reference samples, while in non-galled leaves and galls their content ranged around 0.2% and 0.4%, respectively. Likewise, methyl salicylate, a well-known signal of plant distress, amounted for 1.2% of the sample content of galls, whereas it was only present in trace levels in reference samples. Chemometric analysis based on Heatmap associated with Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) provided a suitable tool to differentiate VOC profiles in vegetal material, and could open new perspectives and opportunities in agricultural and ecological studies for the detection and identification of herbivore-induced plant VOC emissions. Copyright © 2017 Elsevier B.V. All rights reserved.

Discrimination of cherry wines based on their sensory properties and aromatic fingerprinting using HS-SPME-GC-MS and multivariate analysis.

PubMed

Xiao, Zuobing; Liu, Shengjiang; Gu, Yongbo; Xu, Na; Shang, Yi; Zhu, Jiancai

2014-03-01

Volatiles of cherry wines were extracted by headspace solid phase microextraction (HS-SPME) and analyzed by gas chromatography mass spectrometry (GC-MS), multivariate statistical techniques (such as principal component analysis (PCA) and cluster analysis (CA) and correlation analysis) to differentiate sensory attributes of 3 groups of the wines through characterization of volatiles of cherry wine. Seventy-five volatiles were identified in 9 samples, including 29 esters, 22 alcohols, 8 acids, 3 ketones, 5 aldehydes, and 8 miscellaneous compounds. The PCA results showed that the cherry wines were mainly differentiated by 8 sensory attributes. The samples W2, W4, and W7 were grouped around sweet aromatic and the samples W1, W5, and W9 were highly associated with the sweet, esters, green, bitter, and fermented. Nevertheless, the samples W3, W6, and W8 were located close to the sour, alcoholic, and fruity. The final result of correlation analysis was in conformity with the conclusion of PCA. The CA results showed that the group of W2, W4, and W7, and the group of W1, W5, and W9 had less difference than the group of W3, W6, and W8. The reason should be that esterification reactions and fermentation process during the ageing period was more extended. The results of analyzing revealed that HS-SPME-GC-MS coupled with chemometrics could give an appropriate way of characterizing and classifying the cherry wines. Attributes that represent and discriminate among cherry wines might be made use of a better comprehending of the wines and for being utilized in future work. In addition, several chemometrics were used to classify the type of wines and try to install the relationship between volatiles and sensory property. Especially, PCA clearly revealed that the most contributing compounds for sensory attributes of cherry wines, CA was a more applicable way to distinguish types of cherry wines. Therefore, a feasible method that would be helpful to promote the quality of the wines by improving the winemaking process and analyzing aromatic characteristics of wines. © 2014 Institute of Food Technologists®

Formation of complex natural flavours by biotransformation of apple pomace with basidiomycetes.

PubMed

Bosse, Andrea K; Fraatz, Marco A; Zorn, Holger

2013-12-01

Altogether 30 different basidiomycetes were grown submerged in liquid culture media using seven different by-products of the food industry as the only carbon source. Seven fungus/substrate combinations revealed interesting flavour profiles. Culture supernatants of Tyromyces chioneus grown on apple pomace were extracted, and the aroma compounds were analysed by gas chromatography-olfactometry (GC-O). Potent odorants were identified by aroma extract dilution analysis (AEDA), calculation of the odour activity values (OAV), and proven by confection of an aroma model. 3-Phenylpropanal, 3-phenyl-1-propanol, and benzyl alcohol were identified as potent aroma biotransformation products. Headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) experiments showed that 3-phenylpropanal, 3-phenyl-1-propanol, benzyl alcohol, methyl 3-phenylpropionate, methyl 2-phenylacetate, cinnamaldehyde and methyl cinnamate were produced during the cultivation period of eight days. By means of labelling experiments, (E)-cinnamic acid was identified as the precursor of 3-phenylpropanal and 3-phenyl-1-propanol. Basidiomycetes were able to biotransform food by-products to pleasant complex flavour mixtures. Copyright © 2013 Elsevier Ltd. All rights reserved.

Volatiles from a rare Acer spp. honey sample from Croatia.

PubMed

Jerković, Igor; Marijanović, Zvonimir; Malenica-Staver, Mladenka; Lusić, Drazen

2010-06-24

A rare sample of maple (Acer spp.) honey from Croatia was analysed. Ultrasonic solvent extraction (USE) using: 1) pentane, 2) diethyl ether, 3) a mixture of pentane and diethyl ether (1:2 v/v) and 4) dichloromethane as solvents was applied. All the extracts were analysed by GC and GC/MS. The most representative extracts were 3) and 4). Syringaldehyde was the most striking compound, being dominant in the extracts 2), 3) and 4) with percentages 34.5%, 33.1% and 35.9%, respectively. In comparison to USE results of other single Croatian tree honey samples (Robinia pseudoacacia L. nectar honey, Salix spp. nectar and honeydew honeys, Quercus frainetto Ten. honeydew as well as Abies alba Mill. and Picea abies L. honeydew) and literature data the presence of syringaldehyde, previously identified in maple sap and syrup, can be pointed out as a distinct characteristic of the Acer spp. honey sample. Headspace solid-phase microextraction (HS-SPME) combined with GC and GC/MS identified benzaldehyde (16.5%), trans-linalool oxide (20.5%) and 2-phenylethanol (14.9%) as the major compounds that are common in different honey headspace compositions.

Multidimensional analysis of cannabis volatile constituents: identification of 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane as a volatile marker of hashish, the resin of Cannabis sativa L.

PubMed

Marchini, Marie; Charvoz, Céline; Dujourdy, Laurence; Baldovini, Nicolas; Filippi, Jean-Jacques

2014-11-28

The volatile constituents of drug samples derived from Cannabis sativa L. were investigated by means of headspace solid phase microextraction (HS-SPME) and gas chromatography techniques (GC-MS, GC×GC-MS). Samples of cannabis herb and hashish showed clear differences in their volatile chemical profiles, mostly resulting from photo-oxidation processes occurring during the transformation of fresh cannabis herb into hashish. Most unexpectedly, we could demonstrate hashish samples as containing remarkable amounts of a rare and unusual monoterpene - 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane - among the volatile compounds detected in their headspaces. We gave evidence for the formation of this compound from the light induced rearrangement of β-myrcene during the manufacture of hashish. In view of its high abundance among volatile constituents of cannabis resin and its scarce occurrence in other natural volatile extracts, we propose to rename this specific monoterpene hashishene. Copyright © 2014 Elsevier B.V. All rights reserved.

Headspace, volatile and semi-volatile organic compounds diversity and radical scavenging activity of ultrasonic solvent extracts from Amorpha fruticosa honey samples.

PubMed

Jerković, Igor; Marijanović, Zvonimir; Kezić, Janja; Gugić, Mirko

2009-07-27

Volatile organic compounds of Amorpha fruticosa honey samples were isolated by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE), followed by gas chromatography and mass spectrometry analyses (GC, GC-MS), in order to obtain complementary data for overall characterization of the honey aroma. The headspace of the honey was dominated by 2-phenylethanol (38.3-58.4%), while other major compounds were trans- and cis-linalool oxides, benzaldehyde and benzyl alcohol. 2-Phenylethanol (10.5-16.8%) and methyl syringate (5.8-8.2%) were the major compounds of ultrasonic solvent extracts, with an array of small percentages of linalool, benzene and benzoic acid derivatives, aliphatic hydrocarbons and alcohols, furan derivatives and others. The scavenging ability of the series of concentrations of the honey ultrasonic solvent extracts and the corresponding honey samples was tested by a DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. Approximately 25 times lower concentration ranges (up to 2 g/L) of the extracts exhibited significantly higher free radical scavenging potential with respect to the honey samples.

First Report on Rare Unifloral Honey of Endemic Moltkia petraea (Tratt.) Griseb. from Croatia: Detailed Chemical Screening and Antioxidant Capacity.

PubMed

Jerković, Igor; Marijanović, Zvonimir; Zekić, Marina; Tuberoso, Carlo I G

2017-03-01

Rare Moltkia petraea (Tratt.) Griseb. honey from Croatia was first time characterised. The spectrophotometric assays on CIE L*a*b*C ab *h ab ° colour coordinates, total phenol content and antioxidant capacity (FRAP, CUPRAC, DPPH • and ABTS •+ assays) determined higher honey values generally close to dark honeys ranges. Headspace solid-phase microextraction (HS-SPME) on two fibres after GC-FID and GC/MS revealed the major compounds 2-phenylacetaldehyde (12.8%; 15.6%), benzaldehyde (11.1%; 10.0%), octane (9.3%; 7.6%), nonane, propan-2-one, pentan-2-one, pentanal and nonanal (4.9%; 14.5%). Ultrasonic solvent extraction (USE) mainly isolated non-specific higher molecular compounds characteristic of the comb environment. Targeted HLPC-DAD analysis of the honey determined higher concentration of phenylalanine (212.08 mg/kg) and lumichrome (16.25 mg/kg) along with tyrosine and kojic acid. The headspace composition (chemical fingerprint) and high concentration of lumichrome can be considered particular for M. petraea honey. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

HS-SPME-GC-MS analysis of body odor to test the efficacy of foot deodorant formulations.

PubMed

Caroprese, Alessandro; Gabbanini, Simone; Beltramini, Claudia; Lucchi, Elena; Valgimigli, Luca

2009-11-01

Foot malodor is mostly due to short-chain fatty acids produced by bacterial metabolism of eccrine sweating. We aimed to develop a protocol for an objective (instrumental) efficacy evaluation of foot deodorant formulations. Head-space solid-phase microextractions of target fatty acids from the feet of six healthy volunteers were analyzed by GC-MS. A comparative analysis of the treated vs. the untreated foot was performed in each subject after washing the feet with a physiologic solution and incubating at 36 degrees C for 24-72 h in tryptic soy agar growth medium. Acetic, butyric, isobutyric and isovaleric acids were identified as the main contributors to foot malodor in the majority of volunteers. Propionic, valeric and isocaproic acids were also detected in some subjects. Comparative analysis according to the protocol developed showed a statistically significant (P<0.01) reduction of target fatty acids ranging from -26.6% to -77.0%. The protocol developed is a convenient, sensitive and non-invasive method to test the efficacy of foot deodorant formulations in human volunteers.

Aroma Volatile Compounds from Two Fresh Pineapple Varieties in China

PubMed Central

Zheng, Liang-Yong; Sun, Guang-Ming; Liu, Yu-Ge; Lv, Ling-Ling; Yang, Wen-Xiu; Zhao, Wei-Feng; Wei, Chang-Bin

2012-01-01

Volatile compounds from two pineapples varieties (Tainong No.4 and No.6) were isolated by headspace solid phase microextraction (HS-SPME) and identified and quantified by gas chromatography-mass spectrometry (GC/MS). In the Tainong No. 4 and No. 6 pineapples, a total of 11 and 28 volatile compounds were identified according to their retention time on capillary columns and their mass spectra, and quantified with total concentrations of 1080.44 μg·kg−1 and 380.66 μg·kg−1 in the Tainong No.4 and No. 6 pineapples, respectively. The odor active values (OAVs) of volatile compounds from pineapples were also calculated. According to the OAVs, four compounds were defined as the characteristic aroma compounds for the Tainong No. 4 pineapple, including furaneol, 3-(methylthio)propanoic acid methyl ester, 3-(methylthio)propanoic acid ethyl ester and δ-octalactone. The OAVs of five compounds including ethyl-2-methylbutyrate, methyl-2-methylbutyrate, 3-(methylthio)propanoic acid ethyl ester, ethyl hexanoate and decanal were considered to be the characteristic aroma compounds for the Tainong No. 6 pineapple. PMID:22837701

Correlation between the pattern volatiles and the overall aroma of wild edible mushrooms.

PubMed

de Pinho, P Guedes; Ribeiro, Bárbara; Gonçalves, Rui F; Baptista, Paula; Valentão, Patrícia; Seabra, Rosa M; Andrade, Paula B

2008-03-12

Volatile and semivolatile components of 11 wild edible mushrooms, Suillus bellini, Suillus luteus, Suillus granulatus, Tricholomopsis rutilans, Hygrophorus agathosmus, Amanita rubescens, Russula cyanoxantha, Boletus edulis, Tricholoma equestre, Fistulina hepatica, and Cantharellus cibarius, were determined by headspace solid-phase microextraction (HS-SPME) and by liquid extraction combined with gas chromatography-mass spectrometry (GC-MS). Fifty volatiles and nonvolatiles components were formally identified and 13 others were tentatively identified. Using sensorial analysis, the descriptors "mushroomlike", "farm-feed", "floral", "honeylike", "hay-herb", and "nutty" were obtained. A correlation between sensory descriptors and volatiles was observed by applying multivariate analysis (principal component analysis and agglomerative hierarchic cluster analysis) to the sensorial and chemical data. The studied edible mushrooms can be divided in three groups. One of them is rich in C8 derivatives, such as 3-octanol, 1-octen-3-ol, trans-2-octen-1-ol, 3-octanone, and 1-octen-3-one; another one is rich in terpenic volatile compounds; and the last one is rich in methional. The presence and contents of these compounds give a considerable contribution to the sensory characteristics of the analyzed species.

Microextraction by Packed Sorbent (MEPS) and Solid-Phase Microextraction (SPME) as Sample Preparation Procedures for the Metabolomic Profiling of Urine

PubMed Central

Silva, Catarina; Cavaco, Carina; Perestrelo, Rosa; Pereira, Jorge; Câmara, José S.

2014-01-01

For a long time, sample preparation was unrecognized as a critical issue in the analytical methodology, thus limiting the performance that could be achieved. However, the improvement of microextraction techniques, particularly microextraction by packed sorbent (MEPS) and solid-phase microextraction (SPME), completely modified this scenario by introducing unprecedented control over this process. Urine is a biological fluid that is very interesting for metabolomics studies, allowing human health and disease characterization in a minimally invasive form. In this manuscript, we will critically review the most relevant and promising works in this field, highlighting how the metabolomic profiling of urine can be an extremely valuable tool for the early diagnosis of highly prevalent diseases, such as cardiovascular, oncologic and neurodegenerative ones. PMID:24958388

Evaluation of HS-SPME and ultrasonic solvent extraction for monitoring of plant flavours added by the bees to herbhoneys: traceability biomarkers.

PubMed

Kuś, Piotr Marek; Marijanović, Zvonimir; Jerković, Igor

2015-01-01

The volatile composition of 21 herbhoneys (HHs) of 7 different botanical origins was characterised for the first time. Ultrasound solvent extraction (USE) and headspace solid-phase microextraction (HS-SPME) followed by GC-FID/MS were successfully applied as complementary methods for monitoring the volatile plant flavours added by the bees. HHs showed significant compositional variability related to the botanical origin and compounds that could serve as traceability biomarkers were identified. The most important compounds with high abundance were (E,extract; H, headspace): caffeine (up to 68.7%, E) and trans-linalool oxide (up to 26.0%, H) in coffee HH, α-terpineol (up to 8.2%, E; 27.1%, H) and bornyl acetate (up to 3.1, E; 11.9%, H) in pine HH, thymol (up to 3.1%, E; 55.4%, H) in thyme HH. Hawthorn HH was characterised by the presence of herniarin (up to 13.4%, E) and lemon HH contained limonene (up to 1.6%, E; 33.2%, H). Other HHs (nettle and aloe) contained lower amounts of volatiles and their profiles were not specific. In all the HHs, methyl syringate was found and it was most abundant in thyme HH (up to 17.4%, E). The volatile fraction of HHs showed some substantial similarities and differences with the composition of herbs from which they derive. It confirms the selective bee-mediated transfer of phytochemicals, including known flavour-active volatiles into the final product, but also biotransformation of several compounds. Additionally, several similarities to the corresponding natural honeys were observed, but in general HHs exhibited less rich volatile profiles.

Determination of volatile organic compounds (VOCs) from wrapping films and wrapped PDO Italian cheeses by using HS-SPME and GC/MS.

PubMed

Panseri, Sara; Chiesa, Luca Maria; Zecconi, Alfonso; Soncini, Gabriella; De Noni, Ivano

2014-06-25

Nowadays food wrapping assures attractive presentation and simplifies self-service shopping. Polyvinylchloride (PVC)- and polyethylene (PE)-based cling-films are widely used worldwide for wrapping cheeses. For this purpose, films used in retail possess suitable technical properties such as clinginess and unrolling capacity, that are achieved by using specific plasticizers during their manufacturing process. In the present study, the main VOCs of three cling-films (either PVC-based or PE-based) for retail use were characterized by means of Solid-Phase Micro-Extraction and GC/MS. In addition, the effects of cling film type and contact time on the migration of VOCs from the films to four different PDO Italian cheeses during cold storage under light or dark were also investigated. Among the VOCs isolated from cling-films, PVC released 2-ethylhexanol and triacetin. These compounds can likely be considered as a "non-intentionally added substance". These same compounds were also detected in cheeses wrapped in PVC films with the highest concentration found after 20 days storage. The PE cling-film was shown to possess a simpler VOC profile, lacking some molecules peculiar to PVC films. The same conclusions can be drawn for cheeses wrapped in the PE cling-film. Other VOCs found in wrapped cheeses were likely to have been released either by direct transfer from the materials used for the manufacture of cling-films or from contamination of the films. Overall, HS-SPME is shown to be a rapid and solvent free technique to screen the VOCs profile of cling-films, and to detect VOCs migration from cling-films to cheese under real retail storage conditions.

The Study of Fingerprint Characteristics of Dayi Pu-Erh Tea Using a Fully Automatic HS-SPME/GC–MS and Combined Chemometrics Method

PubMed Central

Lv, Shidong; Wu, Yuanshuang; Zhou, Jiangsheng; Lian, Ming; Li, Changwen; Xu, Yongquan; Liu, Shunhang; Wang, Chao; Meng, Qingxiong

2014-01-01

The quality of tea is presently evaluated by the sensory assessment of professional tea tasters, however, this approach is both inconsistent and inaccurate. A more standardized and efficient method is urgently needed to objectively evaluate tea quality. In this study, the chemical fingerprint of 7 different Dayi Pu-erh tea brands and 3 different Ya'an tea brands on the market were analyzed using fully automatic headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS). A total of 78 volatiles were separated, among 75 volatiles were identified by GC–MS in seven Dayi Pu-erh teas, and the major chemical components included methoxyphenolic compounds, hydrocarbons, and alcohol compounds, such as 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 2,6,10,14-tetramethyl-pentadecane, linalool and its oxides, α-terpineol, and phytol. The overlapping ratio of peaks (ORP) of the chromatogram in the seven Dayi Pu-erh tea samples was greater than 89.55%, whereas the ORP of Ya'an tea samples was less than 79.10%. The similarity and differences of the Dayi Pu-erh tea samples were also characterized using correlation coefficient similarity and principal component analysis (PCA). The results showed that the correlation coefficient of similarity of the seven Dayi Pu-erh tea samples was greater than 0.820 and was gathered in a specific area, which showed that samples from different brands were basically the same, despite have some slightly differences of chemical indexes was found. These results showed that the GC-MS fingerprint combined with the PCA approach can be used as an effective tool for the quality assessment and control of Pu-erh tea. PMID:25551231

Evaluation of injection methods for fast, high peak capacity separations with low thermal mass gas chromatography.

PubMed

Fitz, Brian D; Mannion, Brandyn C; To, Khang; Hoac, Trinh; Synovec, Robert E

2015-05-01

Low thermal mass gas chromatography (LTM-GC) was evaluated for rapid, high peak capacity separations with three injection methods: liquid, headspace solid phase micro-extraction (HS-SPME), and direct vapor. An Agilent LTM equipped with a short microbore capillary column was operated at a column heating rate of 250 °C/min to produce a 60s separation. Two sets of experiments were conducted in parallel to characterize the instrumental platform. First, the three injection methods were performed in conjunction with in-house built high-speed cryo-focusing injection (HSCFI) to cryogenically trap and re-inject the analytes onto the LTM-GC column in a narrower band. Next, the three injection methods were performed natively with LTM-GC. Using HSCFI, the peak capacity of a separation of 50 nl of a 73 component liquid test mixture was 270, which was 23% higher than without HSCFI. Similar peak capacity gains were obtained when using the HSCFI with HS-SPME (25%), and even greater with vapor injection (56%). For the 100 μl vapor sample injected without HSCFI, the preconcentration factor, defined as the ratio of the maximum concentration of the detected analyte peak relative to the analyte concentration injected with the syringe, was determined to be 11 for the earliest eluting peak (most volatile analyte). In contrast, the preconcentration factor for the earliest eluting peak using HSCFI was 103. Therefore, LTM-GC is demonstrated to natively provide in situ analyte trapping, although not to as great an extent as with HSCFI. We also report the use of LTM-GC applied with time-of-flight mass spectrometry (TOFMS) detection for rapid, high peak capacity separations from SPME sampled banana peel headspace. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of wood plastic composites made from landfill-derived plastic and sawdust: Volatile compounds and olfactometric analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Félix, Juliana S., E-mail: jfelix@unizar.es; Domeño, Celia, E-mail: cdomeno@unizar.es; Nerín, Cristina, E-mail: cnerin@unizar.es

Graphical abstract: This work details the characterization of VOCs of WPC, produced from residual materials which would have landfills as current destination, and evaluates their odor profile. Highlights: ► More than 140 volatile compounds were identified in raw materials and WPC products. ► Markers were related to the thermal degradation, sawdust or coupling agents. ► WPC prototype showed a characteristic odor profile of burnt, sweet and wax-like. ► Aldehydes, carboxylic acids, ketones and phenols were odor descriptors of WPC. - Abstract: Application of wood plastic composites (WPCs) obtained from recycled materials initially intended for landfill is usually limited by theirmore » composition, mainly focused on release of volatile organic compounds (VOCs) which could affect quality or human safety. The study of the VOCs released by a material is a requirement for new composite materials. Characterization and quantification of VOCs of several WPC produced with low density polyethylene (LDPE) and polyethylene/ethylene vinyl acetate (PE/EVA) films and sawdust were carried out, in each stage of production, by solid phase microextraction in headspace mode (HS-SPME) and gas chromatography–mass spectrometry (GC–MS). An odor profile was also obtained by HS-SPME and GC–MS coupled with olfactometry analysis. More than 140 compounds were observed in the raw materials and WPC samples. Some quantified compounds were considered WPC markers such as furfural, 2-methoxyphenol, N-methylphthalimide and 2,4-di-tert-butylphenol. Hexanoic acid, acetic acid, 2-methoxyphenol, acetylfuran, diacetyl, and aldehydes were the most important odorants. None of the VOCs were found to affect human safety for use of the WPC.« less

Preconcentration of lead using solidification of floating organic drop and its determination by electrothermal atomic absorption spectrometry

PubMed Central

Chamsaz, Mahmoud; Akhoundzadeh, Jeiran; Arbab-zavar, Mohammad Hossein

2012-01-01

A simple microextraction method based on solidification of a floating organic drop (SFOD) was developed for preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrolidinedithiocarbamate (APDC) was used as complexing agent, and the formed complex was extracted into a 20 μL of 1-undecanol. The extracted complex was diluted with ethanol and injected into a graphite furnace. An orthogonal array design (OAD) with OA16 (45) matrix was employed to study the effects of different parameters such as pH, APDC concentration, stirring rate, sample solution temperature and the exposure time on the extraction efficiency. Under the optimized experimental conditions the limit of detection (based on 3 s) and the enhancement factor were 0.058 μg L−1 and 113, respectively. The relative standard deviation (RSD) for 8 replicate determinations of 1 μg L−1 of Pb was 8.8%. The developed method was validated by the analysis of certified reference materials and was successfully applied to the determination of lead in water and infant formula base powder samples. PMID:25685441

Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

PubMed

Yang, Yanqin; Chu, Guohai; Zhou, Guojun; Jiang, Jian; Yuan, Kailong; Pan, Yuanjiang; Song, Zhiyu; Li, Zuguang; Xia, Qian; Lu, Xinbo; Xiao, Weiqiang

2016-03-01

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Automated hollow-fiber liquid-phase microextraction followed by liquid chromatography with mass spectrometry for the determination of benzodiazepine drugs in biological samples.

PubMed

Nazaripour, Ali; Yamini, Yadollah; Ebrahimpour, Behnam; Fasihi, Javad

2016-07-01

In this study, two-phase hollow-fiber liquid-phase microextraction and three-phase hollow-fiber liquid-phase microextraction based on two immiscible organic solvents were compared for extraction of oxazepam and Lorazepam. Separations were performed on a liquid chromatography with mass spectrometry instrument. Under optimal conditions, three-phase hollow-fiber liquid-phase microextraction based on two immiscible organic solvents has a better extraction efficiency. In a urine sample, for three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents, the calibration curves were found to be linear in the range of 0.6-200 and 0.9-200 μg L(-1) and the limits of detection were 0.2 and 0.3 μg L(-1) for oxazepam and lorazepam, respectively. For two-phase hollow fiber liquid-phase microextraction, the calibration curves were found to be linear in the range of 1-200 and 1.5-200 μg L(-1) and the limits of detection were 0.3 and 0.5 μg L(-1) for oxazepam and lorazepam, respectively. In a urine sample, for three-phase hollow-fiber-based liquid-phase microextraction based on two immiscible organic solvents, relative standard deviations in the range of 4.2-4.5% and preconcentration factors in the range of 70-180 were obtained for oxazepam and lorazepam, respectively. Also for the two-phase hollow-fiber liquid-phase microextraction, preconcentration factors in the range of 101-257 were obtained for oxazepam and lorazepam, respectively. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of urinary volatile organic metabolites as potential cancer biomarkers by solid-phase microextraction in combination with gas chromatography-mass spectrometry

PubMed Central

Silva, C L; Passos, M; Câmara, J S

2011-01-01

Background: Non-invasive diagnostic strategies aimed at identifying biomarkers of cancer are of great interest for early cancer detection. Urine is potentially a rich source of volatile organic metabolites (VOMs) that can be used as potential cancer biomarkers. Our aim was to develop a generally reliable, rapid, sensitive, and robust analytical method for screening large numbers of urine samples, resulting in a broad spectrum of native VOMs, as a tool to evaluate the potential of these metabolites in the early diagnosis of cancer. Methods: To investigate urinary volatile metabolites as potential cancer biomarkers, urine samples from 33 cancer patients (oncological group: 14 leukaemia, 12 colorectal and 7 lymphoma) and 21 healthy (control group, cancer-free) individuals were qualitatively and quantitatively analysed. Dynamic solid-phase microextraction in headspace mode (dHS-SPME) using a carboxen-polydimethylsiloxane (CAR/PDMS) sorbent in combination with GC-qMS-based metabolomics was applied to isolate and identify the volatile metabolites. This method provides a potential non-invasive method for early cancer diagnosis as a first approach. To fulfil this objective, three important dHS-SPME experimental parameters that influence extraction efficiency (fibre coating, extraction time and temperature of sampling) were optimised using a univariate optimisation design. The highest extraction efficiency was obtained when sampling was performed at 50°C for 60 min using samples with high ionic strengths (17% sodium chloride, w v−1) and under agitation. Results: A total of 82 volatile metabolites belonging to distinct chemical classes were identified in the control and oncological groups. Benzene derivatives, terpenoids and phenols were the most common classes for the oncological group, whereas ketones and sulphur compounds were the main classes that were isolated from the urine headspace of healthy subjects. The results demonstrate that compound concentrations were dramatically different between cancer patients and healthy volunteers. The positive rates of 16 patients among the 82 identified were found to be statistically different (P<0.05). A significant increase in the peak area of 2-methyl-3-phenyl-2-propenal, p-cymene, anisole, 4-methyl-phenol and 1,2-dihydro-1,1,6-trimethyl-naphthalene in cancer patients was observed. On average, statistically significant lower abundances of dimethyl disulphide were found in cancer patients. Conclusions: Gas chromatographic peak areas were submitted to multivariate analysis (principal component analysis and supervised linear discriminant analysis) to visualise clusters within cases and to detect the volatile metabolites that are able to differentiate cancer patients from healthy individuals. Very good discrimination within cancer groups and between cancer and control groups was achieved. PMID:22085842

A comparison of various modes of liquid-liquid based microextraction techniques: determination of picric acid.

PubMed

Burdel, Martin; Šandrejová, Jana; Balogh, Ioseph S; Vishnikin, Andriy; Andruch, Vasil

2013-03-01

Three modes of liquid-liquid based microextraction techniques--namely auxiliary solvent-assisted dispersive liquid-liquid microextraction, auxiliary solvent-assisted dispersive liquid-liquid microextraction with low-solvent consumption, and ultrasound-assisted emulsification microextraction--were compared. Picric acid was used as the model analyte. The determination is based on the reaction of picric acid with Astra Phloxine reagent to produce an ion associate easily extractable by various organic solvents, followed by spectrophotometric detection at 558 nm. Each of the compared procedures has both advantages and disadvantages. The main benefit of ultrasound-assisted emulsification microextraction is that no hazardous chlorinated extraction solvents and no dispersive solvent are necessary. Therefore, this procedure was selected for validation. Under optimized experimental conditions (pH 3, 7 × 10(-5) mol/L of Astra Phloxine, and 100 μL of toluene), the calibration plot was linear in the range of 0.02-0.14 mg/L and the LOD was 7 μg/L of picric acid. The developed procedure was applied to the analysis of spiked water samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature-controlled ionic liquid-based ultrasound-assisted microextraction for preconcentration of trace quantity of cadmium and nickel by using organic ligand in artificial saliva extract of smokeless tobacco products

NASA Astrophysics Data System (ADS)

Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Asma Jabeen; Afridi, Hassan Imran; Baig, Jameel Ahmed; Brahman, Kapil Dev; Naeemullah; Arain, Salma Aslam

2015-03-01

A new approach was developed for the preconcentration of cadmium (Cd) and nickel (Ni) in artificial saliva extract of dry snuff (brown and black) products using temperature-controlled ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (TIL-UDLLμE) followed by electrothermal atomic absorption spectrometry (ETAAS). The Cd and Ni were complexed with ammonium pyrrolidinedithiocarbamate (APDC), extracted in ionic liquid drops, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6]. The multivariate strategy was applied to estimate the optimum values of experimental variables influence the % recovery of analytes by TIL-UDLLμE method. At optimum experimental conditions, the limit of detection (3s) were 0.05 and 0.14 μg L-1 while relative standard deviations (% RSD) were 3.97 and 3.55 for Cd and Ni respectively. After extraction, the enhancement factors (EF) were 87 and 79 for Cd and Ni, respectively. The RSD for six replicates of 10 μg L-1 Cd and Ni were 3.97% and 3.55% respectively. To validate the proposed method, certified reference material (CRM) of Virginia tobacco leaves was analyzed, and the determined values of Cd and Ni were in good agreement with the certified values. The concentration of Cd and Ni in artificial saliva extracts corresponds to 39-52% and 21-32%, respectively, of the total contents of both elements in dry brown and black snuff products.

Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection to determination of opium alkaloids in human plasma.

PubMed

Ahmadi-Jouibari, Toraj; Fattahi, Nazir; Shamsipur, Mojtaba; Pirsaheb, Meghdad

2013-11-01

A novel, simple, rapid and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine opium alkaloids in human plasma. During the extraction procedure, plasma protein was precipitated by using a mixture of zinc sulfate solution and acetonitrile. Some effective parameters on extraction were studied and optimized. Under the optimum conditions (extraction solvent: 30.0 μl 1-undecanol; disperser solvent: 470 μl acetone; pH: 9; salt addition: 1%(w/v) NaCl and extraction time: 0.5 min), calibration curves are linear in the range of 1.5-1000 μgl(-1) and limit of detections (LODs) are in the range of 0.5-5 μgl(-1). The relative standard deviations (RSDs) for 100 μgl(-1) of morphine and codeine, 10.0 μgl(-1) of papaverine and 20.0 μgl(-1) of noscapine in diluted human plasma are in the range of 4.3-7.4% (n=5). Finally, the method was successfully applied in the determination of opium alkaloids in the actual human plasma samples. The relative recoveries of plasma samples spiked with alkaloids are 88-110.5%. The obtained results show that DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of opium alkaloids in human plasma. Copyright © 2013 Elsevier B.V. All rights reserved.

Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples

PubMed Central

Es’haghi, Zarrin; Hoseini, Hasan Ali; Mohammadi-Nokhandani, Saeed; Ebrahimi, Javad

2013-01-01

A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol–gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV) using a hanging mercury drop electrode (HMDE) was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H)-one and 2-{[2-(2-Hydroxy-ethylamino)-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05–500 ng mL−1 for Cd (II) and Pb (II). The limits of detection for lead and cadmium were 0.015 ng mL−1 and 0.012 ng mL−1, respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II) and Pb (II) in 5 mL of water sample, respectively. PMID:25685537

Electromyographic and biomechanical analysis of step negotiation in Charcot Marie Tooth subjects whose level walk is not impaired.

PubMed

Lencioni, Tiziana; Piscosquito, Giuseppe; Rabuffetti, Marco; Sipio, Enrica Di; Diverio, Manuela; Moroni, Isabella; Padua, Luca; Pagliano, Emanuela; Schenone, Angelo; Pareyson, Davide; Ferrarin, Maurizio

2018-05-01

Charcot-Marie-Tooth (CMT) is a slowly progressive disease characterized by muscular weakness and wasting with a length-dependent pattern. Mildly affected CMT subjects showed slight alteration of walking compared to healthy subjects (HS). To investigate the biomechanics of step negotiation, a task that requires greater muscle strength and balance control compared to level walking, in CMT subjects without primary locomotor deficits (foot drop and push off deficit) during walking. We collected data (kinematic, kinetic, and surface electromyographic) during walking on level ground and step negotiation, from 98 CMT subjects with mild-to-moderate impairment. Twenty-one CMT subjects (CMT-NLW, normal-like-walkers) were selected for analysis, as they showed values of normalized ROM during swing and produced work at push-off at ankle joint comparable to those of 31 HS. Step negotiation tasks consisted in climbing and descending a two-step stair. Only the first step provided the ground reaction force data. To assess muscle activity, each EMG profile was integrated over 100% of task duration and the activation percentage was computed in four phases that constitute the step negotiation tasks. In both tasks, CMT-NLW showed distal muscle hypoactivation. In addition, during step-ascending CMT-NLW subjects had relevant lower activities of vastus medialis and rectus femoris than HS in weight-acceptance, and, on the opposite, a greater activation as compared to HS in forward-continuance. During step-descending, CMT-NLW showed a reduced activity of tibialis anterior during controlled-lowering phase. Step negotiation revealed adaptive motor strategies related to muscle weakness due to disease in CMT subjects without any clinically apparent locomotor deficit during level walking. In addition, this study provided results useful for tailored rehabilitation of CMT patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and application of the sol-gel-derived acrylate/silicone co-polymer coatings for headspace solid-phase microextraction of 2-chloroethyl ethyl sulfide in soil.

PubMed

Liu, Mingming; Zeng, Zhaorui; Fang, Huaifang

2005-05-27

Three types of novel acrylate/silicone co-polymer coatings, including co-poly(methyl acrylate/hydroxy-terminated silicone oil) (MA/OH-TSO), co-poly(methyl methacrylate/OH-TSO) (MMA/OH-TSO) and co-poly(butyl methacrylate/OH-TSO) (BMA/OH-TSO), were prepared for the first time by sol-gel method and cross-linking technology and subsequently applied to headspace solid-phase microextraction (HS-SPME) of 2-chloroethyl ethyl sulfide (CEES), a surrogate of mustard, in soil. The underlying mechanisms of the coating process were discussed and confirmed by IR spectra. The selectivity of the three types of sol-gel-derived acrylate/silicone coated fibers was studied, and the BMA/OH-TSO coated fibers exhibited the highest extraction ability to CEES. The concentration of BMA and OH-TSO in sol solution was optimized, and the BMA/OH-TSO (3:1)-coated fibers possessed the highest extraction efficiency. Compared with commercially available polyacrylate (PA) fiber, the sol-gel-derived BMA/OH-TSO (3:1) fibers showed much higher extraction efficiency to CEES. Therefore, the BMA/OH-TSO (3:1)-coated fibers were chosen for the analysis of CEES in soil matrix. The reproducibility of coating preparation was satisfactory, with the RSD 2.39% within batch and 3.52% between batches, respectively. The coatings proved to be quite stable at high temperature (to 350 degrees C) and in different solvents (organic or inorganic), thus their lifetimes (to 150 times) are longer than conventional fibers. Extraction parameters, such as the volume of water added to the soil, extraction temperature and time, and the ionic strength were optimized. The linearity was from 0.1 to 10 microg/g, the limit of detection (LOD) was 2.7 ng/g, and the RSD was 2.19%. The recovery of CEES was 88.06% in agriculture soil, 92.61% in red clay, and 101.95% in sandy soil, respectively.

Characterization of the leachate in an urban landfill by physicochemical analysis and solid phase microextraction-GC/MS.

PubMed

Banar, Müfide; Ozkan, Aysun; Kürkçüoğlu, Mine

2006-10-01

The aim of this study is to evaluate extensively the characterization and identification of major pollutant parameters by paying attention to the organic chemical pollution for unregulated dumping site leachate in Eskişehir/Turkey. The study that is first and only one research has been very important data related with before new sanitary landfill site in Eskişehir city. For this purpose, in this study leachate samples were collected in-situ at monthly interval for a period of 8 months. Firstly, thirty three physicochemical parameters were monitored. Secondly, SPME technique was used for identification of organic pollutants. Meteorological data were also recorded for the same sampling period to correlate meteorological data and physicochemical parameters. Mean values are used in the correlation analysis. Correlation is shown only for the relationship between air temperature and NO(3) (-). No correlation has been found between rain and leachate quality parameters since the amount of rain was very low during the sampling period. However, analysis results were generally decreased in winter season when each parameter and each sampling point are examined separately. According to correlation between every parameter, especially solid content and dissolved oxygen concentration of leachate is affecting to other parameters. Also, sodium and potassium are changing proportionally with same parameters (suspended solids, fixed solids, dissolved oxygen) and high correlation between chloride and heavy metal concentration is showing. The results were statistically evaluated by use of SPSS 10.0 program. Second part of the study, the leachate was extracted by Solid Phase Microextraction (SPME) technique and then analyzed. Of the methodologies tested in this study, the best one selected was based on 100 micro m polydimethylsiloxane coated fiber (PDMS), headspace with heating (Delta HS) sampling mode and an extraction time of 15 min. at a temperature of 50 degrees C. Thirty three organic compounds in leachate were identified by GC/MS.

Analysis of halonitriles in drinking water using solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

Kristiana, Ina; Joll, Cynthia; Heitz, Anna

2012-02-17

Halonitriles are a class of nitrogen-containing disinfection by-products (DBPs) that have been reported to be more toxic and carcinogenic than the regulated DBPs. While haloacetonitriles (HANs) are often measured in drinking waters, there is little information on the formation, characteristics, and occurrence of other, higher molecular weight halonitriles. Halopropionitriles and halobutyronitriles have been predicted to be highly toxic and carcinogenic, and may have sufficient potency and selectivity to account for epidemiological associations of chlorinated and chloraminated water with adverse health effects. This paper reports on the development, optimisation, and validation of a simple, robust, and sensitive analytical method for the determination of halonitriles in waters, as well as the application of the method to study the formation and characteristics of halonitriles. This is the first reported method development for analysis halopropionitriles and halobutyronitriles, and the first study on their formation and occurrence as DBPs in drinking waters. The new method uses headspace solid-phase microextraction to extract the halonitriles from water, which are then analysed using gas chromatography-mass spectrometry (HS SPME/GC-S). The method demonstrated good sensitivity (detection limits: 0.9-80 ng L⁻¹) and good precision (repeatability: 3.8-12%), and is linear over three orders of magnitude. Matrix effects from raw drinking water containing organic carbon (4.1 mg L⁻¹) were shown to be negligible in the analysis of halonitriles. The optimised method was used to study the stability and persistence of halonitriles in aqueous samples, and the formation and occurrence of halonitriles in waters. Results from laboratory-scale disinfection experiments showed that haloacetonitriles were formed in chlorinated and chloraminated samples, but 2,2-dichloropropionitrile was only measured in chloraminated samples. Results from surveys of several drinking water distribution systems confirmed the laboratory findings. Copyright © 2012 Elsevier B.V. All rights reserved.

Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

ERIC Educational Resources Information Center

Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

2016-01-01

Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

Solid Phase Microextraction and Related Techniques for Drugs in Biological Samples

PubMed Central

Moein, Mohammad Mahdi; Said, Rana; Bassyouni, Fatma

2014-01-01

In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from one side, toward automatization and online coupling of sample preparation units. The primary objective of this review is to present the recent developments in microextraction sample preparation methods for analysis of drugs in biological fluids. Microextraction techniques allow for less consumption of solvent, reagents, and packing materials, and small sample volumes can be used. In this review the use of solid phase microextraction (SPME), microextraction in packed sorbent (MEPS), and stir-bar sorbtive extraction (SBSE) in drug analysis will be discussed. In addition, the use of new sorbents such as monoliths and molecularly imprinted polymers will be presented. PMID:24688797

Identification and Quantification of Pesticides in Environmental Waters With Solid Phase Microextraction and Analysis Using Field-Portable Gas Chromatography-Mass Spectrometry

DTIC Science & Technology

2004-06-10

Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry Name of Candidate: CPT Michael J. Nack...and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry Beyond brief excerpts is with the permission of the copyright owner, and...Pesticides in Environmental Waters with Solid Phase Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry

Lowered pH Alters Decay but Not Speed of Tectorial Membrane Waves

NASA Astrophysics Data System (ADS)

Farrahi, Shirin; Ghaffari, Roozbeh; Freeman, Dennis M.

2011-11-01

Tectorial membrane (TM) traveling waves and mechanical shear impedances were measured in artificial endolymph baths at neutral and acidic pHs. Lowering pH from 7 to 4 significantly decreases the spatial extent of TM waves but has a relatively minor effect on wave speed. At pH 4, the imaginary component of TM shear impedance, which relates to the shear modulus, drops significantly; whereas, the real component, which relates to viscosity, is reduced less. These results suggest that shear modulus, and not viscosity, controls the extent of TM waves at lower pH.

Effect of oxygen on volatile and sensory characteristics of Cabernet Sauvignon during secondary shelf life.

PubMed

Lee, Dong-Hyun; Kang, Bo-Sik; Park, Hyun-Jin

2011-11-09

The oxidation of Cabernet Sauvignon wines during secondary shelf life was studied by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-quadrupole mass spectrometry (GC-qMS) and sensory tests, with the support of multivariate statistical analyses such as OPLS-DA loading plot and PCA score plot. Four different oxidation conditions were established during a 1-week secondary shelf life. Samples collected on a regular basis were analyzed to determine the changes of volatile chemicals, with sensory characteristics evaluated through pattern recognition models. During secondary shelf life the separation among collected samples depended on the degree of oxidation in wine. Isoamyl acetate, ethyl decanoate, nonanoic acid, n-decanoic acid, undecanoic acid, 2-furancarboxylic acid, dodecanoic acid, and phenylacetaldehyde were determined to be associated with the oxidation of the wine. PCA sensory evaluation revealed that least oxidized wine and fresh wine was well-separated from more oxidized wines, demonstrating that sensory characteristics of less oxidized wines tend toward "fruity", "citrous", and "sweetness", while those of more oxidized wines are positively correlated with "animal", "bitterness", and "dairy". The study also demonstrates that OPLS-DA and PCA are very useful statistical tools for the understanding of wine oxidation.

Comparison of two derivatization methods for the analysis of short chain fatty acids in the ambient aerosol using GC-MS

NASA Astrophysics Data System (ADS)

Kim, G.; Jeon, S.

2016-12-01

Fatty acids are one of the important compound classes in the polar organic fraction of ambient aerosols. Among them, short chain fatty acids play a significant role in the atmospheric transformation processes. For short-chain acids, the bottleneck of analysis has been the difficulty of sample preparation due to the high solubility and volatility. To overcome this problem, derivatization of polar organic fraction is widely used with silylation reagents to increase the resolution and sensitivity. Two different derivatization procedures; (1) using the tertbutyldimethylsilyl (TBDMS) derivatization and (2) the headspace-solid phase microextraction (HS-SPME) with in-fiber derivatization are compared using gas chromatography-mass spectrometry (GC-MS). At the second method, simultaneous derivatization and extraction were performed by a poly acrylate (PA) coated fiber doped with pyrenyldiazomethane (PDAM). We investigated the chromatographic property and relative sensitivities of each individual short chain acids according to two different derivatization procedures. For the method validation, the linearity, recovery and method detection limit (MDL) were compared. Also, two derivatization methods were applied to the ambient aerosol samples and evaluated with respect to the effectiveness.

Phytochemical study of the headspace volatile organic compounds of fresh algae and seagrass from the Adriatic Sea (single point collection)

PubMed Central

Marijanović, Zvonimir; Roje, Marin; Kuś, Piotr M.; Jokić, Stela; Čož-Rakovac, Rozelinda

2018-01-01

Performed phytochemical study contributes to the knowledge of volatile organic compounds (VOCs) of Halopteris filicina (Grateloup) Kützing, Dictyota dichotoma (Hudson) J. V. Lamouroux, Posidonia oceanica (L.) Delile and Flabellia petiolata (Turra) Nizamuddin from the Adriatic Sea (single point collection). VOCs were investigated by headspace solid-phase microextraction (HS-SPME) and analysed by gas chromatography and mass spectrometry (GC-MS/FID). H. filicina headspace contained dimethyl sulfide (DMS; 12.8%), C8-compounds (e.g. fucoserratene (I; 9.5%)), benzaldehyde (II; 8.7%), alkane C17, dictyopterene D and C (III, IV), tribromomethane (V), 1-iodopentane, others. F. petiolata headspace was characterized by DMS (22.2%), 6-methylhept-5-en-2-one (9.5%), C17 (9.1%), II (6.5%), compounds I-V. DMS (59.3%), C15 (14.5%), C17 (7.2%) and C19 (6.3%) dominated in P. oceanica headspace. Sesquiterpenes were found in D. dichotoma, predominantly germacrene D (28.3%) followed by other cadinenyl (abundant), muurolenyl and amorphenyl structures. Determined VOCs may be significant for chemosystematics and chemical communications in marine ecosystem. PMID:29738535

Unlocking Phacelia tanacetifolia Benth. honey characterization through melissopalynological analysis, color determination and volatiles chemical profiling.

PubMed

Kuś, Piotr M; Jerković, Igor; Marijanović, Zvonimir; Kranjac, Marina; Tuberoso, Carlo I G

2018-04-01

Phacelia tanacetifolia Benth. honey (14 samples) collected in Poland was characterized by melissopalynological analysis, color determination (CIE L*a*b*C ab *h ab ° coordinates) and volatiles (VOCs) composition. VOCs were isolated by headspace solid-phase microextraction (HS-SPME, two fibers) and ultrasound-assisted solvent extraction (USE, two solvents) and analyzed by GC-MS. Principal component analysis (PCA) and hierarchical-tree clustering (HTC) were applied to show trends and form groups and to indicate the most representative unifloral samples. Six samples were pointed out with average pollen 74.9% and color parameters (L=85.1; a*=-0.8; b*=27.9; C ab *=27.9; h ab *=91.9) that were significantly correlated. High abundance of trans-linalool oxide (27.3-45.9%) that was significantly correlated with the pollen percentages, hexan-1-ol (4.4-5.7%) and lavender lactone (0.8% - 1.5%) were characteristic for their headspace. C 13 -norisoprenoids, mainly (E)-/(Z)-3-oxo-retro-α-ionol (4.7-5.4%; 6.9-9.4%) and vomifoliol (9.0-13.0%) dominated in their USE extracts. Copyright © 2018 Elsevier Ltd. All rights reserved.

Antioxidant capacity and chemical profiles of Satureja montana L. Honey: hotrienol and syringyl derivatives as biomarkers.

PubMed

Jerković, Igor; Tuberoso, Carlo I G; Marijanović, Zvonimir; Kranjac, Marina; Malenica-Staver, M

2015-07-01

The present study is focused on the antioxidant capacity and chemical profiling of eight Croatian Satureja montana L. honey samples. Among the 20 compounds obtained by headspace solid-phase microextraction (HS-SPME) and identified by GC-FID and GC/MS analyses, hotrienol was predominant (75.9-81.7%). The honey matrix volatile/semivolatile profile was investigated by ultrasonic solvent extraction (USE) followed by GC-FID and GC/MS analyses. The major compounds identified by this latter method were the sinapic-acid derivatives methyl syringate (36.2-72.8%) and syringaldehyde (2.2-43.1%). Direct, targeted HPLC-DAD analyses of the native honey samples revealed the presence of methyl syringate (7.10-39.60 mg/kg) and syringic acid (0.10-1.70 mg/kg). In addition, the total phenolic content of the samples was determined by the FolinCiocalteu assay (311.0-465.9 mg GAE/kg), and the antioxidant capacity was evaluated by the DPPH radical-scavenging activity (0.5-1.0 mmol TEAC/kg) and the ferric reducing antioxidant power (2.5-5.1 mmol Fe(2+) /kg). Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Oak (Quercus frainetto Ten.) honeydew honey--approach to screening of volatile organic composition and antioxidant capacity (DPPH and FRAP assay).

PubMed

Jerković, Igor; Marijanović, Zvonimir

2010-05-25

Two samples of oak honeydew honey were investigated. Headspace solid-phase microextraction (HS-SPME) combined with GC and GC/MS enabled identification of the most volatile organic headspace compounds being dominated by terpenes(mainly cis- and trans-linalool oxides). The volatile and less-volatile organic composition of the samples was obtained by ultrasonic assisted extraction (USE) with two solvents (1:2 (v/v) pentane -diethyl ether mixture and dichloromethane) followed by GC and GC/MS analysis. Shikimic pathway derivatives are of particular interest with respect to the botanical origin of honey and the most abundant was phenylacetic acid (up to 16.4%). Antiradical activity (DPPH assay) of the honeydew samples was 4.5 and 5.1 mmol TEAC/kg. Ultrasonic solvent extracts showed several dozen times higher antiradical capacity in comparison to the honeydew. Antioxidant capacity (FRAP assay) of honeydew samples was 4.8 and 16.1 mmol Fe(2+)/kg, while the solvent mixture extracts showed antioxidant activity of 374.5 and 955.9 Fe(2+)/kg, respectively, and the dichloromethane extracts 127.3 and 101.5 mmol Fe(2+)/kg.

Volatile organic compounds of Thai honeys produced from several floral sources by different honey bee species.

PubMed

Pattamayutanon, Praetinee; Angeli, Sergio; Thakeow, Prodpran; Abraham, John; Disayathanoowat, Terd; Chantawannakul, Panuwan

2017-01-01

The volatile organic compounds (VOCs) of four monofloral and one multifloral of Thai honeys produced by Apis cerana, Apis dorsata and Apis mellifera were analyzed by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography and mass spectrometry (GC-MS). The floral sources were longan, sunflower, coffee, wild flowers (wild) and lychee. Honey originating from longan had more VOCs than all other floral sources. Sunflower honey had the least numbers of VOCs. cis-Linalool oxide, trans-linalool oxide, ho-trienol, and furan-2,5-dicarbaldehyde were present in all the honeys studied, independent of their floral origin. Interestingly, 2-phenylacetaldehyde was detected in all honey sample except longan honey produced by A. cerana. Thirty-two VOCs were identified as possible floral markers. After validating differences in honey volatiles from different floral sources and honeybee species, the results suggest that differences in quality and quantity of honey volatiles are influenced by both floral source and honeybee species. The group of honey volatiles detected from A. cerana was completely different from those of A. mellifera and A. dorsata. VOCs could therefore be applied as chemical markers of honeys and may reflect preferences of shared floral sources amongst different honeybee species.

HS-SPME-GC-FID method for detection and quantification of Bacillus cereus ATCC 10702 mediated 2-acetyl-1-pyrroline.

PubMed

Deshmukh, Yogita; Khare, Puja; Patra, D D; Nadaf, Altafhusain B

2014-01-01

A rapid micro-scale solid-phase micro-extraction (SPME) procedure coupled with gas-chromatography with flame ionized detector (GC-FID) was used to extract parts per billion levels of a principle basmati aroma compound "2-acetyl-1-pyrroline" (2-AP) from bacterial samples. In present investigation, optimization parameters of bacterial incubation period, sample weight, pre-incubation time, adsorption time, and temperature, precursors and their concentrations has been studied. In the optimized conditions, detection of 2-AP produced by Bacillus cereus ATCC10702 using only 0.5 g of sample volume was 85 μg/kg. Along with 2-AP, 15 other compounds produced by B. cereus were also reported out of which 14 were reported for the first time consisting mainly of (E)-2-hexenal, pentadecanal, 4-hydroxy-2-butanone, n-hexanal, 2-6-nonadienal, 3-methoxy-2(5H) furanone and 2-acetyl-1-pyridine and octanal. High recovery of 2-AP (87 %) from very less amount of B. cereus samples was observed. The method is reproducible fast and can be used for detection of 2-AP production by B. cereus. © 2014 American Institute of Chemical Engineers.

Kainari, a Unique Greek Traditional Herbal Tea, from the Island of Lesvos: Chemical Analysis and Antioxidant and Antimicrobial Properties

PubMed Central

Bampali, Evangelia; Graikou, Konstantia; Aligiannis, Nektarios

2018-01-01

The chemical composition, as well as the total phenolic content (TPC) and the potential antioxidant and antimicrobial activity, of three Kainari-herbal tea samples from different areas of Lesvos Island (Greece) was evaluated. The rich aroma of the mixtures was studied through GC-MS, as well as through Headspace Solid-Phase Microextraction (HS-SPME)/GC-MS analyses. Cinnamon, clove, nutmeg, pepper, and ginger were identified as main ingredients, while, throughout the chemical analysis of the volatiles of one selected sample, several secondary metabolites have been isolated and identified on the basis of GC-MS as well as spectral evidence as eugenol, cinnamic aldehyde and myristicin, cinnamyl alcohol, alpha-terpinyl acetate, and β-caryophyllene. Furthermore, two food dyes, azorubine and amaranth, were also isolated and identified from the infusions. The total phenolic content was estimated and the free radical scavenging activity was determined by DPPH and ABTS assays and the antimicrobial activity of the extracts was tested showing a very interesting profile against all the assayed microorganisms. Due to its very pleasant aroma and taste properties as well as to its bioactivities, Kainari-herbal tea could be further proposed as functional beverage. PMID:29681979

Effect of storage under extremely low oxygen on the volatile composition of 'Royal Gala' apples.

PubMed

Both, Vanderlei; Brackmann, Auri; Thewes, Fabio Rodrigo; Ferreira, Daniele de Freitas; Wagner, Roger

2014-08-01

The aim of this work was to assess the profile of volatile compounds in 'Royal Gala' apples stored under controlled atmosphere (CA), with O(2) levels ranging from 1.0kPa to as low as 0.5kPa during 8months (0.5°C), followed by 7days of shelf-life at 20°C. Volatile compounds were collected via solid-phase microextraction (HS-SPME) and analysed by gas chromatography. Straight and branched-chain esters exhibited a distinct pattern. The emission of straight-chain esters decreased under extremely low O(2) (0.5kPa), while branched-chain esters were not significantly affected in such condition. 2-Methyl-butyl acetate, a significant contributor to the 'Royal Gala' aroma, was higher in intermediate O(2) concentration, suggesting that lowering the O(2) levels down to 0.7kPa does not negatively affect the volatile composition of 'Royal Gala' apples, as compared to the standard CA (1.0kPa O(2)). The remaining volatile compounds were not strongly affected by storing fruits under extremely low O(2). Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of different methodologies for detailed screening of Taraxacum officinale honey volatiles.

PubMed

Jerković, Igor; Marijanović, Zvonimir; Kranjac, Marina; Radonić, Ani

2015-02-01

Headspace solid-phase microextraction (HS-SPME), ultrasonic solvent extraction (USE) and solid phase extraction (SPE), followed by GC-FID/MS were used for screening of dandelion (Taraxacum officinale Weber) honey headspace, volatiles and semi-volatiles. The obtained results constitute a breakthrough towards screening of dandelion honey since dominant compounds identified in the extracts were not previously reported for this honey type. Nitriles dominated in the headspace, particularly 3-methylpentanenitrile (up to 29.9%) and phenylacetonitrile (up to 20.9%). Lower methyl branched aliphatic acids and norisoprenoids were relevant minor constituents of the headspace. The extracts contained phenylacetic acid (up to 24.0%) and dehydrovomifoliol (up to 19.3%) as predominant compounds, while 3-methylpentanenitrile and phenylacetonitrile were detected in the extracts in minor abundance. Dehydrovomifoliol can be considered more characteristic for dandelion honey in distinction from phenylacetic acid. Low molecular aliphatic acids, benzene derivatives and an array of higher aliphatic compounds were also found in the extracts. The results of SPE/GC-FID/MS were very similar to USE/GC-FID/MS with the solvent dichloromethane. The use of all applied methodologies was relevant for the comprehensive chemical fingerprinting of dandelion honey volatiles.

[Actinobacteria and their odor-producing capacities in a surface water in Shanghai].

PubMed

Chen, Jiao; Bai, Xiao-hui; Lu, Ning; Wang, Xian-yun; Zhang, Yong-hui; Wu, Pan-cheng; Guo, Xin-chi

2014-10-01

The odor in raw water is one of the main sources of odor in drinking water. The occurrence of actinobacteria and their odor producing capacities in a reservoir in.Shanghai were investigated. Gauze's medium and membrane filtration were used for actinobacteria isolation. Through combined methods of 16S rRNA sequencing, colony and hyphae morphology, carbon source utilization, physiological and biochemical characteristics, 40 strains of actinobacteria were identified from the reservoir. Results showed that there were 38 Streptomyces, an Aeromicrobium and a Pseudonocardia. Liquid culture medium and the real reservoir water were used to test the odor producing capacity of these 40 strains of actinobacteria, and headspace solid phase microextraction (HS-SPME) and high resolution gas chromatography mass spectroscopy (GC/MS) were used to analyze the odor compounds 2-methylisoborneol (2-MIB) and geosmin (GSM) in the fermentation liquor. The test results showed that, the odor-producing capacities of these actinobacteria in different fermentation media showed different variation trends, even within the genera Streptomyces. The odor-producing capacity of actinobacteria in the liquid culture medium could not represent their states in the reservoir water or their actual odor contribution to the aquatic environment.

Simple and rapid analysis of endocrine disruptors in liquid medicines and intravenous injection solutions by automated in-tube solid-phase microextraction/high performance liquid chromatography.

PubMed

Mitani, Kurie; Narimatsu, Shizuo; Izushi, Fumio; Kataoka, Hiroyuki

2003-07-14

A simple and rapid method was developed for analyzing contamination of endocrine disruptors in liquid medicines and intravenous injection solutions. Endocrine disrupting compounds such as bisphenol A (BPA), alkylphenols and phthalates were quantitated by on-line in-tube solid-phase microextraction coupled with high performance liquid chromatography (in-tube SPME/HPLC) with UV detection. The liquid medicines and intravenous injection solutions could be used directly without any pretreatment, and the BPA, alkylphenols and phthalates in these solutions were automatically analyzed. The limits of quantification for these compounds were 1-10 ng/ml. Recoveries of these compounds spiked to the intravenous injection solutions was over 80%, except for some phthalates. Di-n-butyl phthalate (DBP) was detected at a concentration of 7-60 ng/ml in most intravenous injection solutions in plastic containers, but it was not detected in solutions in glass bottles. Diethyl phthalate, di-n-propyl phthalate, DBP and di-2-ethylhexyl phthalate (DEHP) were also detected in syrup, lotion and eye drops in plastic containers. On the other hand, BPA and alkylphenols were not detected at all in these solutions. DEHP contamination from an administration set increased when total vitamin formulation was added to the infusion solution. DEHP was easily leached from polyvinyl chloride tubing by polysorbate 80. The in-tube SPME/HPLC method is simple, rapid and automatic, and it provides a useful tool for the screening and determination of endocrine disruptor contamination in liquid medicines and intravenous injection solutions.

Application of dispersive liquid-liquid microextraction for the preconcentration of eight parabens in real samples and their determination by high-performance liquid chromatography.

PubMed

Shen, Xiong; Liang, Jian; Zheng, Luxia; Lv, Qianzhou; Wang, Hong

2017-11-01

A simple and sensitive method for the simultaneous determination of eight parabens in human plasma and urine samples was developed. The samples were preconcentrated using dispersive liquid-liquid microextraction based on the solidification of floating organic drops and determined by high-performance liquid chromatography with ultraviolet detection. The influence of variables affecting the extraction efficiency was investigated and optimized using Placket-Burman design and Box-Behnken design. The optimized values were: 58 μL of 1-decanol (as extraction solvent), 0.65 mL methanol (as disperser solvent), 1.5% w/v NaCl in 5.0 mL of sample solution, pH 10.6, and 4.0 min centrifugation at 4000 rpm. The extract was injected into the high-performance liquid chromatography system for analysis. Under the optimum conditions, the linear ranges for eight parabens in plasma and urine were 1.0-1000 ng/mL, with correlation coefficients above 0.994. The limit of detection was 0.2-0.4 and 0.1-0.4 ng/mL for plasma and urine samples, respectively. Relative recoveries were between 80.3 and 110.7%, while relative standard deviations were less than 5.4%. Finally, the method was applied to analyze the parabens in 98 patients of primary breast cancer. Results showed that parabens existed widely, at least one paraben detected in 96.9% (95/98) of plasma samples and 98.0% (96/98) of urine samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasound-assisted magnetic dispersive solid-phase microextraction: A novel approach for the rapid and efficient microextraction of naproxen and ibuprofen employing experimental design with high-performance liquid chromatography.

PubMed

Ghorbani, Mahdi; Chamsaz, Mahmoud; Rounaghi, Gholam Hossein

2016-03-01

A simple, rapid, and sensitive method for the determination of naproxen and ibuprofen in complex biological and water matrices (cow milk, human urine, river, and well water samples) has been developed using ultrasound-assisted magnetic dispersive solid-phase microextraction. Magnetic ethylendiamine-functionalized graphene oxide nanocomposite was synthesized and used as a novel adsorbent for the microextraction process and showed great adsorptive ability toward these analytes. Different parameters affecting the microextraction were optimized with the aid of the experimental design approach. A Plackett-Burman screening design was used to study the main variables affecting the microextraction process, and the Box-Behnken optimization design was used to optimize the previously selected variables for extraction of naproxen and ibuprofen. The optimized technique provides good repeatability (relative standard deviations of the intraday precision 3.1 and 3.3, interday precision of 5.6 and 6.1%), linearity (0.1-500 and 0.3-650 ng/mL), low limits of detection (0.03 and 0.1 ng/mL), and a high enrichment factor (168 and 146) for naproxen and ibuprofen, respectively. The proposed method can be successfully applied in routine analysis for determination of naproxen and ibuprofen in cow milk, human urine, and real water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards Real-Time Detection of Gait Events on Different Terrains Using Time-Frequency Analysis and Peak Heuristics Algorithm.

PubMed

Zhou, Hui; Ji, Ning; Samuel, Oluwarotimi Williams; Cao, Yafei; Zhao, Zheyi; Chen, Shixiong; Li, Guanglin

2016-10-01

Real-time detection of gait events can be applied as a reliable input to control drop foot correction devices and lower-limb prostheses. Among the different sensors used to acquire the signals associated with walking for gait event detection, the accelerometer is considered as a preferable sensor due to its convenience of use, small size, low cost, reliability, and low power consumption. Based on the acceleration signals, different algorithms have been proposed to detect toe off (TO) and heel strike (HS) gait events in previous studies. While these algorithms could achieve a relatively reasonable performance in gait event detection, they suffer from limitations such as poor real-time performance and are less reliable in the cases of up stair and down stair terrains. In this study, a new algorithm is proposed to detect the gait events on three walking terrains in real-time based on the analysis of acceleration jerk signals with a time-frequency method to obtain gait parameters, and then the determination of the peaks of jerk signals using peak heuristics. The performance of the newly proposed algorithm was evaluated with eight healthy subjects when they were walking on level ground, up stairs, and down stairs. Our experimental results showed that the mean F1 scores of the proposed algorithm were above 0.98 for HS event detection and 0.95 for TO event detection on the three terrains. This indicates that the current algorithm would be robust and accurate for gait event detection on different terrains. Findings from the current study suggest that the proposed method may be a preferable option in some applications such as drop foot correction devices and leg prostheses.

Towards Real-Time Detection of Gait Events on Different Terrains Using Time-Frequency Analysis and Peak Heuristics Algorithm

PubMed Central

Zhou, Hui; Ji, Ning; Samuel, Oluwarotimi Williams; Cao, Yafei; Zhao, Zheyi; Chen, Shixiong; Li, Guanglin

2016-01-01

Real-time detection of gait events can be applied as a reliable input to control drop foot correction devices and lower-limb prostheses. Among the different sensors used to acquire the signals associated with walking for gait event detection, the accelerometer is considered as a preferable sensor due to its convenience of use, small size, low cost, reliability, and low power consumption. Based on the acceleration signals, different algorithms have been proposed to detect toe off (TO) and heel strike (HS) gait events in previous studies. While these algorithms could achieve a relatively reasonable performance in gait event detection, they suffer from limitations such as poor real-time performance and are less reliable in the cases of up stair and down stair terrains. In this study, a new algorithm is proposed to detect the gait events on three walking terrains in real-time based on the analysis of acceleration jerk signals with a time-frequency method to obtain gait parameters, and then the determination of the peaks of jerk signals using peak heuristics. The performance of the newly proposed algorithm was evaluated with eight healthy subjects when they were walking on level ground, up stairs, and down stairs. Our experimental results showed that the mean F1 scores of the proposed algorithm were above 0.98 for HS event detection and 0.95 for TO event detection on the three terrains. This indicates that the current algorithm would be robust and accurate for gait event detection on different terrains. Findings from the current study suggest that the proposed method may be a preferable option in some applications such as drop foot correction devices and leg prostheses. PMID:27706086

Beetroot juice is more beneficial than sodium nitrate for attenuating muscle pain after strenuous eccentric-bias exercise.

PubMed

Clifford, Tom; Howatson, Glyn; West, Daniel J; Stevenson, Emma J

2017-11-01

The aim of this study was to compare the effects of beetroot juice (BTJ) and a nitrate only drink (sodium nitrate; SN) on indices of exercise-induced muscle damage (EIMD). Thirty recreationally active males consumed either BTJ (n = 10), a nitrate-matched SN drink (n = 10), or an isocaloric placebo (PLA; n = 10) immediately and at 24 and 48 h after performing 100 drop jumps. To assess muscle damage, maximal isometric voluntary contractions (MIVCs), countermovement jumps (CMJs), pressure-pain threshold (PPT), creatine kinase (CK), and high-sensitivity C-reactive protein (hs-CRP) were measured before, immediately after and at 24, 48, and 72 h following the drop jumps. BTJ and SN increased serum nitric oxide, which peaked at 2 h post-ingestion (136 ± 78 and 189 ± 79 μmol·L -1 , respectively). PPT decreased in all groups postexercise (P = 0.001), but was attenuated with BTJ compared with SN and PLA (P = 0.043). PPT was 104% ± 26% of baseline values at 72 h after BTJ, 94% ± 16% after SN, and 91% ± 19% after PLA. MIVC and CMJ were reduced following exercise (-15% to 25%) and did not recover to baseline by 72 h in all groups; however, no group differences were observed (P > 0.05). Serum CK increased after exercise but no group differences were present (P > 0.05). hsCRP levels were unaltered by the exercise protocol (P > 0.05). These data suggest that BTJ supplementation is more effective than SN for attenuating muscle pain associated with EIMD, and that any analgesic effects are likely due to phytonutrients in BTJ other than nitrate, or interactions between them.

Does Shoe Collar Height Influence Ankle Joint Kinematics and Kinetics in Sagittal Plane Maneuvers?

PubMed Central

Yang, Yang; Fang, Ying; Zhang, Xini; He, Junliang; Fu, Weijie

2017-01-01

The Objective of the study is to investigate the effects of basketball shoes with different collar heights on ankle kinematics and kinetics and athletic performance in different sagittal plane maneuvers. Twelve participants who wore high-top and low-top basketball shoes (hereafter, HS and LS, respectively) performed a weight-bearing dorsiflexion (WB-DF) maneuver, drop jumps (DJs), and lay-up jumps (LJs). Their sagittal plane kinematics and ground reaction forces were recorded using the Vicon motion capture system and Kistler force plates simultaneously. Moreover, ankle dorsiflexion and plantarflexion angles, moment, power, stiffness, and jump height were calculated. In the WB-DF test, the peak ankle dorsiflexion angle (p = 0.041) was significantly smaller in HS than in LS. Additionally, the peak ankle plantarflexion moment (p = 0.028) and power (p = 0.022) were significantly lower in HS than in LS during LJs but not during DJs. In both jumping maneuvers, no significant differences were found in the jump height or ankle kinematics between the two shoe types. According to the WB-DF test, increasing shoe collar height can effectively reduce the ankle range of motion in the sagittal plane. Although the HS did not restrict the flexion–extension performance of the ankle joint during two jumping maneuvers, an increased shoe collar height can reduce peak ankle plantarflexion moment and peak power during the push-off phase in LJs. Therefore, a higher shoe collar height should be used to circumvent effects on the partial kinetics of the ankle joint in the sagittal plane. Key points An increased shoe collar height effectively reduced ankle joint ROM in the sagittal plane in weight-bearing dorsiflexion maneuver. Shoe collar height did not affect sagittal plane ankle kinematics and had no effect on performance during realistic jumping. Shoe collar height can affect the ankle plantarflexion torque and peak power during the push-off phase in lay-up jump. PMID:29238255

Performance of muscle strength and fatigue tolerance in young trained women supplemented with caffeine.

PubMed

Fett, Carlos A; Aquino, Natalia M; Schantz Junior, Jairo; Brandão, Camila F; de Araújo Cavalcanti, Joás D; Fett, Waleria C

2018-03-01

The aim of this paper was to verify the effect of caffeine supplementation on the muscular strength and fatigue tolerance of young trained women. Eight women of 25±5-years-old, who had undergone a minimum of 12 months of continuous resisted training, Body Mass Index 20-23 kg/m2 were submitted to 4 tests: One Repetition Maximum (1-RM, kg) to pull down (PD), Hack Squat (HS), Bench Press (BP), and Knee Extension Exhaustion (drop-set, 100/80/60 kg, repetitions) (DS). They performed the tests in 4 consecutive blocks one-week apart crossover system: basal without caffeine (B); first caffeine (C1); placebo with starch supplementation (P); second caffeine (C2). Caffeine supplementation 6 mg.kg-1 30 minutes before. The paired t-test and repeated ANOVA with Tukey-Kramer were performed. Respectively for B, C1, P and C2 to each test were PD (52, 54, 56, 55, P>0.05); HS (99, 109, 108, 121*; P<0.001); BP (22, 26*, 25*, 27*; P<0.05); DS (28, 35*,**, 30*, 37**; P<0.001). To comparison of B, P and mean caffeine (C1+C2/2) results respectively were: HS (99, 108*, 115***; P<0.05); BP (22, 25*, 26*; P<0.05); DS (28, 30#, 36**; P<0.01 and P<0.001). The delta ([C1+C2/2]-[B+P/2]) were PD=0 (P>0.05), HS=12 (P=0.04), BP=3 (P=0.007), DS=7 (P=00.1). Caffeine improved tolerance to exhaustion and has tendency to improve strength in this young women. Probably caffeine supplementation is useful to improve performance in women engaged in sports with these physical valences. An investigation with a major numbers of volunteers could elucidate some controversies observed here.

A comparison of sorptive extraction techniques coupled to a new quantitative, sensitive, high throughput GC-MS/MS method for methoxypyrazine analysis in wine.

PubMed

Hjelmeland, Anna K; Wylie, Philip L; Ebeler, Susan E

2016-02-01

Methoxypyrazines are volatile compounds found in plants, microbes, and insects that have potent vegetal and earthy aromas. With sensory detection thresholds in the low ng L(-1) range, modest concentrations of these compounds can profoundly impact the aroma quality of foods and beverages, and high levels can lead to consumer rejection. The wine industry routinely analyzes the most prevalent methoxypyrazine, 2-isobutyl-3-methoxypyrazine (IBMP), to aid in harvest decisions, since concentrations decrease during berry ripening. In addition to IBMP, three other methoxypyrazines IPMP (2-isopropyl-3-methoxypyrazine), SBMP (2-sec-butyl-3-methoxypyrazine), and EMP (2-ethyl-3-methoxypyrazine) have been identified in grapes and/or wine and can impact aroma quality. Despite their routine analysis in the wine industry (mostly IBMP), accurate methoxypyrazine quantitation is hindered by two major challenges: sensitivity and resolution. With extremely low sensory detection thresholds (~8-15 ng L(-1) in wine for IBMP), highly sensitive analytical methods to quantify methoxypyrazines at trace levels are necessary. Here we were able to achieve resolution of IBMP as well as IPMP, EMP, and SBMP from co-eluting compounds using one-dimensional chromatography coupled to positive chemical ionization tandem mass spectrometry. Three extraction techniques HS-SPME (headspace-solid phase microextraction), SBSE (stirbar sorptive extraction), and HSSE (headspace sorptive extraction) were validated and compared. A 30 min extraction time was used for HS-SPME and SBSE extraction techniques, while 120 min was necessary to achieve sufficient sensitivity for HSSE extractions. All extraction methods have limits of quantitation (LOQ) at or below 1 ng L(-1) for all four methoxypyrazines analyzed, i.e., LOQ's at or below reported sensory detection limits in wine. The method is high throughput, with resolution of all compounds possible with a relatively rapid 27 min GC oven program. Copyright © 2015 Elsevier B.V. All rights reserved.

Headspace-SPME-GC/MS as a simple cleanup tool for sensitive 2,6-diisopropylphenol analysis from lipid emulsions and adaptable to other matrices.

PubMed

Pickl, Karin E; Adamek, Viktor; Gorges, Roland; Sinner, Frank M

2011-07-15

Due to increased regulatory requirements, the interaction of active pharmaceutical ingredients with various surfaces and solutions during production and storage is gaining interest in the pharmaceutical research field, in particular with respect to development of new formulations, new packaging material and the evaluation of cleaning processes. Experimental adsorption/absorption studies as well as the study of cleaning processes require sophisticated analytical methods with high sensitivity for the drug of interest. In the case of 2,6-diisopropylphenol - a small lipophilic drug which is typically formulated as lipid emulsion for intravenous injection - a highly sensitive method in the concentration range of μg/l suitable to be applied to a variety of different sample matrices including lipid emulsions is needed. We hereby present a headspace-solid phase microextraction (HS-SPME) approach as a simple cleanup procedure for sensitive 2,6-diisopropylphenol quantification from diverse matrices choosing a lipid emulsion as the most challenging matrix with regard to complexity. By combining the simple and straight forward HS-SPME sample pretreatment with an optimized GC-MS quantification method a robust and sensitive method for 2,6-diisopropylphenol was developed. This method shows excellent sensitivity in the low μg/l concentration range (5-200μg/l), good accuracy (94.8-98.8%) and precision (intraday-precision 0.1-9.2%, inter-day precision 2.0-7.7%). The method can be easily adapted to other, less complex, matrices such as water or swab extracts. Hence, the presented method holds the potential to serve as a single and simple analytical procedure for 2,6-diisopropylphenol analysis in various types of samples such as required in, e.g. adsorption/absorption studies which typically deal with a variety of different surfaces (steel, plastic, glass, etc.) and solutions/matrices including lipid emulsions. Copyright © 2011 Elsevier B.V. All rights reserved.

Production of isotopically labeled standards from a uniformly labeled precursor for quantitative volatile metabolomic studies.

PubMed

Gómez-Cortés, Pilar; Brenna, J Thomas; Sacks, Gavin L

2012-06-19

Optimal accuracy and precision in small-molecule profiling by mass spectrometry generally requires isotopically labeled standards chemically representative of all compounds of interest. However, preparation of mixed standards from commercially available pure compounds is often prohibitively expensive and time-consuming, and many labeled compounds are not available in pure form. We used a single-prototype uniformly labeled [U-(13)C]compound to generate [U-(13)C]-labeled volatile standards for use in subsequent experimental profiling studies. [U-(13)C]-α-Linolenic acid (18:3n-3, ALA) was thermally oxidized to produce labeled lipid degradation volatiles which were subsequently characterized qualitatively and quantitatively. Twenty-five [U-(13)C]-labeled volatiles were identified by headspace solid-phase microextraction-gas chromatography/time-of-flight mass spectrometry (HS-SPME-GC/TOF-MS) by comparison of spectra with unlabeled volatiles. Labeled volatiles were quantified by a reverse isotope dilution procedure. Using the [U-(13)C]-labeled standards, limits of detection comparable to or better than those of previous HS-SPME reports were achieved, 0.010-1.04 ng/g. The performance of the [U-(13)C]-labeled volatile standards was evaluated using a commodity soybean oil (CSO) oxidized at 60 °C from 0 to 15 d. Relative responses of n-decane, an unlabeled internal standard otherwise absent from the mixture, and [U-(13)C]-labeled oxidation products changed by up to 8-fold as the CSO matrix was oxidized, demonstrating that reliance on a single standard in volatile profiling studies yields inaccurate results due to changing matrix effects. The [U-(13)C]-labeled standard mixture was used to quantify 25 volatiles in oxidized CSO and low-ALA soybean oil with an average relative standard deviation of 8.5%. Extension of this approach to other labeled substrates, e.g., [U-(13)C]-labeled sugars and amino acids, for profiling studies should be feasible and can dramatically improve quantitative results compared to use of a single standard.

Can volatile organic metabolites be used to simultaneously assess microbial and mite contamination level in cereal grains and coffee beans?

PubMed

Salvador, Angelo C; Baptista, Inês; Barros, António S; Gomes, Newton C M; Cunha, Angela; Almeida, Adelaide; Rocha, Silvia M

2013-01-01

A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC-ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC-ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans.

Quantification of transformation products of rocket fuel unsymmetrical dimethylhydrazine in soils using SPME and GC-MS.

PubMed

Bakaikina, Nadezhda V; Kenessov, Bulat; Ul'yanovskii, Nikolay V; Kosyakov, Dmitry S

2018-07-01

Determination of transformation products (TPs) of rocket fuel unsymmetrical dimethylhydrazine (UDMH) in soil is highly important for environmental impact assessment of the launches of heavy space rockets from Kazakhstan, Russia, China and India. The method based on headspace solid-phase microextraction (HS SPME) and gas chromatography-mass spectrometry is advantageous over other known methods due to greater simplicity and cost efficiency. However, accurate quantification of these analytes using HS SPME is limited by the matrix effect. In this research, we proposed using internal standard and standard addition calibrations to achieve proper combination of accuracies of the quantification of key TPs of UDMH and cost efficiency. 1-Trideuteromethyl-1H-1,2,4-triazole (MTA-d3) was used as the internal standard. Internal standard calibration allowed controlling matrix effects during quantification of 1-methyl-1H-1,2,4-triazole (MTA), N,N-dimethylformamide (DMF), and N-nitrosodimethylamine (NDMA) in soils with humus content < 1%. Using SPME at 60 °C for 15 min by 65 µm Carboxen/polydimethylsiloxane fiber, recoveries of MTA, DMF and NDMA for sandy and loamy soil samples were 91-117, 85-123 and 64-132%, respectively. For improving the method accuracy and widening the range of analytes, standard addition and its combination with internal standard calibration were tested and compared on real soil samples. The combined calibration approach provided greatest accuracies for NDMA, DMF, N-methylformamide, formamide, 1H-pyrazole, 3-methyl-1H-pyrazole and 1H-pyrazole. For determination of 1-formyl-2,2-dimethylhydrazine, 3,5-dimethylpyrazole, 2-ethyl-1H-imidazole, 1H-imidazole, 1H-1,2,4-triazole, pyrazines and pyridines, standard addition calibration is more suitable. However, the proposed approach and collected data allow using both approaches simultaneously. Copyright © 2018 Elsevier B.V. All rights reserved.

Can Volatile Organic Metabolites Be Used to Simultaneously Assess Microbial and Mite Contamination Level in Cereal Grains and Coffee Beans?

PubMed Central

Salvador, Ângelo C.; Baptista, Inês; Barros, António S.; Gomes, Newton C. M.; Cunha, Ângela; Almeida, Adelaide; Rocha, Silvia M.

2013-01-01

A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC–ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC–ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC–ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans. PMID:23613710

Exploring a volatomic-based strategy for a fingerprinting approach of Vaccinium padifolium L. berries at different ripening stages.

PubMed

Porto-Figueira, Priscilla; Figueira, José A; Berenguer, Pedro; Câmara, José S

2018-04-15

The effect of ripening on the evolution of the volatomic pattern from endemic Vaccinium padifolium L. (Uveira) berries was investigated using headspace-solid phase microextraction (HS-SPME) followed by gas chromatography/quadrupole-mass spectrometry (GC-qMS) and multivariate statistical analysis (MVA). The most significant HS-SPME parameters, namely fibre polymer, ionic strength and extraction time, were optimized in order to improve extraction efficiency. Under optimal experimental conditions (DVB/CAR/PDMS fibre coating, 40°C, 30min extraction time and 5g of sample amount), a total of 72 volatiles of different functionalities were isolated and identified. Terpenes followed by higher alcohols and esters were the predominant classes in the ripening stages - green, break and ripe. Although significant differences in the volatomic profiles at the three stages were obtained, cis-β-ocimene (2.0-40.0%), trans-2-hexenol (2.4-19.4%), cis-3-hexenol (2.5.16.4%), β-myrcene (1.9-13.8%), 1-hexanol (1.7-13.6%), 2-hexenal (0.7-8.0%), 2-heptanone (0.7-7.7%), and linalool (1.9-6.1%) were the main volatile compounds identified. Higher alcohols, carboxylic acids and ketones gradually increased during ripening, whereas monoterpenes significantly decreased. These trends were dominated by the higher alcohols (1-hexanol, cis-3-hexenol, trans-2-hexenol) and monoterpenes (β-myrcene, cis-β-ocimene and trans-β-ocimene). Partial least squares regression (PLSR) revealed that ethyl caprylate (1.000), trans-geraniol (0.995), ethyl isovalerate (-0.994) and benzyl carbinol (0.993) are the key variables that most contributed to the successful differentiation of Uveira berries according to ripening stage. To the best of our knowledge, no study has carried out on the volatomic composition of berries from endemic Uveira. Copyright © 2017 Elsevier Ltd. All rights reserved.

Java project on periodontal diseases: effect of vitamin C/calcium threonate/citrus flavonoids supplementation on periodontal pathogens, CRP and HbA1c.

PubMed

Amaliya, Amaliya; Laine, Marja L; Loos, Bruno G; Van der Velden, Ubele

2015-12-01

To assess in a periodontally diseased rural population deprived from regular dental care and having poor dietary conditions, the effect of vitamin C/calcium threonate/citrus flavonoids (VitC/Ca/Fl) supplementation on subgingival microbiota and plasma levels of vitamin C, HbA1c and hsCRP. The study population consisted of 98 subjects who previously participated in a prospective study on the natural history of periodontitis. Participants were instructed to consume one tablet/day containing 200 mg Ester C(®) calcium ascorbate, 25 mg calcium threonate and 100 mg citrus flavonoids for 90 days. Following parameters were evaluated: prevalence/amount of seven traditional periodontal pathogens, cytomegalovirus, Epstein-Barr virus (EBV); and plasma levels of vitamin C, HbA1c and hsCRP. After VitC/Ca/Fl supplementation, 100% of subjects showed normal plasma vitamin C values compared to 55% before. At baseline, 48% of subjects harboured Aggregatibacter actinomycetemcomitans, >97% the other periodontal pathogens and 73% EBV. Supplementation with VitC/Ca/F reduced the subgingival load of all studied bacteria (p-values: 0.014-0.0001) and EBV (p < 0.0001) substantially in all initially positive subjects. Plasma levels of HbA1c and hsCRP dropped in all subjects (p < 0.0001). This uncontrolled study suggested that supplemental VitC/Ca/Fl may be helpful in reducing subgingival numbers of periodontal pathogens and EBV, and promoting systemic health. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Relation Between Capillary Transit Times and Hemoglobin Saturation Heterogeneity. Part 1: Theoretical Models

PubMed Central

Lücker, Adrien; Secomb, Timothy W.; Weber, Bruno; Jenny, Patrick

2018-01-01

Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15–0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12–0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given. PMID:29755365

The Relation Between Capillary Transit Times and Hemoglobin Saturation Heterogeneity. Part 1: Theoretical Models.

PubMed

Lücker, Adrien; Secomb, Timothy W; Weber, Bruno; Jenny, Patrick

2018-01-01

Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15-0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12-0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given.

The Cytosolic pH of Individual Saccharomyces cerevisiae Cells Is a Key Factor in Acetic Acid Tolerance.

PubMed

Fernández-Niño, Miguel; Marquina, Maribel; Swinnen, Steve; Rodríguez-Porrata, Boris; Nevoigt, Elke; Ariño, Joaquín

2015-11-01

It was shown recently that individual cells of an isogenic Saccharomyces cerevisiae population show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current study, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pHs of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid-tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resumed proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independently of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The Cytosolic pH of Individual Saccharomyces cerevisiae Cells Is a Key Factor in Acetic Acid Tolerance

PubMed Central

Fernández-Niño, Miguel; Marquina, Maribel; Swinnen, Steve; Rodríguez-Porrata, Boris

2015-01-01

It was shown recently that individual cells of an isogenic Saccharomyces cerevisiae population show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current study, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pHs of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid-tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resumed proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independently of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH. PMID:26341199

EVALUATION OF SOLID PHASE MICROEXTRACTION FOR THE ANALYSIS OF HYDROPHILIC COMPOUNDS

EPA Science Inventory

Two commercially available solid phase microextractions (SPME) fibers, polyacrylate and carboxem/polydimethylsiloxane (PDMS), were evaluated for their ability to extract hydrophilic compounds from drinking water. Conditions, such as desorption time, desorption temperature, sample...

A sol-gel based solid phase microextraction fiber for the analysis of aliphatic alcohols in apple juices.

PubMed

Farhadi, Khalil; Maleki, Ramin; Tahmasebi, Raheleh

2010-01-01

A new fiber based on titania-chitin sol-gel coated on a silver wire for the headspace solid phase microextraction of aliphatic alcohols from apple juice samples was developed. The influences of fiber coating composition and microextraction conditions (extraction temperature, extraction time, and ionic strength of the sample matrix) on the fiber performance were investigated. Also, the influence of temperature and time on desorption of analytes from fiber were studied. Under the optimized conditions, a porous fiber with a high extraction capacity and good thermal stability (up to 250 degrees C) was obtained. The proposed headspace solid-phase microextraction-GC method was successfully used for the analysis of aliphatic alcohols in apple juice and concentrate samples. The recovery values were from 92.8 to 98.6%. The RSD (n=5) for all analytes were below 7.8%.

O-Succinyl-L-homoserine-based C4-chemical production: succinic acid, homoserine lactone, γ-butyrolactone, γ-butyrolactone derivatives, and 1,4-butanediol.

PubMed

Hong, Kuk-Ki; Kim, Jeong Hyun; Yoon, Jong Hyun; Park, Hye-Min; Choi, Su Jin; Song, Gyu Hyeon; Lee, Jea Chun; Yang, Young-Lyeol; Shin, Hyun Kwan; Kim, Ju Nam; Cho, Kyung Ho; Lee, Jung Ho

2014-10-01

There has been a significant global interest to produce bulk chemicals from renewable resources using engineered microorganisms. Large research programs have been launched by academia and industry towards this goal. Particularly, C4 chemicals such as succinic acid (SA) and 1,4-butanediol have been leading the path towards the commercialization of biobased technology with the effort of replacing chemical production. Here we present O-Succinyl-L-homoserine (SH) as a new, potentially important platform biochemical and demonstrate its central role as an intermediate in the production of SA, homoserine lactone (HSL), γ-butyrolactone (GBL) and its derivatives, and 1,4-butanediol (BDO). This technology encompasses (1) the genetic manipulation of Escherichia coli to produce SH with high productivity, (2) hydrolysis into SA and homoserine (HS) or homoserine lactone hydrochloride, and (3) chemical conversion of either HS or homoserine lactone HCL (HSL·HCl) into drop-in chemicals in polymer industry. This production strategy with environmental benefits is discussed in the perspective of targeting of fermented product and a process direction compared to petroleum-based chemical conversion, which may reduce the overall manufacturing cost.

Room temperature ionic liquid-based dispersive liquid phase microextraction for the separation/preconcentration of trace Cd(2+) as 1-(2-pyridylazo)-2-naphthol (PAN) complex from environmental and biological samples and determined by FAAS.

PubMed

Khan, Sumaira; Soylak, Mustafa; Kazi, Tasneem Gul

2013-12-01

The current work develops a new green methodology for the separation/preconcentration of cadmium ions (Cd(2+)) using room temperature ionic liquid-dispersive liquid phase microextraction (RTIL-DLME) prior to analysis by flame atomic absorption spectrometry with microsample introduction system. Room temperature ionic liquids (RTIL) are considered "Green Solvents" for their thermally stable and non-volatile properties, here 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] was used as an extractant. The preconcentration of Cd(2+) in different waters and acid digested scalp hair samples were complexed with 1-(2-pyridylazo)-2-naphthol and extracted into the fine drops of RTILs. Some significant factors influencing the extraction efficiency of Cd(2+) and its subsequent determination, including pH, amount of ligand, volume of RTIL, dispersant solvent, sample volume, temperature, and incubation time were investigated in detail. The limit of detection and the enhancement factor under the optimal conditions were 0.05 μg/L and 50, respectively. The relative standard deviation of 100 μg/L Cd(2+) was 4.3 %. The validity of the proposed method was checked by determining Cd(2+) in certified reference material (TM-25.3 fortified water). The sufficient recovery (>98 %) of Cd(2+) with the certified value. The mean concentrations of Cd in lake water 13.2, waste water 15.7 and hair sample 16.8 μg/L, respectively and the developed method was applied satisfactorily to the preconcentration and determination of Cd(2+) in real samples.

Automation of static and dynamic non-dispersive liquid phase microextraction. Part 2: Approaches based on impregnated membranes and porous supports.

PubMed

Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

2016-02-11

A critical overview on automation of modern liquid phase microextraction (LPME) approaches based on the liquid impregnation of porous sorbents and membranes is presented. It is the continuation of part 1, in which non-dispersive LPME techniques based on the use of the extraction phase (EP) in the form of drop, plug, film, or microflow have been surveyed. Compared to the approaches described in part 1, porous materials provide an improved support for the EP. Simultaneously they allow to enlarge its contact surface and to reduce the risk of loss by incident flow or by components of surrounding matrix. Solvent-impregnated membranes or hollow fibres are further ideally suited for analyte extraction with simultaneous or subsequent back-extraction. Their use can therefore improve the procedure robustness and reproducibility as well as it "opens the door" to the new operation modes and fields of application. However, additional work and time are required for membrane replacement and renewed impregnation. Automation of porous support-based and membrane-based approaches plays an important role in the achievement of better reliability, rapidness, and reproducibility compared to manual assays. Automated renewal of the extraction solvent and coupling of sample pretreatment with the detection instrumentation can be named as examples. The different LPME methodologies using impregnated membranes and porous supports for the extraction phase and the different strategies of their automation, and their analytical applications are comprehensively described and discussed in this part. Finally, an outlook on future demands and perspectives of LPME techniques from both parts as a promising area in the field of sample pretreatment is given. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of needle trap micro-extraction and solid-phase micro-extraction: Obtaining comprehensive information on volatile emissions from in vitro cultures.

PubMed

Oertel, Peter; Bergmann, Andreas; Fischer, Sina; Trefz, Phillip; Küntzel, Anne; Reinhold, Petra; Köhler, Heike; Schubert, Jochen K; Miekisch, Wolfram

2018-05-14

Volatile organic compounds (VOCs) emitted from in vitro cultures may reveal information on species and metabolism. Owing to low nmol L -1 concentration ranges, pre-concentration techniques are required for gas chromatography-mass spectrometry (GC-MS) based analyses. This study was intended to compare the efficiency of established micro-extraction techniques - solid-phase micro-extraction (SPME) and needle-trap micro-extraction (NTME) - for the analysis of complex VOC patterns. For SPME, a 75 μm Carboxen®/polydimethylsiloxane fiber was used. The NTME needle was packed with divinylbenzene, Carbopack X and Carboxen 1000. The headspace was sampled bi-directionally. Seventy-two VOCs were calibrated by reference standard mixtures in the range of 0.041-62.24 nmol L -1 by means of GC-MS. Both pre-concentration methods were applied to profile VOCs from cultures of Mycobacterium avium ssp. paratuberculosis. Limits of detection ranged from 0.004 to 3.93 nmol L -1 (median = 0.030 nmol L -1 ) for NTME and from 0.001 to 5.684 nmol L -1 (median = 0.043 nmol L -1 ) for SPME. NTME showed advantages in assessing polar compounds such as alcohols. SPME showed advantages in reproducibility but disadvantages in sensitivity for N-containing compounds. Micro-extraction techniques such as SPME and NTME are well suited for trace VOC profiling over cultures if the limitations of each technique is taken into account. Copyright © 2018 John Wiley & Sons, Ltd.

Quantitative and enantioselective analysis of monoterpenes from plant chambers and in ambient air using SPME

NASA Astrophysics Data System (ADS)

Yassaa, N.; Custer, T.; Song, W.; Pech, F.; Kesselmeier, J.; Williams, J.

2010-08-01

A solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS) system has been developed for quantifying enantiomeric and nonenantiomeric monoterpenes in plant chamber studies and ambient air. Performance of this system was checked using a capillary diffusion system to produce monoterpene standards. The adsorption efficiency, competitive adsorption and chromatographic peak resolution of monoterpene enantiomer pairs were compared for three SPME fibre coatings: 75 μm Carboxen-PDMS (CAR-PDMS), 50/30 μm, divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) and 65 μm divinylbenzene-polydimethyl-siloxane (DVB-PDMS). Key parameters such as the linearity and reproducibility of the SPME system have been investigated in this work. The best compromise between the enantiomeric separation of monoterpenes and competitive adsorption of the isoprenoids on the solid SPME fibre coating was found for DVB-PDMS fibres. The optimum conditions using DVB-PDMS fibres were applied to measure the exchange rates of monoterpenes in the emission of Quercus ilex using a laboratory whole plant enclosure under light and dark conditions, as well as in ambient air. With 592 and 223 ng m-2 s-1, respectively, β-myrcene and limonene were the predominant monoterpenes in the emission of Q. ilex. These values were closely comparable to those obtained using a zNose and cartridge GC-FID systems.

Rapid differentiation of Chinese hop varieties (Humulus lupulus) using volatile fingerprinting by HS-SPME-GC-MS combined with multivariate statistical analysis.

PubMed

Liu, Zechang; Wang, Liping; Liu, Yumei

2018-01-18

Hops impart flavor to beer, with the volatile components characterizing the various hop varieties and qualities. Fingerprinting, especially flavor fingerprinting, is often used to identify 'flavor products' because inconsistencies in the description of flavor may lead to an incorrect definition of beer quality. Compared to flavor fingerprinting, volatile fingerprinting is simpler and easier. We performed volatile fingerprinting using head space-solid phase micro-extraction gas chromatography-mass spectrometry combined with similarity analysis and principal component analysis (PCA) for evaluating and distinguishing between three major Chinese hops. Eighty-four volatiles were identified, which were classified into seven categories. Volatile fingerprinting based on similarity analysis did not yield any obvious result. By contrast, hop varieties and qualities were identified using volatile fingerprinting based on PCA. The potential variables explained the variance in the three hop varieties. In addition, the dendrogram and principal component score plot described the differences and classifications of hops. Volatile fingerprinting plus multivariate statistical analysis can rapidly differentiate between the different varieties and qualities of the three major Chinese hops. Furthermore, this method can be used as a reference in other fields. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

SPME-GC-MS analysis of commercial henna samples (Lawsonia inermis L.).

PubMed

Mengoni, Tamara; Peregrina, Dolores Vargas; Censi, Roberta; Cortese, Manuela; Ricciutelli, Massimo; Maggi, Filippo; Di Martino, Piera

2016-01-01

The aim of this work was to provide a characterisation of volatile constituents from different commercial batches of henna (Lawsonia inermis) leaves of different geographic origin. Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used for the purpose. A total of 72 components were identified by GC-MS in the headspace of different henna samples which proved to differ considerably from each other, because they were characterised by different classes of components, mainly aliphatic compounds (9.0-64.7%), terpenoids (5.8-45.5%) and aromatics (7.9-45.2%), with alkanes (0.9-18.5%), aldehydes (2.1-18.8%) and carboxylic acids (3.1-29.3%), monoterpenes (3.4-30.0%) and sesquiterpenes (0.8-23.7%) and phenyl propanoids (0.6-43.1%), being the most abundant, respectively. Major representatives of these groups were n-hexadecane (0.5-4.7%), (2E)-hexenal (0.5-11.7%) and acetic acid (2.8-24.5%), limonene (0.8-14.7%), carvol (3.8-7.1%), geranyl acetone (1.4-7.9%) and (E)-caryophyllene (3.3-8.4%), and (E)-anethole (0.6-35.0%), respectively. We assume that factors such as the manufacturing process, the storage conditions and the different geographic origin of the samples may contribute to such variability.

Aroma changes of black tea prepared from methyl jasmonate treated tea plants*

PubMed Central

Shi, Jiang; Wang, Li; Ma, Cheng-ying; Lv, Hai-peng; Chen, Zong-mao; Lin, Zhi

2014-01-01

Methyl jasmonate (MeJA) was widely applied in promoting food quality. Aroma is one of the key indicators in judging the quality of tea. This study examined the effect of exogenous MeJA treatment on tea aroma. The aroma components in black tea prepared from MeJA-treated fresh tea leaves were extracted using headspace solid-phase microextraction (HS-SPME) and were analyzed using gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry (GC-O). Forty-five volatile compounds were identified. The results revealed that the MeJA-treated black tea had higher levels of terpene alcohols and hexenyl esters than the untreated tea. Moreover, several newly components, including copaene, cubenol, and indole, were induced by the MeJA treatment. The activities of polyphenol oxidase and β-glucosidase in fresh tea leaves changed after the MeJA treatment. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the gene expression levels of polyphenol oxidase and β-primeverosidase were upregulated by two and three folds, respectively, by the MeJA treatment (P<0.01); however, the gene expression of β-glucosidase was downregulated to a half level. In general, the aroma quality of the MeJA-treated black tea was clearly improved. PMID:24711352

Analysis of volatile organic compounds in compost samples: A potential tool to determine appropriate composting time.

PubMed

Zhu, Fengxiang; Pan, Zaifa; Hong, Chunlai; Wang, Weiping; Chen, Xiaoyang; Xue, Zhiyong; Yao, Yanlai

2016-12-01

Changes in volatile organic compound contents in compost samples during pig manure composting were studied using a headspace, solid-phase micro-extraction method (HS-SPME) followed by gas chromatography with mass spectrometric detection (GC/MS). Parameters affecting the SPME procedure were optimized as follows: the coating was carbon molecular sieve/polydimethylsiloxane (CAR/PDMS) fiber, the temperature was 60°C and the time was 30min. Under these conditions, 87 compounds were identified from 17 composting samples. Most of the volatile components could only be detected before day 22. However, benzenes, alkanes and alkenes increased and eventually stabilized after day 22. Phenol and acid substances, which are important factors for compost quality, were almost undetectable on day 39 in natural compost (NC) samples and on day 13 in maggot-treated compost (MC) samples. Our results indicate that the approach can be effectively used to determine the composting times by analysis of volatile substances in compost samples. An appropriate composting time not only ensures the quality of compost and reduces the loss of composting material but also reduces the generation of hazardous substances. The appropriate composting times for MC and NC were approximately 22days and 40days, respectively, during the summer in Zhejiang. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative fingerprinting by headspace--two-dimensional comprehensive gas chromatography-mass spectrometry of solid matrices: some challenging aspects of the exhaustive assessment of food volatiles.

PubMed

Nicolotti, Luca; Cordero, Chiara; Cagliero, Cecilia; Liberto, Erica; Sgorbini, Barbara; Rubiolo, Patrizia; Bicchi, Carlo

2013-10-10

The study proposes an investigation strategy that simultaneously provides detailed profiling and quantitative fingerprinting of food volatiles, through a "comprehensive" analytical platform that includes sample preparation by Headspace Solid Phase Microextraction (HS-SPME), separation by two-dimensional comprehensive gas chromatography coupled with mass spectrometry detection (GC×GC-MS) and data processing using advanced fingerprinting approaches. Experiments were carried out on roasted hazelnuts and on Gianduja pastes (sugar, vegetable oil, hazelnuts, cocoa, nonfat dried milk, vanilla flavorings) and demonstrated that the information potential of each analysis can better be exploited if suitable quantitation methods are applied. Quantitation approaches through Multiple Headspace Extraction and Standard Addition were compared in terms of performance parameters (linearity, precision, accuracy, Limit of Detection and Limit of Quantitation) under headspace linearity conditions. The results on 19 key analytes, potent odorants, and technological markers, and more than 300 fingerprint components, were used for further processing to obtain information concerning the effect of the matrix on volatile release, and to produce an informative chemical blueprint for use in sensomics and flavoromics. The importance of quantitation approaches in headspace analysis of solid matrices of complex composition, and the advantages of MHE, are also critically discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Quantitative and enantioselective analysis of monoterpenes from plant chambers and in ambient air using SPME

NASA Astrophysics Data System (ADS)

Yassaa, N.; Custer, T.; Song, W.; Pech, F.; Kesselmeier, J.; Williams, J.

2010-11-01

A headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS) system has been developed for quantifying enantiomeric and nonenantiomeric monoterpenes in plant chamber studies and ambient air. Performance of this system was checked using a capillary diffusion system to produce monoterpene standards. The adsorption efficiency, competitive adsorption and chromatographic peak resolution of monoterpene enantiomer pairs were compared for three SPME fibre coatings: 75 μm Carboxen-PDMS (CAR-PDMS), 50/30 μm divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) and 65 μm divinylbenzene-polydimethylsiloxane (DVB-PDMS). Key parameters such as the linearity and reproducibility of the SPME system have been investigated in this work. The best compromise between the enantiomeric separation of monoterpenes and competitive adsorption of the isoprenoids on the solid SPME fibre coating was found for DVB-PDMS fibres. The optimum conditions using DVB-PDMS fibres were applied to measure the exchange rates of monoterpenes in the emission of Quercus ilex using a laboratory whole plant enclosure under light and dark conditions, as well as in ambient air. With 592 and 223 ng m-2 s-1 respectively, β-myrcene and limonene were the predominant monoterpenes in the emission of Q. ilex. These values were closely comparable to those obtained using a zNose and cartridge GC-FID systems.

Study of flavour compounds from orange juices by HS-SPME and GC-MS

NASA Astrophysics Data System (ADS)

Schmutzer, G.; Avram, V.; Covaciu, F.; Feher, I.; Magdas, A.; David, L.; Moldovan, Z.

2013-11-01

The flavour of the orange juices, which gives the taste and odour of the product, is an important criterion about the products quality for consumers. A fresh single strength and two commercial orange juices (obtained from concentrate) flavour profile were studied using a selective and sensitive gas chromatography - mass spectrometry (GC-MS) analytical system, after a solvent free, single step preconcentration and extraction technique, the headspace solid phase microextraction (HP-SPME). In the studied orange juices 55 flavour compounds were detected and classified as belonging to the esters, alcohols, ketones, monoterpenes and sesquiterpenes chemical families. The fresh single strength orange juice was characterized by high amount of esters, monoterpenes and sesquiterpenes. Limonene and valencene were the most abundant flavours in this fresh natural orange juice. Alcohols and ketones were found in higher concentration in the commercial orange juices made from concentrate, than in the single strength products. Nevertheless, in commercial juices the most abundant flavour was limonene and α-terpineol. The results highlight clear differences between fresh singles strength orange juice and juice from concentrate. The orange juices reconstructed from concentrate, made in Romania, present low quantity of flavour compounds, suggesting the absence or a low rearomatization process, but extraneous components were not detected.

Analysis of Listeria using exogenous volatile organic compound metabolites and their detection by static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS).

PubMed

Taylor, Carl; Lough, Fraser; Stanforth, Stephen P; Schwalbe, Edward C; Fowlis, Ian A; Dean, John R

2017-07-01

Listeria monocytogenes is a Gram-positive bacterium and an opportunistic food-borne pathogen which poses significant risk to the immune-compromised and pregnant due to the increased likelihood of acquiring infection and potential transmission of infection to the unborn child. Conventional methods of analysis suffer from either long turn-around times or lack the ability to discriminate between Listeria spp. reliably. This paper investigates an alternative method of detecting Listeria spp. using two novel enzyme substrates that liberate exogenous volatile organic compounds in the presence of α-mannosidase and D-alanyl aminopeptidase. The discriminating capabilities of this approach for identifying L. monocytogenes from other species of Listeria are investigated. The liberated volatile organic compounds (VOCs) are detected using an automated analytical technique based on static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS). The results obtained by SHS-MCC-GC-IMS are compared with those obtained by the more conventional analytical technique of headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results found that it was possible to differentiate between L. monocytogenes and L. ivanovii, based on their VOC response from α-mannosidase activity.

Identification of volatile compounds associated with the aroma of white strawberries (Fragaria chiloensis).

PubMed

Prat, Loreto; Espinoza, María Inés; Agosin, Eduardo; Silva, Herman

2014-03-15

Fragaria chiloensis (L.) Mill spp. chiloensis form chiloensis, is a strawberry that produces white fruits with unique aromas. This species, endemic to Chile, is one of the progenitors of Fragaria x ananassa Duch. In order to identify the volatile compounds that might be responsible for aroma, these were extracted, and analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O) and compared with sensory analyses. Three methods of extraction were used: solvent-assisted evaporation (SAFE), headspace solid phase micro-extraction (HS-SPME) and liquid-liquid extraction (LLE). Ninety-nine volatile compounds were identified by GC-MS, of which 75 showed odor activity using GC-O. Based on the highest dilution factor (FD = 1000) and GC-O intensity ≥2, we determined 20 major compounds in white strawberry fruit that contribute to its aroma. We chose 51 compounds to be tested against their commercial standards. The identities were confirmed by comparison of their linear retention indices against the commercial standards. The aroma of white strawberry fruits was reconstituted with a synthetic mixture of most of these compounds. The volatile profile of white strawberry fruit described as fruity, green-fresh, floral, caramel, sweet, nutty and woody will be a useful reference for future strawberry breeding programs. © 2013 Society of Chemical Industry.

Quantitative analysis of perfumes in talcum powder by using headspace sorptive extraction.

PubMed

Ng, Khim Hui; Heng, Audrey; Osborne, Murray

2012-03-01

Quantitative analysis of perfume dosage in talcum powder has been a challenge due to interference of the matrix and has so far not been widely reported. In this study, headspace sorptive extraction (HSSE) was validated as a solventless sample preparation method for the extraction and enrichment of perfume raw materials from talcum powder. Sample enrichment is performed on a thick film of poly(dimethylsiloxane) (PDMS) coated onto a magnetic stir bar incorporated in a glass jacket. Sampling is done by placing the PDMS stir bar in the headspace vial by using a holder. The stir bar is then thermally desorbed online with capillary gas chromatography-mass spectrometry. The HSSE method is based on the same principles as headspace solid-phase microextraction (HS-SPME). Nevertheless, a relatively larger amount of extracting phase is coated on the stir bar as compared to SPME. Sample amount and extraction time were optimized in this study. The method has shown good repeatability (with relative standard deviation no higher than 12.5%) and excellent linearity with correlation coefficients above 0.99 for all analytes. The method was also successfully applied in the quantitative analysis of talcum powder spiked with perfume at different dosages. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ripening-dependent metabolic changes in the volatiles of pineapple (Ananas comosus (L.) Merr.) fruit: II. Multivariate statistical profiling of pineapple aroma compounds based on comprehensive two-dimensional gas chromatography-mass spectrometry.

PubMed

Steingass, Christof Björn; Jutzi, Manfred; Müller, Jenny; Carle, Reinhold; Schmarr, Hans-Georg

2015-03-01

Ripening-dependent changes of pineapple volatiles were studied in a nontargeted profiling analysis. Volatiles were isolated via headspace solid phase microextraction and analyzed by comprehensive 2D gas chromatography and mass spectrometry (HS-SPME-GC×GC-qMS). Profile patterns presented in the contour plots were evaluated applying image processing techniques and subsequent multivariate statistical data analysis. Statistical methods comprised unsupervised hierarchical cluster analysis (HCA) and principal component analysis (PCA) to classify the samples. Supervised partial least squares discriminant analysis (PLS-DA) and partial least squares (PLS) regression were applied to discriminate different ripening stages and describe the development of volatiles during postharvest storage, respectively. Hereby, substantial chemical markers allowing for class separation were revealed. The workflow permitted the rapid distinction between premature green-ripe pineapples and postharvest-ripened sea-freighted fruits. Volatile profiles of fully ripe air-freighted pineapples were similar to those of green-ripe fruits postharvest ripened for 6 days after simulated sea freight export, after PCA with only two principal components. However, PCA considering also the third principal component allowed differentiation between air-freighted fruits and the four progressing postharvest maturity stages of sea-freighted pineapples.

Volatile metabolomic signature of human breast cancer cell lines

PubMed Central

Silva, Catarina L.; Perestrelo, Rosa; Silva, Pedro; Tomás, Helena; Câmara, José S.

2017-01-01

Breast cancer (BC) remains the most prevalent oncologic pathology in women, causing huge psychological, economic and social impacts on our society. Currently, the available diagnostic tools have limited sensitivity and specificity. Metabolome analysis has emerged as a powerful tool for obtaining information about the biological processes that occur in organisms, and is a useful platform for discovering new biomarkers or make disease diagnosis using different biofluids. Volatile organic compounds (VOCs) from the headspace of cultured BC cells and normal human mammary epithelial cells, were collected by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography combined with mass spectrometry (GC–MS), thus defining a volatile metabolomic signature. 2-Pentanone, 2-heptanone, 3-methyl-3-buten-1-ol, ethyl acetate, ethyl propanoate and 2-methyl butanoate were detected only in cultured BC cell lines. Multivariate statistical methods were used to verify the volatomic differences between BC cell lines and normal cells in order to find a set of specific VOCs that could be associated with BC, providing comprehensive insight into VOCs as potential cancer biomarkers. The establishment of the volatile fingerprint of BC cell lines presents a powerful approach to find endogenous VOCs that could be used to improve the BC diagnostic tools and explore the associated metabolomic pathways. PMID:28256598

Unbiased profiling of volatile organic compounds in the headspace of Allium plants using an in-tube extraction device.

PubMed

Kusano, Miyako; Kobayashi, Makoto; Iizuka, Yumiko; Fukushima, Atsushi; Saito, Kazuki

2016-02-29

Plants produce and emit important volatile organic compounds (VOCs), which have an essential role in biotic and abiotic stress responses and in plant-plant and plant-insect interactions. In order to study the bouquets from plants qualitatively and quantitatively, a comprehensive, analytical method yielding reproducible results is required. We applied in-tube extraction (ITEX) and solid-phase microextraction (SPME) for studying the emissions of Allium plants. The collected HS samples were analyzed by gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS), and the results were subjected to multivariate analysis. In case of ITEX-method Allium cultivars released more than 300 VOCs, out of which we provisionally identified 50 volatiles. We also used the VOC profiles of Allium samples to discriminate among groups of A. fistulosum, A. chinense (rakkyo), and A. tuberosum (Oriental garlic). As we found 12 metabolite peaks including dipropyl disulphide with significant changes in A. chinense and A. tuberosum when compared to the control cultivar, these metabolite peaks can be used for chemotaxonomic classification of A. chinense, tuberosum, and A. fistulosum. Compared to SPME-method our ITEX-based VOC profiling technique contributes to automatic and reproducible analyses. Hence, it can be applied to high-throughput analyses such as metabolite profiling.

Emerging Environmental Contaminants and Soled Phase Microextraction: Janusz Pawliszyn's Legacy in the Environmental Arena

EPA Science Inventory

Solid phase microextraction (SPME) has revolutionized the way samples are extracted, enabling rapid, automated, and solventless extraction of many different sample types, including air, water, soil, and biological samples. As such, SPME is widely used for environmental, food, fo...

Application of liquid-liquid microextraction for the effective separation and simultaneous determination of 11 pharmaceuticals in wastewater samples using HPLC-MS/MS.

PubMed

Diuzheva, Alina; Balogh, József; Jekő, József; Cziáky, Zoltán

2018-05-17

A dispersive liquid-liquid microextraction method for the simultaneous determination of 11 pharmaceuticals has been developed. The method is based on a microextraction procedure applied to wastewater samples from different regions of Hungary followed by high performance liquid chromatography with mass spectrometry. The effect of the nature of the extractant, dispersive solvent, different additives and extraction time were examined on the extraction efficiently of the dispersive liquid-liquid microextraction method. Under optimal conditions, the linearity for determining the pharmaceuticals was in the range of 1-500 ng mL -1 , with the correlation coefficients ranging from 0.9922 to 0.9995. The limits of detection and limits of quantification were in the range 0.31-6.65 and 0.93-22.18 ng mL -1 , respectively. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

SOLID PHASE MICROEXTRACTION FOR TRACE LEVEL ANALYSIS OF DISINFECTION BY-PRODUCTS

EPA Science Inventory

This presentation focuses on the development of a solid-phase microextraction (SPME)-gas chromatography (GC)/ion trap mass spectrometry (MS) method for the analysis of semivolatile disinfection by-products (DBPs) in drinking water in the low ug/L range. These DBPs were selected ...

Thermal evolution of the western South Atlantic and the adjacent continent during Termination 1

NASA Astrophysics Data System (ADS)

Chiessi, C. M.; Mulitza, S.; Mollenhauer, G.; Silva, J. B.; Groeneveld, J.; Prange, M.

2015-06-01

During Termination 1, millennial-scale weakening events of the Atlantic meridional overturning circulation (AMOC) supposedly produced major changes in sea surface temperatures (SSTs) of the western South Atlantic, and in mean air temperatures (MATs) over southeastern South America. It has been suggested, for instance, that the Brazil Current (BC) would strengthen (weaken) and the North Brazil Current (NBC) would weaken (strengthen) during slowdown (speed-up) events of the AMOC. This anti-phase pattern was claimed to be a necessary response to the decreased North Atlantic heat piracy during periods of weak AMOC. However, the thermal evolution of the western South Atlantic and the adjacent continent is so far largely unknown. Here we address this issue, presenting high-temporal-resolution SST and MAT records from the BC and southeastern South America, respectively. We identify a warming in the western South Atlantic during Heinrich Stadial 1 (HS1), which is followed first by a drop and then by increasing temperatures during the Bølling-Allerød, in phase with an existing SST record from the NBC. Additionally, a similar SST evolution is shown by a southernmost eastern South Atlantic record, suggesting a South Atlantic-wide pattern in SST evolution during most of Termination 1. Over southeastern South America, our MAT record shows a two-step increase during Termination 1, synchronous with atmospheric CO2 rise (i.e., during the second half of HS1 and during the Younger Dryas), and lagging abrupt SST changes by several thousand years. This delay corroborates the notion that the long duration of HS1 was fundamental in driving the Earth out of the last glacial.

Thermal evolution of the western South Atlantic and the adjacent continent during Termination 1

NASA Astrophysics Data System (ADS)

Chiessi, C. M.; Mulitza, S.; Mollenhauer, G.; Silva, J. B.; Groeneveld, J.; Prange, M.

2014-12-01

During Termination 1, millennial-scale weakening events of the Atlantic meridional overturning circulation (AMOC) supposedly produced major changes in sea surface temperatures (SST) of the western South Atlantic, and in mean air temperatures (MAT) over southeastern South America. It was suggested, for instance, that the Brazil Current (BC) would strengthen (weaken) and the North Brazil Current (NBC) would weaken (strengthen) during slowdown (speed-up) events of the AMOC. This anti-phase pattern was claimed to be a necessary response to the decreased North Atlantic heat piracy during periods of weak AMOC. However, the thermal evolution of the western South Atlantic and the adjacent continent is largely unknown and a compelling record of the BC-NBC anti-phase behavior remains elusive. Here we address this issue, presenting high temporal resolution SST and MAT records from the BC and southeastern South America, respectively. We identify a warming in the western South Atlantic during Heinrich Stadial 1 (HS1), which is followed first by a drop and then by increasing temperatures during the Bølling-Allerød, in-phase with an existing NBC record. Additionally, a similar SST evolution is shown by a southernmost eastern South Atlantic record, suggesting a South Atlantic-wide pattern in SST evolution during most of Termination 1. Over southeastern South America, our MAT record shows a two-step increase during Termination 1, synchronous with atmospheric CO2 rise (i.e., during the second half of HS1 and during the Younger Dryas), and lagging abrupt SST changes by several thousand years. This delay corroborates the notion that the long duration of HS1 was fundamental to drive the Earth out of the last glacial.

Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

PubMed

Xing, Han-Zhu; Wang, Xia; Chen, Xiang-Feng; Wang, Ming-Lin; Zhao, Ru-Song

2015-05-01

A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9-110%. These findings indicate that accelerated solvent extraction with dispersive liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discovering Volatile Chemicals from Window Weatherstripping through Solid-Phase Microextraction/Gas Chromatography-Mass Spectrometry

ERIC Educational Resources Information Center

Rosu, Cornelia; Cueto, Rafael; Veillion, Lucas; David, Connie; Laine, Roger A.; Russo, Paul S.

2017-01-01

Volatile compounds from polymeric materials such as weatherstripping were identified by solid-phase microextraction (SPME), a solvent-free analytical method, coupled to gas chromatography-mass spectrometry (GC-MS). These compounds, originating from additives and fillers used in weatherstripping processing, were mostly polycyclic aromatic…

Headspace analysis of polar organic compounds in biological matrixes using solid phase microextraction (SPME)

USDA-ARS?s Scientific Manuscript database

Analysis of biological fluids and waste material is difficult and tedious given the sample matrix. A rapid automated method for the determination of volatile fatty acids and phenolic and indole compounds was developed using a multipurpose sampler (MPS) with solid phase microextraction (SPME) and GC-...

Determination of Plant Volatiles Using Solid Phase Microextraction GC-MS

ERIC Educational Resources Information Center

Van Bramer, Scott; Goodrich, Katherine R.

2015-01-01

This experiment combines analytical techniques of solid phase microextraction and gas chromatography-mass spectrometry with easily relatable and accessible plant volatile chemistry (floral and vegetative scents of local/available plants). The biosynthesis and structure of these chemicals are of interest in the areas of organic chemistry,…

Rapid screening of oxytetracycline residue in catfish muscle by dispersive liquid-liquid microextraction and europium-sensitized luminescence

USDA-ARS?s Scientific Manuscript database

Oxytetracycline (OTC) residue in catfish muscle was screened by dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). After extraction in EDTA, HCl, and acetonitrile, cleanup was carried out by DLLME, and ESL was measured at microgram = 385 nm and wavelength = ...

Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup

USDA-ARS?s Scientific Manuscript database

A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally de...

A Southern Ocean driver of atmospheric CO2

NASA Astrophysics Data System (ADS)

Ronge, T.; Geibert, W.; Lippold, J.; Lamy, F.; Schnetger, B.; Tiedemann, R.

2017-12-01

A prominent two-step rise in atmospheric CO2 marked the end of the last glacial. The steps coincided with climatic intervals Heinrich Stadial 1 (HS1) and the Younger Dryas (YD). Records of 231Pa/230Th on sediment cores bathed by NADW, revealed a rapid reduction of the Atlantic Meridional Overturning Circulation (AMOC), during these intervals. It was argued that a weakened AMOC would have significantly reduced the efficiency of the biological pump and thus might have contributed to the rise in atmospheric CO2. Despite playing an important role, this process fails to account for the enigmatic drop in atmospheric Δ14C and δ13C during HS1 that marks the first step of the CO2-rise. Increasing CO2-concentrations with a simultaneous drop in their Δ14C, call for the ventilation of an old and 14C-depleted carbon reservoir. In this respect, several studies point to the presence of very old, 14C-depleted deep-waters in the glacial Southern Ocean, which rejuvenated during the last deglaciation. However, the accumulation of 14C-depleted, carbon-rich waters in the deep Southern Ocean requires circulation patterns that significantly differ from todays. Here we present a combined set of 231Pa/230Th-, Rare Earth Element- and XRF-proxy records to understand the evolution of the South Pacific Overturning Circulation (SPOC) over the last 35,000 years. Our reconstructions are based on a transect of five sediment cores from the Southwest Pacific, covering the AAIW as well as the UCDW and LCDW. Our data show that throughout the last glacial the SPOC was significantly weakened. This reduction favored the observed accumulation of 14C-depleted CO2 in Circumpolar Deep Waters (CDW). Parallel to the HS1 increase of atmospheric CO2, the deep circulation picked up its pace and recovered toward the Holocene. This trend is in remarkable agreement with water mass radiocarbon reconstructions from the very same area, as well as with atmospherical changes in CO2, Δ14C and δ13C. Hence, we are confident that the Southern Ocean - represented here by the South Pacific - played the dominant role in the first rise in atmospheric CO2. In addition the observed deglacial SPOC strengthening may have supported the transport of warm CDW onto the shelf areas since the timing of retreating West Antarctic ice sheets is in good agreement with our recent reconstructions.

Novel strategies for sample preparation in forensic toxicology.

PubMed

Samanidou, Victoria; Kovatsi, Leda; Fragou, Domniki; Rentifis, Konstantinos

2011-09-01

This paper provides a review of novel strategies for sample preparation in forensic toxicology. The review initially outlines the principle of each technique, followed by sections addressing each class of abused drugs separately. The novel strategies currently reviewed focus on the preparation of various biological samples for the subsequent determination of opiates, benzodiazepines, amphetamines, cocaine, hallucinogens, tricyclic antidepressants, antipsychotics and cannabinoids. According to our experience, these analytes are the most frequently responsible for intoxications in Greece. The applications of techniques such as disposable pipette extraction, microextraction by packed sorbent, matrix solid-phase dispersion, solid-phase microextraction, polymer monolith microextraction, stir bar sorptive extraction and others, which are rapidly gaining acceptance in the field of toxicology, are currently reviewed.

SIMPLE METHOD FOR ESTIMATING POLYCHLORINATED BIPHENYL CONCENTRATIONS ON SOILS AND SEDIMENTS USING SUBCRITICAL WATER EXTRACTION COUPLED WITH SOLID-PHASE MICROEXTRACTION. (R825368)

EPA Science Inventory

A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a seale...

Separation of cucurbitane triterpenoids from bitter melon drinks and determination of partition coefficients using vortex-assisted dispersive liquid-phase microextraction followed by UHPLC analysis

USDA-ARS?s Scientific Manuscript database

A rapid, effective technique applying vortex-assisted liquid–liquid microextraction (VALLME) prior to ultra high performance liquid chromatography-evaporating light scattering detectection/ mass spectroscopy (UHPLC-ELSD/MS) determination was developed for the analysis of four cucurbitane triterpenoi...

Solid-phase microextraction coupled with high performance liquid chromatography: a complementary technique to solid-phase microextraction-gas chromatography for the analysis of pesticide residues in strawberries.

PubMed

Wang, Z; Hennion, B; Urruty, L; Montury, M

2000-11-01

Solid-phase microextraction coupled with high performance liquid chromatography has been studied for the analysis of methiocarb, napropamide, fenoxycarb and bupirimate in strawberries. The strawberries were blended and centrifuged. Then, an aliquot of the resulting extracting solution was subjected to solid-phase microextraction (SPME) on a 60 microns polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 45 min at room temperature. The extracted pesticides on the SPME fibre were desorbed into SPME/high performance liquid chromatography (HPLC) interface for HPLC analysis with diode-array detection (DAD). The method is organic solvent-free for the whole extraction process and is simple and easy to manipulate. The detection limits were shown to be at low microgram kg-1 level and the linear response covered the range from 0.05 to 2 mg kg-1 of pesticides in strawberries with a regression coefficient larger than 0.99. A good repeatability with RSDs between 2.92 and 9.25% was obtained, depending on compounds.

Determination of metal ions in tea samples using task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction coupled to liquid chromatography with ultraviolet detection.

PubMed

Werner, Justyna

2016-04-01

Task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction was used for the preconcentration of cadmium(II), cobalt(II), and lead(II) ions in tea samples, which were subsequently analyzed by liquid chromatography with UV detection. The proposed method of preconcentration is free of volatile organic compounds, which are often used as extractants and dispersing solvents in classic techniques of microextraction. A task-specific ionic liquid trioctylmethylammonium thiosalicylate was used as an extractant and a chelating agent. Ultrasound was used to disperse the ionic liquid. After microextraction, the phases were separated by centrifugation, and the ionic liquid phase was solubilized in methanol and directly injected into the liquid chromatograph. Selected microextraction parameters, such as the volume of ionic liquid, the pH of the sample, the duration of ultrasound treatment, the speed and time of centrifugation, and the effect of ionic strength, were optimized. Under optimal conditions an enrichment factor of 200 was obtained for each analyte. The limits of detection were 0.002 mg/kg for Cd(II), 0.009 mg/kg for Co(II), and 0.013 mg/kg for Pb(II). The accuracy of the proposed method was evaluated by an analysis of the Certified Reference Materials (INCT-TL-1, INCT-MPH-2) with the recovery values in the range of 90-104%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dispersive liquid-liquid microextraction combined with microwave-assisted derivatization for determining lipoic acid and its metabolites in human urine.

PubMed

Tsai, Chia-Ju; Chen, Yen-Ling; Feng, Chia-Hsien

2013-10-04

This study explored dispersive liquid-liquid microextraction for extraction and concentration of lipoic acid in human urine. To improve the detection of lipoic acid by both capillary liquid chromatography (CapLC) with UV detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), microwave-assisted derivatization with 4-bromomethyl-6,7-dimethoxycoumarin was performed to render lipoic acid chromophores for UV detection and also high ionization efficiency in MALDI. All parameters that affected lipoic acid extraction and derivatization from urine were investigated and optimized. In the analyses of human urine samples, the two methods had a linear range of 0.1-20 μM with a correlation coefficient of 0.999. The detection limits of CapLC-UV and MALDI-TOF MS were 0.03 and 0.02 μM (S/N ≧ 3), respectively. The major metabolites of lipoic acid, including 6,8-bismethylthio-octanoic acid, 4,6-bismethylthio-hexanoic acid, and 2,4-bismethylthio-butanoic acid were also extracted by dispersive liquid-liquid microextraction and detected by MALDI-TOF MS. The minor metabolites (undetectable by MALDI-TOF MS), bisnorlipoic acid and tetranorlipoic acid were also extracted by dispersive liquid-liquid microextraction and identified with an LTQ Orbitrap mass spectrometer. After dispersive liquid-liquid microextraction and microwave-assisted derivatization, all lipoic acid derivatizations and metabolites were structurally confirmed by LTQ Orbitrap. Copyright © 2013 Elsevier B.V. All rights reserved.

Rapid determination of 54 pharmaceutical and personal care products in fish samples using microwave-assisted extraction-Hollow fiber-Liquid/solid phase microextraction.

PubMed

Zhang, Yi; Guo, Wen; Yue, Zhenfeng; Lin, Li; Zhao, Fengjuan; Chen, Peijin; Wu, Weidong; Zhu, Hong; Yang, Bo; Kuang, Yanyun; Wang, Jiong

2017-04-15

In this paper, a simple, rapid, solvent-less and environmental friendliness microextraction method, microwave-assisted extraction-hollow fiber-liquid/solid phase microextraction (MAE-HF-L/SME), was developed for simultaneous extraction and enrichment of 54 trace hydrophilic/lipophilic pharmaceutical and personal care products (PPCPs) from fish samples. A solid-phase extraction material, solid-phase microextraction (SPME) fiber, was synthesized. The SPME fiber had a homogeneous, loose structure and good mechanical properties, and they exhibited a good adsorption capacity for most PPCPs selected. The material formed the basis for the method of MAE-HF-L/SME. A method of liquid chromatography-high resolution mass spectroscopy (LC-HRMS) for analysis of 54 PPCPs. Under optimal synthesis and extraction conditions, the limits of detection (LODs, n=3) and the limits of quantitation (LOQs, n=10) for the 54 PPCPs were between 0.01-0.50μg·kg -1 and 0.052.00μg·kg -1 , respectively. Percent recoveries and the relative standard deviations (RSDs) in spiked fish samples (n=6) were between 56.3%-119.9% and 0.3%-17.1%, respectively. The microextraction process of 54 PPCPs in MAE-HF-L/SME took approximately 12min. The method has a low matrix interference and high enrichment factor and may be applicable for determination of 54 different PPCPs in fish samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

PubMed

Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

2017-08-29

With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

Porous organic polymers with different pore structures for sensitive solid-phase microextraction of environmental organic pollutants.

PubMed

Huang, Zhoubing; Liu, Shuqin; Xu, Jianqiao; Yin, Li; Zheng, Juan; Zhou, Ningbo; Ouyang, Gangfeng

2017-10-09

Adsorption capacity is the major sensitivity-limited factor in solid-phase microextraction. Due to its light-weight properties, large specific surface area and high porosity, especially tunable pore structures, the utilization of porous organic polymers as solid-phase microextraction adsorbents has attracting researchers' attentions. However, these works mostly concentrated on the utilization of specific porous organic polymers for preparing high-performance solid-phase microextraction coatings. The relationship between pore structures and adsorption performance of the porous organic polymers still remain unclear. Herein, three porous organic polymers with similar properties but different pore distributions were prepared by condensation polymerization reaction of phloroglucinol and terephthalaldehyde, which were fabricated as solid-phase microextraction coatings subsequently. The adsorption capacity of the porous organic polymers-coated fibers were evaluated by using benzene and its derivatives (i.e.,benzene, toluene, ethylbenzene and m-xylene) and polycyclic aromatic hydrocarbons as the target analytes. The results showed that the different adsorption performance of these porous organic polymers was mainly caused by their different pore volumes instead of their surface areas or pore sizes. Finally, the proposed method by using the mesoporous organic polymer coating was successfully applied to the determination of benzene and its derivatives in environmental water samples. As for analytical performance, high pre-concentration factors (74-2984), satisfactory relative recoveries (94.5 ± 18.5-116.9 ± 12.5%), intraday precision (2.44-5.34%), inter-day precision (4.62-7.02%), low limit of detections (LODs, 0.10-0.29 ng L -1 ) and limit of quantifications (LOQs, 0.33-0.96 ng L -1 ) were achieved under the optimal conditions. This study provides an important idea in the rational design of porous organic polymers for solid-phase microextraction or other adsorption applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermodynamic and transport properties of frozen and reacting pH2-oH2 mixtures

NASA Technical Reports Server (NTRS)

Carter, H. G.; Bullock, R. E.

1972-01-01

Application of experimental state data and spectroscopic term values shows that the thermodynamic and transport properties of reacting pH2-oH2 mixtures are considerably different than those of chemically frozen pH2 at temperatures below 300 R. Calculated H-S data also show that radiation-induced pH2-oH2 equilibration at constant enthalpy produces a temperature drop of at least 28 R, corresponding to an ideal shaft work loss of 15% or more for a turbine operating downstream from the point of conversion. Aside from differences in thermodynamic and transport properties, frozen pH2-oH2 mixtures may differ from pure pH2 on a purely hydrodynamical basis.

Clinical and electrophysiological findings in mesial temporal lobe epilepsy with hippocampal sclerosis, based on the recent histopathological classifications.

PubMed

Tezer, F Irsel; Xasiyev, Farid; Soylemezoglu, Figen; Bilginer, Burcak; Oguz, Kader Karli; Saygi, Serap

2016-11-01

Hippocampal sclerosis (HS) is a common pathology in MTLE, patients may show different surgical outcomes and clinical features. The 2013 ILAE classification subdivides HS into 3 types (HS type 1: severe neuronal loss and gliosis predominantly in CA1 and CA4 regions; - HS type 2: CA1 predominant; HS type 3: CA4 predominant) and includes "gliosis only, as no-HS". The association of clinical and electrophysiological findings with different HS types has not been reported previously in detail. 48 patients who had undergone temporal lobectomy with amygdalohippocampectomy due to mesial TLE-HS between February 2014 and February 2016 were included. The patients were divided into five groups: patients with HS ILAE type 1, HS ILAE type 2, HS ILAE type 3, FCD type IIIa, or gliosis/no HS. The correlation between HS ILAE types and clinical/EEG findings in patients with MTLE due to HS was investigated. Of the 48 patients 30 were male. In 23 patients, the resection was on the left side (48%). Three patients had only gliosis, 25 patients had HS ILAE type 1, 7 had HS ILAE type 2, and 4 had HS ILAE type 3. Nine of the 48 patients had cortical lamination abnormalities in the temporal lobe associated with HS (FCD type IIIa). All patients were seizure free for early follow up. There was no association between type of HS in terms of duration of epilepsy, onset age of epilepsy, lateralized or localized semiological findings, or interictal/ictal EEG findings. Family history of epilepsy or SGTCSs were statistically more frequent in patients with types 2 and 3 HS and status epilepticus was more frequent in patients with HS-FCD type IIIa. The patients with HS types 2 and 3 have more frequent SGTCS or status epilepticus as well as increased family history of epilepsy. These findings can be helpful in understanding the epileptogenicity-prognoses of HS. Copyright © 2016 Elsevier B.V. All rights reserved.

PARTITION INFRARED METHOD FOR TOTAL GASOLINE RANGE ORGANICS IN WATER BASED ON SOLID PHASE MICROEXTRACTION. (R825343)

EPA Science Inventory

A new method is described for determining total gasoline-range organics
(TGRO) in water that combines solid-phase microextraction (SPME) and infrared
(IR) spectroscopy. In this method, the organic compounds are extracted from
250-mL of water into a small square (3....

SCREENING METHOD FOR NITROAROMATIC COMPOUNDS IN WATER BASED ON SOLID-PHASE MICROEXTRACTION AND INFRARED SPECTROSCOPY. (R825343)

EPA Science Inventory

A new method is described for determining nitroaromatic compounds in water
that combines solid-phase microextraction (SPME) and infrared (IR) spectroscopy. In this method, the compounds are extracted from a 250-mL volume of water into a small square (3.2 cm ? 3.2 cm ? 61.2...

HIGH LEVELS OF MONOAROMATIC COMPOUNDS LIMIT THE USE OF SOLID-PHASE MICROEXTRACTION OF METHYL TERTIARY BUTYL ETHER AND TERTIARY BUTYL ALCOHOL

EPA Science Inventory

Recently, two papers reported the use of solid-phase microextraction (SPME) with polydimethylsiloxane(PDMS)/Carboxen fibers to determine trace levels of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (tBA) in water. Attempts were made to apply this technique to th...

Effects of humic substances supplementation provided through drinking water on performance, carcass traits and meat quality of broilers.

PubMed

Ozturk, E; Ocak, N; Coskun, I; Turhan, S; Erener, G

2010-02-01

The present study aimed at evaluating the effects of different doses of humic substances (HS) in waterer pan on broiler performances and meat quality. For the trial, 480 chicks (ROSS 308) were allocated into four groups (HS0, HS150, HS300 and HS450) of 120 equally mixed-sex birds, each receiving a drinking water supplemented with 0, 150, 300 and 450 ppm of a humic acid (provided by 0.0%, 0.5%, 1.0% and 1.5% of HS, v/v) respectively. At the age of 21 and 42 days, feed consumption and live weight were taken. At the age of 42 days, 16 birds per treatment were slaughtered, dressing percentages, digestive tract traits were evaluated and samples of breast (pectoralis major) and thigh (iliotibialis) meat were taken to evaluate the changes in colour characteristics (CIE L*, a* and b*) and chemical composition. The body weight gain increased by the HS300 in relation to the HS0 and HS450, and decreased by the HS450 in relation to the HS0. The feed consumption of birds in the HS450 and feed efficiency of birds in the HS300 were lower and higher than those in the other treatments respectively. The carcass weight of broilers in the HS150 and HS300 were higher than those of in the HS0 and HS450. The carcass weight decreased by the HS450 in relation to the other treatments. The dressing percentage increased by the HS150 in relation to the HS450. The HS450 resulted in breast and thigh meat colour that were lighter than those found in the HS0 birds. The HS450 increased fat content of thigh meat in relation to the HS0. It was concluded that the humic acid supplementation at 300 ppm and 450 ppm appears to have a measurable impact on live performance improving feed efficiency and lightness of breast and thigh meat colours in broilers respectively.

Liquid-liquid microextraction of synthetic pigments in beverages using a hydrophobic deep eutectic solvent.

PubMed

Zhu, Shuqiang; Zhou, Jia; Jia, Hongfang; Zhang, Haixia

2018-03-15

A method was developed for the determination of eight synthetic pigments in beverage samples by liquid-liquid microextraction followed by high performance liquid chromatography. Using hydrophobic deep eutectic solvent (DES) as the microextraction solvent, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH value, vortex time and salt content. Detection limits were in the range 0.016-1.12 ng/mL, recoveries were in the range 74.5-102.5% and relative standard deviations were <5.4%. The method is simple, green and practical, and could be applied to the extraction and determination of synthetic pigments in beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

In situ ionic liquid dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry for the determination of organophosphorus pesticides.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2018-07-20

Nine organophosphorus pesticides (OPPs) were determined in environmental waters from different origins using in situ ionic liquid dispersive liquid microextraction (IL-DLLME). This preconcentration technique was coupled to gas chromatography-mass spectrometry (GC-MS) using microvial insert thermal desorption, an approach that uses a thermal desorption injector as sample introduction system. The parameters affecting both the microextraction and sample injection steps were optimized. The proposed method showed good precision, with RSD values ranging from 4.1 to 9.7%, accuracy with recoveries in the 85-118% range, and sensitivity with DLs ranging from 5 to 16 ng L -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental design for the optimization of the derivatization reaction in determining chlorophenols and chloroanisoles by headspace-solid-phase microextraction-gas chromatography/mass spectrometry.

PubMed

Morales, Rocío; Sarabia, Luis A; Sánchez, M Sagrario; Ortiz, M Cruz

2013-06-28

The paper shows some tools (its interpretation and usefulness) to optimize a derivatization reaction and to more easily interpret and visualize the effect that some experimental factors exert on several analytical responses of interest when these responses are in conflict. The entire proposed procedure has been applied in the optimization of equilibrium/extraction temperature and extraction time in the acetylation reaction of 2,4,6-trichlorophenol; 2,3,4,6-tetrachlorophenol, pentachlorophenol and 2,4,6-tribromophenol as internal standard (IS) in presence of 2,4,6-trichloroanisole, 2,3,5,6-tetrachloroanisole, pentachloroanisole and 2,4,6-trichloroanisole-d5 as IS. The procedure relies on the second order advantage of PARAFAC (parallel factor analysis) that allows the unequivocal identification and quantification, mandatory according international regulations (in this paper the EU document SANCO/12495/2011), of the acetyl-chlorophenols and chloroanisoles that are determined by means of a HS-SPME-GC/MS automated device. The joint use of a PARAFAC decomposition and a Doehlert design provides the data to fit a response surface for each analyte. With the fitted surfaces, the overall desirability function and the Pareto-optimal front are used to describe the relation between the conditions of the derivatization reaction and the quantity extracted of each analyte. The visualization by using a parallel coordinates plot allows a deeper knowledge about the problem at hand as well as the wise selection of the conditions of the experimental factors for achieving specific goals about the responses. In the optimal experimental conditions (45°C and 25min) the determination by means of an automated HS-SPME-GC/MS system is carried out. By using the regression line fitted between calculated and true concentrations, it has been checked that the procedure has neither proportional nor constant bias. The decision limits, CCa, for probability a of false positive set to 0.05, vary between 0.221 and 0.420µgL(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Toward the stereochemical identification of prohibited characterizing flavors in tobacco products: the case of strawberry flavor.

PubMed

Paschke, Meike; Hutzler, Christoph; Henkler, Frank; Luch, Andreas

2015-08-01

With the revision of the European Tobacco Products Directive (2014/40/EU), characterizing flavors such as strawberry, candy, vanillin or chocolate will be prohibited in cigarettes and fine-cut tobacco. Product surveillance will therefore require analytical means to define and subsequently detect selected characterizing flavors that are formed by supplemented flavors within the complex matrix tobacco. We have analyzed strawberry-flavored tobacco products as an example for characterizing fruit-like aroma. Using this approach, we looked into aroma components to find indicative patterns or features that can be used to satisfy obligatory product information as requested by the European Directive. Accordingly, a headspace solid-phase microextraction (HS-SPME) technique was developed and coupled to subsequent gas chromatography-mass spectrometry (GC/MS) to characterize different strawberry-flavored tobacco products (cigarettes, fine-cut tobacco, liquids for electronic cigarettes, snus, shisha tobacco) for their volatile additives. The results were compared with non-flavored, blend characteristic flavored and other fruity-flavored cigarettes, as well as fresh and dried strawberries. Besides different esters and aldehydes, the terpenes linalool, α-terpineol, nerolidol and limonene as well as the lactones γ-decalactone, γ-dodecalactone and γ-undecalactone could be verified as compounds sufficient to convey some sort of strawberry flavor to tobacco. Selected flavors, i.e., limonene, linalool, α-terpineol, citronellol, carvone and γ-decalactone, were analyzed further with respect to their stereoisomeric composition by using enantioselective HS-SPME-GC/MS. These experiments confirmed that individual enantiomers that differ in taste or physiological properties can be distinguished within the tobacco matrix. By comparing the enantiomeric composition of these compounds in the tobacco with that of fresh and dried strawberries, it can be concluded that non-natural strawberry aroma is usually used to produce strawberry-flavored tobacco products. Such authenticity control can become of interest particularly when manufacturers claim that natural sources were used for flavoring of products. Although the definition of characterizing flavors by analytical means remains challenging, specific compounds or features are required to be defined for routine screening of reported information. Clarifications by sensory testing might still be necessary, but could be limited to a few preselected samples.

Identification of absorbed constituents in the rabbit plasma and cerebrospinal fluid after intranasal administration of Asari Radix et Rhizoma by HS-SPME-GC-MS and HPLC-APCI-IT-TOF-MSn.

PubMed

Li, Chen; Xu, Feng; Xie, De-Mei; Jing, Yu; Shang, Ming-Ying; Liu, Guang-Xue; Wang, Xuan; Cai, Shao-Qing

2014-04-17

Traditional Chinese Medicine (TCM) nasal therapy has been utilized to treat numerous diseases for over two millennia. It has many advantages compared with other routes. In this article, headspace-solid phase microextraction-gas chromatography-mass spectrometry and high performance liquid chromatography-atmospheric pressure chemical ionization-ion trap-time of flight-multistage mass spectrometry were applied for the first time to analyze the absorbed constituents in rabbit plasma and cerebrospinal fluid (CSF) after intranasal administration of Asari Radix et Rhizoma (AR). In total, 47 absorbed AR constituents including 14 monoterpenes, 10 phenylpropanoids, four benzene derivatives, two alkanes, nine N-alkylamides and eight lignans were tentatively identified in the rabbit plasma and CSF. Thirty-three absorbed constituents are found to have different bioactivities related to the pharmacological actions of AR through bibliography data retrieval. These indicated that many types of constituents of TCM can be absorbed at the nasal cavity into both rabbit blood and CSF. This is the first study to explore the absorption of AR, and comprehensively analyze the absorbed constituents after intranasal administration of TCM. These findings extend our understanding of the effective substances of AR, and inspire us to make a hypothesis on the mechanism of additive effect of multiple constituents of TCMs, which is very worthy of further investigation.

Identification of leaf volatiles from olive (Olea europaea) and their possible role in the ovipositional preferences of olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae).

PubMed

Malheiro, Ricardo; Casal, Susana; Cunha, Sara C; Baptista, Paula; Pereira, José Alberto

2016-01-01

The olive fly, Bactrocera oleae (Rossi), is a monophagous pest that displays an oviposition preference among cultivars of olive (Olea europaea L.). To clarify the oviposition preference, the olive leaf volatiles of three olive cultivars (Cobrançosa, Madural and Verdeal Transmontana) were assessed by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) at six different periods of olive fruit maturation and degrees of infestation. A total of 39 volatiles were identified, mainly esters and alcohols, with a minor percentage of aldehydes, ketones and terpenic compounds, including sesquiterpenes. At sampling dates with higher degrees of infestation, cv. Cobrançosa had, simultaneously, significantly lower infestation degrees and higher volatile amounts than the other two cultivars, with a probable deterrent effect for oviposition. The green leaf volatiles (GLVs) (Z)-3-hexen-1-ol and (Z)-3-hexen-1-ol acetate) were the main compounds identified in all cultivars, together with toluene. The abundance of GLVs decreased significantly throughout maturation, without significant differences among cultivars, while toluene showed a general increase and positive correlation with olive fly infestation levels. The results obtained could broaden our understanding of the roles of various types and amounts of olive volatiles in the environment, especially in olive fly host selection and cultivar preference. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of the photoprotective effect of β-cyclodextrin on the emission of volatile degradation products of ranitidine.

PubMed

Jamrógiewicz, Marzena; Wielgomas, Bartosz; Strankowski, Michał

2014-09-01

The process of the photo-excitation of ranitidine hydrochloride (RAN) in a solid state makes visible changes to its colour and generates an unpleasant odour. The purpose of the present study was to observe the protective effects of β-cyclodextrin (CD) complexation as well as the effect of the mixture of two stoichiometries 1:1 and 1:2 (RAN:CD, IC) on the photostability of samples in a solid state. Samples of inclusion complexes (IC) and physical mixtures (PM) were prepared and irradiated for 48h in a Suntest CPS+ chamber. Irradiated samples were analyzed using nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (FT-IR), the differential scanning calorimetry method (DSC) and thermogravimetry analysis (TGA). Volatiles were monitored with the use of headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The protective effect of CD was noticed with respect to IC, and also PM. Achieved photostabilization of complexed RAN against photodegradation could be explained due to either the inclusion of the furan part of RAN into the CD cavity as shown by the (1)H NMR ROESY (rotation frame nuclear Overhauser effect spectroscopy) spectrum or the screening effect of CD. FT-IR spectra, DSC curves and microscope images of irradiated samples of protected RAN did not indicate any physical changes, such as phase transfer. Copyright © 2014 Elsevier B.V. All rights reserved.

Mass spectrometry identification of alkyl-substituted pyrazines produced by Pseudomonas spp. isolates obtained from wine corks.

PubMed

Bañeras, Lluís; Trias, Rosalia; Godayol, Anna; Cerdán, Laura; Nawrath, Thorben; Schulz, Stefan; Anticó, Enriqueta

2013-06-15

We investigated the pyrazine production of 23 Pseudomonas isolates obtained from cork in order to assess their implications in off-flavour development. Off-flavour development in cork stoppers is a crucial process in maintaining the high quality of some wines. Pyrazine production was analyzed by headspace solid-phase-microextraction (HS-SPME) and gas chromatography coupled with mass spectrometry (GC-MS). Five out of the 23 isolates, i.e. Pseudomonas koreensis TCA20, Pseudomonas palleroniana TCA16, Pseudomonas putida TCA23 and N7, and Pseudomonas stutzeri TRA27a were able to produce branched alkyl-substituted pyrazines. For isolates N7 and TCA16, 14 compounds could be identified as pyrazines. The use of mineral media supplemented with different carbon and nitrogen sources resulted in changes in the pyrazine production capacity. In the two strains the amount of pyrazines produced was higher with glucose and decreased significantly with lactate. In all cases, 2,5-di(1-methylethyl)pyrazine was found to be dominant and independent of amino acid addition, suggesting a completely de novo synthesis. Aroma descriptions of most alkyl substituted pyrazines include mild vegetal aromas, not necessarily undesirable for the cork manufacturing industry. Methoxypyrazines, exhibiting earthy and musty aromas, could not be detected in any of the strains analysed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants

PubMed Central

Gondo, Thamani T.; Mmualefe, Lesego C.; Okatch, Harriet

2016-01-01

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R 2 > 0.9900) in the range of 2 to 100 ng g−1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g−1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants. PMID:27725893

Organochlorine pesticides and parasites in Mugil incilis collected in Cartagena Bay, Colombia.

PubMed

Jaramillo-Colorado, Beatriz E; Arroyo-Salgado, Bárbara; Ruiz-Garcés, Luis Carlos

2015-11-01

Nematode parasites of the Anisakides family are often found in people living in countries where fish is consumed raw or partially cooked. This research shows the histological changes in the liver and spleen of Mugil incilis, collected in Cartagena Bay. These changes are associated with pollution by organochlorine pesticides and their possible influence on the parasite. Organochlorine compounds were extracted using the headspace-solid-phase microextraction (HS-SPME) technique. Residual amounts in the muscle of M. incilis such as β-HCH, γ-HCH, heptachlor, aldrin, endosulfan, 4,4'-DDE, and dieldrin, among others, were identified by gas chromatography connected to an electron capture detector, indicating that the fauna of Cartagena Bay are exposed to these pollutants. Histological analysis was carried out on liver and spleen samples of M. incilis which were fixed, processed, and embedded in paraffin. The presence of melano-macrophages, granulomes, and trematodes in the liver was the most important changes observed. Larval prevalence for the Anisakis spp. was determined to be 1.6%; for Pseudoterranova spp., 25.3%, and for Contracaecum spp., 57.8%. Other parasites such as acanthocephalans were also reported for a total of 15.3%. Nevertheless, no significant correlation between parasites and organochlorines was found. This study is the first to correlate the presence of organochlorine compounds and histological damage in the liver and spleen of M. incilis, with the presence of parasites in fish from Cartagena Bay (Colombia).

Cosmetic wastewater treatment using the Fenton, Photo-Fenton and H2O2/UV processes.

PubMed

Marcinowski, Piotr P; Bogacki, Jan P; Naumczyk, Jeremi H

2014-01-01

Advanced Oxidation Processes (AOPs), such as the Fenton, photo-Fenton and H2O2/UV processes, have been investigated for the treatment of cosmetic wastewaters that were previously coagulated by FeCl3. The Photo-Fenton process at pH 3.0 with 1000/100 mg L(-1) H2O2/Fe(2+) was the most effective (74.0% Chemical Oxygen Demand (COD) removal). The Fenton process with 1200/500 mg L(-1) H2O2/Fe(2+) achieved a COD removal of 72.0%, and the H2O2/UV process achieved a COD removal of 47.0%. Spreading the H2O2 doses over time to obtain optimal conditions did not improve COD removal. The kinetics of the Fenton and photo-Fenton processes may be described by the following equation: d[COD]/dt = -a[COD] t(m) (t represents time and a and m are constants). The rate of COD removal by the H2O2/UV process may be described by a second-order reaction equation. Head Space, Solid-Phase MicroExtraction, Gas Chromatography and Mass Spectrometry (HS-SPME-GC-MS) were used to identify 48 substances in precoagulated wastewater. Among these substances, 26 were fragrances. Under optimal AOP conditions, over 99% of the identified substances were removed in 120 min.

In situ Raman-based detections of the hydrothermal vent and cold seep fluids

NASA Astrophysics Data System (ADS)

Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

2016-04-01

Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS-, SO42-, HSO4-, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42-, and the increase of CO2 and well resolved H2S and HS- peaks. At the white smoker of Onsen site the strong HSO4-peak observed at high temperature quickly dropped with strong accompanying increase of SO42-and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS- and CO2 signals. We also have detected the concentrations of CH4,H2S, HS-, SO42-, and S8 in cold seep fluids and the surrounding sediment pore water from the northern South China Sea. Several sediment pore water profiles nearly at the cold seep vent showed the characteristic loss of SO42-, and the increase of CH4, H2S and HS- peaks. Dissolved S8 and CH4had been first found at the fluids under the lush biological communities of the cold seep. This may indicate some bacteria mats at the lush biological communities oxidize hydrogen sulfide and produce elemental sulfur as a byproduct. Our research suggests that the in situ observed H2S:HS-, and HSO4-:SO42- ratios provide elegant pH sensitive "dyes" with which to diagnose the geochemical reactions occurring.

HsTRPA of the Red Imported Fire Ant, Solenopsis invicta, Functions as a Nocisensor and Uncovers the Evolutionary Plasticity of HsTRPA Channels

PubMed Central

Wang, Xinyue; Li, Tianbang; Tominaga, Makoto

2018-01-01

Solenopsis invicta, the red imported fire ant, represents one of the most devastating invasive species. To understand their sensory physiology, we identified and characterized their Hymenoptera-specific (Hs) TRPA channel, SiHsTRPA. Consistent with the sensory functions of SiHsTRPA, it is activated by heat, an electrophile, and an insect repellent. Nevertheless, SiHsTRPA does not respond to most of the honey bee ortholog (AmHsTRPA)-activating compounds. The jewel wasp ortholog (NvHsTRPA) is activated by these compounds even though it outgroups both AmHsTRPA and SiHsTRPA. Characterization of AmHsTRPA/SiHsTRPA chimeric channels revealed that the amino acids in the N terminus, as well as ankyrin repeat 2 (AR2) of AmHsTRPA, are essential for the response to camphor. Furthermore, amino acids in ARs 3 and 5–7 were specifically required for the response to diallyl disulfide. Thus, amino acid substitutions in the corresponding domains of SiHsTRPA during evolution would be responsible for the loss of chemical sensitivity. SiHsTRPA-activating compounds repel red imported fire ants, suggesting that SiHsTRPA functions as a sensor for noxious compounds. SiHsTRPA represents an example of the species-specific modulation of orthologous TRPA channel properties by amino acid substitutions in multiple domains, and SiHsTRPA-activating compounds could be used to develop a method for controlling red imported fire ants. PMID:29445768

Ig synthesis and class switching do not require the presence of the hs4 enhancer in the 3' IgH regulatory region.

PubMed

Vincent-Fabert, Christelle; Truffinet, Véronique; Fiancette, Remi; Cogné, Nadine; Cogné, Michel; Denizot, Yves

2009-06-01

Several studies have reported that regulatory elements located 3' of the IgH locus (namely hs3a, hs1,2, hs3b, and hs4) might play a role during class switch recombination (CSR) and Ig synthesis. While individual deletion of hs3a or hs1,2 had no effect, pairwise deletion of hs3b (an inverted copy of hs3a) and hs4 markedly affected CSR and Ig expression. Among these two elements, hs4 was tentatively presented with the master role due to its unique status within the 3' regulatory region: distal position outside repeated regions, early activation in pre-B cells, strong activity throughout B cell ontogeny. To clarify its role, we generated mice with a clean deletion of the hs4 after replacement with a floxed neo(R) cassette. Surprisingly, and as for previous deletion of hs3a or hs1,2, deletion of hs4 did not affect either in vivo CSR or the secretion level of any Ig isotype. In vitro CSR and Ig secretion in response to LPS and cytokines was not affected either. The only noticeable effects of the hs4 deletion were a decrease in the number of B splenocytes and a decreased membrane IgM expression. In conclusion, while dispensable for CSR and Ig transcription in plasma cells, hs4 mostly appears to contribute to Ig transcription in resting B lymphocytes.

Speciation of AsIII and AsV in fruit juices by dispersive liquid–liquid microextraction and hydride generation-atomic fluorescence spectrometry

USDA-ARS?s Scientific Manuscript database

A new procedure was developed to speciate and quantify As(III) and As(V) in fruit juices. At pH 3.0, As(III) and ammonium pyrrolidine dithiocarbamate (APDC) formed a complex, which was extracted into carbon tetrachloride by dispersive liquid–liquid microextraction (DLLME) and subsequently quantified...

Comparison of characteristic flavor and aroma volatiles in melons and standards using solid phase microextraction (SPME) and Stir Bar Sorptive Extraction (SBSE) with GC-MS.

USDA-ARS?s Scientific Manuscript database

Stir bar sorptive extraction (SBSE) is a technique for extraction and analysis of organic compounds in aqueous matrices, similar in theory to solid phase microextraction (SPME). SBSE has been successfully used to analyze several organic compounds, including food matrices. When compared with SPME, ...

Rapid Analysis of Chemical Warfare Agents and Their Hydrolysis Products by Desorption Electrospray Ionization Mass Spectrometry (DESI-MS)

DTIC Science & Technology

2009-10-01

of chemical warfare agents in natural water samples by solid-phase microextraction. Anal. Chem., 69, 1866-72. [36] Sng , M.T. and Ng ,W.F. (1999). In...liquid phase microextraction of alkylphosphonic acids from water. J. Chromatogr. A., 1141, 151-157. [43] Lee, H.S.N., Sng , M.T., Basheer, C., and Lee

An effective hybrid firefly algorithm with harmony search for global numerical optimization.

PubMed

Guo, Lihong; Wang, Gai-Ge; Wang, Heqi; Wang, Dinan

2013-01-01

A hybrid metaheuristic approach by hybridizing harmony search (HS) and firefly algorithm (FA), namely, HS/FA, is proposed to solve function optimization. In HS/FA, the exploration of HS and the exploitation of FA are fully exerted, so HS/FA has a faster convergence speed than HS and FA. Also, top fireflies scheme is introduced to reduce running time, and HS is utilized to mutate between fireflies when updating fireflies. The HS/FA method is verified by various benchmarks. From the experiments, the implementation of HS/FA is better than the standard FA and other eight optimization methods.

Determination of arsenic and selenium by hydride generation and headspace solid phase microextraction coupled with optical emission spectrometry

NASA Astrophysics Data System (ADS)

Tyburska, Anna; Jankowski, Krzysztof; Rodzik, Agnieszka

2011-07-01

A hydride generation headspace solid phase microextraction technique has been developed in combination with optical emission spectrometry for determination of total arsenic and selenium. Hydrides were generated in a 10 mL volume septum-sealed vial and subsequently collected onto a polydimethylsiloxane/Carboxen solid phase microextraction fiber from the headspace of sample solution. After completion of the sorption, the fiber was transferred into a thermal desorption unit and the analytes were vaporized and directly introduced into argon inductively coupled plasma or helium microwave induced plasma radiation source. Experimental conditions of hydride formation reaction as well as sorption and desorption of analytes have been optimized showing the significant effect of the type of the solid phase microextraction fiber coating, the sorption time and hydrochloric acid concentration of the sample solution on analytical characteristics of the method developed. The limits of detection of arsenic and selenium were 0.1 and 0.8 ng mL - 1 , respectively. The limit of detection of selenium could be improved further using biosorption with baker's yeast Saccharomyces cerevisiae for analyte preconcentration. The technique was applied for the determination of total As and Se in real samples.

Improved chip design for integrated solid-phase microextraction in on-line proteomic sample preparation.

PubMed

Bergkvist, Jonas; Ekström, Simon; Wallman, Lars; Löfgren, Mikael; Marko-Varga, György; Nilsson, Johan; Laurell, Thomas

2002-04-01

A recently introduced silicon microextraction chip (SMEC), used for on-line proteomic sample preparation, has proved to facilitate the process of protein identification by sample clean up and enrichment of peptides. It is demonstrated that a novel grid-SMEC design improves the operating characteristics for solid-phase microextraction, by reducing dispersion effects and thereby improving the sample preparation conditions. The structures investigated in this paper are treated both numerically and experimentally. The numerical approach is based on finite element analysis of the microfluidic flow in the microchip. The analysis is accomplished by use of the computational fluid dynamics-module FLOTRAN in the ANSYS software package. The modeling and analysis of the previously reported weir-SMEC design indicates some severe drawbacks, that can be reduced by changing the microextraction chip geometry to the grid-SMEC design. The overall analytical performance was thereby improved and also verified by experimental work. Matrix-assisted laser desorption/ionization mass spectra of model peptides extracted from both the weir-SMEC and the new grid-SMEC support the numerical analysis results. Further use of numerical modeling and analysis of the SMEC structures is also discussed and suggested in this work.

Hollow-Fibre-Supported Dispersive Liquid-Liquid Microextraction for Determination of Atrazine and Triclosan in Aqueous Samples

PubMed Central

Letseka, Thabiso

2017-01-01

We report the application of the dispersive liquid-liquid microextraction coupled to hollow-fibre membrane-assisted liquid-phase microextraction and its application for extraction of atrazine and triclosan. Under optimum conditions, namely, 25 μL of a 1 : 4 chlorobenzene : ethyl acetate mixture dispersed in 1 mL of aqueous sample, 10% (m/v) NaCl, a magnetic stirrer speed at 600 rpm, and 10 minutes' extraction time with toluene-filled fibre as the acceptor phase, the method demonstrates sufficient figures of merit. These include linearity (R2 ≥ 0.9975), intravial precision (%RSD ≤ 7.6), enrichment factors (127 and 142), limits of detection (0.0081 and 0.0169 µg/mL), and recovery from river water and sewerage (96–101%). The relatively high detection limits are attributed to the flame ionization detector which is less preferred than a mass spectrometer in trace analyses. This is the first report of a homogenous mixture of the dispersed organic solvent in aqueous solutions and its employment in extraction of organic compounds from aqueous solutions. It therefore adds yet another candidate in the pool of miniaturised solvent microextraction techniques. PMID:29158736

Graphene-sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii.

PubMed

Xing, Rongrong; Hu, Shuang; Chen, Xuan; Bai, Xiaohong

2014-09-01

A novel graphene-sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high-performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99-104%) and precision (1.1-10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vortex-assisted liquid-liquid microextraction for the rapid screening of short-chain chlorinated paraffins in water.

PubMed

Chang, Chia-Yu; Chung, Wu-Hsun; Ding, Wang-Hsien

2016-01-01

The rapid screening of trace levels of short-chain chlorinated paraffins in various aqueous samples was performed by a simple and reliable procedure based on vortex-assisted liquid-liquid microextraction combined with gas chromatography and electron capture negative ionization mass spectrometry. The optimal vortex-assisted liquid-liquid microextraction conditions for 20 mL water sample were as follows: extractant 400 μL of dichloromethane; vortex extraction time of 1 min at 2500 × g; centrifugation of 3 min at 5000 × g; and no ionic strength adjustment. Under the optimum conditions, the limit of quantitation was 0.05 μg/L. Precision, as indicated by relative standard deviations, was less than 9% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was above 91%. The vortex-assisted liquid-liquid microextraction with gas chromatography and electron capture negative ionization mass spectrometry method was successfully applied to quantitatively extract short-chain chlorinated paraffins from samples of river water and the effluent of a wastewater treatment plant, and the concentrations ranged from 0.8 to 1.6 μg/L. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of an accelerated solvent extraction dispersive liquid-liquid microextraction method for the separation and determination of essential oil from Ligusticum chuanxiong Hort by gas chromatography with mass spectrometry.

PubMed

Yang, Guang; Sun, Qiushi; Hu, Zhiyan; Liu, Hua; Zhou, Tingting; Fan, Guorong

2015-10-01

In this study, an accelerated solvent extraction dispersive liquid-liquid microextraction coupled with gas chromatography and mass spectrometry was established and employed for the extraction, concentration and analysis of essential oil constituents from Ligusticum chuanxiong Hort. Response surface methodology was performed to optimize the key parameters in accelerated solvent extraction on the extraction efficiency, and key parameters in dispersive liquid-liquid microextraction were discussed as well. Two representative constituents in Ligusticum chuanxiong Hort, (Z)-ligustilide and n-butylphthalide, were quantitatively analyzed. It was shown that the qualitative result of the accelerated solvent extraction dispersive liquid-liquid microextraction approach was in good agreement with that of hydro-distillation, whereas the proposed approach took far less extraction time (30 min), consumed less plant material (usually <1 g, 0.01 g for this study) and solvent (<20 mL) than the conventional system. To sum up, the proposed method could be recommended as a new approach in the extraction and analysis of essential oil. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parameters optimization using experimental design for headspace solid phase micro-extraction analysis of short-chain chlorinated paraffins in waters under the European water framework directive.

PubMed

Gandolfi, F; Malleret, L; Sergent, M; Doumenq, P

2015-08-07

The water framework directives (WFD 2000/60/EC and 2013/39/EU) force European countries to monitor the quality of their aquatic environment. Among the priority hazardous substances targeted by the WFD, short chain chlorinated paraffins C10-C13 (SCCPs), still represent an analytical challenge, because few laboratories are nowadays able to analyze them. Moreover, an annual average quality standards as low as 0.4μgL(-1) was set for SCCPs in surface water. Therefore, to test for compliance, the implementation of sensitive and reliable analysis method of SCCPs in water are required. The aim of this work was to address this issue by evaluating automated solid phase micro-extraction (SPME) combined on line with gas chromatography-electron capture negative ionization mass spectrometry (GC/ECNI-MS). Fiber polymer, extraction mode, ionic strength, extraction temperature and time were the most significant thermodynamic and kinetic parameters studied. To determine the suitable factors working ranges, the study of the extraction conditions was first carried out by using a classical one factor-at-a-time approach. Then a mixed level factorial 3×2(3) design was performed, in order to give rise to the most influent parameters and to estimate potential interactions effects between them. The most influent factors, i.e. extraction temperature and duration, were optimized by using a second experimental design, in order to maximize the chromatographic response. At the close of the study, a method involving headspace SPME (HS-SPME) coupled to GC/ECNI-MS is proposed. The optimum extraction conditions were sample temperature 90°C, extraction time 80min, with the PDMS 100μm fiber and desorption at 250°C during 2min. Linear response from 0.2ngmL(-1) to 10ngmL(-1) with r(2)=0.99 and limits of detection and quantification, respectively of 4pgmL(-1) and 120pgmL(-1) in MilliQ water, were achieved. The method proved to be applicable in different types of waters and show key advantages, such as simplicity, automation and sensitivity, required for the monitoring programs linked to the WFD. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of hollow fiber-supported liquid-phase microextraction coupled with HPLC for the determination of guaifenesin enantiomer-protein binding.

PubMed

Hatami, Mehdi; Farhadi, Khalil

2012-07-01

A hollow fiber liquid-phase microextraction technique coupled with high-performance liquid chromatography with fluorescence detection was employed for determination and evaluation of the binding characteristics of drugs to bovine serum albumin (BSA). Enantiomers of guaifenesin (an expectorant drug) were investigated as a model system. After optimization of some influencing parameters on microextraction, the proposed method was used for calculation of the target drug distribution coefficient between n-octanol and the buffer solution as well as study of drug-BSA binding in physiological conditions. The developed method shows a new, improved and simple procedure for determination of free drug concentration in biological fluids and the extent of drug-protein binding. Copyright © 2011 John Wiley & Sons, Ltd.

Dispersive liquid-phase microextraction with solidification of floating organic droplet coupled with high-performance liquid chromatography for the determination of Sudan dyes in foodstuffs and water samples.

PubMed

Chen, Bo; Huang, Yuming

2014-06-25

Dispersive liquid-phase microextraction with solidification of floating organic drop (SFO-DLPME) is one of the most interesting sample preparation techniques developed in recent years. In this paper, a new, rapid, and efficient SFO-DLPME coupled with high-performance liquid chromatography (HPLC) was established for the extraction and sensitive detection of banned Sudan dyes, namely, Sudan I, Sudan II, Sudan III, and Sudan IV, in foodstuff and water samples. Various factors, such as the type and volume of extractants and dispersants, pH and volume of sample solution, extraction time and temperature, ion strength, and humic acid concentration, were investigated and optimized to achieve optimal extraction of Sudan dyes in one single step. After optimization of extraction conditions using 1-dodecanol as an extractant and ethanol as a dispersant, the developed procedure was applied for extraction of the target Sudan dyes from 2 g of food samples and 10 mL of the spiked water samples. Under the optimized conditions, all Sudan dyes could be easily extracted by the proposed SFO-DLPME method. Limits of detection of the four Sudan dyes obtained were 0.10-0.20 ng g(-1) and 0.03 μg L(-1) when 2 g of foodstuff samples and 10 mL of water samples were adopted, respectively. The inter- and intraday reproducibilities were below 4.8% for analysis of Sudan dyes in foodstuffs. The method was satisfactorily used for the detection of Sudan dyes, and the recoveries of the target for the spiked foodstuff and water samples ranged from 92.6 to 106.6% and from 91.1 to 108.6%, respectively. These results indicated that the proposed method is simple, rapid, sensitive, and suitable for the pre-concentration and detection of the target dyes in foodstuff samples.

An Effective Hybrid Firefly Algorithm with Harmony Search for Global Numerical Optimization

PubMed Central

Guo, Lihong; Wang, Gai-Ge; Wang, Heqi; Wang, Dinan

2013-01-01

A hybrid metaheuristic approach by hybridizing harmony search (HS) and firefly algorithm (FA), namely, HS/FA, is proposed to solve function optimization. In HS/FA, the exploration of HS and the exploitation of FA are fully exerted, so HS/FA has a faster convergence speed than HS and FA. Also, top fireflies scheme is introduced to reduce running time, and HS is utilized to mutate between fireflies when updating fireflies. The HS/FA method is verified by various benchmarks. From the experiments, the implementation of HS/FA is better than the standard FA and other eight optimization methods. PMID:24348137

Calcified neurocysticercosis lesions and hippocampal sclerosis: potential dual pathology?

PubMed

Rathore, Chaturbhuj; Thomas, Bejoy; Kesavadas, Chandrasekharan; Radhakrishnan, Kurupath

2012-04-01

In areas where cysticercosis is endemic, calcified neurocysticercosis lesion(s) (CNL) and hippocampal sclerosis (HS) commonly coexist in patients with localization-related epilepsies. To understand the pathogenesis of HS associated with CNL, we compared the characteristics of three groups of patients with antiepileptic drug-resistant epilepsies: CNL with HS, CNL without HS (CNL alone), and HS without CNL (HS alone). In comparison to patients with CNL alone, those with CNL with HS had CNL more frequently located in the ipsilateral temporal lobe. Those with CNL with HS had a lower incidence of febrile seizures, older age at initial precipitating injury and at onset of habitual complex partial seizures, and more frequent clustering of seizures and extratemporal/bitemporal interictal epileptiform discharges as compared to patients with HS alone. Our study illustrates that HS associated with CNL might have a different pathophysiologic basis as compared to classical HS. Wiley Periodicals, Inc. © 2012 International League Against Epilepsy.

Rapid rule out of acute myocardial infarction using undetectable levels of high-sensitivity cardiac troponin.

PubMed

Rubini Giménez, Maria; Hoeller, Rebeca; Reichlin, Tobias; Zellweger, Christa; Twerenbold, Raphael; Reiter, Miriam; Moehring, Berit; Wildi, Karin; Mosimann, Tamina; Mueller, Mira; Meller, Bernadette; Hochgruber, Thomas; Ziller, Ronny; Sou, Seoung Mann; Murray, Karsten; Sakarikos, Konstantin; Ernst, Susanne; Gea, Joaquim; Campodarve, Isabel; Vilaplana, Carles; Haaf, Philip; Steuer, Stephan; Minners, Jan; Osswald, Stefan; Mueller, Christian

2013-10-09

We examined whether undetectable levels of high-sensitivity cardiac Troponin (hs-cTn) can be used to rule out acute myocardial infarction (AMI) with a single blood draw at presentation to the emergency department (ED). In a prospective multicenter study we used 4 different hs-cTn assays (hs-cTnT Roche, and hs-cTnI Siemens, hs-cTnI Beckman Coulter and hs-cTnI Abbott) in consecutive patients presenting with acute chest pain. The final diagnosis of AMI was adjudicated by two independent cardiologists using all available data including serial hs-cTnT levels. Mean follow up was 24 months. Among 2072 consecutive patients with available hs-cTnT levels, 21% had an adjudicated diagnosis of AMI. Among AMI patients, 98.2% had initially detectable levels of hs-cTnT (sensitivity 98.2%, 95%CI 96.3%-99.2%, negative predictive value (NPV) 98.6%, 95%CI 97.0%-99.3%). Undetectable levels of hs-cTnT ruled out AMI in 26.5% of patients at presentation. The NPV was similar with the three hs-cTnI assays: among 1180 consecutive patients with available hs-cTnI (Siemens), the NPV was 98.8%; among 1151 consecutive patients with available hs-cTnI (Beckman Coulter), the NPV was 99.2%; among 1567 consecutive patients with available hs-cTnI (Abbott), the NPV was 100.0%. The percentage of patients with undetectable levels of hs-cTnI was similar among the three hs-cTnI assays and ranged from 11.4% to 13.9%. Undetectable levels of hs-cTn at presentation have a very high NPV and seem to allow the simple and rapid rule out of AMI. This criteria applies to much more patients with hs-TnT as compared to the investigated hs-cTnI assays. © 2013.

Addendum to "Harmony of computational quantum chemistry and experimental chemistry: Comprehensive DFT studies, microsynthesis, and characterization of mustard gas polysulfide analogues" [J. Mol. Struct. (2018) 57-62

NASA Astrophysics Data System (ADS)

Saeidian, Hamid; Faraz, Sajjad Mousavi; Mirjafary, Zohreh; Babri, Mehran

2018-07-01

Recently, Blum from OPCW laboratory investigated HD, HS2, HS3 and higher polysulfides and their corresponding reactive intermediates by using Amsterdam Density Functional (ADF) calculations [22, 23]. In his presentation, he mentioned that analysis of MO energy levels for episulfonium ions of HD, HS2 and HS3 shows that the sulfur centered LUMOs for HS2 and HS3 are LUMO+1 for HD ion; and LUMOs energy levels of HS2 and HS3 are decreased by addition of polarizable sulfur atoms. He also showed that no four-membered sulfonium ion ring structures are formed for HS2, HS3 and higher polysulfides; and episulfonium ion is the only reactive intermediate for them.

Quantitative Analysis of Bisphenol A Leached from Household Plastics by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry (SPME-GC-MS)

ERIC Educational Resources Information Center

Johnson, Bettie Obi; Burke, Fernanda M.; Harrison, Rebecca; Burdette, Samantha

2012-01-01

The measurement of trace levels of bisphenol A (BPA) leached out of household plastics using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is reported here. BPA is an endocrine-disrupting compound used in the industrial manufacture of polycarbonate plastic bottles and epoxy resin can liners. This experiment…

Solid-phase microextraction of hydrocarbons from water in a centrifuge

NASA Astrophysics Data System (ADS)

Ryabov, A. Yu.; Chuikin, A. V.; Velikov, A. A.

2016-06-01

The results of our study of solid-phase microextraction of substances using a centrifuge for determining the microquantities of hydrocarbon impurities in water are presented. The cartridge diameter, sorbent mass, and solvent volume were shown to affect the percent extraction of substances and the analytical signal intensity. The relationship between the cartridge geometry, the sorbent mass, and the solvent volume was considered.

β-Globin locus control region HS2 and HS3 interact structurally and functionally

PubMed Central

Jackson, David A.; McDowell, Jennifer C.; Dean, Ann

2003-01-01

The overall structure of the DNase I hypersensitive sites (HSs) that comprise the β-globin locus control region (LCR) is highly conserved among mammals, implying that the HSs have conserved functions. However, it is not well understood how the LCR HSs, either individually or collectively, activate transcription. We analyzed the interactions of HS2, HS3 and HS4 with the human ε- and β-globin genes in chromatinized episomes in fetal/embryonic K562 cells. Only HS2 activates transcription of the ε-globin gene, while all three HSs activate the β-globin gene. HS3 stimulates the β-globin gene constitutively, but HS2 and HS4 transactivation requires expression of the transcription factor EKLF, which is not present in K562 cells but is required for β-globin expression in vivo. To begin addressing how the individual HSs may interact with one another in a complex, we linked the β-globin gene to both the HS2 and HS3. HS2 and HS3 together resulted in synergistic stimulation of β-globin transcription. Unexpectedly, mutated, inactive forms of HS2 impeded the activation of the β-globin gene by HS3. Thus, there appear to be distinct interactions among the HSs and between the HSs and the globin genes. These preferential, non-exclusive interactions may underlie an important structural and functional cooperativity among the regulatory sequences of the β-globin locus in vivo. PMID:12582237

MRI-negative PET-positive temporal lobe epilepsy: a distinct surgically remediable syndrome.

PubMed

Carne, R P; O'Brien, T J; Kilpatrick, C J; MacGregor, L R; Hicks, R J; Murphy, M A; Bowden, S C; Kaye, A H; Cook, M J

2004-10-01

Most patients with non-lesional temporal lobe epilepsy (NLTLE) will have the findings of hippocampal sclerosis (HS) on a high resolution MRI. However, a significant minority of patients with NLTLE and electroclinically well-lateralized temporal lobe seizures have no evidence of HS on MRI. Many of these patients have concordant hypometabolism on fluorodeoxyglucose-PET ([18F]FDG-PET). The pathophysiological basis of this latter group remains uncertain. We aimed to determine whether NLTLE without HS on MRI represents a variant of or a different clinicopathological syndrome from that of NLTLE with HS on MRI. The clinical, EEG, [18F]FDG-PET, histopathological and surgical outcomes of 30 consecutive NLTLE patients with well-lateralized EEG but without HS on MRI (HS-ve TLE) were compared with 30 consecutive age- and sex-matched NLTLE patients with well-lateralized EEG with HS on MRI (HS+ve TLE). Both the HS+ve TLE group and the HS-ve TLE patients had a high degree of [18F]FDG-PET concordant lateralization (26 out of 30 HS-ve TLE versus 27 out of 27 HS+ve TLE). HS-ve TLE patients had more widespread hypometabolism on [18F]FDG-PET by blinded visual analysis [odds ratio (OR = + infinity (2.51, -), P = 0.001]. The HS-ve TLE group less frequently had a history of febrile convulsions [OR = 0.077 (0.002-0.512), P = 0.002], more commonly had a delta rhythm at ictal onset [OR = 3.67 (0.97-20.47), P = 0.057], and less frequently had histopathological evidence of HS [OR = 0 (0-0.85), P = 0.031]. There was no significant difference in surgical outcome despite half of those without HS having a hippocampal-sparing procedure. Based on the findings outlined, HS-ve PET-positive TLE may be a surgically remediable syndrome distinct from HS+ve TLE, with a pathophysiological basis that primarily involves lateral temporal neocortical rather than mesial temporal structures.

Influence of gantry rotation time and scan mode on image quality in ultra-high-resolution CT system.

PubMed

Honda, Osamu; Yanagawa, Masahiro; Hata, Akinori; Kikuchi, Noriko; Miyata, Tomo; Tsukagoshi, Shinsuke; Uranishi, Ayumi; Tomiyama, Noriyuki

2018-06-01

To investigate the image quality of helical scan (HS) mode and non-helical scan (non-HS) mode on ultra-high-resolution CT in different gantry rotation time. non-HS with 0.35 s/rot (non-HS200 mA/0.35 s). Three observers compared each non-HS image with HS image, and scored non-HS images by using 3-point scale, paying attention to normal findings, abnormal findings, noise, streak artifact, and overall image quality. Statistical analysis was performed with Steel-Dwass test. Overall image quality (score: 2.45) and noise (score: 2.42) of non-HS 200 mA/1.5s was statistically best (p < 0.0005). Overall Image quality and noise of non-HS200 mA/0.75 s (score: 2.0) was comparable to that of HS200 mA/1.5 s. CTDIvol of HS200 mA/1.5 s is 23.2 mGy. CTDIvol of non-HS200 mA/1.5 s, non-HS200 mA/0.75 s, non-HS200 mA/0.35 s is 19.2 mGy, 9.8 mGy, 4.7 mGy. Overall image quality and noise of non-helical scan is better than that of helical scan in the same rotation time. Overall Image quality of non-HS200 mA/0.75 s is comparable to that of HS200 mA/1.5 s, though the radiation dose of non-HS200 mA/0.75 s is lower than that of HS200 mA/1.5 s. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid discovery and functional characterization of terpene synthases from four endophytic xylariaceae

DOE PAGES

Wu, Weihua; Tran, William; Taatjes, Craig A.; ...

2016-02-17

Endophytic fungi are ubiquitous plant endosymbionts that establish complex and poorly understood relationships with their host organisms. Many endophytic fungi are known to produce a wide spectrum of volatile organic compounds (VOCs) with potential energy applications, which have been described as "mycodiesel". Many of these mycodiesel hydrocarbons are terpenes, a chemically diverse class of compounds produced by many plants, fungi, and bacteria. Due to their high energy densities, terpenes, such as pinene and bisabolene, are actively being investigated as potential "drop-in" biofuels for replacing diesel and aviation fuel. In this study, we rapidly discovered and characterized 26 terpene synthases (TPSs)more » derived from four endophytic fungi known to produce mycodiesel hydrocarbons. The TPS genes were expressed in an E. coli strain harboring a heterologous mevalonate pathway designed to enhance terpene production, and their product profiles were determined using Solid Phase Micro-Extraction (SPME) and GC-MS. Lastly, out of the 26 TPS’s profiled, 12 TPS’s were functional, with the majority of them exhibiting both monoterpene and sesquiterpene synthase activity.« less

Rapid discovery and functional characterization of terpene synthases from four endophytic xylariaceae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Weihua; Tran, William; Taatjes, Craig A.

Endophytic fungi are ubiquitous plant endosymbionts that establish complex and poorly understood relationships with their host organisms. Many endophytic fungi are known to produce a wide spectrum of volatile organic compounds (VOCs) with potential energy applications, which have been described as "mycodiesel". Many of these mycodiesel hydrocarbons are terpenes, a chemically diverse class of compounds produced by many plants, fungi, and bacteria. Due to their high energy densities, terpenes, such as pinene and bisabolene, are actively being investigated as potential "drop-in" biofuels for replacing diesel and aviation fuel. In this study, we rapidly discovered and characterized 26 terpene synthases (TPSs)more » derived from four endophytic fungi known to produce mycodiesel hydrocarbons. The TPS genes were expressed in an E. coli strain harboring a heterologous mevalonate pathway designed to enhance terpene production, and their product profiles were determined using Solid Phase Micro-Extraction (SPME) and GC-MS. Lastly, out of the 26 TPS’s profiled, 12 TPS’s were functional, with the majority of them exhibiting both monoterpene and sesquiterpene synthase activity.« less

Ionic-liquid-based dispersive liquid-liquid microextraction combined with magnetic solid-phase extraction for the determination of aflatoxins B1 , B2 , G1 , and G2 in animal feeds by high-performance liquid chromatography with fluorescence detection.

PubMed

Zhao, Jiao; Zhu, Yan; Jiao, Yang; Ning, Jinyan; Yang, Yaling

2016-10-01

A novel two-step extraction technique combining ionic-liquid-based dispersive liquid-liquid microextraction with magnetic solid-phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high-performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid-liquid microextraction, and hydrophobic pelargonic acid modified Fe 3 O 4 magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins-containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid-liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid-liquid microextraction and magnetic solid-phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3-103.7% with relative standard deviations of 3.2-6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B 1 , B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combination of magnetic dispersive micro solid-phase extraction and supramolecular solvent-based microextraction followed by high-performance liquid chromatography for determination of trace amounts of cholesterol-lowering drugs in complicated matrices.

PubMed

Arghavani-Beydokhti, Somayeh; Rajabi, Maryam; Asghari, Alireza

2017-07-01

A novel, efficient, rapid, simple, sensitive, selective, and environmentally friendly method termed magnetic dispersive micro solid-phase extraction combined with supramolecular solvent-based microextraction (Mdμ-SPE-SSME) followed by high-performance liquid chromatography (HPLC) with UV detection is introduced for the simultaneous microextraction of cholesterol-lowering drugs in complicated matrices. In the first microextraction procedure, using layered double hydroxide (LDH)-coated Fe 3 O 4 magnetic nanoparticles, an efficient sample cleanup is simply and rapidly provided without the need for time-consuming centrifugation and elution steps. In the first step, desorption of the target analytes is easily performed through dissolution of the LDH-coated magnetic nanoparticles containing the target analytes in an acidic solution. In the next step, an emulsification microextraction method based on a supramolecular solvent is used for excellent preconcentration, ultimately resulting in an appropriate determination of the target analytes in real samples. Under the optimal experimental conditions, the Mdμ-SPE-SSME-HPLC-UV detection procedure provides good linearity in the ranges of 1.0-1500 ng mL -1 , 1.5-2000 ng mL -1 , and 2.0-2000 ng mL -1 with coefficients of determination of 0.995 or less, low limits of detection (0.3, 0.5, and 0.5 ng mL -1 ), and good extraction repeatabilities (relative standard deviations below 7.8%, n = 5) in deionized water for rosuvastatin, atorvastatin, and gemfibrozil, respectively. Finally, the proposed method is successfully applied for the determination of the target analytes in complicated matrices. Graphical Abstract Mdμ-SPE-SSME procedure.

Simultaneous sampling and analysis of indoor air infested with Cimex lectularius L. (Hemiptera: Cimicidae) by solid phase microextraction, thin film microextraction and needle trap device.

PubMed

Eom, In-Yong; Risticevic, Sanja; Pawliszyn, Janusz

2012-02-24

Air in a room infested by Cimex lectularius L. (Hemiptera: Cimicidae) was sampled simultaneously by three different sampling devices including solid phase microextraction (SPME) fiber coatings, thin film microextraction (TFME) devices, and needle trap devices (NTDs) and then analyzed by gas chromatography-mass spectrometry (GC-MS). The main focus of this study was to fully characterize indoor air by identifying compounds extracted by three different microextraction formats and, therefore, perform both the device comparison and more complete characterization of C. lectularius pheromone. The NTD technique was capable of extracting both (E)-2-hexenal and (E)-2-octenal, which were previously identified as alarm pheromones of bedbugs, and superior NTD recoveries for these two components allowed reliable identification based on mass spectral library searching and linear temperature programmed retention index (LTPRI) technique. While the use of DVB/CAR/PDMS SPME fiber coatings provided complementary sample fingerprinting and profiling results, TFME sampling devices provided discriminative extraction coverage toward highly volatile analytes. In addition to two alarm pheromones, relative abundances of all other analytes were recorded for all three devices and aligned across all examined samples, namely, highly infested area, less infested area, and control samples which were characterized by different bedbug populations. The results presented in the current study illustrate comprehensive characterization of infested indoor air samples through the use of three different non-invasive SPME formats and identification of novel components comprising C. lectularius pheromone, therefore, promising future alternatives for use of potential synthetic pheromones for detection of infestations. Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of 7 days of hindlimb suspension and intermittent weight support on rat muscle mechanical properties

NASA Technical Reports Server (NTRS)

Pierotti, David J.; Roy, Roland R.; Flores, Vinicio; Edgerton, Reggie

1990-01-01

The effect of intermittent periods of weight support on a decrease in mass of the soleus (Sol) and medial gastrocnemius (MG) muscles atrophied by hindlimb suspension (HS) was investigated in rats subjected to continuous HS for seven days or an HS plus intermittent (10 min every 6 hrs of slow walking on a treadmill) weight support (HS-WS). After 7 d HS, the Sol weight relative to body weight was 21 and 9 percent lower in Hs and HS-WS, respectively, than in control rats. Maximum tetanic tension/muscle mass ratio was significantly lower in HS than in controls; the HS-WS rats had values similar to controls, whereas the maximum tetanic tension/muscle weight was significantly elevated in HS-WS compared to controls. Contraction times were 25 percent faster in the Sol and unchanged in the MG of HS rats, indicating that a low-force short-duration exercise regime results in a significant functional recovery in the 'slow' Sol, whereas the 'fast' MG is less affected.

Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review.

PubMed

de la Calle, Inmaculada; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

2016-09-14

An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. Copyright © 2016 Elsevier B.V. All rights reserved.

HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049: four new long-period cataclysmic variables

NASA Astrophysics Data System (ADS)

Aungwerojwit, A.; Gänsicke, B. T.; Rodríguez-Gil, P.; Hagen, H.-J.; Harlaftis, E. T.; Papadimitriou, C.; Lehto, H.; Araujo-Betancor, S.; Heber, U.; Fried, R. E.; Engels, D.; Katajainen, S.

2005-12-01

We present time-resolved optical spectroscopy and photometry of four relatively bright (V˜14.0-15.5) long-period cataclysmic variables (CVs) discovered in the Hamburg Quasar Survey: HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049. Their respective orbital periods, 243.69±0.49 min, 232.550±0.049 min, 212.7±0.2 min, and 225.90±0.23 min are determined from radial velocity and photometric variability studies. HS 0506+7725 is characterised by strong Balmer and He emission lines, short-period (~10-20 min) flickering, and weak X-ray emission in the ROSAT All Sky Survey. The detection of a deep low state (B≃18.5) identifies HS 0506+7725 as a member of the VY Scl stars. HS 0139+0559, HS 0229+8016, and HS 0642+5049 display thick-disc like spectra and no or only weak flickering activity. HS 0139+0559 and HS 0229+8016 exhibit clean quasi-sinusoidal radial velocity variations of their emission lines but no or very little orbital photometric variability. In contrast, we detect no radial velocity variation in HS 0642+5049 but a noticeable orbital brightness variation. We identify all three systems either as UX UMa-type novalike variables or as Z Cam-type dwarf novae. Our identification of these four new systems underlines that the currently known sample of CVs is rather incomplete even for bright objects. The four new systems add to the clustering of orbital periods in the 3-4 h range found in the sample of HQS selected CVs, and we discuss the large incidence of magnetic CVs and VY Scl/SW Sex stars found in this period range among the known population of CVs.

Analysis of chromatin structure of rat alpha1-acid glycoprotein gene; changes in DNase I hypersensitive sites after thyroid hormone, glucocorticoid hormone and turpentine oil treatment.

PubMed Central

Matsukawa, T; Kawasaki, H; Tanaka, M; Ohba, Y

1997-01-01

Transcription of the ratalpha1-acid glycoprotein (AGP) gene is activated by glucocorticoid, thyroid hormone (T3) and cytokines. Following these treatments, the chromatin structure of this gene was analyzed by means of digestion with DNase I or micrococcal nuclease. Four DNase I hypersensitive sites were observed in the 5'-upstream region of the rat AGP gene of liver cells. They were designated HS1, HS2, HS3 and HS4 (3'-->5'). After T3treatment the sensitivity of HS1 and HS2 increased and after dexamethasone (Dex) treatment that of all four sites did so. Three new sites appeared after turpentine oil treatment, while the sensitivities of HS3 and HS4 increased. We conclude that transcriptional activation of the gene by T3and Dex have very similar mechanisms, but that at the inflammation stage they become slightly different. The increase in sensitivity at HS1 and HS2 after T3treatment in vivo was successfully reproduced in a cell-free system by in vitro treatment with T3. HS1, HS2 and HS3 were also sensitive for micrococcal nuclease. PMID:9185575

Analysis of Explosives in Soil Using Solid Phase Microextraction and Gas Chromatography: Environmental Analysis

DTIC Science & Technology

2006-01-01

ENVIRONMENTAL ANALYSIS Analysis of Explosives in Soil Using Solid Phase Microextraction and Gas Chromatography Howard T. Mayfield Air Force Research...Abstract: Current methods for the analysis of explosives in soils utilize time consuming sample preparation workups and extractions. The method detection...chromatography/mass spectrometry to provide a con- venient and sensitive analysis method for explosives in soil. Keywords: Explosives, TNT, solid phase

Development and Efficacy Testing of Next Generation Cyanide Antidotes

DTIC Science & Technology

2013-10-01

Preparation of mDMTS A-2.2. HPLC method for DMTS determination in Micelles A-2.3. Head-space solid phase micro-extraction- gas chromatography -mass...Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS). Analytical and...min. Peak integration was performed using Star Chromatography Workstation Version 6.20. A-2.3. Head-space solid phase micro-extraction- gas

Development of an Alternative Mixed Odor Delivery Device (MODD) for Canine Training

DTIC Science & Technology

2017-05-10

solid phase microextraction (SPME) and analysis by gas chromatography / mass spectrometry (GC/MS). Like the computational modeling, the laboratory...outlet was extracted by solid phase microextraction (SPME) and analyzed by gas chromatography with mass spectrometry (GC/MS). A polydimethylsiloxane...Menning and H. Ostmark, "Detection of liquid and homemade explosives: What do we need to know about their properties?," in Detection of Liquid

Some Immunochemical Properties of Dextransucrase and Invertase from Streptococcus mutans

PubMed Central

Fukui, Kazuhiro; Fukui, Yoshio; Moriyama, Takafumi

1974-01-01

Dextransucrase and invertase of some strains of Streptococcus mutans were examined by immunodiffusion with antisera against enzymes purified from strain HS-6 (Bratthall's serotype a). Both antisera cross-reacted with crude enzyme preparations from the other serotype a (strains HS-1 and AHT) and d organisms (strains KIR, OMZ176, and OMZ65) but not with those from serotype b (strains FA-1 and BHT) or c organisms (strains GS-5, Ingbritt, and NCTC 10449). Based upon the antiserum used, the orders of antigenic similarity of the cross-reacting enzymes to the HS-6 enzymes were HS-6 > HS-1 > AHT = KIR = OMZ176 = OMZ65 for dextransucrase and HS-6 = HS-1 > AHT = KIR = OMZ176 = OMZ65 for invertase. It was found that the enzymes from serotype a organisms were not always antigenically homogeneous, as seen between strains HS-6, HS-1, or AHT for dextransucrase, and between the HS group and strain AHT for invertase. Antiserum against the HS-6 dextransucrase markedly inhibited the heterologous dextransucrases of serotype a organisms with the exception of strain HS-1 and d organisms, with or without the addition of dextran. Images PMID:16558114

Magnetic stirrer induced dispersive ionic-liquid microextraction for the determination of vanadium in water and food samples prior to graphite furnace atomic absorption spectrometry.

PubMed

Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa

2015-04-01

A new dispersive liquid-liquid microextraction, magnetic stirrer induced dispersive ionic-liquid microextraction (MS-IL-DLLME) was developed to quantify the trace level of vanadium in real water and food samples by graphite furnace atomic absorption spectrometry (GFAAS). In this extraction method magnetic stirrer was applied to obtained a dispersive medium of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] in aqueous solution of (real water samples and digested food samples) to increase phase transfer ratio, which significantly enhance the recovery of vanadium - 4-(2-pyridylazo) resorcinol (PAR) chelate. Variables having vital role on desired microextraction methods were optimised to obtain the maximum recovery of study analyte. Under the optimised experimental variables, enhancement factor (EF) and limit of detection (LOD) were achieved to be 125 and 18 ng L(-1), respectively. Validity and accuracy of the desired method was checked by analysis of certified reference materials (SLRS-4 Riverine water and NIST SRM 1515 Apple leaves). The relative standard deviation (RSD) for 10 replicate determinations at 0.5 μg L(-1) of vanadium level was found to be <5.0%. This method was successfully applied to real water and acid digested food samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigation of fragrance stability used in the formulation of cosmetic and hygienic products using headspace solid-phase microextraction by nanostructured materials followed by gas chromatography with mass spectrometry.

PubMed

Masoum, Saeed; Gholami, Ali; Ghaheri, Salehe; Bouveresse, Delphine Jouan-Rimbaud; Cordella, Christophe B Y; Rutledge, Douglas N

2016-07-01

A new composite coating of polypyrrole and sodium lauryl ether sulfate was electrochemically prepared on a stainless-steel wire using cyclic voltammetry. The application and performance of the fiber was evaluated for the headspace solid-phase microextraction of a fragrance in aqueous bleach samples followed by gas chromatography combined with mass spectrometry to assess the fragrance stability in this kind of household cleaning product. To obtain a stable and efficient composite coating, parameters related to the coating process such as scan rate and numbers of cycles were optimized using a central composite design. In addition, the effects of various parameters on the extraction efficiency of the headspace solid-phase microextraction process such as extraction temperature and time, ionic strength, sample volume, and stirring rate were investigated by experimental design methods using Plackett-Burman and Doehlert designs. The optimum values of 53°C and 28 min for sample temperature and time, respectively, were found through response surface methodology. Results show that the combination of polypyrrole and sodium lauryl ether sulfate in a composite form presents desirable opportunities to produce new materials to study fragrance stability by headspace solid-phase microextraction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography.

PubMed

Faraji, Mohammad; Hamdamali, Mohammadrezza; Aryanasab, Fezzeh; Shabanian, Meisam

2018-07-13

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L -1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L -1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L -1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). Copyright © 2018. Published by Elsevier B.V.

Comparison between solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HFLPME) for determination of extractables from post-consumer recycled PET into food simulants.

PubMed

Oliveira, Éder Costa; Echegoyen, Yolanda; Cruz, Sandra Andrea; Nerin, Cristina

2014-09-01

Hollow fiber liquid phase microextraction (HFLPME) and solid phase microextraction (SPME) methods for pre-concentration of contaminants (toluene, benzophenone, tetracosane and chloroform) in food simulants were investigated. For HFLPME 1-heptanol, 2-octanone and dibutyl-ether were studied as extracting solvents. Analysis by gas chromatography coupled to mass spectrometry (GC-MS), flame ionization (GC-FID) and electron capture detectors (GC-ECD) were carried out. In addition, the methods were employed to evaluate the safety in use of a PET material after the recycling process (comprising washing, extrusion and solid state polymerization (SSP)) through extractability studies of the contaminants using 10% (v/v) ethanol in deionized water and 3% (w/v) acetic acid in deionized water as food simulants in different conditions: 10 days at 40°C and 2h at 70°C. The HFLPME preconcentration method provided increased sensitivity when compared to the SPME method and allowed to analyze concentration levels below 10 µg surrogate per kg food simulant. The results of the extractability studies showed considerable reductions after the extrusion and SSP processes and indicated the compliance with regulations for using recycled PET in contact with food. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

PubMed

Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

2015-09-01

In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization and determination of Cd (II) in different environmental water samples with dispersive liquid-liquid microextraction preconcentration combined with inductively coupled plasma optical emission spectrometry.

PubMed

Salahinejad, Maryam; Aflaki, Fereydoon

2011-06-01

Dispersive liquid-liquid microextraction followed by inductively coupled plasma-optical emission spectrometry has been investigated for determination of Cd(II) ions in water samples. Ammonium pyrrolidine dithiocarbamate was used as chelating agent. Several factors influencing the microextraction efficiency of Cd (II) ions such as extracting and dispersing solvent type and their volumes, pH, sample volume, and salting effect were optimized. The optimization was performed both via one variable at a time, and central composite design methods and the optimum conditions were selected. Both optimization methods showed nearly the same results: sample size 5 mL; dispersive solvent ethanol; dispersive solvent volume 2 mL; extracting solvent chloroform; extracting solvent volume 200 [Formula: see text]L; pH and salt amount do not affect significantly the microextraction efficiency. The limits of detection and quantification were 0.8 and 2.5 ng L( - 1), respectively. The relative standard deviation for five replicate measurements of 0.50 mg L( - 1) of Cd (II) was 4.4%. The recoveries for the spiked real samples from tap, mineral, river, dam, and sea waters samples ranged from 92.2% to 104.5%.

Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

PubMed

Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

2016-08-01

A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fibroblast Growth Factor-based Signaling through Synthetic Heparan Sulfate Blocks Copolymers Studied Using High Cell Density Three-dimensional Cell Printing*

PubMed Central

Sterner, Eric; Masuko, Sayaka; Li, Guoyun; Li, Lingyun; Green, Dixy E.; Otto, Nigel J.; Xu, Yongmei; DeAngelis, Paul L.; Liu, Jian; Dordick, Jonathan S.; Linhardt, Robert J.

2014-01-01

Four well-defined heparan sulfate (HS) block copolymers containing S-domains (high sulfo group content) placed adjacent to N-domains (low sulfo group content) were chemoenzymatically synthesized and characterized. The domain lengths in these HS block co-polymers were ∼40 saccharide units. Microtiter 96-well and three-dimensional cell-based microarray assays utilizing murine immortalized bone marrow (BaF3) cells were developed to evaluate the activity of these HS block co-polymers. Each recombinant BaF3 cell line expresses only a single type of fibroblast growth factor receptor (FGFR) but produces neither HS nor fibroblast growth factors (FGFs). In the presence of different FGFs, BaF3 cell proliferation showed clear differences for the four HS block co-polymers examined. These data were used to examine the two proposed signaling models, the symmetric FGF2-HS2-FGFR2 ternary complex model and the asymmetric FGF2-HS1-FGFR2 ternary complex model. In the symmetric FGF2-HS2-FGFR2 model, two acidic HS chains bind in a basic canyon located on the top face of the FGF2-FGFR2 protein complex. In this model the S-domains at the non-reducing ends of the two HS proteoglycan chains are proposed to interact with the FGF2-FGFR2 protein complex. In contrast, in the asymmetric FGF2-HS1-FGFR2 model, a single HS chain interacts with the FGF2-FGFR2 protein complex through a single S-domain that can be located at any position within an HS chain. Our data comparing a series of synthetically prepared HS block copolymers support a preference for the symmetric FGF2-HS2-FGFR2 ternary complex model. PMID:24563485

Calculation of the Internal and External Risk of Stored Ammunition and Explosives by Means of the Computer Model RISKANAL

DTIC Science & Technology

1998-07-01

950.0 140.0 HS8 HS 8 8 5 0 420.0 50.0 HS9 HS 9 9 2 0 190.0 -245.0 HS10 HS 10 10 1 0 10.0 -245.0 HS11 HS 11 11 1 0 -150.0 50.0 RD1 RD 12 13 1000 50...Ceelen 8 DM&P TNO-DO 9 * DM&P TNO-DQ, accountco6rdinator KL 10* TNO-FEL, Bibliotheek 11 /13 Bibliotheek KMA 14* Lid Instituuts Advies Raad PML Prof. B...Vastgesteld door Maj. Wt. Ceelen Vastgesteld d.d. 9 juni 1998 (deze rubricering wijzigt niet) Titel Ongerubriceerd Managementuittreksel Ongerubriceerd

Diseases associated with hidranitis suppurativa: part 2 of a series on hidradenitis.

PubMed

Scheinfeld, Noah

2013-06-15

Hidradenitis suppurativa (HS), a pathologic follicular disease, impacts patients' lives profoundly and usually occurs in isolation. The diseases with the strongest association are obesity, depression, and pain. HS is associated with many diseases including acne conglobata (AC), dissecting cellulitis, pilonidal cysts, and obesity. Pyoderma fistulans sinifica (fox den disease) appears to be the same entity as Hurley Stage 2 of 3 HS. The rate of acne vulgaris in HS patients mirrors unaffected controls. The most common, albeit still uncommon, association is with seronegative, haplotype unlinked arthritis (most importantly B27), in particular spondolyarthritis. Crohn disease and HS occur together at a rate that varies from 0.6% to 38% in retrospective cases series. Ulcerative colitis occurred with HS in 14% of patients in one series. The next most common association is with pyoderma gangrenosum, but this association is likely under-reported. Synovitis-Acne-Pustulosis Hyperostosis-Osteitis (SAPHO) syndrome, which is rare, has more than 10 reports linking it to HS. Nine case reports have linked Dowling-Degos disease (DDD) to HS and two reports related HS to Fox-Fordyce disease (FF), but because both occur in the axilla this might be a mere coincidence. HS is rarely associated with ophthalmic pathology. Specifically, more than 5 reports link it to Keratitis-Ichthyosis-Deafness syndrome (KID); greater than10 cases link it to interstitial keratitis and 2 cases are linked to Behçet's disease. The presence of proteinuria and acute nephritis link HS to the kidney, especially since and reports have documented resolution of HS after renal transplant. Florid steatocystoma multiplex, Sjogren Syndrome, and HS have been linked and their reports likely underestimate their coincidence because all these entities involve occlusion (albeit by different mechanisms). Three reports link HS and amyloid, but both share some common genetic underpinnings and thus the coincidence of these diseases is likely underreported. Pyoderma vegetans has been noted in 2 cases of HS and 4 cases of Inflammatory Bowel Disease (IBD) and is likely a clue to the linkage of the pathology of IBD and HS. Pityriasis rubra pilaris, in particular Type VI related to HIV, has a relationship more commonly with acne conglobata, but with HS also. Single case reports of diseases associated with HS include systemic lupus erythematosus, acromegaly, Down syndrome, Bazex-Dupre´-Christol, and prurtis ani, but these might be coincidences. Pyogenic Arthritis, Pyoderma gangrenosum, and Acne (PAPA Syndrome) and Pyoderma gangrenosum, Acne, and Suppurative Hidradenitis (PASH Syndrome) are pyodermic-arthritic syndromes that are associated with HS. Erythema nodosum and granulomatous lobular mastitis have been reported with HS but the significance of these reports is uncertain. Because of scarring, HS can result in lymphedema including scrotal elephantiasis and verrucous lymphedema. HS is sometimes accompanied by obesity, hypertension, and anemia and can be considered a disease in the spectrum of metabolic syndrome, a skin disease with systemic consequences. HS, like other types of chronic inflammation when long standing in the perianal and perineal areas, can result in squamous cell cancer. A variety of drugs can induce HS. These include lithium, sirolimus, cyclosporine, vemurafenib, and oral contraceptives. Inverse psoriasis or psoriasis vulgaris as a side effect of infliximab therapy may be associated with HS. These associations aside, most cases of HS occur in isolation without coincident morbidity.

"Magnetic resonance imaging negative positron emission tomography positive" temporal lobe epilepsy: FDG-PET pattern differs from mesial temporal lobe epilepsy.

PubMed

Carne, R P; Cook, M J; MacGregor, L R; Kilpatrick, C J; Hicks, R J; O'Brien, T J

2007-01-01

Some patients with temporal lobe epilepsy (TLE) lack evidence of hippocampal sclerosis (HS) on MRI (HS-ve). We hypothesized that this group would have a different pattern of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) hypometabolism than typical mesial TLE/HS patients with evidence of hippocampal atrophy on magnetic resonance imaging (MRI) (HS+ve), with a lateral temporal neocortical rather than mesial focus. Thirty consecutive HS-ve patients and 30 age- and sex-matched HS+ve patients with well-lateralized EEG were identified. FDG-PET was performed on 28 HS-ve patients and 24 HS+ve patients. Both groups were compared using statistical parametric mapping (SPM), directly and with FDG-PET from 20 healthy controls. Both groups showed lateralized temporal hypometabolism compared to controls. In HS+ve, this was antero-infero-mesial (T = 17.13); in HS-ve the main clustering was inferolateral (T = 17.63). When directly compared, HS+ve had greater hypometabolism inmesial temporal/hippocampal regions (T = 4.86); HS-ve had greater inferolateral temporal hypometabolism (T = 4.18). These data support the hypothesis that focal hypometabolism involves primarily lateal neocortical rather than mesial temporal structures in 'MRI-negative PET-positive TLE.'

Transport of H2S and HS(-) across the human red blood cell membrane: rapid H2S diffusion and AE1-mediated Cl(-)/HS(-) exchange.

PubMed

Jennings, Michael L

2013-11-01

The rates of H2S and HS(-) transport across the human erythrocyte membrane were estimated by measuring rates of dissipation of pH gradients in media containing 250 μM H2S/HS(-). Net acid efflux is caused by H2S/HS(-) acting analogously to CO2/HCO3(-) in the Jacobs-Stewart cycle. The steps are as follows: 1) H2S efflux through the lipid bilayer and/or a gas channel, 2) extracellular H2S deprotonation, 3) HS(-) influx in exchange for Cl(-), catalyzed by the anion exchange protein AE1, and 4) intracellular HS(-) protonation. Net acid transport by the Cl(-)/HS(-)/H2S cycle is more efficient than by the Cl(-)/HCO3(-)/CO2 cycle because of the rapid H2S-HS(-) interconversion in cells and medium. The rates of acid transport were analyzed by solving the mass flow equations for the cycle to produce estimates of the HS(-) and H2S transport rates. The data indicate that HS(-) is a very good substrate for AE1; the Cl(-)/HS(-) exchange rate is about one-third as rapid as Cl(-)/HCO3(-) exchange. The H2S permeability coefficient must also be high (>10(-2) cm/s, half time <0.003 s) to account for the pH equilibration data. The results imply that H2S and HS(-) enter erythrocytes very rapidly in the microcirculation of H2S-producing tissues, thereby acting as a sink for H2S and lowering the local extracellular concentration, and the fact that HS(-) is a substrate for a Cl(-)/HCO3(-) exchanger indicates that some effects of exogenous H2S/HS(-) may not result from a regulatory role of H2S but, rather, from net acid flux by H2S and HS(-) transport in a Jacobs-Stewart cycle.

Improving Self-Regulation for Obesity Prevention in Head Start: A Randomized Controlled Trial.

PubMed

Lumeng, Julie C; Miller, Alison L; Horodynski, Mildred A; Brophy-Herb, Holly E; Contreras, Dawn; Lee, Hannah; Sturza, Julie; Kaciroti, Niko; Peterson, Karen E

2017-05-01

To determine the effect of an intervention to improve emotional and behavioral self-regulation in combination with an obesity-prevention program on the prevalence of obesity and obesity-related behaviors in preschoolers. This was a cluster-randomized intervention trial in Head Start (HS) classrooms conducted in each of 4 academic years from 2011 to 2015. Participants (697 children; 49% boys; mean age: 4.1 ± 0.5 years; 48% white, 30% African American, 12% Hispanic) were randomly assigned by classroom to 1 of 3 intervention arms: (1) HS + Preschool Obesity Prevention Series (POPS) + Incredible Years Series (IYS) (HS enhanced by the POPS [program targeting evidence-based obesity-prevention behaviors] and the IYS [program to improve children's self-regulation]), (2) HS+POPS, or (3) HS. Primary outcomes were changes in prevalence of obesity, overweight/obesity, BMI z score, and teacher-reported child emotional and behavioral self-regulation; secondary outcomes were dietary intake, outdoor play, screen time, and parent nutrition knowledge and nutrition self-efficacy. HS+POPS+IYS improved teacher-reported self-regulation compared with HS+POPS ( P < .001) and HS ( P < .001), but there was no effect on the prevalence of obesity (16.4% preintervention to 14.3% postintervention in HS+POPS+IYS versus 17.3% to 14.4% in HS+POPS [ P = .54] versus 12.2% to 13.0% in HS [ P = .33]). There was no effect of HS+POPS compared with HS alone ( P = .16). There was no effect on other outcomes except for sugar-sweetened beverage intake (HS+POPS+IYS resulted in a greater decline than HS; P = .005). An intervention for parents and children to improve HS preschoolers' emotional and behavioral self-regulation in combination with an obesity-prevention curriculum did not reduce obesity prevalence or most obesity-related behaviors. Copyright © 2017 by the American Academy of Pediatrics.

A rapid space-resolved solid-phase microextraction method as a powerful tool to determine contaminants in wine based on their volatility.

PubMed

Liu, Min; Peng, Qing-Qing; Chen, Yu-Feng; Tang, Qian; Feng, Qing

2015-06-01

A novel space-resolved solid phase microextraction (SR-SPME) technique was developed to facilitate simultaneously analyte monitoring within heterogeneous samples. Graphene (G) and graphene oxide (GO) were coated separately to the segmented fibers which were successfully used for the solid-phase microextraction of two contaminants with dramatically different volatility: 2,4,6-trichloroanisole (TCA) and dibutyl phthalate (DBP). The space-resolved fiber showed good precision (5.4%, 6.8%), low detection limits (0.3ng/L, 0.3ng/L), and wide linearity (1.0-250.0ng/L, 1.0-250.0ng/L) under the optimized conditions for TCA and DBP, respectively. The method was applied to simultaneous analysis of the two contaminates with satisfactory recoveries, which were 96.96% and 98.20% for wine samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dispersive liquid-liquid microextraction of phenolic compounds from vegetable oils using a magnetic ionic liquid.

PubMed

Zhu, Shuqiang; Wang, Lijun; Su, Along; Zhang, Haixia

2017-08-01

A novel method was developed for the determination of two endocrine-disrupting chemicals, bisphenol A and 4-nonylphenol, in vegetable oil by dispersive liquid-liquid microextraction followed by ultra high performance liquid chromatography with tandem mass spectrometry. Using a magnetic liquid as the microextraction solvent, several key parameters were optimized, including the type and volume of the magnetic liquid, extraction time, amount of dispersant, and the type of reverse extractant. The detection limits for bisphenol A and 4-nonylphenol were 0.1 and 0.06 μg/kg, respectively. The recoveries were 70.4-112.3%, and the relative standard deviations were less than 4.2%. The method is simple for the extraction of bisphenol A and 4-nonylphenol from vegetable oil and suitable for routine analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of ten pyrethroids in various fruit juices: comparison of dispersive liquid-liquid microextraction sample preparation and QuEChERS method combined with dispersive liquid-liquid microextraction.

PubMed

Zhang, Yaohai; Zhang, Xuelian; Jiao, Bining

2014-09-15

Dispersive liquid-liquid microextraction (DLLME) sample preparation and the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with DLLME were developed and compared for the analysis of ten pyrethroids in various fruit juices using gas chromatography-electron capture detection (GC-ECD). QuEChERS-DLLME method has found its widespread applications to all the fruit juices including those samples with more complex matrices (orange, lemon, kiwi and mango) while DLLME was confined to the fruit juices with simpler matrices (apple, pear, grape and peach). The two methods provided acceptable recoveries and repeatability. In addition, the applicabilities of two methods were demonstrated with the real samples and further confirmed by gas chromatography-mass spectrometry (GC-MS). Copyright © 2014. Published by Elsevier Ltd.

Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid-Liquid Microextraction Coupled with UV-Vis Spectrophotometry.

PubMed

Nejad, Mina Ghasemi; Faraji, Hakim; Moghimi, Ali

2017-04-01

In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86 μL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100 µg mL -1 . LOD and LOQ were 3.4 and 11.6 ng mL -1 , respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

Bubbles in solvent microextraction: the influence of intentionally introduced bubbles on extraction efficiency.

PubMed

Williams, D Bradley G; George, Mosotho J; Meyer, Riaan; Marjanovic, Ljiljana

2011-09-01

Significant improvements to microdrop extractions of triazine pesticides are realized by the intentional incorporation of an air bubble into the solvent microdroplet used in this microextraction technique. The increase is attributed partly to greater droplet surface area resulting from the air bubble being incorporated into the solvent droplet as opposed to it sitting thereon and partly to thin film phenomena. The method is useful at nanogram/liter levels (LOD 0.002-0.012 μg/L, LOQ 0.007-0.039 μg/L), is precise (7-12% at 10 μg/L concentration level), and is validated against certified reference materials containing 0.5 and 5.0 μg/L analyte. It tolerates water and fruit juice as matrixes without serious matrix effects. This new development brings a simple, inexpensive, and efficient preconcentration technique to bear which rivals solid phase microextraction methods.

Fuel spill identification using solid-phase extraction and solid-phase microextraction. 1. Aviation turbine fuels.

PubMed

Lavine, B K; Brzozowski, D M; Ritter, J; Moores, A J; Mayfield, H T

2001-12-01

The water-soluble fraction of aviation jet fuels is examined using solid-phase extraction and solid-phase microextraction. Gas chromatographic profiles of solid-phase extracts and solid-phase microextracts of the water-soluble fraction of kerosene- and nonkerosene-based jet fuels reveal that each jet fuel possesses a unique profile. Pattern recognition analysis reveals fingerprint patterns within the data characteristic of fuel type. By using a novel genetic algorithm (GA) that emulates human pattern recognition through machine learning, it is possible to identify features characteristic of the chromatographic profile of each fuel class. The pattern recognition GA identifies a set of features that optimize the separation of the fuel classes in a plot of the two largest principal components of the data. Because principal components maximize variance, the bulk of the information encoded by the selected features is primarily about the differences between the fuel classes.

Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

PubMed

Gao, Man; Qu, Jingang; Chen, Kai; Jin, Lide; Dahlgren, Randy Alan; Wang, Huili; Tan, Chengxia; Wang, Xuedong

2017-11-01

In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g., polarity or specific functional groups). Herein, we developed a salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan, and methyltriclosan, with log K ow ranging from -1.32 to 5.40 in complex milk and environmental water matrices. The disperser in the ionic-liquid-based dispersive liquid-liquid microextraction was converted to the extraction solvent in the subsequent salting-out-assisted microextraction procedures, and thus a single solvent performed a dual role as both extractant and disperser in the SILM-DS process. Acetonitrile was selected as the dual-role solvent because of its strong affinity for both ionic liquids and water, as well as the extractant in the salting-out step. Optimized experimental conditions were 115 μL [C 8 MIM][PF 6 ] as extractor, 1200 μL acetonitrile as dual-role solvent, pH 2.0, 5.0 min ultrasound extraction time, 3.0 g Na 2 SO 4 , and 3.0 min vortex extraction time. Under optimized conditions, the recoveries of the five pollutants ranged from 74.5 to 106.9%, and their LODs were 0.12-0.75 μg kg -1 in milk samples and 0.11-0.79 μg L -1 in environmental waters. Experimental precision based on relative standard deviation was 1.4-6.4% for intraday and 2.3-6.5% for interday analyses. Compared with previous methods, the prominent advantages of the newly developed method are simultaneous determination of pollutants with a wide range of polarities and a substantially reduced workload for ordinary environmental monitoring and food tests. Therefore, the new method has great application potential for simultaneous determination of trace pollutants with strongly contrasting polarities in several analytical fields. Graphical Abstract A salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) was developed for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan and methyltriclosan, with log K ow ranging from -1.32 to 5.40. The novelty of SILM-DS method lies in (1) simultaneous quantification of pollutants with contrasting polarity; (2) microextraction based on a dual-role solvent (as a disperser and extractant); (3) giving high recoveries for analytes with a wide range of polarities; and (4) reducing workload for ordinary environmental monitoring and food tests.

Prevalence of Hippocampal Sclerosis in a Clinicopathologically Characterized Cohort.

PubMed

Malek-Ahmadi, Michael; Kahlon, Vickram; Adler, Charles H; Obradov, Aleksandra; Thind, Kabir; Shill, Holly A; Sue, Lucia I; Caviness, John N; Jacobson, Sandra; Sabbagh, Marwan N

2013-01-01

Hippocampal sclerosis (HS) is a neuropathological finding that frequently occurs with pathologies, such as Alzheimer's disease (AD). Prevalence estimates of HS in autopsy-confirmed dementia samples have varied between 0.4% and 24.5%. However, the prevalence of HS within other pathologic groups has not been well characterized. Utilizing a sample of 910 prospectively followed and clinicopathologically confirmed dementia cases, we determined the prevalence of HS among the sample and within specific pathologic groups. HS prevalence of the sample was compared to reported HS prevalence rates in other autopsy-confirmed dementia samples. The age range of the sample was 43 to 106 years, with a mean of 81.49±8.45. Of the 910 cases, 505 were male and 405 were female. For the entire sample, the average educational level was 14.59±2.65years. Of the 910 individuals, 47 (5.16%) cases had HS pathology present at autopsy. Among the 561 AD cases, 26 (4.43%) had HS pathology present. The frontotemporal dementia (FTD)/Pick's group had the highest percentage of cases with HS pathology (23.08%) followed by primary progressive aphasia (PPA) (16.67%) and Parkinson's disease with dementia (PDD) (5.34%). The HS prevalence rate of this study was not significantly different from all but 2 studies. The prevalence of HS pathology in this sample of autopsy-confirmed dementia cases was similar to other reported HS prevalence rates. This study is the first to report the presence of HS pathology in PDD cases.

Attenuation of salt-induced hypertension by aqueous calyx extract of Hibiscus sabdariffa.

PubMed

Mojiminiyi, F B O; Audu, Z; Etuk, E U; Ajagbonna, O P

2012-12-18

The aqueous calyx extract of Hibiscus sabdariffa (HS) has a folk reputation as an antihypertensive agent. On account of its antioxidant properties and probably high K+ concentration, we hypothesized that HS may attenuate the development of salt-induced hypertension. Sprague-Dawley rats (n=8 each) were treated for 12 weeks as follows: control (normal diet + water), salt-loaded (8% salt diet + water), HS (normal diet + 6 mg/ml HS), salt+HS (8% salt diet + 6 mg/ml HS) and furosemide (normal diet+ 0.25mg/Kg furosemide). Their blood pressure and heart rates were measured and responses to noradrenalin and acetylcholine (0.01 mg/kg respectively) were estimated. The cationic concentration of 6 mg/ml HS was determined. The Na+ and K+ concentrations of 6 mg/ml HS were 3.6 and 840 mmol/l respectively. The mean arterial pressure (MAP±SEM; mmHg) of salt loaded rats (184.6±29.8) was significantly higher than control (113.2±3.0; P<0.05), HS (90.0±7.4; P<0.001) salt+HS (119.4±8.9; P<0.05) and furosemide (94.9±11.5; P<0.01). The MAP of salt+HS and control rats did not differ significantly and the effect of HS was comparable to furosemide. The pressor response to noradrenalin or vasodilator response to acetylcholine remained similar in all groups. These results suggest that HS attenuated the development of salt-induced hypertension and this attenuation may be associated with its high K+ content or high potassium: sodium ratio and not with altered pressor/depressor response to noradrenalin or acetylcholine. Also the effects of HS and furosemide on blood pressure are comparable.

Resuscitative therapy with erythropoietin reduces oxidative stress and inflammatory responses of vital organs in a rat severe fixed-volume hemorrhagic shock model.

PubMed

Ranjbaran, Mina; Kadkhodaee, Mehri; Seifi, Behjat; Mirzaei, Reza; Ahghari, Parisa

2018-01-01

Hemorrhagic shock (HS) still has a high mortality rate and none of the known resuscitative regimens completely reverse its adverse outcomes. This study investigated the effects of different models of resuscitative therapy on the healing of organ damage in a HS model. Male Wistar rats were randomized into six groups: Sham, without HS induction; HS, without resuscitation; HS+Blood, resuscitation with the shed blood; HS+Blood+NS, resuscitation with blood and normal saline; HS+Blood+RL, resuscitation with blood and Ringer's lactate; EPO, erythropoietin was added to the blood and RL. Blood and urine samples were obtained 3 h after resuscitation. Kidney, liver and brain tissue samples were harvested for multiple organ failure evaluation. Survival rate was the highest in the Sham, EPO and HS+Blood+RL groups compared to others. Plasma creatinine concentration, ALT, AST, urinary NAG activity and renal NGAL mRNA expression significantly increased in the HS+Blood+RL group compared to the Sham group. There was a significant increase in tissue oxidative stress markers and pro-inflammatory cytokines in HS+Blood+RL group compared to the Sham rats. EPO had more protective effects on multiple organ failure compared to the HS+Blood+RL group. EPO, as a resuscitative treatment, attenuated HS-induced organ damage. It seems that it has a potential to be attractive for clinical trials.

Surgical pathology of epilepsy-associated non-neoplastic cerebral lesions: a brief introduction with special reference to hippocampal sclerosis and focal cortical dysplasia

PubMed Central

Miyata, Hajime; Hori, Tomokatsu; Vinters, Harry V.

2014-01-01

Among epilepsy-associated non-neoplastic lesions, mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS) and malformation of cortical development (MCD) including focal cortical dysplasia (FCD), are the two most frequent causes of drug-resistant focal epilepsies constituting about 50% of all surgical pathology of epilepsy. Several distinct histological patterns have been historically recognized in both HS and FCD, and several studies have tried to perform clinicopathological correlation; results, however, have been controversial, particularly in terms of postsurgical seizure outcome. Recently, the International League Against Epilepsy constituted a Task Forces of Neuropathology and FCD within the Commission on Diagnostic Methods, to establish an international consensus of histological classification of HS and FCD, respectively, based on agreement with the recognition of the importance of defining a histopathological classification system that reliably has some clinicopathological correlation. Such consensus classifications are likely to facilitate future clinicopathological study. Meanwhile, we reviewed neuropathology of 41 surgical cases of mTLE, and confirmed three type/patterns of HS along with no HS, based on the qualitative evaluation of the distribution and severity of neuronal loss and gliosis within hippocampal formation; i.e., HS type 1 (61%) equivalent to ‘classical’ Ammon’s horn sclerosis, HS type 2 (2%) representing CA1 sclerosis, HS type 3 (17%) equivalent to end folium sclerosis, and no HS (19%). Furthermore we performed a neuropathological comparative study on mTLE-HS and dementia associated HS (d-HS) in elderly, and confirmed that neuropathological features differ between mTLE-HS and d-HS in the distribution of hippocampal neuronal loss and gliosis, morphology of reactive astrocytes and their protein expression, and presence of concomitant neurodegenerative changes particularly Alzheimer type and TDP-43 pathologies. These differences may account, at least in part, for the difference in pathogenesis and epileptogenicity of HS in mTLE and senile dementia. However, the etiology and pathogenesis of most epileptogenic lesions are yet to be elucidated. PMID:23530853

Dietary enzymatically treated Artemisia annua L. supplementation alleviates liver oxidative injury of broilers reared under high ambient temperature

NASA Astrophysics Data System (ADS)

Wan, Xiaoli; Zhang, Jingfei; He, Jintian; Bai, Kaiwen; Zhang, Lili; Wang, Tian

2017-09-01

Heat stress induced by high ambient temperature is a major concern in commercial broiler production. To evaluate the effects of dietary enzymatically treated Artemisia annua L. (EA) supplementation on growth performance and liver oxidative injury of broilers reared under heat stress, a total of 320 22-day-old male broilers were randomly allotted into five groups with eight replicates of eight birds each. Broilers in the control group were housed at 22 ± 1 °C and fed the basal diet. Broilers in the HS, HS-EA1, HS-EA2, and HS-EA3 groups were fed basal diet supplemented with 0, 0.75, 1.00, and 1.25 g/kg EA, respectively, and reared under cyclic high temperature (34 ± 1 °C for 8 h/day and 22 ± 1 °C for 16 h/day). Broilers fed EA diets had higher final body weight, average daily body weight gain, and average daily feed intake, as well as liver concentration of reduced glutathione, activities of antioxidant enzymes, abilities to inhibit hydroxyl radical and superoxide radical (HS-EA2 and HS-EA3), and lower liver concentrations of reactive oxygen metabolites, malondialdehyde, and protein carbonyl (HS-EA1, HS-EA2, and HS-EA3) than HS group ( P < 0.05). EA treatment downregulated the mRNA levels of heat shock proteins 70 and 90, upregulated the mRNA levels of nuclear factor erythroid 2-related factor 2 (HS-EA1, HS-EA2, and HS-EA3) and heme oxygenase 1 (HS-EA2 and HS-EA3) in liver of heat-treated broilers ( P < 0.05). In conclusion, EA alleviated heat stress-induced growth depression and liver oxidative injury in broilers, possibly through improving the antioxidant capacity and regulating the pertinent mRNA expression. The appropriate inclusion level of EA in broiler diet is 1.00-1.25 g/kg.

Endogenous level of acetic acid in yellowfin tuna (Thunnus albacares): a pilot study about a possible controversy on its residue nature.

PubMed

Chiesa, Luca Maria; Pasquale, Elisa; Panseri, Sara; Britti, Domenico; Malandra, Renato; Villa, Roberto; Arioli, Francesco

2017-03-01

A method based on headspace solid-phase microextraction (HS-SPME) followed by GC-MS analysis was developed for the determination of underivatised acetic acid in fresh tuna fish muscle. Parameters such as the fibre selected and the extraction time and temperature were optimised and the linearity, detection limits and precision of the whole analytical procedure were assessed. The method was then applied to determine the acetic acid concentration in fresh yellowfin tuna muscles (Thunnus albacares) in order to evaluate the endogenous level and its variations during the shelf life under different storage conditions. A qualitative comparison was also made with variations in histamine levels to evaluate the possibility of the joint monitoring of acetic acid and histamine to identify fish stored in poor conditions. The caudal area always had a lower content of acetic acid than the ventral area, independent of the storage time and temperature. A difference was found between the 6- and 3-day time points and day 0 at a storage temperature of 8°C and between the 6-day time point and day 0 at a storage temperature of 0°C, independent of the anatomical area of the sampled tissue. The evaluation of acetic acid could represent an important approach in the field of food safety to detect the illicit use of acetic acid as an antibacterial preservative treatment or to eliminate the unpleasant smell of trimethylamine.

Recognition of beer brand based on multivariate analysis of volatile fingerprint.

PubMed

Cajka, Tomas; Riddellova, Katerina; Tomaniova, Monika; Hajslova, Jana

2010-06-18

Automated head-space solid-phase microextraction (HS-SPME)-based sampling procedure, coupled to gas chromatography-time-of-flight mass spectrometry (GC-TOFMS), was developed and employed for obtaining of fingerprints (GC profiles) of beer volatiles. In total, 265 speciality beer samples were collected over a 1-year period with the aim to distinguish, based on analytical (profiling) data, (i) the beers labelled as Rochefort 8; (ii) a group consisting of Rochefort 6, 8, 10 beers; and (iii) Trappist beers. For the chemometric evaluation of the data, partial least squares discriminant analysis (PLS-DA), linear discriminant analysis (LDA), and artificial neural networks with multilayer perceptrons (ANN-MLP) were tested. The best prediction ability was obtained for the model that distinguished a group of Rochefort 6, 8, 10 beers from the rest of beers. In this case, all chemometric tools employed provided 100% correct classification. Slightly worse prediction abilities were achieved for the models "Trappist vs. non-Trappist beers" with the values of 93.9% (PLS-DA), 91.9% (LDA) and 97.0% (ANN-MLP) and "Rochefort 8 vs. the rest" with the values of 87.9% (PLS-DA) and 84.8% (LDA) and 93.9% (ANN-MLP). In addition to chromatographic profiling, also the potential of direct coupling of SPME (extraction/pre-concentration device) with high-resolution TOFMS employing a direct analysis in real time (DART) ion source has been demonstrated as a challenging profiling approach. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Carotenoid-cleavage activities of crude enzymes from Pandanous amryllifolius.

PubMed

Ningrum, Andriati; Schreiner, Matthias

2014-11-01

Carotenoid degradation products, known as norisoprenoids, are aroma-impact compounds in several plants. Pandan wangi is a common name of the shrub Pandanus amaryllifolius. The genus name 'Pandanus' is derived from the Indonesian name of the tree, pandan. In Indonesia, the leaves from the plant are used for several purposes, e.g., as natural colorants and flavor, and as traditional treatments. The aim of this study was to determine the cleavage of β-carotene and β-apo-8'-carotenal by carotenoid-cleavage enzymes isolated from pandan leaves, to investigate dependencies of the enzymatic activities on temperature and pH, to determine the enzymatic reaction products by using Headspace Solid Phase Microextraction Gas Chromatography/Mass Spectrophotometry (HS-SPME GC/MS), and to investigate the influence of heat treatment and addition of crude enzyme on formation of norisoprenoids. Crude enzymes from pandan leaves showed higher activity against β-carotene than β-apo-8'-carotenal. The optimum temperature of crude enzymes was 70°, while the optimum pH value was 6. We identified β-ionone as the major volatile reaction product from the incubations of two different carotenoid substrates, β-carotene and β-apo-8'-carotenal. Several treatments, e.g., heat treatment and addition of crude enzymes in pandan leaves contributed to the norisoprenoid content. Our findings revealed that the crude enzymes from pandan leaves with carotenoid-cleavage activity might provide a potential application, especially for biocatalysis, in natural-flavor industry. Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.

Development of a headspace-solid phase micro extraction method to monitor changes in volatile profile of rose (Rosa hybrida, cv David Austin) petals during processing.

PubMed

Bianchi, Giulia; Nuzzi, Monica; Avitabile Leva, Alexa; Rizzolo, Anna

2007-05-25

In the present study, headspace solid phase microextraction combined to capillary gas chromatography (HS-SPME-GC) has been applied for the determination of changes in the volatile profile of rose petals (Rosa hybrida, cvs David Austin) following processing (heat treatment and addition as an ingredient to a food product--for example yoghurt). Four SPME fibres at two sampling temperatures (40 and 60 degrees C) with a sampling time of 30 min were examined. Volatile profiles were detected either by FID or/and by olfactometry (ODP-II, Gerstel). Fibre testing was performed using raw rose petals for sampling temperature selection and an 18 characteristic rose volatile standard mixture in water was used to compare fibre performances at the sampling temperature of 60 degrees C. Polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibre at the sampling temperature of 60 degrees C was the most suitable to sample the rose alcohols phenyl ethanol, citronellol, nerol, geraniol and eugenol, as assessed by GC-olfactometry, not only from raw petals, but also from processed rose petals and the food product. PDMS-DVB fibre also showed a desired low affinity to volatiles from yoghurt, which reduces the influence of food matrix on the volatile profile. The method was linear over two orders of magnitude and had satisfactory repeatability, with limits of detection for the rose alcohols ranging from <1 to 10 ng/ml concentration levels.

Analytical tools for identification of non-intentionally added substances (NIAS) coming from polyurethane adhesives in multilayer packaging materials and their migration into food simulants.

PubMed

Félix, Juliana S; Isella, Francesca; Bosetti, Osvaldo; Nerín, Cristina

2012-07-01

Adhesives used in food packaging to glue different materials can provide several substances as potential migrants, and the identification of potential migrants and migration tests are required to assess safety in the use of adhesives. Solid-phase microextraction in headspace mode and gas chromatography coupled to mass spectrometry (HS-SPME-GC-MS) and ChemSpider and SciFinder databases were used as powerful tools to identify the potential migrants in the polyurethane (PU) adhesives and also in the individual plastic films (polyethylene terephthalate, polyamide, polypropylene, polyethylene, and polyethylene/ethyl vinyl alcohol). Migration tests were carried out by using Tenax(®) and isooctane as food simulants, and the migrants were analyzed by gas chromatography coupled to mass spectrometry. More than 63 volatile and semivolatile compounds considered as potential migrants were detected either in the adhesives or in the films. Migration tests showed two non-intentionally added substances (NIAS) coming from PU adhesives that migrated through the laminates into Tenax(®) and into isooctane. Identification of these NIAS was achieved through their mass spectra, and 1,6-dioxacyclododecane-7,12-dione and 1,4,7-trioxacyclotridecane-8,13-dione were confirmed. Caprolactam migrated into isooctane, and its origin was the external plastic film in the multilayer, demonstrating real diffusion through the multilayer structure. Comparison of the migration values between the simulants and conditions will be shown and discussed.

Influence of storage on volatile profiles in roasted almonds (Prunus dulcis).

PubMed

Lee, Jihyun; Xiao, Lu; Zhang, Gong; Ebeler, Susan E; Mitchell, Alyson E

2014-11-19

Hexanal, peroxide value, and lipid hydroperoxides are common indicators of lipid oxidation in food products. However, these markers are not always reliable as levels are dynamic and often can be detected only after significant oxidation has occurred. Changes in the volatile composition of light- and dark-roast almonds were evaluated during storage over 24 weeks at 25 or 35 °C using headspace solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS). Several volatile changes were identified in association with early oxidation events in roasted almonds. Hexenal decreased significantly during the first 6 weeks of storage and did not increase above initial levels until 20-24 weeks of storage depending upon the degree of roast. In contrast, levels of 1-heptanol and 1-octanol increased at 16-20 weeks, depending upon the degree of roast, and no initial losses were observed. Seventeen new compounds, absent in raw and freshly roasted almonds but detectable after 6 weeks of storage, were identified. Of these, 2-octanone, 2-nonanone, 3-octen-2-one, 2-decanone, (E)-2-decenal, 2,4-nonadienal, pentyl oxirane, and especially acetic acid increased significantly (that is, >10 ng/g). The degree of roasting did not correlate with the levels of these compounds. Significant decreases in roasting-related aroma volatiles such as 2-methylbutanal, 3-methylbutanal, furfural, 2-phenylacetaldehyde, 2,3-butanedione, 2-methylpyrazine, and 1-methylthio-2-propanol were observed by 4 weeks of storage independent of the degree of roast or storage conditions.

Graphene deposited onto aligned zinc oxide nanorods as an efficient coating for headspace solid-phase microextraction of gasoline fractions from oil samples.

PubMed

Wen, Congying; Li, Mengmeng; Li, Wangbo; Li, Zizhou; Duan, Wei; Li, Yulong; Zhou, Jie; Li, Xiyou; Zeng, Jingbin

2017-12-29

The content of gasoline fraction in oil samples is not only an important indicator of oil quality, but also an indispensable fundamental data for oil refining and processing. Before its determination, efficient preconcentration and separation of gasoline fractions from complicated matrices is essential. In this work, a thin layer of graphene (G) was deposited onto oriented ZnO nanorods (ZNRs) as a SPME coating. By this approach, the surface area of G was greatly enhanced by the aligned ZNRs, and the surface polarity of ZNRs was changed from polar to less polar, which were both beneficial for the extraction of gasoline fractions. In addition, the ZNRs were well protected by the mechanically and chemically stable G, making the coating highly durable for use. With headspace SPME (HS-SPME) mode, the G/ZNRs coating can effectively extract gasoline fractions from various oil samples, whose extraction efficiency achieved 1.5-5.4 and 2.1-8.2 times higher than those of a G and commercial 7-μm PDMS coating respectively. Coupled with GC-FID, the developed method is sensitive, simple, cost effective and easily accessible for the analysis of gasoline fractions. Moreover, the method is also feasible for the detection of gasoline markers in simulated oil-polluted water, which provides an option for the monitoring of oil spill accident. Copyright © 2017 Elsevier B.V. All rights reserved.

Analyzing the flavor compounds in Chinese traditional fermented shrimp pastes by HS-SPME-GC/MS and electronic nose

NASA Astrophysics Data System (ADS)

Fan, Yan; Yin, Li'ang; Xue, Yong; Li, Zhaojie; Hou, Hu; Xue, Changhu

2017-04-01

Shrimp paste is a type of condiments with high nutritional value. However, the flavors of shrimp paste, particularly the non-uniformity flavors, have limited its application in food processing. In order to identify the characteristic flavor compounds in Chinese traditional shrimp pastes, five kinds of typical commercial products were evaluated in this study. The differences in the volatile composition of the five products were investigated. Solid phase micro-extraction method was employed to extract the volatile compounds. GC-MS and electronic nose were applied to identify the compounds, and the data were analyzed using principal component analysis (PCA). A total of 62 volatile compounds were identified, including 8 alcohols, 7 aldehydes, 3 ketones, 7 ethers, 7 acids, 3 esters, 6 hydrocarbons, 12 pyrazines, 2 phenols, and 7 other compounds. The typical volatile compounds contributing to the flavor of shrimp paste were found as follows: dimethyl disulfide, dimethyl tetrasulfide, dimethyl trisulfide, 2, 3, 5-trimethyl-6-ethyl pyrazine, ethyl-2, 5-dimethyl-pyrazine, phenol and indole. Propanoic acid, butanoic acid, furans, and 2-hydroxy-3-pentanone caused unpleasant odors, such as pungent and rancid odors. Principal component analysis showed that the content of volatile compounds varied depending on the processing conditions and shrimp species. These results indicated that the combinations of multiple analysis and identification methods could make up the limitations of a single method, enhance the accuracy of identification, and provide useful information for sensory research and product development.

Identification of odor volatile compounds and deodorization of Paphia undulata enzymatic hydrolysate

NASA Astrophysics Data System (ADS)

Chen, Deke; Chen, Xin; Chen, Hua; Cai, Bingna; Wan, Peng; Zhu, Xiaolian; Sun, Han; Sun, Huili; Pan, Jianyu

2016-12-01

Unfavorable fishy odour is an inevitable problem in aquatic products. In the present study, headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) analysis of volatiles from untreated samples and three deodorized samples (under the optimal conditions) of Paphia undulata enzymatic hydrolysate revealed that the compounds contributing to the distinctive odor were 1-octen-3-ol, n-hexanal, n-heptanal, 2,4-heptadienal, and 2,4-decadienal, whereas n-pentanal, n-octanal, n-octanol, benzaldehyde, 2-ethylfuran and 2-pentylfuran were the main contributors to the aromatic flavor. The deodorizing effects of activated carbon (AC) adsorption, yeast extract (YE) masking and tea polyphenol (TP) treatment on a P. undulata enzymatic hydrolysate were investigated using orthogonal experiments with sensory evaluation as the index. The following optimized deodorization conditions were obtained: AC adsorption (35 mg mL-1, 80°C, 40 min), YE masking (7 mg mL-1, 45°C, 30 min) and TP treatment (0.4 mg mL-1, 40°C, 50 min). AC adsorption effectively removed off-flavor volatile aldehydes and ketones. YE masking modified the odor profile by increasing the relative contents of aromatic compounds and decreasing the relative contents of aldehydes and ketones. The TP treatment was not effective in reducing the odor score, but it significantly reduced the relative content of aldehydes while increasing that of alkanes. It is also notable that TP effectively suppressed trimethylamine (TMA) formation in a P. undulate hydrolysate solution for a period of 72 h.

Humic supramolecular structures have polar surfaces and unpolar cores in native soil.

PubMed

Fischer, Thomas

2017-09-01

It was the aim of our study to prove the hypothesis that humic substances (HS) in native soil are spatially arranged in descending order of polarity, meaning that highly polar supramolecular subunits shield less polar subunits against the free soil solution and form layers of descending polarity. To address this aim, we consecutively extracted humic substances from soil with 8 M (HS1), 4 M (HS2), 2 M (HS3), 1 M (HS4) and 0.5 M LiCl (HS5) solution in 0.2 M LiOH after Cu 2+ adsorption in batch soil column experiments. Adsorption was performed for 1, 10 and 60 min with concentrations ranging from 9.5 to 110 mg L -1 Cu 2+ in 0.02 M CaCl 2 solution. We assumed that high ionic strength facilitates extraction of most polar organic compounds, with polarity of the extracted HS decreasing with decreasing ionic strength, and that Cu extracted together with the successive HS solely formed coordination complexes, facilitating its use as a tracer for organic matter studies. We hypothesized a delayed Cu adsorption on the less polar fractions in case of spatial shielding due to interception on overlying fractions, and a concurrent Cu adsorption in case of random spatial arrangement. It was concluded that humic substances are shielded against each other in the order of descending polarity of the supramolecular subunits (free soil solution | HS1 | HS2 | HS3 | HS4 | HS5). Copyright © 2017 Elsevier Ltd. All rights reserved.

Rapid analysis of aflatoxins B1, B2, and ochratoxin A in rice samples using dispersive liquid-liquid microextraction combined with HPLC.

PubMed

Lai, Xian-Wen; Sun, Dai-Li; Ruan, Chun-Qiang; Zhang, He; Liu, Cheng-Lan

2014-01-01

A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic liquid phase microextraction combined with fluorescence spectrometry for preconcentration and quantitation of carvedilol in pharmaceutical preparations and biological media.

PubMed

Zeeb, Mohsen; Mirza, Behrooz

2015-04-30

Carvedilol belongs to a group of medicines termed non-selective beta-adrenergic blocking agents. In the presented approach, a practical and environmentally friendly microextraction method based on the application of ionic liquids (ILs) was followed by fluorescence spectrometry for trace determination of carvedilol in pharmaceutical and biological media. A rapid and simple ionic liquid phase microextraction was utilized for preconcentration and extraction of carvedilol. A hydrophobic ionic liquid (IL) was applied as a microextraction solvent. In order to disperse the IL through the aqueous media and extract the analyte of interest, IL was injected into the sample solution and a proper temperature was applied and then for aggregating the IL-phase, the sample was cooled in an ice water-bath. The aqueous media was centrifuged and IL-phase collected at the bottom of the test tube was introduced to the micro-cell of spectrofluorimeter, in order to determine the concentration of the enriched analyte. Main parameters affecting the accuracy and precision of the proposed approach were investigated and optimized values were obtained. A linear response range of 10-250 μg I(-1) and a limit of detection (LOD) of 1.7 μg I(-1) were obtained. Finally, the presented method was utilized for trace determination of carvedilol in commercial pharmaceutical preparations and biological media.

Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

PubMed

Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

2014-11-01

An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

PubMed

Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

2016-06-01

An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of Aroclor 1260 in soil samples by gas chromatography with mass spectrometry and solid-phase microextraction.

PubMed

Zhang, Mengliang; Jackson, Glen P; Kruse, Natalie A; Bowman, Jennifer R; Harrington, Peter de B

2014-10-01

A novel fast screening method was developed for the determination of polychlorinated biphenyls that are constituents of the commercial mixture, Aroclor 1260, in soil matrices by gas chromatography with mass spectrometry combined with solid-phase microextraction. Nonequilibrium headspace solid-phase microextraction with a 100 μm polydimethylsiloxane fiber was used to extract polychlorinated biphenyls from 0.5 g of soil matrix. The use of 2 mL of saturated potassium dichromate in 6 M sulfuric acid solution improved the reproducibility of the extractions and the mass transfer of the polychlorinated biphenyls from the soil matrix to the microextraction fiber via the headspace. The extraction time was 30 min at 100°C. The percent recoveries, which were evaluated using an Aroclor 1260 standard and liquid injection, were within the range of 54.9-65.7%. Two-way extracted ion chromatogram data were used to construct calibration curves. The relative error was <±15% and the relative standard deviation was <15%, which are respective measures of the accuracy and precision. The method was validated with certified soil samples and the predicted concentrations for Aroclor 1260 agreed with the certified values. The method was demonstrated to be linear from 10 to 1000 ng/g for Aroclor 1260 in dry soil. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vortex-assisted magnetic β-cyclodextrin/attapulgite-linked ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the fast determination of four fungicides in water samples.

PubMed

Yang, Miyi; Xi, Xuefei; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

2015-02-13

A novel microextraction technique combining magnetic solid-phase microextraction (MSPME) with ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) to determine four fungicides is presented in this work for the first time. The main factors affecting the extraction efficiency were optimized by the one-factor-at-a-time approach and the impacts of these factors were studied by an orthogonal design. Without tedious clean-up procedure, analytes were extracted from the sample to the adsorbent and organic solvent and then desorbed in acetonitrile prior to chromatographic analysis. Under the optimum conditions, good linearity and high enrichment factors were obtained for all analytes, with correlation coefficients ranging from 0.9998 to 1.0000 and enrichment factors ranging 135 and 159 folds. The recoveries for proposed approach were between 98% and 115%, the limits of detection were between 0.02 and 0.04 μg L(-1) and the RSDs changed from 2.96 to 4.16. The method was successfully applied in the analysis of four fungicides (azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin) in environmental water samples. The recoveries for the real water samples ranged between 81% and 109%. The procedure proved to be a time-saving, environmentally friendly, and efficient analytical technique. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of microextraction by packed sorbent, liquid-liquid microextraction and derivatization pretreatment of diet-derived phenolic acids in plasma by gas chromatography with triple quadrupole mass spectrometry.

PubMed

Bustamante, Luis; Cárdenas, Diana; von Baer, Dietrich; Pastene, Edgar; Duran-Sandoval, Daniel; Vergara, Carola; Mardones, Claudia

2017-09-01

Miniaturized sample pretreatments for the analysis of phenolic metabolites in plasma, involving protein precipitation, enzymatic deconjugation, extraction procedures, and different derivatization reactions were systematically evaluated. The analyses were conducted by gas chromatography with mass spectrometry for the evaluation of 40 diet-derived phenolic compounds. Enzyme purification was necessary for the phenolic deconjugation before extraction. Trimethylsilanization reagent and two different tetrabutylammonium salts for derivatization reactions were compared. The optimum reaction conditions were 50 μL of trimethylsilanization reagent at 90°C for 30 min, while tetrabutylammonium salts were associated with loss of sensitivity due to rapid activation of the inert gas chromatograph liner. Phenolic acids extractions from plasma were optimized. Optimal microextraction by packed sorbent performance was achieved using an octadecylsilyl packed bed and better recoveries for less polar compounds, such as methoxylated derivatives, were observed. Despite the low recovery for many analytes, repeatability using an automated extraction procedure in the gas chromatograph inlet was 2.5%. Instead, using liquid-liquid microextraction, better recoveries (80-110%) for all analytes were observed at the expense of repeatability (3.8-18.4%). The phenolic compounds in gerbil plasma samples, collected before and 4 h after the administration of a calafate extract, were analyzed with the optimized methodology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abiotic association of PAEs with humic substances and its influence on the fate of PAEs in landfill leachate.

PubMed

Xiaoli, Chai; Rong, Ji; Jun, Wu; Huanhuan, Tong; Youcai, Zhao

2010-03-01

An equilibrium dialysis combined with a (14)C-labeling method was used to study the abiotic association of phthalic acid esters (PAEs) with dissolved humic substances (HS) and its influence on the fate of PAEs in landfill leachate. Elemental analysis and FTIR spectral analysis were carried out on the humic acid (HA) and fulvic acid (FA) components of HS to examine the relationship between the structure of HS and the intensity of the association of the PAEs with HS (K(A)). The results show that the association intensity of HS with PAEs depends greatly on both the properties of the PAEs and the source of HS. The HS have a strong association reaction with dibutyl phthalic acid, which might explain the higher concentration of dibutyl phthalic acid detected in landfill leachate. The pH value strongly affects the K(A) of HS, and it decreases radically when the pH increase from 3.0 to 9.0. The non-specific hydrophobic interaction between HS and PAEs plays a more important role in the abiotic association of HS with PAEs. Elemental analysis and FTIR spectra suggest that the high K(A) values are related to the high aromatic content and larger molecular weight of HS. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Interleukin-6 treatment reverses apoptosis and blunts susceptibility to intraperitoneal bacterial challenge following hemorrhagic shock.

PubMed

Arikan, Ayse Akcan; Yu, Bi; Mastrangelo, Mary-Ann; Tweardy, David J

2006-03-01

Resuscitation from hemorrhagic shock (HS) predisposes to subsequent infections. Susceptibility to infection following sepsis has been attributed to apoptosis. Interleukin (IL)-6 has been shown to have antiapoptotic properties and to decrease postresuscitation inflammation in rodent and porcine models of HS. The objective was to determine if HS increases host susceptibility to infection, if IL-6 administration at resuscitation reduces this susceptibility, and if changes in susceptibility to infection are accompanied by parallel changes in apoptosis. Mice were randomized into three groups-HS, sham, and no-surgery control-and each group was further randomized to receive either IL-6 (3 microg/kg; HS/IL-6) or placebo (HS/P) at the start of resuscitation. In the HS-infection protocol, each mouse was challenged intraperitoneally the next day with a sublethal dose of Staphylococcus aureus (4x107 colony-forming units); 24 hrs later, the peritoneal cavity was lavaged and the major organs were harvested for culture. In the HS-apoptosis protocol, the livers were harvested the next day and analyzed by means of the terminal deoxynucleotidyl transferase dUTP-biotin nick-end-labeling (TUNEL) assay. HS/P mice had a six- to eight-fold increase in total bacterial counts in comparison with sham and control mice that was attributable to a seven- to nine-fold increase in liver burden. IL-6 treatment reduced total and liver bacterial counts in HS/IL-6 mice by 62% and 69%, respectively, to levels statistically indistinguishable from IL-6-treated sham and control mice. The number of TUNEL-positive liver cells in the HS/P group was increased eight-fold vs. that in the sham group (p=.002); IL-6 resuscitation completely reversed the HS-induced increase in TUNEL-positive cells in the HS/IL-6 group (p=.002). IL-6 treatment at resuscitation eliminated the HS-mediated increase in total and liver bacterial burden and protected the liver from HS-induced apoptosis. Reduced liver apoptosis may explain the ability of IL-6 to blunt the HS-induced increase in susceptibility to bacterial challenge.

Does help structures play a role in reducing the variation of dwell time in IPSA planning for gynaecological brachytherapy application?

PubMed Central

Mahantshetty, Umesh; Deshpande, DD; Sharma, Smriti; Shrivastava, SK

2011-01-01

Purpose To report our experience of dosimetric comparison of IPSA and manual plans, with a focus on the use of help structures (HS) during optimization. Material and methods 33 patients who underwent MR image-based HDR intracavitary-brachytherapy for cervix cancer based on GYN-ESTRO recommendations were selected for evaluation. Tandem/ovoid (T/O) and Vienna applicators were used. HS of diameter of 5 mm were drawn around the tandem/needles/ovoid and ring. Three plans were generated: manual optimized plan (MOPT), IPSA without help structures (IPSA_woHS) and IPSA with help structures (IPSA_wHS). Dose-volume parameters and the loading pattern were evaluated. Results For T/O, the use of HS did not make significant impact in the dose-volume parameters and in the loading of tandem and ovoids, however steep variation was found in the individual dwell time. In case of Vienna applicator, inclusion of HS in the optimization made a significant impact in loading of needles. The percentage ratio of total time of needles to the tandem (TN/T%) was found to be 14±2.5, 53±9, 22±6 for MOPT, IPSA_woHS and IPSA_wHS, respectively, which implies that in IPSA_woHS the dwell time in needles were half of the dwell time in the tandem, while in MOPT the needles were loaded only in 14%, and in IPSA_wHS it was 22% of the dwell time of tandem. Inclusion of HS in the optimization has reduced the contribution of dwell time of needle in IPSA_wHS. The individual variation of dwell time was also reduced in IPSA_wHS, however drawing of HS is a time consuming procedure and may not be practical for a routine practice. Conclusion The role of HS was evaluated for IPSA for T/O and Vienna-applicator, the use of HS may be beneficial in case of combined intracavitary – interstitial approach. PMID:23346124

The spindle kinesin-like protein HsEg5 is an autoantigen in systemic lupus erythematosus.

PubMed

Whitehead, C M; Winkfein, R J; Fritzler, M J; Rattner, J B

1996-10-01

Autoantibodies directed against the mitotic spindle apparatus (MSA) have been shown to target an antigen referred to as NuMA (nuclear mitotic apparatus). In this study, we identified a second MSA antigen as the spindle kinesin-like protein HsEg5. We studied the frequency of antibodies to HsEg5 in human sera that demonstrate the MSA pattern of staining, the frequency of autoantibodies to HsEg5 in patients with systemic lupus erythematosus (SLE), and the clinical features of patients with antibodies to HsEg5. A prototype serum from an SLE patient was used to isolate a 4.8-kilobase complementary DNA (cDNA) from a HeLa cDNA library. Western blot, immunoprecipitation, and sequence analysis revealed that the antigen was an approximately 130-kd protein, HsEg5. The frequency of autoantibodies to recombinant HsEg5 in 51 sera that demonstrated an MSA pattern of staining on HEp-2 and HeLa cells was detected by immunoblotting 2 constructs of the cDNA. The clinical features of patients with antibodies directed against HsEg5 was obtained by retrospective chart review. The antigen responsible for the MSA-35 pattern was identified as the human kinesin-like protein HsEg5. Seven of 51 sera (14%) that demonstrated an MSA pattern of staining reacted with recombinant HsEg5. Six of 7 of the HsEg5-positive patients (86%) had SLE, and 1 had Sjögren's syndrome. The indirect immunofluorescent staining pattern of sera that reacted with HsEg5 could be distinguished from the other sera that reacted with NuMA. In an unselected cohort of 52 SLE patients, 3 (6%) had autoantibodies reactive with the recombinant HsEg5. Autoantibodies to MSA fall into 2 major classes: those reactive with NuMA and those reactive with HsEg5. Autoantibodies to HsEg5 are found in a lower frequency than NuMA in sera that demonstrate the MSA pattern of staining and appear to be specifically associated with SLE. HsEg5 can be distinguished from NuMA by indirect immunofluorescence and Western blotting.

Early diagnosis of myocardial infarction using absolute and relative changes in cardiac troponin concentrations.

PubMed

Irfan, Affan; Reichlin, Tobias; Twerenbold, Raphael; Meister, Marc; Moehring, Berit; Wildi, Karin; Bassetti, Stefano; Zellweger, Christa; Gimenez, Maria Rubini; Hoeller, Rebeca; Murray, Karsten; Sou, Seoung Mann; Mueller, Mira; Mosimann, Tamina; Reiter, Miriam; Haaf, Philip; Ziller, Ronny; Freidank, Heike; Osswald, Stefan; Mueller, Christian

2013-09-01

Absolute changes in high-sensitivity cardiac troponin T (hs-cTnT) seem to have higher diagnostic accuracy in the early diagnosis of acute myocardial infarction compared with relative changes. It is unknown whether the same applies to high-sensitivity cardiac troponin I (hs-cTnI) assays and whether the combination of absolute and relative change might further increase accuracy. In a prospective, international multicenter study, high-sensitivity cardiac troponin (hs-cTn) was measured with 3 novel assays (hs-cTnT, Roche Diagnostics Corp, Indianapolis, Ind; hs-cTnI, Beckman Coulter Inc, Brea, Calif; hs-cTnI, Siemens, Munich, Germany) in a blinded fashion at presentation and after 1 and 2 hours in a blinded fashion in 830 unselected patients with suspected acute myocardial infarction. The final diagnosis was adjudicated by 2 independent cardiologists. The area under the receiver operating characteristic curve for diagnosing acute myocardial infarction was significantly higher for 1- and 2-hour absolute versus relative hs-cTn changes for all 3 assays (P < .001). The area under the receiver operating characteristic curve of the combination of 2-hour absolute and relative change (hs-cTnT 0.98 [95% confidence interval {CI}, 0.97-0.99]; hs-cTnI, Beckman Coulter Inc, 0.97 [95% CI, 0.96-0.99]; hs-cTnI, Siemens, 0.96 [95% CI, 0.93-0.99]) were high and provided some benefit compared with the use of absolute change alone for hs-cTnT, but not for the hs-cTnI assays. Reclassification analysis confirmed the superiority of absolute changes versus relative changes. Absolute changes seem to be the preferred metrics for both hs-cTnT and hs-cTnI in the early diagnosis of acute myocardial infarction. The combination of absolute and relative changes provides a small added value for hs-cTnT, but not for hs-cTnI. Copyright © 2013 Elsevier Inc. All rights reserved.

Metabolic responses and "omics" technologies for elucidating the effects of heat stress in dairy cows.

PubMed

Min, Li; Zhao, Shengguo; Tian, He; Zhou, Xu; Zhang, Yangdong; Li, Songli; Yang, Hongjian; Zheng, Nan; Wang, Jiaqi

2017-06-01

Heat stress (HS) negatively affects various industries that rely on animal husbandry, particularly the dairy industry. A better understanding of metabolic responses in HS dairy cows is necessary to elucidate the physiological mechanisms of HS and offer a new perspective for future research. In this paper, we review the current knowledge of responses of body metabolism (lipid, carbohydrate, and protein), endocrine profiles, and bovine mammary epithelial cells during HS. Furthermore, we summarize the metabolomics and proteomics data that have revealed the metabolite profiles and differentially expressed proteins that are a feature of HS in dairy cows. Analysis of metabolic changes and "omics" data demonstrated that HS is characterized by reduced lipolysis, increased glycolysis, and catabolism of amino acids in dairy cows. Here, analysis of the impairment of immune function during HS and of the inflammation that arises after long-term HS might suggest new strategies to ameliorate the effects of HS in dairy production.

A Pediatrician’s Practical Guide to Diagnosing and Treating Hereditary Spherocytosis in Neonates

PubMed Central

Yaish, Hassan M.; Gallagher, Patrick G.

2015-01-01

Newborn infants who have hereditary spherocytosis (HS) can develop anemia and hyperbilirubinemia. Bilirubin-induced neurologic dysfunction is less likely in these neonates if the diagnosis of HS is recognized and appropriate treatment provided. Among neonates listed in the USA Kernicterus Registry, HS was the third most common underlying hemolytic condition after glucose-6-phosphate dehydrogenase deficiency and ABO hemolytic disease. HS is the leading cause of direct antiglobulin test (direct Coombs) negative hemolytic anemia requiring erythrocyte transfusion in the first months of life. We anticipate that as physicians become more familiar with diagnosing HS in the newborn period, fewer neonates with HS will develop hazardous hyperbilirubinemia or present to emergency departments with unanticipated symptomatic anemia. We predict that early suspicion, prompt diagnosis and treatment, and anticipatory guidance will prevent adverse outcomes in neonates with HS. The purpose of this article was to review the neonatal presentation of HS and to provide practical and up-to-date means of diagnosing and treating HS in neonates. PMID:26009624

Structure and epitope distribution of heparan sulfate is disrupted in experimental lung hypoplasia: a glycobiological epigenetic cause for malformation?

PubMed

Thompson, Sophie M; Connell, Marilyn G; van Kuppevelt, Toin H; Xu, Ruoyan; Turnbull, Jeremy E; Losty, Paul D; Fernig, David G; Jesudason, Edwin C

2011-06-14

Heparan sulfate (HS) is present on the surface of virtually all mammalian cells and is a major component of the extracellular matrix (ECM), where it plays a pivotal role in cell-cell and cell-matrix cross-talk through its large interactome. Disruption of HS biosynthesis in mice results in neonatal death as a consequence of malformed lungs, indicating that HS is crucial for airway morphogenesis. Neonatal mortality (~50%) in newborns with congenital diaphragmatic hernia (CDH) is principally associated with lung hypoplasia and pulmonary hypertension. Given the importance of HS for lung morphogenesis, we investigated developmental changes in HS structure in normal and hypoplastic lungs using the nitrofen rat model of CDH and semi-synthetic bacteriophage ('phage) display antibodies, which identify distinct HS structures. The pulmonary pattern of elaborated HS structures is developmentally regulated. For example, the HS4E4V epitope is highly expressed in sub-epithelial mesenchyme of E15.5 - E17.5 lungs and at a lower level in more distal mesenchyme. However, by E19.5, this epitope is expressed similarly throughout the lung mesenchyme.We also reveal abnormalities in HS fine structure and spatiotemporal distribution of HS epitopes in hypoplastic CDH lungs. These changes involve structures recognised by key growth factors, FGF2 and FGF9. For example, the EV3C3V epitope, which was abnormally distributed in the mesenchyme of hypoplastic lungs, is recognised by FGF2. The observed spatiotemporal changes in HS structure during normal lung development will likely reflect altered activities of many HS-binding proteins regulating lung morphogenesis. Abnormalities in HS structure and distribution in hypoplastic lungs can be expected to perturb HS:protein interactions, ECM microenvironments and crucial epithelial-mesenchyme communication, which may contribute to lung dysmorphogenesis. Indeed, a number of epitopes correlate with structures recognised by FGFs, suggesting a functional consequence of the observed changes in HS in these lungs. These results identify a novel, significant molecular defect in hypoplastic lungs and reveals HS as a potential contributor to hypoplastic lung development in CDH. Finally, these results afford the prospect that HS-mimetic therapeutics could repair defective signalling in hypoplastic lungs, improve lung growth, and reduce CDH mortality.

2-O Heparan Sulfate Sulfation by Hs2st Is Required for Erk/Mapk Signalling Activation at the Mid-Gestational Mouse Telencephalic Midline

PubMed Central

Chan, Wai Kit; Howe, Katherine; Clegg, James M.; Guimond, Scott E.; Price, David J.; Turnbull, Jeremy E.; Pratt, Thomas

2015-01-01

Heparan sulfate (HS) is a linear carbohydrate composed of polymerized uronate-glucosamine disaccharide units that decorates cell surface and secreted glycoproteins in the extracellular matrix. In mammals HS is subjected to differential sulfation by fifteen different heparan sulfotransferase (HST) enzymes of which Hs2st uniquely catalyzes the sulfation of the 2-O position of the uronate in HS. HS sulfation is postulated to be important for regulation of signaling pathways by facilitating the interaction of HS with signaling proteins including those of the Fibroblast Growth Factor (Fgf) family which signal through phosphorylation of extracellular signal-regulated kinases Erk1/2. In the developing mouse telencephalon Fgf2 signaling regulates proliferation and neurogenesis. Loss of Hs2st function phenocopies the thinned cerebral cortex of mutant mice in which Fgf2 or Erk1/2 function are abrogated, suggesting the hypothesis that 2-O-sulfated HS structures play a specific role in Fgf2/Erk signaling pathway in this context in vivo. This study investigated the molecular role of 2-O sulfation in Fgf2/Erk signaling in the developing telencephalic midline midway through mouse embryogenesis at E12.5. We examined the expression of Hs2st, Fgf2, and Erk1/2 activity in wild-type and Hs2st-/- mice. We found that Hs2st is expressed at high levels at the midline correlating with high levels of Erk1/2 activation and Erk1/2 activation was drastically reduced in the Hs2st-/- mutant at the rostral telencephalic midline. We also found that 2-O sulfation is specifically required for the binding of Fgf2 protein to Fgfr1, its major cell-surface receptor at the rostral telencephalic midline. We conclude that 2-O sulfated HS structures generated by Hs2st are needed to form productive signaling complexes between HS, Fgf2 and Fgfr1 that activate Erk1/2 at the midline. Overall, our data suggest the interesting possibility that differential expression of Hs2st targets the rostral telencephalic midline for high levels of Erk signaling by increasing the sensitivity of cells to an Fgf2 signal that is rather more widespread. PMID:26075383

Structure and epitope distribution of heparan sulfate is disrupted in experimental lung hypoplasia: a glycobiological epigenetic cause for malformation?

PubMed Central

2011-01-01

Background Heparan sulfate (HS) is present on the surface of virtually all mammalian cells and is a major component of the extracellular matrix (ECM), where it plays a pivotal role in cell-cell and cell-matrix cross-talk through its large interactome. Disruption of HS biosynthesis in mice results in neonatal death as a consequence of malformed lungs, indicating that HS is crucial for airway morphogenesis. Neonatal mortality (~50%) in newborns with congenital diaphragmatic hernia (CDH) is principally associated with lung hypoplasia and pulmonary hypertension. Given the importance of HS for lung morphogenesis, we investigated developmental changes in HS structure in normal and hypoplastic lungs using the nitrofen rat model of CDH and semi-synthetic bacteriophage ('phage) display antibodies, which identify distinct HS structures. Results The pulmonary pattern of elaborated HS structures is developmentally regulated. For example, the HS4E4V epitope is highly expressed in sub-epithelial mesenchyme of E15.5 - E17.5 lungs and at a lower level in more distal mesenchyme. However, by E19.5, this epitope is expressed similarly throughout the lung mesenchyme. We also reveal abnormalities in HS fine structure and spatiotemporal distribution of HS epitopes in hypoplastic CDH lungs. These changes involve structures recognised by key growth factors, FGF2 and FGF9. For example, the EV3C3V epitope, which was abnormally distributed in the mesenchyme of hypoplastic lungs, is recognised by FGF2. Conclusions The observed spatiotemporal changes in HS structure during normal lung development will likely reflect altered activities of many HS-binding proteins regulating lung morphogenesis. Abnormalities in HS structure and distribution in hypoplastic lungs can be expected to perturb HS:protein interactions, ECM microenvironments and crucial epithelial-mesenchyme communication, which may contribute to lung dysmorphogenesis. Indeed, a number of epitopes correlate with structures recognised by FGFs, suggesting a functional consequence of the observed changes in HS in these lungs. These results identify a novel, significant molecular defect in hypoplastic lungs and reveals HS as a potential contributor to hypoplastic lung development in CDH. Finally, these results afford the prospect that HS-mimetic therapeutics could repair defective signalling in hypoplastic lungs, improve lung growth, and reduce CDH mortality. PMID:21672206

Hidradenitis Suppurativa Is Associated with Polycystic Ovary Syndrome: A Population-Based Analysis in the United States.

PubMed

Garg, Amit; Neuren, Erica; Strunk, Andrew

2018-06-01

Polycystic ovary syndrome (PCOS) has been linked to hidradenitis suppurativa (HS). However, evidence establishing a relationship between the two conditions is limited. We sought to determine the prevalence of PCOS among patients with HS and the strength of the association. We performed a cross-sectional analysis involving 22,990 patients with HS using clinical data from a multihealth system analytics platform comprising more than 55 million unique patients across all census regions of the United States. The prevalence of PCOS among patients with HS was 9.0%, compared with 2.9% in patients without HS (P < 0.0001). The likelihood of patients with HS having PCOS was 2.14 (95% confidence interval 2.04-2.24) times that of patients without HS, and PCOS was associated with HS across all subgroups. The strength of the HS association with PCOS was similar to that of diabetes mellitus (odds ratio 2.88, 95% confidence interval 2.83-2.93) and obesity (odds ratio 3.93, 95% confidence interval 3.87-3.99) with PCOS. The influence of disease severity on the strength of association with PCOS could not be assessed, nor could an HS phenotype for patients also having PCOS. This analysis could not establish directionality of relationship, nor causal link. In conclusion, PCOS is associated with HS, and patients with HS who have symptoms or signs of androgen excess should be screened for PCOS. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Effect of sleep deprivation on driving safety in housestaff.

PubMed

Marcus, C L; Loughlin, G M

1996-12-01

Sleep deprivation is known to affect driving safety. Housestaff (HS) are routinely sleep-deprived when on call. We hypothesized that this would affect their driving. We therefore administered questionnaires regarding driving to 70 pediatric HS, who were on call every fourth night, and to 85 faculty members (FAC), who were rarely disturbed at night. HS were questioned about events during their residency, and FAC were questioned about events during the preceding three years. There was an 87% response rate for each group. HS slept 2.7 +/- 0.9 (SD) hours when on call vs 7.2 +/- 0.8 hours when not on call (p < 0.001). 44% of HS had fallen asleep when stopped at a light, vs 12.5% FAC (p < 0.001). 23% of HS had fallen asleep while driving vs. 8% FAC (ns). A total of 49% of HS had fallen asleep at the wheel; 90% of these events occurred post-call. In contrast, only 13% of FAC had fallen asleep at the wheel (p < 0.001). HS had received a total of 25 traffic citations for moving violations vs. 15 for FAC and were involved in 20 motor vehicle accidents vs. 11 for FAC. One traffic citation clearly resulted from HS falling asleep at the wheel vs. none for FAC. We conclude that HS frequently fall asleep when driving post-call. We speculate that current HS work schedules may place some HS at risk for injury to themselves and others. Further study, using prospectively objective measures is indicated.

Metabolites of hirsuteine and hirsutine, the major indole alkaloids of Uncaria rhynchophylla, in rats.

PubMed

Nakazawa, Takahiro; Banba, Koh-ichi; Hata, Kazumasa; Nihei, Yutaka; Hoshikawa, Ayumi; Ohsawa, Keisuke

2006-08-01

The metabolic fate of hirsuteine (HT) and hirsutine (HS), the major indole alkaloids of Uncaria rhynchophylla, was investigated using rats. On HPLC analysis, urine from rats orally administered HT were found to contain two metabolites (HT1 and HT2) together with unchanged HT. Similarly HS also was metabolized to two compounds (HS1 and HS2). Metabolite structures were determined to be 11-hydroxyhirsuteine-11-O-beta-D-glucuronide (HT1), 11-hydroxyhirsuteine (HT2), 11-hydroxyhirsutine-11-O-beta-D-glucuronide (HS1) and 11-hydroxyhirsutine (HS2), based on spectroscopic and chemical data. HT1 and HS1 were also detected in bile from rats administered HT and HS, respectively. Total cumulative urinary excretion within 72 h of oral administration was approximately 14% and 26% of the HT and HS doses, respectively, while total cumulative biliary excretion was 35% and 46%, respectively. HT and HS 11-hydroxylation were catalyzed by rat liver microsomes. This 11-hydroxylation activity was inhibited by addition of SKF-525A (a nonselective CYP inhibitor) or cimetidine (a CYP2C inhibitor). These results indicate that orally administered HT and HS are converted to 11-hydroxy metabolites in rats, and that the metabolites are predominantly excreted in bile rather than urine following glucuronidation. Furthermore, the results suggest that CYP2C enzymes are involved, at least in part, in the specific 11-hydroxylation of HT and HS.

Alleviation of chronic heat stress in broilers by dietary supplementation of betaine and turmeric rhizome powder: dynamics of performance, leukocyte profile, humoral immunity, and antioxidant status.

PubMed

Akhavan-Salamat, Hossein; Ghasemi, Hossein Ali

2016-01-01

Heat stress (HS), one of the most serious climate problems of tropical and subtropical countries, negatively affects the production performance of broilers. Keeping this in view, the current study was aimed at elucidating the effects of supplementing betaine (Bet) and dried turmeric rhizome powder (TRP), either singly or in combination, on growth performance, leukocyte profile, humoral immunity, and antioxidant status in broilers kept under chronic HS. A total of 625 one-day-old Ross male chicks were randomly assigned to five treatment groups (5 replicates of 25 birds per replicate pen). From day 1, the birds were either kept at the thermoneutral zone (TN) or exposed to HS (33 ± 1°C) to the conclusion of study, day 42. THeat stress (HS), one of the most serious climate problems of tropical and subtropical countries, negatively affects the production performance of broilers. Keeping this in view, the current study was aimed at elucidating the effects of supplementing betaine (Bet) and dried turmeric rhizome powder (TRP), either singly or in combination, on growth performance, leukocyte profile, humoral immunity, and antioxidant status in broilers kept under chronic HS. A total of 625 one-day-old Ross male chicks were randomly assigned to five treatment groups (5 replicates of 25 birds per replicate pen). From day 1, the birds were either kept at the thermoneutral zone (TN) or exposed to HS (33 ± 1°C) to the conclusion of study, day 42. The treatment groups were as follows: thermoneutral control (TN-CON), HS-CON, HS-Bet, HS-TRP, and HS-BT (fed Bet and TRP). The results showed that decreases in body weight gain, feed intake, and increases in feed-to-gain ratio and mortality induced by HS were partially restored by dietary supplementation of Bet and TRP. The heterophil/lymphocyte ratio, total, and IgG antibody titers against sheep red blood cell for secondary responses in the HS-TRP and HS-BT groups were also similar to those of the broilers in the TN-CON group but better (P < 0.05) than for HS-CON group. An increase (P < 0.05) in serum concentration of malondialdehyde induced by HS was significantly decreased by dietary supplementations. The serum glutathione peroxidase and superoxide dismutase activities were also higher (P < 0.05) in the supplemented groups compared to both TN and HS-CON groups. In conclusion, dietary supplementation of either Bet or TRP alone or in combination can partially ameliorate some of the detrimental effects of HS in broilers. Results also suggest that TRP might be better than Bet for improving stress tolerance and immune response in heat-stressed broilers.he treatment groups were as follows: thermoneutral control (TN-CON), HS-CON, HS-Bet, HS-TRP, and HS-BT (fed Bet and TRP). The results showed that decreases in body weight gain, feed intake, and increases in feed-to-gain ratio and mortality induced by HS were partially restored by dietary supplementation of Bet and TRP. The heterophil/lymphocyte ratio, total, and IgG antibody titers against sheep red blood cell for secondary responses in the HS-TRP and HS-BT groups were also similar to those of the broilers in the TN-CON group but better (P < 0.05) than for HS-CON group. An increase (P < 0.05) in serum concentration of malondialdehyde induced by HS was significantly decreased by dietary supplementations. The serum glutathione peroxidase and superoxide dismutase activities were also higher (P < 0.05) in the supplemented groups compared to both TN and HS-CON groups. In conclusion, dietary supplementation of either Bet or TRP alone or in combination can partially ameliorate some of the detrimental effects of HS in broilers. Results also suggest that TRP might be better than Bet for improving stress tolerance and immune response in heat-stressed broilers.

An evaporation-assisted dispersive liquid-liquid microextraction technique as a simple tool for high performance liquid chromatography tandem-mass spectrometry determination of insecticides in wine.

PubMed

Timofeeva, Irina; Kanashina, Daria; Moskvin, Leonid; Bulatov, Andrey

2017-08-25

A sample pre-treatment technique based on evaporation-assisted dispersive liquid-liquid microextraction (EVA-DLLME), followed by HPLC-MS/MS has been developed for the determination of organophosphate insecticides (malathion, diazinon, phosalone) in wine samples. The procedure includes the addition of mixture of organic solvents (with density higher than water), consisting of the extraction (low density) and volatile (high density) solvents, to aqueous sample followed by heating of the mixture obtained, what promotes the volatile solvent evaporation and moving extraction solvent droplets from down to top of the aqueous sample and, as a consequence, microextraction of target analytes. To initiate the evaporation process an initiator is required. It was established that hexanol (extraction solvent) and dichloromethane (volatile solvent) mixture (1:1, v/v) provides effective microextraction of the insecticides from wine samples with recovery from 92 to 103%. The conditions of insecticides' microextraction such as selection of extraction solvent, ratio of hexanol/dichloromethane and hexanol/sample, type and concentration of initiator, and effect of ethanol as one of the main components of wine have been studied. Under optimal experimental conditions the linear detection ranges were found to be 10 -7 -10 -3 gL -1 for malathion, 10 -9 -10 -4 gL -1 for diazinon, and 10 -6 -10 -2 gL -1 for phosalone. The LODs, calculated from a blank test, based on 3σ, found to be 3×10 -8 gL -1 for malathion, 3×10 -10 gL -1 for diazinon and 3×10 -7 gL -1 for phosalone. The advantages of EVA-DLLME are the rapidity, simplicity, high sample throughput and low cost. As an outcome, the analytical results agreed fairly well with the results obtained by a reference GC-MS method. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a novel naphthoic acid ionic liquid and its application in "no-organic solvent microextraction" for determination of triclosan and methyltriclosan in human fluids and the method optimization by central composite design.

PubMed

Wang, Hui; Gao, Jiajia; Yu, Nana; Qu, Jingang; Fang, Fang; Wang, Huili; Wang, Mei; Wang, Xuedong

2016-07-01

In traditional ionic liquids (ILs)-based microextraction, the hydrophobic and hydrophilic ILs are often used as extractant and disperser, respectively. However, the functional effects of ILs are not utilized in microextraction procedures. Herein, we introduced 1-naphthoic acid into imidazolium ring to synthesize a novel ionic liquid 1-butyl-3-methylimidazolium naphthoic acid salt ([C4MIM][NPA]), and its structure was characterized by IR, (1)H NMR and MS. On the basis of its acidic property and lower solubility than common [CnMIM][BF4], it was used as a mixing dispersive solvent with [C4MIM][BF4] in "functionalized ionic liquid-based no organic solvent microextraction (FIL-NOSM)". Utilization of [C4MIM][NPA] in FIL-NOSM procedures has two obvious advantages: (1) it promoted the non-polar environment, increased volume of the sedimented phase, and thus could enhance the extraction recoveries of triclosan (TCS) and methyltriclosan (MTCS) by more than 10%; and (2) because of the acidic property, it can act as a pH modifier, avoiding extra pH adjustment step. By combining single factor optimization and central composite design, the main factors in the FIL-NOSM method were optimized. Under the optimal conditions, the relative recoveries of TCS and MTCS reached up to 98.60-106.09%, and the LODs of them were as low as 0.12-0.15µgL(-1) in plasma and urine samples. In total, this [C4MIM][NPA]-based FIL-NOSM method provided high extraction efficiency, and required less pretreatment time and unutilized any organic solvent. To the best of our knowledge, this is the first application of [C4mim][NPA]-based microextraction method for the simultaneous quantification of trace TCS and MTCS in human fluids. Copyright © 2016 Elsevier B.V. All rights reserved.