Automated GC-MS analysis of free amino acids in biological fluids.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Gronwald, Wolfram; Oefner, Peter J

2008-07-15

A gas chromatography-mass spectrometry (GC-MS) method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate is carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acids, thereby allowing automation of the entire procedure, including addition of reagents, extraction and injection into the GC-MS. The total analysis time was 30 min and 30 amino acids could be reliably quantified using 19 stable isotope-labeled amino acids as internal standards. Limits of detection (LOD) and lower limits of quantification (LLOQ) were in the range of 0.03-12 microM and 0.3-30 microM, respectively. The method was validated using a certified amino acid standard and reference plasma, and its applicability to different biological fluids was shown. Intra-day precision for the analysis of human urine, blood plasma, and cell culture medium was 2.0-8.8%, 0.9-8.3%, and 2.0-14.3%, respectively, while the inter-day precision for human urine was 1.5-14.1%.

Urine Multi-drug Screening with GC-MS or LC-MS-MS Using SALLE-hybrid PPT/SPE.

PubMed

Lee, Junhui; Park, Jiwon; Go, Ahra; Moon, Heesung; Kim, Sujin; Jung, Sohee; Jeong, Wonjoon; Chung, Heesun

2018-05-14

To intoxicated patients in the emergency room, toxicological analysis can be considerably helpful for identifying the involved toxicants. In order to develop a urine multi-drug screening (UmDS) method, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) were used to determine targeted and unknown toxicants in urine. A GC-MS method in scan mode was validated for selectivity, limit of detection (LOD) and recovery. An LC-MS-MS multiple reaction monitoring (MRM) method was validated for lower LOD, recovery and matrix effect. The results of the screening analysis were compared with patient medical records to check the reliability of the screen. Urine samples collected from an emergency room were extracted through a combination of salting-out assisted liquid-liquid extraction (SALLE) and hybrid protein precipitation/solid phase extraction (hybrid PPT/SPE) plates and examined by GC-MS and LC-MS-MS. GC-MS analysis was performed as unknown drug screen and LC-MS-MS analysis was conducted as targeted drug screen. After analysis by GC-MS, a library search was conducted using an in-house library established with the automated mass spectral deconvolution and identification system (AMDISTM). LC-MS-MS used Cliquid®2.0 software for data processing and acquisition in MRM mode. An UmDS method by GC-MS and LC-MS-MS was developed by using a SALLE-hybrid PPT/SPE and in-house library. The results of UmDS by GC-MS and LC-MS-MS showed that toxicants could be identified from 185 emergency room patient samples containing unknown toxicants. Zolpidem, acetaminophen and citalopram were the most frequently encountered drugs in emergency room patients. The UmDS analysis developed in this study can be used effectively to detect toxic substances in a short time. Hence, it could be utilized in clinical and forensic toxicology practices.

Analysis of pesticide residues in strawberries and soils by GC-MS/MS, LC-MS/MS and two-dimensional GC-time-of-flight MS comparing organic and integrated pest management farming.

PubMed

Fernandes, Virgínia C; Lehotay, Steven J; Geis-Asteggiante, Lucía; Kwon, Hyeyoung; Mol, Hans G J; van der Kamp, Henk; Mateus, Nuno; Domingues, Valentina F; Delerue-Matos, Cristina

2014-01-01

This study analysed 22 strawberry and soil samples after their collection over the course of 2 years to compare the residue profiles from organic farming with integrated pest management practices in Portugal. For sample preparation, we used the citrate-buffered version of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. We applied three different methods for analysis: (1) 27 pesticides were targeted using LC-MS/MS; (2) 143 were targeted using low pressure GC-tandem mass spectrometry (LP-GC-MS/MS); and (3) more than 600 pesticides were screened in a targeted and untargeted approach using comprehensive, two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS). Comparison was made of the analyses using the different methods for the shared samples. The results were similar, thereby providing satisfactory confirmation of both similarly positive and negative findings. No pesticides were found in the organic-farmed samples. In samples from integrated pest management practices, nine pesticides were determined and confirmed to be present, ranging from 2 µg kg(-1) for fluazifop-p-butyl to 50 µg kg(-1) for fenpropathrin. Concentrations of residues in strawberries were less than European maximum residue limits.

Comprehensive and quantitative profiling of lipid species in human milk, cow milk and a phospholipid-enriched milk formula by GC and MS/MSALL.

PubMed

Sokol, Elena; Ulven, Trond; Færgeman, Nils J; Ejsing, Christer S

2015-06-01

Here we present a workflow for in-depth analysis of milk lipids that combines gas chromatography (GC) for fatty acid (FA) profiling and a shotgun lipidomics routine termed MS/MS ALL for structural characterization of molecular lipid species. To evaluate the performance of the workflow we performed a comparative lipid analysis of human milk, cow milk, and Lacprodan® PL-20, a phospholipid-enriched milk protein concentrate for infant formula. The GC analysis showed that human milk and Lacprodan have a similar FA profile with higher levels of unsaturated FAs as compared to cow milk. In-depth lipidomic analysis by MS/MS ALL revealed that each type of milk sample comprised distinct composition of molecular lipid species. Lipid class composition showed that the human and cow milk contain a higher proportion of triacylglycerols (TAGs) as compared to Lacprodan. Notably, the MS/MS ALL analysis demonstrated that the similar FA profile of human milk and Lacprodan determined by GC analysis is attributed to the composition of individual TAG species in human milk and glycerophospholipid species in Lacprodan. Moreover, the analysis of TAG molecules in Lacprodan and cow milk showed a high proportion of short-chain FAs that could not be monitored by GC analysis. The results presented here show that complementary GC and MS/MS ALL analysis is a powerful approach for characterization of molecular lipid species in milk and milk products. : Milk lipid analysis is routinely performed using gas chromatography. This method reports the total fatty acid composition of all milk lipids, but provides no structural or quantitative information about individual lipid molecules in milk or milk products. Here we present a workflow that integrates gas chromatography for fatty acid profiling and a shotgun lipidomics routine termed MS/MS ALL for structural analysis and quantification of molecular lipid species. We demonstrate the efficacy of this complementary workflow by a comparative analysis of

HIGH SPEED GC/MS FOR AIR ANALYSIS

EPA Science Inventory

A high speed GC/MS system consisting of a gas chromatograph equipped with a narrow bandwidth injection accessory and using a time-of-flight mass spectrometer detector has been adapted for analysis of ambient whole air samples which have been collected in passivated canisters. ...

Trace analysis of muramic acid in indoor air using an automated derivatization instrument and GC-MS(2) or GC-MS(3).

PubMed

Harley, William M; Kozar, Michael P; Fox, Alvin

2002-09-01

An automated derivatization instrument has been developed for the preparation of alditol acetates from bacterial hydrolysates for analysis by gas chromatography-mass spectrometry (GC-MS). The current report demonstrates the utility of the automated instrument for the more demanding task of trace analysis of muramic acid (Mur) in airborne dust using gas chromatography-tandem mass spectrometry (GC-MS(2)). Conditions for efficient derivatization of Mur, vital for trace analysis, are rigorous including lactam and imido group formation under anhydrous conditions. Furthermore, as the detection limit is lowered, possible contamination or carry-over of samples becomes an increasingly greater consideration and must not occur. The instrument meets these criteria and was successfully used for assaying the levels of Mur in laboratory air, which were found to be much lower than in the previous studies of heavily occupied schools and agricultural environments. The potential for GC-MS(3) in further lowering the detection limit was also demonstrated.

PyMS: a Python toolkit for processing of gas chromatography-mass spectrometry (GC-MS) data. Application and comparative study of selected tools.

PubMed

O'Callaghan, Sean; De Souza, David P; Isaac, Andrew; Wang, Qiao; Hodkinson, Luke; Olshansky, Moshe; Erwin, Tim; Appelbe, Bill; Tull, Dedreia L; Roessner, Ute; Bacic, Antony; McConville, Malcolm J; Likić, Vladimir A

2012-05-30

Gas chromatography-mass spectrometry (GC-MS) is a technique frequently used in targeted and non-targeted measurements of metabolites. Most existing software tools for processing of raw instrument GC-MS data tightly integrate data processing methods with graphical user interface facilitating interactive data processing. While interactive processing remains critically important in GC-MS applications, high-throughput studies increasingly dictate the need for command line tools, suitable for scripting of high-throughput, customized processing pipelines. PyMS comprises a library of functions for processing of instrument GC-MS data developed in Python. PyMS currently provides a complete set of GC-MS processing functions, including reading of standard data formats (ANDI- MS/NetCDF and JCAMP-DX), noise smoothing, baseline correction, peak detection, peak deconvolution, peak integration, and peak alignment by dynamic programming. A novel common ion single quantitation algorithm allows automated, accurate quantitation of GC-MS electron impact (EI) fragmentation spectra when a large number of experiments are being analyzed. PyMS implements parallel processing for by-row and by-column data processing tasks based on Message Passing Interface (MPI), allowing processing to scale on multiple CPUs in distributed computing environments. A set of specifically designed experiments was performed in-house and used to comparatively evaluate the performance of PyMS and three widely used software packages for GC-MS data processing (AMDIS, AnalyzerPro, and XCMS). PyMS is a novel software package for the processing of raw GC-MS data, particularly suitable for scripting of customized processing pipelines and for data processing in batch mode. PyMS provides limited graphical capabilities and can be used both for routine data processing and interactive/exploratory data analysis. In real-life GC-MS data processing scenarios PyMS performs as well or better than leading software packages. We

PyMS: a Python toolkit for processing of gas chromatography-mass spectrometry (GC-MS) data. Application and comparative study of selected tools

PubMed Central

2012-01-01

Background Gas chromatography–mass spectrometry (GC-MS) is a technique frequently used in targeted and non-targeted measurements of metabolites. Most existing software tools for processing of raw instrument GC-MS data tightly integrate data processing methods with graphical user interface facilitating interactive data processing. While interactive processing remains critically important in GC-MS applications, high-throughput studies increasingly dictate the need for command line tools, suitable for scripting of high-throughput, customized processing pipelines. Results PyMS comprises a library of functions for processing of instrument GC-MS data developed in Python. PyMS currently provides a complete set of GC-MS processing functions, including reading of standard data formats (ANDI- MS/NetCDF and JCAMP-DX), noise smoothing, baseline correction, peak detection, peak deconvolution, peak integration, and peak alignment by dynamic programming. A novel common ion single quantitation algorithm allows automated, accurate quantitation of GC-MS electron impact (EI) fragmentation spectra when a large number of experiments are being analyzed. PyMS implements parallel processing for by-row and by-column data processing tasks based on Message Passing Interface (MPI), allowing processing to scale on multiple CPUs in distributed computing environments. A set of specifically designed experiments was performed in-house and used to comparatively evaluate the performance of PyMS and three widely used software packages for GC-MS data processing (AMDIS, AnalyzerPro, and XCMS). Conclusions PyMS is a novel software package for the processing of raw GC-MS data, particularly suitable for scripting of customized processing pipelines and for data processing in batch mode. PyMS provides limited graphical capabilities and can be used both for routine data processing and interactive/exploratory data analysis. In real-life GC-MS data processing scenarios PyMS performs as well or better than

GC-MS Quantitation and Identification of Bisphenol-A Isolated from Water

ERIC Educational Resources Information Center

Mead, Ralph N.; Seaton, Pamela J.

2011-01-01

Isolation and identification of organic compounds is a necessary skill chemistry students must be able to do with proficiency. In this upper-level undergraduate laboratory, students isolate bisphenol-A (BPA; 4-4'-isopropylidenediphenol) from water using solid-phase extraction (SPE) followed by derivatization with analysis by GC-MS. The students…

Quantitative Measurement of Bromoform in Swimming Pool Water Using SPME with GC-MS. An Undergraduate Instrumental Analysis Experiment

NASA Astrophysics Data System (ADS)

Hardee, John R.; Long, John; Otts, Julie

2002-05-01

A senior-level undergraduate laboratory experiment that demonstrates the use of solid-phase microextraction (SPME) and capillary gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of bromoform in swimming pool water. Bromoform was extracted by SPME from the headspace of vials containing sodium chloride-saturated swimming pool water. Bromoform concentrations were determined from comparisons of peak areas on a student-generated calibration curve. Students compared results to OSHA water and air exposure limits for bromoform.

Simultaneous determination of rhamnose, xylitol, arabitol, fructose, glucose, inositol, sucrose, maltose in jujube (Zizyphus jujube Mill.) extract: comparison of HPLC-ELSD, LC-ESI-MS/MS and GC-MS.

PubMed

Sun, Shihao; Wang, Hui; Xie, Jianping; Su, Yue

2016-01-01

Jujube extract is commonly used as a food additive and flavoring. The sensory properties of the extract, especially sweetness, are a critical factor determining the product quality and therefore affecting consumer acceptability. Small molecular carbohydrates make major contribution to the sweetness of the jujube extract, and their types and contents in the extract have direct influence on quality of the product. So, an appropriate qualitative and quantitative method for determination of the carbohydrates is vitally important for quality control of the product. High performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD), liquid chromatography-electronic spay ionization tandem mass spectrometry (LC-ESI-MS/MS), and gas chromatography-mass spectrometry (GC-MS) methods have been developed and applied to determining small molecular carbohydrates in jujube extract, respectively. Eight sugars and alditols were identified from the extract, including rhamnose, xylitol, arabitol, fructose, glucose, inositol, sucrose, and maltose. Comparisons were carried out to investigate the performance of the methods. Although the methods have been found to perform satisfactorily, only three sugars (fructose, glucose and inositol) could be detected by all these methods. Meanwhile, a similar quantitative result for the three sugars can be obtained by the methods. Eight sugars and alditols in the jujube extract were determined by HPLC-ELSD, LC-ESI-MS/MS and GC-MS, respectively. The LC-ELSD method and the LC-ESI-MS/MS method with good precision and accuracy were suitable for quantitative analysis of carbohydrates in jujube extract; although the performance of the GC-MS method for quantitative analysis was inferior to the other methods, it has a wider scope in qualitative analysis. A multi-analysis technique should be adopted in order to obtain complete constituents of about the carbohydrates in jujube extract, and the methods should be employed according to the

PCI-GC-MS-MS approach for identification of non-amino organic acid and amino acid profiles.

PubMed

Luan, Hemi; Yang, Lin; Ji, Fenfen; Cai, Zongwei

2017-03-15

Alkyl chloroformate have been wildly used for the fast derivatization of metabolites with amino and/or carboxyl groups, coupling of powerful separation and detection systems, such as GC-MS, which allows the comprehensive analysis of non-amino organic acids and amino acids. The reagents involving n-alkyl chloroformate and n-alcohol are generally employed for providing symmetric labeling terminal alkyl chain with the same length. Here, we developed an asymmetric labeling strategy and positive chemical ionization gas chromatography-tandem mass spectrometry (PCI-GC-MS-MS) approach for determination of non-amino organic acids and amino acids, as well as the short chain fatty acids. Carboxylic and amino groups could be selectively labelled by propyl and ethyl groups, respectively. The specific neutral loss of C 3 H 8 O (60Da), C 3 H 5 O 2 (74Da) and C 4 H 8 O 2 (88Da) were useful in the selective identification for qualitative analysis of organic acids and amino acid derivatives. PCI-GC-MS-MS using multiple reaction monitoring (MRM) was applied for semi-quantification of typical non-amino organic acids and amino acids. This method exhibited a wide range of linear range, good regression coefficient (R 2 ) and repeatability. The relative standard deviation (RSD) of targeted metabolites showed excellent intra- and inter-day precision (<5%). Our method provided a qualitative and semi-quantitative PCI-GC-MS-MS, coupled with alkyl chloroformate derivatization. Copyright © 2016 Elsevier B.V. All rights reserved.

GC-FID coupled with chemometrics for quantitative and chemical fingerprinting analysis of Alpinia oxyphylla oil.

PubMed

Miao, Qing; Kong, Weijun; Zhao, Xiangsheng; Yang, Shihai; Yang, Meihua

2015-01-01

Analytical methods for quantitative analysis and chemical fingerprinting of volatile oils from Alpinia oxyphylla were established. The volatile oils were prepared by hydrodistillation, and the yields were between 0.82% and 1.33%. The developed gas chromatography-flame ionization detection (GC-FID) method showed good specificity, linearity, reproducibility, stability and recovery, and could be used satisfactorily for quantitative analysis. The results showed that the volatile oils contained 2.31-77.30 μL/mL p-cymene and 12.38-99.34 mg/mL nootkatone. A GC-FID fingerprinting method was established, and the profiles were analyzed using chemometrics. GC-MS was used to identify the principal compounds in the GC-FID profiles. The profiles of almost all the samples were consistent and stable. The harvesting time and source were major factors that affected the profile, while the volatile oil yield and the nootkatone content had minor secondary effects. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of a GC/MS method for the qualitative and quantitative analysis of mixtures of free fatty acids and metal soaps in paint samples.

PubMed

La Nasa, Jacopo; Modugno, Francesca; Aloisi, Matteo; Lluveras-Tenorio, Anna; Bonaduce, Ilaria

2018-02-25

In this paper we present a new analytical GC/MS method for the analysis of mixtures of free fatty acids and metal soaps in paint samples. This approach is based on the use of two different silylating agents: N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS). Our experimentation demonstrated that HMDS does not silylate fatty acid carboxylates, so it can be used for the selective derivatization and GC/MS quantitative analysis of free fatty acids. On the other hand BSTFA is able to silylate both free fatty acids and fatty acids carboxylates. The reaction conditions for the derivatization of carboxylates with BSTFA were thus optimized with a full factorial 3 2 experimental design using lead stearate and lead palmitate as model systems. The analytical method was validated following the ICH guidelines. The method allows the qualitative and quantitative analysis of fatty acid carboxylates of sodium, calcium, magnesium, aluminium, manganese, cobalt, copper, zinc, cadmium, and lead and of lead azelate. In order to exploit the performances of the new analytical method, samples collected from two reference paint layers, from a gilded 16th century marble sculpture, and from a paint tube belonging to the atelier of Edvard Munch, used in the last period of his life (1916-1944), were characterized. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid and Simultaneous Analysis of 360 Pesticides in Brown Rice, Spinach, Orange, and Potato Using Microbore GC-MS/MS.

PubMed

Lee, Jonghwa; Kim, Leesun; Shin, Yongho; Lee, Junghak; Lee, Jiho; Kim, Eunhye; Moon, Joon-Kwan; Kim, Jeong-Han

2017-04-26

A multiresidue method for the simultaneous and rapid analysis of 360 pesticides in representative agricultural produce (brown rice, orange, spinach, and potato) was developed using a modified QuEChERS procedure combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Selected reaction monitoring transition parameters (e.g., collision energy, precursor and product ions) in MS/MS were optimized to achieve the best selectivity and sensitivity for a wide range of GC-amenable pesticides. A short (20 m) microbore (0.18 mm i.d.) column resulted in better signal-to-noise ratio with reduced analysis time than a conventional narrowbore column (30 m × 0.25 mm i.d.). The priming injection dramatically increased peak areas by masking effect on a new GC liner. The limit of quantitation was <0.01 mg/kg, and the correlation coefficients (r 2 ) of matrix-matched standards were >0.99 within the range of 0.0025-0.1 mg/kg. Acetonitrile with 0.1% formic acid without additional buffer salts was used for pesticide extraction, whereas only primary-secondary amine (PSA) was used for dispersive solid phase extraction (dSPE) cleanup, to achieve good recoveries for most of the target analytes. The recoveries ranged from 70 to 120% with relative standard deviations of ≤20% at 0.01 and 0.05 mg/kg spiking levels (n = 6) in all samples, indicating acceptable accuracy and precision of the method. Seventeen real samples from local markets were analyzed by using the optimized method, and 14 pesticides in 11 incurred samples were found at below the maximum residue limits.

Benefit of the Use of GCxGC/MS Profiles for 1D GC/MS Data Treatment Illustrated by the Analysis of Pyrolysis Products from East Asian Handmade Papers

NASA Astrophysics Data System (ADS)

Han, Bin; Lob, Silvia; Sablier, Michel

2018-06-01

In this study, we report the use of pyrolysis-GCxGC/MS profiles for an optimized treatment of data issued from pyrolysis-GC/MS combined with the automatic deconvolution software Automated Mass Spectral Deconvolution and Identification System (AMDIS). The method was illustrated by the characterization of marker compounds of East Asian handmade papers through the examination of pyrolysis-GCxGC/MS data to get information which was used for manually identifying low concentrated and co-eluting compounds in 1D GC/MS data. The results showed that the merits of a higher separation power for co-eluting compounds and a better sensitivity for low concentration compounds offered by a GCxGC system can be used effectively for AMDIS 1D GC/MS data treatment: (i) the compound distribution in pyrolysis-GCxGC/MS profiles can be used as "peak finder" for manual check of low concentration and co-eluting compound identification in 1D GC/MS data, and (ii) pyrolysis-GCxGC/MS profiles can provide better quality mass spectra with observed higher match factors in the AMDIS automatic match process. The combination of 2D profile with AMDIS was shown to contribute efficiently to a better characterization of compound profiles in the chromatograms obtained by 1D analysis in focusing on the mass spectral identification. [Figure not available: see fulltext.

HPLC-MS and GC-MS analyses combined with orthogonal partial least squares to identify cytotoxic constituents from turmeric (Curcuma longa L.).

PubMed

Jiang, Jianlan; Zhang, Huan; Li, Zidan; Zhang, Xiaohang; Su, Xin; Li, Yan; Qiao, Bin; Yuan, Yingjin

2013-08-01

We investigated the fingerprints of 48 batches of turmeric total extracts (TTE) by HPLC-MS-MS and GC-MS analyses and 43 characteristic peaks (22 constituents from HPLC-MS-MS; 21 from GC-MS) were analyzed qualitatively and quantitatively. An MTT {3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide} assay was implemented to measure the cytotoxicity of the TTE against HeLa cells. Then we utilized orthogonal partial least squares analysis, which correlated the chemical composition of the TTE to its cytotoxic activity, to identify potential cytotoxic constituents from turmeric. The result showed that 19 constituents contributed significantly to the cytotoxicity. The obtained result was verified by canonical correlation analysis. Comparison with previous reports also indicated some interaction between the curcuminoids and sesquiterpenoids in turmeric.

Quantitative analysis of the endogenous GHB level in the hair of the Chinese population using GC/MS/MS.

PubMed

Shi, Yan; Cui, Xiaopei; Shen, Min; Xiang, Ping

2016-04-01

Endogenous production complicates interpretation when gamma-hydroxybutyrate (GHB) is measured in hair for forensic purposes. A method capable of quantifying the endogenous concentration of GHB in human head hair was developed and validated using GC/MS/MS. Hair was digested under alkaline conditions (1 mol/L NaOH, 90 °C 10 min), and GHB-d6 was used as an internal standard. Before derivatization with BSTFA and ethyl acetate, a liquid-liquid extraction with ethyl acetate under acidic conditions was performed. GHB-TMS derivatives were detected using GC/MS/MS in the multiple-reaction monitoring mode. This method exhibited good linearity (y = 0.018x + 0.038, R(2) = 0.9998), and the limit of detection was 0.02 ng/mg. The extraction recoveries were more than 60%, and the inter-day and intra-day relative standard deviations (RSD) were less than 15%. This method has been applied for the analysis of the endogenous GHB in hair samples from 66 drug-free Chinese donors. The mean measured concentration for 0-3 cm hair was 1.93 ± 1.40 ng/mg (n = 66), and extreme values were in the range of 0.28-4.91 ng/mg. The mean male endogenous GHB level was 2.95 ng/mg (0.92-4.91 ng/mg, n = 35), while the mean female level was 0.77 ng/mg (0.28-1.95 ng/mg, n = 31). This method was applied to a forensic case for the determination of GHB in hair samples but it is hard to make a reasonable "cut off" in hair. The solution is to use each subject as his own control. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Comprehensive and quantitative profiling of lipid species in human milk, cow milk and a phospholipid-enriched milk formula by GC and MS/MSALL

PubMed Central

Sokol, Elena; Ulven, Trond; Færgeman, Nils J; Ejsing, Christer S

2015-01-01

Here we present a workflow for in-depth analysis of milk lipids that combines gas chromatography (GC) for fatty acid (FA) profiling and a shotgun lipidomics routine termed MS/MSALL for structural characterization of molecular lipid species. To evaluate the performance of the workflow we performed a comparative lipid analysis of human milk, cow milk, and Lacprodan® PL-20, a phospholipid-enriched milk protein concentrate for infant formula. The GC analysis showed that human milk and Lacprodan have a similar FA profile with higher levels of unsaturated FAs as compared to cow milk. In-depth lipidomic analysis by MS/MSALL revealed that each type of milk sample comprised distinct composition of molecular lipid species. Lipid class composition showed that the human and cow milk contain a higher proportion of triacylglycerols (TAGs) as compared to Lacprodan. Notably, the MS/MSALL analysis demonstrated that the similar FA profile of human milk and Lacprodan determined by GC analysis is attributed to the composition of individual TAG species in human milk and glycerophospholipid species in Lacprodan. Moreover, the analysis of TAG molecules in Lacprodan and cow milk showed a high proportion of short-chain FAs that could not be monitored by GC analysis. The results presented here show that complementary GC and MS/MSALL analysis is a powerful approach for characterization of molecular lipid species in milk and milk products. Practical applications : Milk lipid analysis is routinely performed using gas chromatography. This method reports the total fatty acid composition of all milk lipids, but provides no structural or quantitative information about individual lipid molecules in milk or milk products. Here we present a workflow that integrates gas chromatography for fatty acid profiling and a shotgun lipidomics routine termed MS/MSALL for structural analysis and quantification of molecular lipid species. We demonstrate the efficacy of this complementary workflow by a

"One-pot" ethyl chloroformate derivatization and liquid-liquid extraction of reduced glutathione in erythrocyte and its quantitative GC-MS analysis.

PubMed

Manca, Alessandra; Alladio, Eugenio; Massarenti, Paola; Puccinelli, M Paola; De Francesco, Antonella; Del Grosso, Erika; Mengozzi, Giulio; Pazzi, Marco; Vincenti, Marco

2017-12-01

A simple "one-pot" derivatization and liquid-liquid extraction (LLE) procedure was developed for GC-MS analysis of reduced glutathione (GSH) analysis in erythrocytes. The metabolite was extracted by 5% (w/v) TCA, the supernatant treated with ECF and ethanol-pyridine media, the derivative separated and detected by gas chromatography-mass spectrometry using a short non-polar capillary GC column at a high column-head pressure. Total analysis time was 11min. The process was optimized by a Design of Experiment. The method was validated showing a good linearity over the 25.4-813.4μM concentration range, providing satisfactory results in terms of intra-day and inter-day precision as well as an optimal accuracy. The new method was evaluated in a pilot study involving patients with severe protein malnutrition. Comparison of this group with a group of healthy subjects revealed significantly lower GSH concentrations in erythrocytes in the former, thus proving that the described GC-MS method could be employed for fast and simple GSH analysis in clinical studies. Copyright © 2017 Elsevier B.V. All rights reserved.

TagFinder for the quantitative analysis of gas chromatography--mass spectrometry (GC-MS)-based metabolite profiling experiments.

PubMed

Luedemann, Alexander; Strassburg, Katrin; Erban, Alexander; Kopka, Joachim

2008-03-01

Typical GC-MS-based metabolite profiling experiments may comprise hundreds of chromatogram files, which each contain up to 1000 mass spectral tags (MSTs). MSTs are the characteristic patterns of approximately 25-250 fragment ions and respective isotopomers, which are generated after gas chromatography (GC) by electron impact ionization (EI) of the separated chemical molecules. These fragment ions are subsequently detected by time-of-flight (TOF) mass spectrometry (MS). MSTs of profiling experiments are typically reported as a list of ions, which are characterized by mass, chromatographic retention index (RI) or retention time (RT), and arbitrary abundance. The first two parameters allow the identification, the later the quantification of the represented chemical compounds. Many software tools have been reported for the pre-processing, the so-called curve resolution and deconvolution, of GC-(EI-TOF)-MS files. Pre-processing tools generate numerical data matrices, which contain all aligned MSTs and samples of an experiment. This process, however, is error prone mainly due to (i) the imprecise RI or RT alignment of MSTs and (ii) the high complexity of biological samples. This complexity causes co-elution of compounds and as a consequence non-selective, in other words impure MSTs. The selection and validation of optimal fragment ions for the specific and selective quantification of simultaneously eluting compounds is, therefore, mandatory. Currently validation is performed in most laboratories under human supervision. So far no software tool supports the non-targeted and user-independent quality assessment of the data matrices prior to statistical analysis. TagFinder may fill this gap. TagFinder facilitates the analysis of all fragment ions, which are observed in GC-(EI-TOF)-MS profiling experiments. The non-targeted approach allows the discovery of novel and unexpected compounds. In addition, mass isotopomer resolution is maintained by TagFinder processing. This

Analysis of Alkaloids from Physalis peruviana by Capillary GC, Capillary GC-MS, and GC-FTIR.

PubMed

Kubwabo, C; Rollmann, B; Tilquin, B

1993-04-01

The alkaloid composition of the aerial parts and roots of PHYSALIS PERUVIANA was analysed by capillary GC (GC (2)), GC (2)-MS and GC (2)-FTIR. Eight alkaloids were identified, three of those alkaloids are 3beta-acetoxytropane and two N-methylpyrrolidinylhygrine isomers, which were not previously found in the genus PHYSALIS. A reproduction of the identification of alkaloids detected in the plant by the use of retention indices has been proposed.

Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

PubMed Central

Zanchetti Meneghini, Leonardo; Rübensam, Gabriel; Claudino Bica, Vinicius; Ceccon, Amanda; Barreto, Fabiano; Flores Ferrão, Marco; Bergold, Ana Maria

2014-01-01

A simple and inexpensive method based on solvent extraction followed by low temperature clean-up was applied for determination of seven pyrethroids residues in bovine raw milk using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron-capture detector (GC-ECD). Sample extraction procedure was established through the evaluation of seven different extraction protocols, evaluated in terms of analyte recovery and cleanup efficiency. Sample preparation optimization was based on Doehlert design using fifteen runs with three different variables. Response surface methodologies and polynomial analysis were used to define the best extraction conditions. Method validation was carried out based on SANCO guide parameters and assessed by multivariate analysis. Method performance was considered satisfactory since mean recoveries were between 87% and 101% for three distinct concentrations. Accuracy and precision were lower than ±20%, and led to no significant differences (p < 0.05) between results obtained by GC-ECD and GC-MS/MS techniques. The method has been applied to routine analysis for determination of pyrethroid residues in bovine raw milk in the Brazilian National Residue Control Plan since 2013, in which a total of 50 samples were analyzed. PMID:25380457

Evaluation of volatiles from two subtropical strawberry cultivars using GC-olfactometry, GC-MS odor activity values, and sensory analysis

USDA-ARS?s Scientific Manuscript database

Flavor profiles of two Florida strawberry cultivars were determined using GC-olfactometry,GC-MS, odor activity values (OAVs) and sensory analysis. Thirty-six aroma active compounds were detected using GC-O. Thirty-four were identified. The major odor-active compounds in decreasing intensity were: me...

Combined analysis by GC (RI), GC-MS and 13C NMR of the supercritical fluid extract of Abies alba twigs.

PubMed

Duquesnoy, Emilie; Marongiu, Bruno; Castola, Vincent; Piras, Alessandra; Porcedda, Silvia; Casanova, Joseph

2010-12-01

Two samples (leaves and twigs) of Abies alba Miller from Corsica were extracted using supercritical CO2 and their chemical compositions were compared with those of the essential oils obtained from the same batch of plant material. In total 45 components were identified using combined analysis by GC (RI), GC-MS and 13C NMR. It was observed that the contents of monoterpenes (mainly represented by limonene, alpha-pinene and camphene) were significantly lower in the supercritical fluid extract (SFE) than in the essential oil (EO). Conversely, the proportions of sesquiterpenes were much higher in CO2 extracts than in essential oils (around 30% vs 4%). Cis-abienol, a diterpene alcohol, was identified only in SFE, and the proportions of this constituent (7.5% and 17.3%) were determined using quantitative 13C NMR since it was under estimated using the standard conditions of GC.

Analysis of acrylamide by LC-MS/MS and GC-MS in processed Japanese foods.

PubMed

Ono, H; Chuda, Y; Ohnishi-Kameyama, M; Yada, H; Ishizaka, M; Kobayashi, H; Yoshida, M

2003-03-01

Acrylamide concentrations in processed foods (63 samples covering 31 product types) from Japan were analysed by LC-MS/MS and GC-MS methods. The limit of detection and limit of quantification of acrylamide were 0.2 ng x ml(-1) (6 fmol) and 0.8 ng x ml(-1) (22 fmol), respectively, by LC-MS/MS, and those of 2,3-dibromopropionamide derived from acrylamide were 12 ng x ml(-1) (52 fmol) and 40 ng x ml(-1) (170 fmol), respectively, by GC-MS. Repeatability given as RSD was <5 and <15% for the LC-MS/MS and GC-MS methods, respectively. High correlation (r(2) - 0.946) was observed between values obtained by the two methods. Most potato crisps and whole potato-based fried snacks showed acrylamide concentrations >1000 microg x kg(-1). The concentrations in non-whole potato-based snacks, rice crackers processed by grilling or frying, and candied sweet potatoes were lower compared with those in the potato crisps and the whole potato-based fried snacks. One of the whole potato-based fried snacks, however, showed low acrylamide concentration (<50 microg x kg(-1)) suggesting the formation of acrylamide is strongly influenced by processing conditions. Acrylamide concentrations in instant precooked noodles and won-tons were <100 microg x kg(-1) with only one exception. Roasted barley grains for 'Mugi-cha' tea contained 200-600 microg x kg(-1) acrylamide.

COMPARATIVE EVALUATION OF GC/MS (GAS CHROMATOGRAPHY/MASS SPECTROMETRY) DATA ANALYSIS PROCESSING

EPA Science Inventory

Mass spectra obtained by fused silica capillary gas chromatography/mass spectrometry/data system (GC/MS/DS) analysis of mixtures of organic chemicals adsorbed on Tenax GC cartridges was subjected to manual and automated interpretative techniques. Synthetic mixtures (85 chemicals ...

Development of quantitative screen for 1550 chemicals with GC-MS.

PubMed

Bergmann, Alan J; Points, Gary L; Scott, Richard P; Wilson, Glenn; Anderson, Kim A

2018-05-01

With hundreds of thousands of chemicals in the environment, effective monitoring requires high-throughput analytical techniques. This paper presents a quantitative screening method for 1550 chemicals based on statistical modeling of responses with identification and integration performed using deconvolution reporting software. The method was evaluated with representative environmental samples. We tested biological extracts, low-density polyethylene, and silicone passive sampling devices spiked with known concentrations of 196 representative chemicals. A multiple linear regression (R 2  = 0.80) was developed with molecular weight, logP, polar surface area, and fractional ion abundance to predict chemical responses within a factor of 2.5. Linearity beyond the calibration had R 2  > 0.97 for three orders of magnitude. Median limits of quantitation were estimated to be 201 pg/μL (1.9× standard deviation). The number of detected chemicals and the accuracy of quantitation were similar for environmental samples and standard solutions. To our knowledge, this is the most precise method for the largest number of semi-volatile organic chemicals lacking authentic standards. Accessible instrumentation and software make this method cost effective in quantifying a large, customizable list of chemicals. When paired with silicone wristband passive samplers, this quantitative screen will be very useful for epidemiology where binning of concentrations is common. Graphical abstract A multiple linear regression of chemical responses measured with GC-MS allowed quantitation of 1550 chemicals in samples such as silicone wristbands.

Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS.

PubMed

Sousa, José A; Domingues, Valentina F; Rosas, Mónica S; Ribeiro, Susana O; Alvim-Ferraz, Conceiçao M; Delerue-Matos, Cristina F

2011-01-01

The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 μg m⁻³) and during the unloading of gasoline the achieved concentration was 8371 μg m⁻³; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 μg m⁻³ except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 μg m⁻³) than in coffee shops where this is forbidden (4 μg m⁻³). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene.

Open Probe fast GC-MS - combining ambient sampling ultra-fast separation and in-vacuum ionization for real-time analysis.

PubMed

Keshet, U; Alon, T; Fialkov, A B; Amirav, A

2017-07-01

An Open Probe inlet was combined with a low thermal mass ultra-fast gas chromatograph (GC), in-vacuum electron ionization ion source and a mass spectrometer (MS) of GC-MS for obtaining real-time analysis with separation. The Open Probe enables ambient sampling via sample vaporization in an oven that is open to room air, and the ultra-fast GC provides ~30-s separation, while if no separation is required, it can act as a transfer line with 2 to 3-s sample transfer time. Sample analysis is as simple as touching the sample, pushing the sample holder into the Open Probe oven and obtaining the results in 30 s. The Open Probe fast GC was mounted on a standard Agilent 7890 GC that was coupled with an Agilent 5977A MS. Open Probe fast GC-MS provides real-time analysis combined with GC separation and library identification, and it uses the low-cost MS of GC-MS. The operation of Open Probe fast GC-MS is demonstrated in the 30-s separation and 50-s full analysis cycle time of tetrahydrocannabinol and cannabinol in Cannabis flower, sub 1-min analysis of trace trinitrotoluene transferred from a finger onto a glass surface, vitamin E in canola oil, sterols in olive oil, polybrominated flame retardants in plastics, alprazolam in Xanax drug pill and free fatty acids and cholesterol in human blood. The extrapolated limit of detection for pyrene is <1 fg, but the concentration is too high and the software noise calculation is untrustworthy. The broad range of compounds amenable for analysis is demonstrated in the analysis of reserpine. The possible use with alternate standard GC-MS and Open Probe fast GC-MS is demonstrated in the analysis of heroin in its street drug powder. The use of Open Probe with the fast GC acting as a transfer line is demonstrated in <10-s analysis without separation of ibuprofen and estradiol. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Quantitative Determination of Perfluorochemicals and Fluorotelomer Alcohols in Plants from Biosolid-Amended Fields using LC/MS/MS and GC/MS

EPA Science Inventory

Analytical methods for determining perfluorochemicals (PFCs) and fluorotelomer alcohols (FTOHs) in plants using liquid chromatography/tandem mass spectrometry (LC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) were developed, and applied to quantify a suite of analytes i...

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

PubMed

Kim, Young-Min; Kim, Jae Woo; Moon, Hye Mi; Lee, Min-Jin; Hosaka, Akihiko; Watanabe, Atsushi; Teramae, Norio; Park, Young-Kwon; Myung, Seung-Woon

2017-01-01

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis. The calibration curve for the TD method showed good linearity (correlation coefficient, r 2 = 0.9998) and precision values (below 5.3% RSD). NMP recovery rates in different polymer matrices (PS, PMMA and PVC) were in the range of 98.8 to 106.6% with RSD values below 5.0%. The quantification result (600 mg NMP/kg PVC) for the blind NMP carrying sample in a PVC matrix by TD-GC/MS was higher than that (532 mg NMP/kg PVC) by solvent extraction-GC/MS method.

Method for factor analysis of GC/MS data

DOEpatents

Van Benthem, Mark H; Kotula, Paul G; Keenan, Michael R

2012-09-11

The method of the present invention provides a fast, robust, and automated multivariate statistical analysis of gas chromatography/mass spectroscopy (GC/MS) data sets. The method can involve systematic elimination of undesired, saturated peak masses to yield data that follow a linear, additive model. The cleaned data can then be subjected to a combination of PCA and orthogonal factor rotation followed by refinement with MCR-ALS to yield highly interpretable results.

Comparison of GC-MS, GC-MRM-MS, and GC × GC to characterise higher plant biomarkers in Tertiary oils and rock extracts

NASA Astrophysics Data System (ADS)

Eiserbeck, Christiane; Nelson, Robert K.; Grice, Kliti; Curiale, Joseph; Reddy, Christopher M.

2012-06-01

Higher plant biomarkers occur in various compound classes with an array of isomers that are challenging to separate and identify. Traditional one-dimensional (1D) gas chromatographic (GC) techniques achieved impressive results in the past, but have reached limitations in many cases. Comprehensive two-dimensional gas chromatography (GC × GC) either coupled to a flame ionization detector (GC × GC-FID) or time-of-flight mass spectrometer (GC × GC-TOFMS) is a powerful tool to overcome the challenges of 1D GC, such as the resolution of unresolved complex mixture (UCM). We studied a number of Tertiary, terrigenous oils, and source rocks from the Arctic and Southeast Asia, with special focus on angiosperm biomarkers, such as oleanoids and lupanoids. Different chromatographic separation and detection techniques such as traditional 1D GC-MS, metastable reaction monitoring (GC-MRM-MS), GC × GC-FID, and GC × GC-TOFMS are compared and applied to evaluate the differences and advantages in their performance for biomarker identification. The measured 22S/(22S + 22R) homohopane ratios for all applied techniques were determined and compare exceptionally well (generally between 2% and 10%). Furthermore, we resolved a variety of angiosperm-derived compounds that co-eluted using 1D GC techniques, demonstrating the superior separation power of GC × GC for these biomarkers, which indicate terrigenous source input and Cretaceous or younger ages. Samples of varying thermal maturity and biodegradation contain higher plant biomarkers from various stages of diagenesis and catagenesis, which can be directly assessed in a GC × GC chromatogram. The analysis of whole crude oils and rock extracts without loss in resolution enables the separation of unstable compounds that are prone to rearrangement (e.g. unsaturated triterpenoids such as taraxer-14-ene) when exposed to fractionation techniques like molecular sieving. GC × GC-TOFMS is particularly valuable for the successful separation of

Selective and comprehensive analysis of organohalogen compounds by GC × GC-HRTofMS and MS/MS.

PubMed

Hashimoto, Shunji; Zushi, Yasuyuki; Takazawa, Yoshikatsu; Ieda, Teruyo; Fushimi, Akihiro; Tanabe, Kiyoshi; Shibata, Yasuyuki

2018-03-01

Thousands of organohalogen compounds, including hazardous chemicals such as polychlorinated biphenyls (PCBs) and other persistent organic pollutants (POPs), were selectively and simultaneously detected and identified with simple, or no, purification from environmental sample extracts by using several advanced methods. The methods used were software extraction from two-dimensional gas chromatography-high-resolution time-of-flight mass spectrometry (GC × GC-HRTofMS) data, measurement by negative chemical ionization with HRTofMS, and neutral loss scanning (NLS) with GC × GC-MS/MS. Global and selective detection of organochlorines and bromines in environmental samples such as sediments and fly ash was achieved by NLS using GC × GC-MS/MS (QQQ), with the expected losses of 35 Cl and 79 Br. We confirmed that negative chemical ionization was effective for sensitive and selective ionization of organohalogens, even using GC × GC-HRTofMS. The 2D total ion chromatograms obtained by using negative chemical ionization and selective extraction of organohalogens using original software from data measured by electron impact ionization were very similar; the software thus functioned well to extract organohalogens. Combining measurements made by using these different methods will help to detect organohalogens selectively and globally. However, to compare the data obtained by individual measurements, the retention times of the peaks on the 2D chromatograms need to match.

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.

GC-MS analysis of bio-active compounds in methanolic extract of Lactuca runcinata DC

PubMed Central

Kanthal, Lakshmi Kanta; Dey, Akalanka; Satyavathi, K.; Bhojaraju, P.

2014-01-01

Background: The presence of phytochemical constitutes has been reported from species of the Compositae (Asteraceae). Hitherto no reports exist on the phytochemical components and biological activity of Lactuca runcinata DC. Objective: The present study was designed to determine the bioactive compounds in the whole plant methanol extract of Lactuca runcinata. Materials and Methods: Phytochemical screening of the entire herb of Lactuca runcinata DC revealed the presence of some bio-active components. Gas chromatography-mass spectrometry (GC-MS) analysis of the whole plant methanol extract of Lactuca runcinata was performed on a GC-MS equipment (Thermo Scientific Co.) Thermo GC-TRACE ultra ver.: 5.0, Thermo MS DSQ II. Results: The phytochemical tests showed the presence of alkaloids, cardiac glycosides, flavonoids, phenols, phlobatannin, reducing sugars, saponins, steroids, tannins, terpenoids, volatile oils, carbohydrates, and protein/amino acids in methanolic extract of L. runcinata. The GC-MS analysis has shown the presence of different phytochemical compounds in the methanolic extract of Lactuca runcinata. A total of 21 compounds were identified representing 84.49% of total methanolic extract composition. Conclusion: From the results, it is evident that Lactuca runcinata contains various phytocomponents and is recommended as a plant of phytopharmaceutical importance. PMID:24497744

Metabolomics driven analysis of six Nigella species seeds via UPLC-qTOF-MS and GC-MS coupled to chemometrics.

PubMed

Farag, Mohamed A; Gad, Haidy A; Heiss, Andreas G; Wessjohann, Ludger A

2014-05-15

Nigella sativa, commonly known as black cumin seed, is a popular herbal supplement that contains numerous phytochemicals including terpenoids, saponins, flavonoids, alkaloids. Only a few of the ca. 15 species in the genus Nigella have been characterized in terms of phytochemical or pharmacological properties. Here, large scale metabolic profiling including UPLC-PDA-MS and GC-MS with further multivariate analysis was utilized to classify 6 Nigella species. Under optimized conditions, we were able to annotate 52 metabolites including 8 saponins, 10 flavonoids, 6 phenolics, 10 alkaloids, and 18 fatty acids. Major peaks in UPLC-MS spectra contributing to the discrimination among species were assigned as kaempferol glycosidic conjugates, with kaempferol-3-O-[glucopyranosyl-(1→2)-galactopyranosyl-(1→2)-glucopyranoside, identified as potential taxonomic marker for N. sativa. Compared with GC-MS, UPLC-MS was found much more efficient in Nigella sample classification based on genetic and geographical origin. Nevertheless, both GC-MS and UPLC-MS support the remote position of Nigella nigellastrum in relation to the other taxa. Copyright © 2013 Elsevier Ltd. All rights reserved.

High Throughput Analytical Techniques for the Determination and Confirmation of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea by GC/MS, GC/MS/MS, and LC/MS/MS: Collaborative Study, First Action 2014.09.

PubMed

Pang, Guo-Fang; Fan, Chun-Lin; Cao, Yan-Zhong; Yan, Fang; Li, Yan; Kang, Jian; Chen, Hui; Chang, Qiao-Ying

2015-01-01

Thirty laboratories from fom North and South America, Europe, and Asia participated in this AOAC collaborative study (15 from China; five from Germany; two each from Italy and the United States; and one each from the Republic of Korea, Canada, Spain, Japan, Belgium, and India). Participants represented government regulatory, commercial testing, university, research institute, and private laboratories. The single-laboratory validated (SLV) tea method was evaluated in the collaborative study to determine the recovery and reproducibility of the method under multilaboratory conditions. Since there were no restrictions regarding the type of analytical instrumentation to use for the analyses, laboratories used a combination of equipment that included GC/MS, GC/MS/MS, and LC/MS/MS instruments from 22 different manufacturers, 21 brands of GC and LC columns, 13 different GC temperature programming profiles, 11 LC gradient elution programs, and six different vendor manufactured SPE cartridges. Even though all the analytical performance parameters for all the 653 compounds had been determined in the SLV study, guidance was obtained from an expert review panel of the AOAC Method-Centric Committee on Pesticide Residues to conduct the multilaboratory collaborative study based on 20 selected compounds that can be analyzed by GC/MS and 20 compounds that can be analyzed by LC/MS/MS. Altogether, 560 samples covering the 40 selected pesticides were analyzed in the study. These samples included green tea and oolong tea samples fortified typically at the European Union maximum residue limit for regulatory guidance and compliance, aged tea samples incurred with 20 pesticides, and green tea and oolong tea samples incurred with five pesticides. The analysis of the 560 samples generated a total of 82 459 test results by the 30 participating laboratories. One laboratory failed to meet the proficiency requirements in the precollaborative study. Therefore, its data submitted for the

Multiple internal standard normalization for improving HS-SPME-GC-MS quantitation in virgin olive oil volatile organic compounds (VOO-VOCs) profile.

PubMed

Fortini, Martina; Migliorini, Marzia; Cherubini, Chiara; Cecchi, Lorenzo; Calamai, Luca

2017-04-01

The commercial value of virgin olive oils (VOOs) strongly depends on their classification, also based on the aroma of the oils, usually evaluated by a panel test. Nowadays, a reliable analytical method is still needed to evaluate the volatile organic compounds (VOCs) and support the standard panel test method. To date, the use of HS-SPME sampling coupled to GC-MS is generally accepted for the analysis of VOCs in VOOs. However, VOO is a challenging matrix due to the simultaneous presence of: i) compounds at ppm and ppb concentrations; ii) molecules belonging to different chemical classes and iii) analytes with a wide range of molecular mass. Therefore, HS-SPME-GC-MS quantitation based upon the use of external standard method or of only a single internal standard (ISTD) for data normalization in an internal standard method, may be troublesome. In this work a multiple internal standard normalization is proposed to overcome these problems and improving quantitation of VOO-VOCs. As many as 11 ISTDs were used for quantitation of 71 VOCs. For each of them the most suitable ISTD was selected and a good linearity in a wide range of calibration was obtained. Except for E-2-hexenal, without ISTD or with an unsuitable ISTD, the linear range of calibration was narrower with respect to that obtained by a suitable ISTD, confirming the usefulness of multiple internal standard normalization for the correct quantitation of VOCs profile in VOOs. The method was validated for 71 VOCs, and then applied to a series of lampante virgin olive oils and extra virgin olive oils. In light of our results, we propose the application of this analytical approach for routine quantitative analyses and to support sensorial analysis for the evaluation of positive and negative VOOs attributes. Copyright © 2017 Elsevier B.V. All rights reserved.

Hair analysis for delta(9)-THC, delta(9)-THC-COOH, CBN and CBD, by GC/MS-EI. Comparison with GC/MS-NCI for delta(9)-THC-COOH.

PubMed

Baptista, Maria João; Monsanto, Paula Verâncio; Pinho Marques, Estela Gouveia; Bermejo, Ana; Avila, Sofia; Castanheira, Alice Martelo; Margalho, Cláudia; Barroso, Mário; Vieira, Duarte Nuno

2002-08-14

A sensitive analytical method was developed for quantitative analysis of delta(9)-tetrahydrocannabinol (delta(9)-THC), 11-nor-delta(9)-tetrahydrocannabinol-carboxylic acid (delta(9)-THC-COOH), cannabinol (CBN) and cannabidiol (CBD) in human hair. The identification of delta(9)-THC-COOH in hair would document Cannabis use more effectively than the detection of parent drug (delta(9)-THC) which might have come from environmental exposure. Ketamine was added to hair samples as internal standard for CBN and CBD. Ketoprofen was added to hair samples as internal standard for the other compounds. Samples were hydrolyzed with beta-glucuronidase/arylsulfatase for 2h at 40 degrees C. After cooling, samples were extracted with a liquid-liquid extraction procedure (with chloroform/isopropyl alcohol, after alkalinization, and n-hexane/ethyl acetate, after acidification), which was developed in our laboratory. The extracts were analysed before and after derivatization with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH) using a Hewlett Packard gas chromatographer/mass spectrometer detector, in electron impact mode (GC/MS-EI). Derivatized delta(9)-THC-COOH was also analysed using a Hewlett Packard gas chromatographer/mass spectrometer detector, in negative ion chemical ionization mode (GC/MS-NCI) using methane as the reagent gas. Responses were linear ranging from 0.10 to 5.00 ng/mg hair for delta(9)-THC and CBN, 0.10-10.00 ng/mg hair for CBD, 0.01-5.00 ng/mg for delta(9)-THC-COOH (r(2)>0.99). The intra-assay precisions ranged from <0.01 to 12.40%. Extraction recoveries ranged from 80.9 to 104.0% for delta(9)-THC, 85.9-100.0% for delta(9)-THC-COOH, 76.7-95.8% for CBN and 71.0-94.0% for CBD. The analytical method was applied to 87 human hair samples, obtained from individuals who testified in court of having committed drug related crimes. Quantification of delta(9)-THC-COOH using GC/MS-NCI was found to be more convenient than GC/MS-EI. The latter may give rise

Biodiesel production from microalgal isolates of southern Pakistan and quantification of FAMEs by GC-MS/MS analysis

PubMed Central

2012-01-01

Background Microalgae have attracted major interest as a sustainable source for biodiesel production on commercial scale. This paper describes the screening of six microalgal species, Scenedesmus quadricauda, Scenedesmus acuminatus, Nannochloropsis sp., Anabaena sp., Chlorella sp. and Oscillatoria sp., isolated from fresh and marine water resources of southern Pakistan for biodiesel production and the GC-MS/MS analysis of their fatty acid methyl esters (FAMEs). Results Growth rate, biomass productivity and oil content of each algal species have been investigated under autotrophic condition. Biodiesel was produced from algal oil by acid catalyzed transesterification reaction and resulting fatty acid methyl esters (FAMEs) content was analyzed by GC/MS. Fatty acid profiling of the biodiesel, obtained from various microalgal oils showed high content of C-16:0, C-18:0, cis-Δ9C-18:1, cis-Δ11C-18:1 (except Scenedesmus quadricauda) and 10-hydroxyoctadecanoic (except Scenedesmus acuminatus). Absolute amount of C-14:0, C-16:0 and C-18:0 by a validated GC-MS/MS method were found to be 1.5-1.7, 15.0-42.5 and 4.2-18.4 mg/g, respectively, in biodiesel obtained from various microalgal oils. Biodiesel was also characterized in terms of cetane number, kinematic viscosity, density and higher heating value and compared with the standard values. Conclusion Six microalgae of local origin were screened for biodiesel production. A method for absolute quantification of three important saturated fatty acid methyl esters (C-14, C-16 and C-18) by gas chromatography-tandem mass spectrometry (GC-MS/MS), using multiple reactions monitoring (MRM) mode, was employed for the identification and quantification of biodiesels obtained from various microalgal oils. The results suggested that locally found microalgae can be sustainably harvested for the production of biodiesel. This offers the tremendous economic opportunity for an energy-deficient nation. PMID:23216896

On-line Analysis of Catalytic Reaction Products Using a High-Pressure Tandem Micro-reactor GC/MS.

PubMed

Watanabe, Atsushi; Kim, Young-Min; Hosaka, Akihiko; Watanabe, Chuichi; Teramae, Norio; Ohtani, Hajime; Kim, Seungdo; Park, Young-Kwon; Wang, Kaige; Freeman, Robert R

2017-01-01

When a GC/MS system is coupled with a pressurized reactor, the separation efficiency and the retention time are directly affected by the reactor pressure. To keep the GC column flow rate constant irrespective of the reaction pressure, a restrictor capillary tube and an open split interface are attached between the GC injection port and the head of a GC separation column. The capability of the attached modules is demonstrated for the on-line GC/MS analysis of catalytic reaction products of a bio-oil model sample (guaiacol), produced under a pressure of 1 to 3 MPa.

Fast, high temperature and thermolabile GC--MS in supersonic molecular beams

NASA Astrophysics Data System (ADS)

Dagan, Shai; Amirav, Aviv

1994-05-01

This work describes and evaluates the coupling of a fast gas chromatograph (GC) based on a short column and high carrier gas flow rate to a supersonic molecular beam mass spectrometer (MS). A 50 cm long megabore column serves for fast GC separation and connects the injector to the supersonic nozzle source. Sampling is achieved with a conventional syringe based splitless sample injection. The injector contains no septum and is open to the atmosphere. The linear velocity of the carrier gas is controlled by a by-pass (make-up) gas flow introduced after the column and prior to the supersonic nozzle. The supersonic expansion serves as a jet separator and the skimmed supersonic molecular beam (SMB) is highly enriched with the heavier organic molecules. The supersonic molecular beam constituents are ionized either by electron impact (EI) or hyperthermal surface ionization (HSI) and mass analyzed. A 1 s fast GC--MS of four aromatic molecules in methanol is demonstrated and some fundamental aspects of fast GC--MS with time limit constraints are outlined. The flow control (programming) of the speed of analysis is shown and the analysis of thermolabile and relatively non-volatile molecules is demonstrated and discussed. The tail-free, fast GC--MS of several mixtures is shown and peak tailing of caffeine is compared with that of conventional GC--MS. The improvement of the peak shapes with the SMB--MS is analyzed with the respect to the elimination of thermal vacuum chamber background. The extrapolated minimum detected amount was about 400 ag of anthracence-d10, with an elution time which was shorter than 2s. Repetitive injections could be performed within less than 10 s. The fast GC--MS in SMB seems to be ideal for fast target compound analysis even in real world, complex mixtures. The few seconds GC--MS separation and quantification of lead (as tetraethyllead) in gasoline, caffeine in coffee, and codeine in a drug is demonstrated. Controlled HSI selectivity is demonstrated in

Origin Discrimination of Osmanthus fragrans var. thunbergii Flowers using GC-MS and UPLC-PDA Combined with Multivariable Analysis Methods.

PubMed

Zhou, Fei; Zhao, Yajing; Peng, Jiyu; Jiang, Yirong; Li, Maiquan; Jiang, Yuan; Lu, Baiyi

2017-07-01

Osmanthus fragrans flowers are used as folk medicine and additives for teas, beverages and foods. The metabolites of O. fragrans flowers from different geographical origins were inconsistent in some extent. Chromatography and mass spectrometry combined with multivariable analysis methods provides an approach for discriminating the origin of O. fragrans flowers. To discriminate the Osmanthus fragrans var. thunbergii flowers from different origins with the identified metabolites. GC-MS and UPLC-PDA were conducted to analyse the metabolites in O. fragrans var. thunbergii flowers (in total 150 samples). Principal component analysis (PCA), soft independent modelling of class analogy analysis (SIMCA) and random forest (RF) analysis were applied to group the GC-MS and UPLC-PDA data. GC-MS identified 32 compounds common to all samples while UPLC-PDA/QTOF-MS identified 16 common compounds. PCA of the UPLC-PDA data generated a better clustering than PCA of the GC-MS data. Ten metabolites (six from GC-MS and four from UPLC-PDA) were selected as effective compounds for discrimination by PCA loadings. SIMCA and RF analysis were used to build classification models, and the RF model, based on the four effective compounds (caffeic acid derivative, acteoside, ligustroside and compound 15), yielded better results with the classification rate of 100% in the calibration set and 97.8% in the prediction set. GC-MS and UPLC-PDA combined with multivariable analysis methods can discriminate the origin of Osmanthus fragrans var. thunbergii flowers. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

High-Throughput Analytical Techniques for the Determination of the Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea, Part VII: A GC-MS, GC-MS/MS, and LC-MS/MS Study of the Degradation Profiles of Pesticide Residues in Green Tea.

PubMed

Chang, Qiao-Ying; Pang, Guo-Fang; Fan, Chun-Lin; Chen, Hui; Yang, Fang; Li, Jie; Wen, Bi-Fang

2016-11-01

GC-MS, GC-tandem MS (MS/MS), and LC-MS/MS were used to mathematically define the degradation profiles of pesticide residues in two field trials. Nineteen pesticides were studied in the first field trial and 11 in the second. The results of the field trials demonstrated that the degradation profiles of pesticide residues in green tea can be described with power functions to successfully estimate the amount of time, following pesticide application, pesticide residues appearing in tea in concentrations at and/or above the maximum residue limit (MRL) decrease to concentrations below the MRL. Stability tests on green tea samples stored at room temperature were conducted to determine whether pesticide-incurred green tea samples prepared according to the method used in the field trials would be suitable for the preparation of reference standards for laboratory-proficiency testing trials. This paper reports the results of a GC-MS, GC-MS/MS, and LC-MS/MS study, as well as the suitability of the samples prepared under these conditions for use as pesticide reference standards in tea analysis.

Environmental and forensic applications of field-portable GC-MS: an overview.

PubMed

Eckenrode, B A

2001-06-01

GC-MS can provide analytical information that is most reliable for many types of organic analyses. As field-portable GC-MS analytical systems evolve, the application scenarios have diversified as well. With the development of rugged fieldable systems, these instruments were demonstrated to be usable in the harsh environment of the jungle and in chemical demilitarization or military reconnaissance situations. Continuous unattended operations of a GC-MS for 12- or 24-hour monitoring applications in the field have been shown to be possible. A real-time algorithm strategy is proposed, which can be developed to aid in the advancement of field-portable mass spectrometry applied to chemical warfare agent analysis in military vehicles and can be used to raise the standard for field data quality. Each of these capabilities is discussed with the intent on reviewing analysis situations that can be expanded because of developments in field GC-MS instrumentation.

Preliminary phytochemical screening, Antibacterial potential and GC-MS analysis of two medicinal plant extracts.

PubMed

Vijayaram, Seerangaraj; Kannan, Suruli; Saravanan, Konda Mani; Vasantharaj, Seerangaraj; Sathiyavimal, Selvam; P, Palanisamy Senthilkumar

2016-05-01

The presence study was aimed to catalyze the primary metabolites and their confirmation by using GC-MS analysis and antibacterial potential of leaf extract of two important medicinal plant viz., Eucalyptus and Azadirachta indica. The antibacterial potential of the methanol leaf extract of the studied species was tested against Escherichia coli, Pseudomonas aeruginosa, Klebsiellap neumoniae, Streptococcus pyogens, Staphylococcus aureus using by agar well diffusion method. The higher zone of inhibition (16mm) was observed against the bacterium Pseudomonas aeruginosa at 100μl concentration of methanol leaf extract. Preliminary phytochemical analysis of studied species shows that presence of phytochemical compounds like steroids, phenolic compounds and flavonoids. GC-MS analysis confirms the occurrence of 20 different compounds in the methanol leaf extract of the both studied species.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF PESTICIDE SAMPLES BY GC/MS (BCO-L-15.1)

EPA Science Inventory

The purpose of this SOP is to describe the methods used for detection and quantification by gas chromatography/mass spectrometry (GC/MS) of pesticides in a variety of matrices, including air, house dust, soil, and handwipes. This analysis involves automated gas GC/MS analysis us...

Control of separation and quantitative analysis by GC-FTIR

NASA Astrophysics Data System (ADS)

Semmoud, A.; Huvenne, Jean P.; Legrand, P.

1992-03-01

Software for 3-D representations of the 'Absorbance-Wavenumber-Retention time' is used to control the quality of the GC separation. Spectral information given by the FTIR detection allows the user to be sure that a chromatographic peak is 'pure.' The analysis of peppermint essential oil is presented as an example. This assurance is absolutely required for quantitative applications. In these conditions, we have worked out a quantitative analysis of caffeine. Correlation coefficients between integrated absorbance measurements and concentration of caffeine are discussed at two steps of the data treatment.

eRah: A Computational Tool Integrating Spectral Deconvolution and Alignment with Quantification and Identification of Metabolites in GC/MS-Based Metabolomics.

PubMed

Domingo-Almenara, Xavier; Brezmes, Jesus; Vinaixa, Maria; Samino, Sara; Ramirez, Noelia; Ramon-Krauel, Marta; Lerin, Carles; Díaz, Marta; Ibáñez, Lourdes; Correig, Xavier; Perera-Lluna, Alexandre; Yanes, Oscar

2016-10-04

Gas chromatography coupled to mass spectrometry (GC/MS) has been a long-standing approach used for identifying small molecules due to the highly reproducible ionization process of electron impact ionization (EI). However, the use of GC-EI MS in untargeted metabolomics produces large and complex data sets characterized by coeluting compounds and extensive fragmentation of molecular ions caused by the hard electron ionization. In order to identify and extract quantitative information on metabolites across multiple biological samples, integrated computational workflows for data processing are needed. Here we introduce eRah, a free computational tool written in the open language R composed of five core functions: (i) noise filtering and baseline removal of GC/MS chromatograms, (ii) an innovative compound deconvolution process using multivariate analysis techniques based on compound match by local covariance (CMLC) and orthogonal signal deconvolution (OSD), (iii) alignment of mass spectra across samples, (iv) missing compound recovery, and (v) identification of metabolites by spectral library matching using publicly available mass spectra. eRah outputs a table with compound names, matching scores and the integrated area of compounds for each sample. The automated capabilities of eRah are demonstrated by the analysis of GC-time-of-flight (TOF) MS data from plasma samples of adolescents with hyperinsulinaemic androgen excess and healthy controls. The quantitative results of eRah are compared to centWave, the peak-picking algorithm implemented in the widely used XCMS package, MetAlign, and ChromaTOF software. Significantly dysregulated metabolites are further validated using pure standards and targeted analysis by GC-triple quadrupole (QqQ) MS, LC-QqQ, and NMR. eRah is freely available at http://CRAN.R-project.org/package=erah .

GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

ERIC Educational Resources Information Center

Henck, Colin; Nally, Luke

2007-01-01

An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

Monitoring industrial wastewater by online GC-MS with direct aqueous injection.

PubMed

Wortberg, M; Ziemer, W; Kugel, M; Müller, H; Neu, H-J

2006-03-01

An online GC-MS-system for automated monitoring of crude wastewater at a complex chemical production site is presented. The modular system is, in principal, based on commercial equipment, but utilizes a special, two-stage injector, which consists of a splitless vaporization chamber on top of a PTV injector filled with Tenax. This set-up enables direct injection of wastewater. Almost 140 volatile and semi-volatile compounds are calibrated down to 1 mg L(-1), which is sufficient for analysis of the influent of the wastewater-treatment plant. Two instruments analyze alternately, every 20 min, and the instrument cycle time is 40 min. The quantitative results are transferred to a database which is connected to a process-control system. Depending on the nature and concentration of a compound, an alarm can be generated and the wastewater stream can be diverted into an "off spec tank" if necessary. The GC-MS-system operates quasi-continuously with a system availability >98%. Data quality is automatically controlled in each run and by daily analysis of a quality-control sample. The development of a novel stacked PTV-PTV injector design to expand the range of analytes to selected basic compounds is described.

Characterization of Leaf Extracts of Schinus terebinthifolius Raddi by GC-MS and Chemometric Analysis

PubMed Central

Carneiro, Fabíola B.; Lopes, Pablo Q.; Ramalho, Ricardo C.; Scotti, Marcus T.; Santos, Sócrates G.; Soares, Luiz A. L.

2017-01-01

Background: Schinus terebinthifolius Raddi belongs to Anacardiacea family and is widely known as “aroeira.” This species originates from South America, and its extracts are used in folk medicine due to its therapeutic properties, which include antimicrobial, anti-inflammatory, and antipyretic effects. The complexity and variability of the chemical constitution of the herbal raw material establishes the quality of the respective herbal medicine products. Objective: Thus, the purpose of this study was to investigate the variability of the volatile compounds from leaves of S. terebinthifolius. Materials and Methods: The samples were collected from different states of the Northeast region of Brazil and analyzed with a gas chromatograph coupled to a mass spectrometer (GC-MS). The collected data were analyzed using multivariate data analysis. Results: The samples’ chromatograms, obtained by GC-MS, showed similar chemical profiles in a number of peaks, but some differences were observed in the intensity of these analytical markers. The chromatographic fingerprints obtained by GC-MS were suitable for discrimination of the samples; these results along with a statistical treatment (principal component analysis [PCA]) were used as a tool for comparative analysis between the different samples of S. terebinthifolius. Conclusion: The experimental data show that the PCA used in this study clustered the samples into groups with similar chemical profiles, which builds an appropriate approach to evaluate the similarity in the phytochemical pattern found in the different leaf samples. SUMMARY The leave extracts of Schinus terebinthifolius were obtained by turbo-extractionThe extracts were partitioned with hexane and analyzed by GC-MSThe chromatographic data were analyzed using the principal component analysis (PCA)The PCA plots showed the main compounds (phellandrene, limonene, and carene), which were used to group the samples from a different geographical location in

Testing for nandrolone metabolites in urine samples of professional athletes and sedentary subjects by GC/MS/MS analysis.

PubMed

Gambelunghe, Cristiana; Sommavilla, Marco; Rossi, Ruggero

2002-12-01

The concentrations of nandrolone metabolites, 19-norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) were analysed in urine samples of professional athletes doing intense physical activity and sedentary subjects to verify if there was endogenous production of nandrolone and if there was any link between physical effort and the urinary metabolites of the steroid. We collected 18 urine samples from professional footballers age range 20-30 years, all from the same team, and 18 urine samples from males not doing any physical activity, age range 20-30 years. Neither group used nandrolone. Qualitative and quantitative analyses of urinary nandrolone metabolites were carried out by GC/MS followed by GC/MS/MS to confirm positive samples. This technique has been demonstrated to be an excellent analytical approach for the determination of anabolic steroids at very low detection limits in complex matrices such as urine. In five urine samples from professional footballers traces of 19-NA were detected. No trace of 19-NA was found in the group of sedentary subjects and no trace of 19-NE was found in any urine sample. The absence of nandrolone metabolites in sedentary subjects supports the hypothesis that the presence of 19-NA and 19-NE could be linked to physical effort even though the origin is not yet clear. Copyright 2002 John Wiley & Sons, Ltd.

Application of GC/MS Soft Ionization for Isomeric Biological Compound Analysis.

PubMed

Furuhashi, Takeshi; Okuda, Koji

2017-09-03

Isomers are compounds with the same molecular formula. Many different types of isomers are ubiquitous and play important roles in living organisms. Despite their early discovery, the actual analysis of isomers has been tricky and has confounded researchers. Using mass spectrometry (MS) to distinguish or identify isomers is an emergent topic and challenge for analytical chemists. We review some techniques for analyzing isomers with emphasis on MS, e.g., the roles of ion reaction, hydrogen-deuterium exchange, ion mobility mass spectrometry, ion spectroscopy, and energy change in producing isomer-specific fragments. In particular, soft ionization for gas chromatography-mass spectrometry (GC-MS) is a focus in this review. Awareness of the advantages and technical problems of these techniques would inspire innovation in future approaches.

GC-MS quantitative analysis of black market pharmaceutical products containing anabolic androgenic steroids seized by the Brazilian Federal Police.

PubMed

Neves, Diana Brito da Justa; Caldas, Eloisa Dutra

2017-06-01

The use of counterfeit or substandard medicines can have an important health impact, resulting in therapeutic failure, be toxic or even cause death. Anabolic steroids are a frequent target for counterfeiters worldwide, being the second most frequent counterfeited class in Brazil. The aims of this work were to optimize and validate a GC-MS method for the quantitative determination of anabolic steroids in tablet, aqueous suspension and oil solution forms, and to analyze pharmaceutical products sent to Brazilian Federal Police (BFP) for forensic analysis. Sample preparation included extraction with methanol in ultrasonic bath followed by centrifugation. The method was successfully validated and 345 samples of pharmaceutical products were analyzed (328 medicines and 17 dietary supplements). About 42% of the medicines were counterfeits, 28.7% of tablets, 12.0% of suspensions and 65.2% of oil solutions; 11% were considered substandards. Five dietary supplements contained undeclared anabolic steroids, including two containing methandrostenolone at 5.4 and 5.8mg/capsule, equivalent to levels found in medicines. The proposed method is suitable for implementation in routine analysis for identification of counterfeits and substandard products. The analytical results show the need to raise awareness of consumers over the risks from the consumption of anabolic steroids from the clandestine market and for more incisive actions from government agencies aiming at decreasing the availability of these products. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Propofol by GC/MS and Fast GC/MS-TOF in Two Cases of Poisoning.

PubMed

Procaccianti, Paolo; Farè, Fiorenza; Argo, Antonella; Casagni, Eleonora; Arnoldi, Sebastiano; Facheris, Sara; Visconti, Giacomo Luca; Roda, Gabriella; Gambaro, Veniero

2017-11-01

Two cases of suspected acute and lethal intoxication caused by propofol were delivered by the judicial authority to the Department of Sciences for Health Promotion and Mother-Child Care in Palermo, Sicily. In the first case a female nurse was found in a hotel room, where she lived with her mother; four 10 mg/mL vials and two 20 mg/mL vials of propofol were found near the decedent along with syringes and needles. In the second case a male nurse was found in the operating room of a hospital, along with a used syringe. In both cases a preliminary systematic and toxicological analysis indicated the presence of propofol in the blood and urine. As a result, a method for the quantitative determination of propofol in biological fluids was optimized and validated using a liquid-liquid extraction protocol followed by GC/MS and fast GC/MS-TOF. In the first case, the concentration of propofol in blood was determined to be 8.1 μg/mL while the concentration of propofol in the second case was calculated at 1.2 μg/mL. Additionally, the tissue distribution of propofol was determined for both cases. Brain and liver concentrations of propofol were, respectively, 31.1 and 52.2 μg/g in Case 1 and 4.7 and 49.1 μg/g in Case 2. Data emerging from the autopsy findings, histopathological exams as well as the toxicological results aided in establishing that the deaths were due to poisoning, however, the manner of death in each were different: homicide in Case 1 and suicide in Case 2. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Puzzling Alcohol Dehydration Reaction Solved by GC-MS Analysis

NASA Astrophysics Data System (ADS)

Pelter, Michael W.; Macudzinski, Rebecca M.

1999-06-01

We have adapted the dehydration of 2-methyl-2-propanol to a "puzzle" approach for use in our second-semester chemistry major organic laboratory. The reaction of 2-methyl-2-propanol with ~50% sulfuric acid at 100 °C yields isobutylene, which reacts further by a "puzzling" reaction. By coupling the GC/MS analysis of the product mixture with their knowledge of the mechanism of alcohol dehydration and alkene reactivity, students are able to identify the major products of this reaction.

A fast and reliable method for GHB quantitation in whole blood by GC-MS/MS (TQD) for forensic purposes.

PubMed

Castro, André L; Tarelho, Sónia; Dias, Mário; Reis, Flávio; Teixeira, Helena M

2016-02-05

Gamma-hydroxybutyric acid (GHB) is an endogenous compound with a story of clinical use since the 1960s. However, due to its secondary effects, it has become a controlled substance, entering the illicit market. A fully validated, sensitive and reproducible method for the quantification of GHB by methanolic precipitation and GC-MS/MS (TQD) in whole blood is presented. Using 100μL of whole blood, obtained results included a LOD and LLOQ of 0.1mg/L and a recovery of 86% in a working range between 0.1 and 100mg/L. This method is sensitive and specific to detect the presence of GHB in small amounts of whole blood (both ante-mortem or post-mortem), and is, to the authors' knowledge, the first GC-MS-MS TQD method that uses different precursor ions and product ions for the identification of GHB and GHB-D6 (internal standard). Hence, this method may be especially useful for the study of endogenous values in this biological sample. Copyright © 2015 Elsevier B.V. All rights reserved.

Investigation of Imposter Perfumes Using GC-MS

ERIC Educational Resources Information Center

Mowery, Kelly A.; Blanchard, Daniel E.; Smith, Stephanie; Betts, Thomas A.

2004-01-01

An experiment to initiate students into several features of gas chromatograph-mass spectrometers (GC-MS) through the study of branded and counterfeit perfumes is described. The experiment enables the students to appreciate the power of GC-MS in distinguishing between original and imitation perfumes, and in analyzing data with its application…

Pesticide residues in cashew apple, guava, kaki and peach: GC-μECD, GC-FPD and LC-MS/MS multiresidue method validation, analysis and cumulative acute risk assessment.

PubMed

Jardim, Andréia Nunes Oliveira; Mello, Denise Carvalho; Goes, Fernanda Caroline Silva; Frota Junior, Elcio Ferreira; Caldas, Eloisa Dutra

2014-12-01

A multiresidue method for the determination of 46 pesticides in fruits was validated. Samples were extracted with acidified ethyl acetate, MgSO4 and CH3COONa and cleaned up by dispersive SPE with PSA. The compounds were analysed by GC-FPD, GC-μECD or LC-MS/MS, with LOQs from 1 to 8 μg/kg. The method was used to analyse 238 kaki, cashew apple, guava, and peach fruit and pulp samples, which were also analysed for dithiocarbamates (DTCs) using a spectrophotometric method. Over 70% of the samples were positive, with DTC present in 46.5%, λ-cyhalothrin in 37.1%, and omethoate in 21.8% of the positive samples. GC-MS/MS confirmed the identities of the compounds detected by GC. None of the pesticides found in kaki, cashew apple and guava was authorised for these crops in Brazil. The risk assessment has shown that the cumulative acute intake of organophosphorus or pyrethroid compounds from the consumption of these fruits is unlikely to pose a health risk to consumers. Copyright © 2014 Elsevier Ltd. All rights reserved.

The MetabolomeExpress Project: enabling web-based processing, analysis and transparent dissemination of GC/MS metabolomics datasets.

PubMed

Carroll, Adam J; Badger, Murray R; Harvey Millar, A

2010-07-14

Standardization of analytical approaches and reporting methods via community-wide collaboration can work synergistically with web-tool development to result in rapid community-driven expansion of online data repositories suitable for data mining and meta-analysis. In metabolomics, the inter-laboratory reproducibility of gas-chromatography/mass-spectrometry (GC/MS) makes it an obvious target for such development. While a number of web-tools offer access to datasets and/or tools for raw data processing and statistical analysis, none of these systems are currently set up to act as a public repository by easily accepting, processing and presenting publicly submitted GC/MS metabolomics datasets for public re-analysis. Here, we present MetabolomeExpress, a new File Transfer Protocol (FTP) server and web-tool for the online storage, processing, visualisation and statistical re-analysis of publicly submitted GC/MS metabolomics datasets. Users may search a quality-controlled database of metabolite response statistics from publicly submitted datasets by a number of parameters (eg. metabolite, species, organ/biofluid etc.). Users may also perform meta-analysis comparisons of multiple independent experiments or re-analyse public primary datasets via user-friendly tools for t-test, principal components analysis, hierarchical cluster analysis and correlation analysis. They may interact with chromatograms, mass spectra and peak detection results via an integrated raw data viewer. Researchers who register for a free account may upload (via FTP) their own data to the server for online processing via a novel raw data processing pipeline. MetabolomeExpress https://www.metabolome-express.org provides a new opportunity for the general metabolomics community to transparently present online the raw and processed GC/MS data underlying their metabolomics publications. Transparent sharing of these data will allow researchers to assess data quality and draw their own insights from published

GC-MS and LC-MS approaches for determination of tocopherols and tocotrienols in biological and food matrices.

PubMed

Bartosińska, E; Buszewska-Forajta, M; Siluk, D

2016-08-05

Tocopherols and tocotrienols, widely described as vitamin E derivatives, have been proven to take part in a number of important biological functions. Among them, antioxidant properties had been investigated and documented in the literature. Since tocochromanols have revealed their plausible beneficial impact on several pathological processes, such as cancerogenesis or cognitive impairment diseases, there is a growing interest in quantitative determination of these compounds in biological fluids, tissues and plant organs. However, due to vitamin E chemical features, such as lipophilic and non-polar characteristics, quantitative determination of the compounds seems to be problematic. In this paper we present current analytical approaches in tocopherols and tocotrienols determination in biological and food matrices with the use of chromatographic techniques, especially gas chromatography (GC) and high performance liquid chromatography (HPLC) coupled with mass spectrometry. Derivatization techniques applied for GC-MS analysis in the case of tocol derivatives, especially silylation and acylation, are described. Significant attention is paid to ionization process of tocopherols and tocotrienols. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection of the Spermicide Nonoxynol-9 Via GC-MS

NASA Astrophysics Data System (ADS)

Musah, Rabi A.; Vuong, Angela L.; Henck, Colin; Shepard, Jason R. E.

2012-05-01

The spermicide nonoxynol-9 is actually a complex mixture of dozens of closely related amphiphilic compounds, and the chemical properties of this assortment significantly hamper its characterization by GC-MS. The inability to perform routine GC-MS testing on nonoxynol-9 has limited its evidentiary value in forensic casework, which relies heavily on this technique for analysis. A disturbing trend in sexual assault is the use of condoms by assailants, to avoid leaving behind DNA evidence that can connect a perpetrator to a victim. This observation necessitates the development of alternative methods for the analysis of trace evidence that can show causal links between a victim and a suspect. Detection of lubricants associated with sexual assault is one such way to establish this connection. The development of GC-MS methods that permit facile detection of both nonoxynol-9 alone and nonoxynol-9 extracted from other complex matrices that have potential as trace evidence in sexual assault is reported. A detection limit of 2.14 μg of nonoxynol-9 is demonstrated, and a detailed mass spectral profile that elaborates on what is known of its structure is provided.

N,N-Dimethyltryptamine and dichloromethane: rearrangement of quaternary ammonium salt product during GC-EI and CI-MS-MS analysis.

PubMed

Brandt, Simon D; Martins, Cláudia P B; Freeman, Sally; Dempster, Nicola; Wainwright, Mark; Riby, Philip G; Alder, John F

2008-05-12

N,N-Dimethyltryptamine (DMT) 1 is a simple tryptamine derivative with powerful psychoactive properties. It is abundant in nature and easily accessible through a variety of synthetic routes. Most work-up procedures require the use of organic solvents and halogenated representatives are often employed. DMT was found to be reactive towards dichloromethane, either during work-up or long term storage therein, which led to the formation of the quaternary ammonium salt N-chloromethyl-DMT chloride 2. Analysis of this side-product by gas chromatography ion trap mass spectrometry (GC-MS), both in electron and chemical ionisation tandem MS modes, gave only degradation products. For example, 2 could not be detected but appeared to have rearranged to 3-(2-chloroethyl)indole 3 and 2-methyltetrahydro-beta-carboline 4, whereas HPLC analysis enabled the detection of 2. GC-MS is a standard tool for the fingerprinting of drug products. The identification of a particular synthetic route is based on the analysis of impurities, provided these side products can be established to be route-specific. The in situ detection of both 3 and 4 within a DMT sample may have led to erroneous conclusions with regards to the identification of the synthetic route.

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

PubMed

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Volatile and key odourant compounds of Turkish Berberis crataegina fruit using GC-MS-Olfactometry.

PubMed

Sonmezdag, Ahmet Salih; Kelebek, Hasim; Selli, Serkan

2018-04-01

This research was conducted to identify the aroma and aroma-active compounds of Berberis crataegina for the first time. Volatile profile of B. crataegina was obtained using the purge and trap extraction method with dichloromethane. Gas chromatography was coupled to mass spectrometry (GC-MS) allowed the quantitative and qualitative detection of 22 compounds in the sample. Aldehydes were the main chemical group in the sample and followed by aromatic alcohols and lactone. Aroma extract dilution analysis was implemented for the specification of key odourants of B. crataegina. In total, eight key odourants were detected in the extract of the sample, using GC-MS-Olfactometry and aldehydes were the leading chemical group. The key odourants, found to be contributing to the overall aroma in B. crataegina, were nonanal (FD = 1024; green, flowery), hexanal (FD = 512; green) and linalool (FD = 256; flowery, rose) because of high FD factors.

AUTOMATED SOLID PHASE EXTRACTION GC/MS FOR ANALYSIS OF SEMIVOLATILES IN WATER AND SEDIMENTS

EPA Science Inventory

Data is presented on the development of a new automated system combining solid phase extraction (SPE) with GC/MS spectrometry for the single-run analysis of water samples containing a broad range of organic compounds. The system uses commercially available automated in-line sampl...

GC/MS Analysis of the Essential Oil of Vernonia cinerea.

PubMed

Joshi, Rajesh K

2015-07-01

The hydro-distilled essential oil obtained from the roots of V. cinerea Less. (Asteraceae) was investigated by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Twenty-five constituents were identified, which represented 97.4% of the total oil. The major compounds were α-muurolene (30.7%), β-caryophyllene (9.6%), α-selinene (8.7%), cyperene (6.7%) and α-gurjunene (6.5%). The essential oil was dominated by sesquiterpene hydrocarbons (87.8%).

Analysis of Volatile Fragrance and Flavor Compounds by Headspace Solid Phase Microextraction and GC-MS: An Undergraduate Instrumental Analysis Experiment

NASA Astrophysics Data System (ADS)

Galipo, Randolph C.; Canhoto, Alfredo J.; Walla, Michael D.; Morgan, Stephen L.

1999-02-01

A senior-level undergraduate laboratory experiment that demonstrates the use of solid-phase microextraction (SPME) and capillary gas chromatography-mass spectrometry (GC-MS) was developed for the identification of volatile compounds in consumer products. SPME minimizes sample preparation and concentrates volatile analytes in a solvent-free manner. Volatile flavor and fragrance compounds were extracted by SPME from the headspace of vials containing shampoos, chewing gums, and perfumes and analyzed by GC-MS. Headspace SPME was shown to be more sensitive than conventional headspace analysis of similar samples performed with an airtight syringe. Analysis times were less than 30 min, allowing multiple analyses to be performed in a typical laboratory class period.

Integrated metabolomic profiling of hepatocellular carcinoma in hepatitis C cirrhosis through GC/MS and UPLC/MS-MS.

PubMed

Fitian, Asem I; Nelson, David R; Liu, Chen; Xu, Yiling; Ararat, Miguel; Cabrera, Roniel

2014-10-01

The metabolic pathway disturbances associated with hepatocellular carcinoma (HCC) remain unsatisfactorily characterized. Determination of the metabolic alterations associated with the presence of HCC can improve our understanding of the pathophysiology of this cancer and may provide opportunities for improved disease monitoring of patients at risk for HCC development. To characterize the global metabolic alterations associated with HCC arising from hepatitis C (HCV)-associated cirrhosis using an integrated non-targeted metabolomics methodology employing both gas chromatography/mass spectrometry (GC/MS) and ultrahigh-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC/MS-MS). The global serum metabolomes of 30 HCC patients, 27 hepatitis C cirrhosis disease controls and 30 healthy volunteers were characterized using a metabolomics approach that combined two metabolomics platforms, GC/MS and UPLC/MS-MS. Random forest, multivariate statistics and receiver operator characteristic analysis were performed to identify the most significantly altered metabolites in HCC patients vs. HCV-cirrhosis controls and which therefore exhibited a close association with the presence of HCC. Elevated 12-hydroxyeicosatetraenoic acid (12-HETE), 15-HETE, sphingosine, γ-glutamyl oxidative stress-associated metabolites, xanthine, amino acids serine, glycine and aspartate, and acylcarnitines were strongly associated with the presence of HCC. Elevations in bile acids and dicarboxylic acids were highly correlated with cirrhosis. Integrated metabolomic profiling through GC/MS and UPLC/MS-MS identified global metabolic disturbances in HCC and HCV-cirrhosis. Aberrant amino acid biosynthesis, cell turnover regulation, reactive oxygen species neutralization and eicosanoid pathways may be hallmarks of HCC. Aberrant dicarboxylic acid metabolism, enhanced bile acid metabolism and elevations in fibrinogen cleavage peptides may be signatures of cirrhosis. © 2014 John

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.

Determination of residual solvents in pharmaceuticals by thermal desorption-GC/MS.

PubMed

Hashimoto, K; Urakami, K; Fujiwara, Y; Terada, S; Watanabe, C

2001-05-01

A novel method for the determination of residual solvents in pharmaceuticals by thermal desorption (TD)-GC/MS has been established. A programmed temperature pyrolyzer (double shot pyrolyzer) is applied for the TD. This method does not require any sample pretreatment and allows very small amounts of the sample. Directly desorbed solvents from intact pharmaceuticals (ca. 1 mg) in the desorption cup (5 mm x 3.8 mm i.d.) were cryofocused at the head of a capillary column prior to a GC/MS analysis. The desorption temperature was set at a point about 20 degrees C higher than the melting point of each sample individually, and held for 3 min. The analytical results using 7 different pharmaceuticals were in agreement with those obtained by direct injection (DI) of the solution, followed by USP XXIII. This proposed TD-GC/MS method was demonstrated to be very useful for the identification and quantification of residual solvents. Furthermore, this method was simple, allowed rapid analysis and gave good repeatability.

Quantification of Neural Ethanol and Acetaldehyde Using Headspace GC-MS

PubMed Central

Heit, Claire; Eriksson, Peter; Thompson, David C; Fritz, Kristofer S; Vasiliou, Vasilis

2016-01-01

BACKGROUND There is controversy regarding the active agent responsible for alcohol addiction. The theory that ethanol itself was the agent in alcohol drinking behavior was widely accepted until acetaldehyde was found in the brain. The importance of acetaldehyde formation in the brain role is still subject to speculation due to the lack of a method to accurately assay the acetaldehyde levels directly. A highly sensitive GC-MS method to reliably determine acetaldehyde concentration with certainty is needed to address whether neural acetaldehyde is indeed responsible for increased alcohol consumption. METHODS A headspace gas chromatograph coupled to selected ion monitoring mass spectrometry was utilized to develop a quantitative assay for acetaldehyde and ethanol. Our GC-MS approach was carried out using a Bruker Scion 436-GC SQ MS. RESULTS Our approach yields limits of detection of acetaldehyde in the nanomolar range and limits of quantification in the low micromolar range. Our linear calibration includes 5 concentrations with a least square regression greater than 0.99 for both acetaldehyde and ethanol. Tissue analyses using this method revealed the capacity to quantify ethanol and acetaldehyde in blood, brain, and liver tissue from mice. CONCLUSIONS By allowing quantification of very low concentrations, this method may be used to examine the formation of ethanol metabolites, specifically acetaldehyde, in murine brain tissue in alcohol research. PMID:27501276

Techniques for quantitative LC-MS/MS analysis of protein therapeutics: advances in enzyme digestion and immunocapture.

PubMed

Fung, Eliza N; Bryan, Peter; Kozhich, Alexander

2016-04-01

LC-MS/MS has been investigated to quantify protein therapeutics in biological matrices. The protein therapeutics is digested by an enzyme to generate surrogate peptide(s) before LC-MS/MS analysis. One challenge is isolating protein therapeutics in the presence of large number of endogenous proteins in biological matrices. Immunocapture, in which a capture agent is used to preferentially bind the protein therapeutics over other proteins, is gaining traction. The protein therapeutics is eluted for digestion and LC-MS/MS analysis. One area of tremendous potential for immunocapture-LC-MS/MS is to obtain quantitative data where ligand-binding assay alone is not sufficient, for example, quantitation of antidrug antibody complexes. Herein, we present an overview of recent advance in enzyme digestion and immunocapture applicable to protein quantitation.

LC-MS/MS and GC-MS methods in propofol detection: Evaluation of the two analytical procedures.

PubMed

Vaiano, Fabio; Serpelloni, Giovanni; Focardi, Martina; Fioravanti, Alessia; Mari, Francesco; Bertol, Elisabetta

2015-11-01

Propofol is a short-acting hypnotic agent that is commonly used to induce and maintain anesthesia. Propofol abuse and its involvement in suicide deaths have increased in recent years, especially among healthcare personnel. An example is the suicide of a 61-year-old nurse found with a propofol drip in his left arm. We describe the postmortem concentration of propofol in various tissues (femoral and cardiac blood, bile, urine, brain, and liver) and in the drip. The toxicological analyses were performed through two analytical methods, differing in derivatization reaction and in instrumentation: silylation for gas chromatograph-mass spectrometer (GC-MS), as routinely performed in our laboratory for this kind of analyses (lower limits of quantification-LLOQ-in urine and blood: 0.3 and 5ng/ml); for liquid chromatograph-tandem mass spectrometer (LC-MS/MS) an innovative azo-coupling derivatization (LLOQ: 0.0004 and 0.1ng/ml). This latter produces an azo-derivative (molecular composition: C18H22ON2; molecular weight: 282Da) highly ionizable in electro-spray ion source, both in negative and positive ionizations. These two methods were compared to evaluate the effectiveness of this new LC-MS/MS analysis. An acidic hydrolysis (HCl 6N, 100°C, and 1h) was performed for the biological samples (1ml or 1g) irrespective of the analytical method applied. The drip content was extracted adding phosphate buffer (pH 8) and a dichloromethane/ethylacetate 8:2 (v:v) mixture. Derivatization steps were: silylation with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)+tetramethylammonium hydroxide (TMAH) for GC-MS; regarding LC-MS/MS, azo-coupling reaction with the aryl-diazonium salt (0-5°C, and 30min). The analyses were achieved in selected-ion monitoring for GC-MS (m/z, 235,250,73 propofol"; m/z, 252,267,27 propofol-d17) and in multiple reaction monitoring ([M-H](-): m/z 283→241,77, azo-propofol; m/z 299→251,77, azo-propofol-d17) for LC-MS/MS. Autopsy showed no significant findings

Analysis of residual monomers in dendritic methacrylate copolymers and composites by HPLC and headspace-GC/MS.

PubMed

Viljanen, Eeva K; Langer, Sarka; Skrifvars, Mikael; Vallittu, Pekka K

2006-09-01

The aim of this study was to analyze the residual monomer content of photopolymerized dendritic methacrylate copolymers and particulate filler composites. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) was compared with high performance liquid chromatography (HPLC). The resin mixtures consisted of a dendritic methacrylate monomer, methyl methacrylate and acetoacetoxyethyl methacrylate in varied proportions. In addition, one of the composites contained 1,4-butanediol dimethacrylate. Camphorquinone and 2-(N,N-dimethylamino)ethyl methacrylate were used as the light-activated initiator system. The content of residual methyl methacrylate and acetoacetoxyethyl methacrylate after 40 s photopolymerization were analyzed with HPLC and HS-GC/MS. The content of residual methyl methacrylate decreased and residual acetoacetoxyethyl methacrylate increased with increasing concentration of acetoacetoxyethyl methacrylate in the resin mixture. The results with both methods had the same trend. The addition of acetoacetoxyethyl methacrylate enhanced the copolymerization of methyl methacrylate, but did not decrease the total residual monomer content. The HS-GC/MS method was found to be a feasible method in the analysis of low-boiling residuals in dental polymers.

[In-situ measurement of background atmospheric HCFC-142b using GC-MS and GC-ECD method].

PubMed

Guo, Li-feng; Yao, Bo; Zhou, Ling-xi; Li, Pei-chang; Xu, Lin

2013-05-01

Custom-made GC-MS and GC-ECD in-situ measurement systems were established at the Shangdianzi GAW Regional station. From May 2010 to May 2011, the precisions for GC-MS and GC-ECD systems were 0.23% and 0.88%, respectively, and the HCFC-142b mole fraction during the observation period ranged from 21 x 10(-12) to 355 x 10(-12). The result of the independent-sample T test was P > 0.05, and there was no significant difference in HCFC-142b mole fraction measured by the two systems. The small difference of HCFC-142b mole fraction measured by GC-MS and GC-ECD might be associated with the different sampling time and precision of the two systems. A statistical filter of "robust local regression" was applied to separate HCFC-142b background and pollution data. The mean difference, median difference, 25 and 75 percent difference of background data measured by GC-MS and GC-ECD were all within the precisions. The pollution events captured by the two systems showed similar characters. Results from both systems showed a higher HCFC-142b level in summer and autumn than in winter. The pollution mole fraction of the two systems showed similar seasonal changes.

Effective and sensitive determination of eleven disinfection byproducts in drinking water by DLLME and GC-MS.

PubMed

On, Jiwon; Pyo, Heesoo; Myung, Seung-Woon

2018-10-15

The aim of this study was to optimize the dispersive liquid-liquid microextraction (DLLME) parameters for simultaneous analysis through DLLME-gas chromatography-mass spectrometry (GC-MS) of six iodo-trihalomethanes, four haloacetonitriles, and one halonitromethane, which are residual disinfection products found in drinking water. Eleven disinfection by-product (DBPs) remaining in aqueous samples were extracted and concentrated using a simple, rapid, and environmentally friendly DLLME method, and then analyzed simultaneously by GC-MS. The optimized DLLME parameters were a sample volume of 5 mL, 100 μL of dichloromethane as the extraction solvent, 1 mL of methanol as the dispersion solvent, an extraction time of 60 s, and 1.5 g of sodium chloride for the salting out effect. The enrichment factor values obtained using the established DLLME-GC-MS method were 19.8-141.5, and the limit of detection and limit of quantification were 0.22-1.19 μg/L and 0.75-3.98 μg/L, respectively. The calibration curves had correlation coefficients (r 2 ) of 0.9958-0.9992 in the concentration range of 0.5-40 μg/L, and they exhibited good linearity in quantitative analysis. This new method could be useful for analyzing eleven DBPs that remain in drinking water. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of vitamins D2 and D3 in selected food matrices by online high-performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS).

PubMed

Nestola, Marco; Thellmann, Andrea

2015-01-01

An online normal-phase liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS) method was developed for the determination of vitamins D2 and D3 in selected food matrices. Transfer of the sample from HPLC to GC was realized by large volume on-column injection; detection was performed with a time-of-flight mass spectrometer (TOF-MS). Typical GC problems in the determination of vitamin D such as sample degradation or sensitivity issues, previously reported in the literature, were not observed. Determination of total vitamin D content was done by quantitation of its pyro isomer based on an isotopically labelled internal standard (ISTD). Extracted ion traces of analyte and ISTD showed cross-contribution, but non-linearity of the calibration curve was not determined inside the chosen calibration range by selection of appropriate quantifier ions. Absolute limits of detection (LOD) and quantitation (LOQ) for vitamins D2 and D3 were calculated as approximately 50 and 150 pg, respectively. Repeatability with internal standard correction was below 2 %. Good agreement between quantitative results of an established high-performance liquid chromatography with UV detection (HPLC-UV) method and HPLC-GC-MS was found. Sterol-enriched margarine was subjected to HPLC-GC-MS and HPLC-MS/MS for comparison, because HPLC-UV showed strong matrix interferences. HPLC-GC-MS produced comparable results with less manual sample cleanup. In summary, online hyphenation of HPLC and GC allowed a minimization in manual sample preparation with an increase of sample throughput.

Results of the First Mars Organic Molecule Analyzer (MOMA) GC-MS Coupling

NASA Astrophysics Data System (ADS)

Buch, Arnaud; Pinnick, Veronica; Szopa, Cyril; Danell, Ryan; Grand, Noel; Van Amerom, Friso; Glavin, Daniel; Freissinet, Caroline; Humeau, Olivier; Coll, Patrice; Arevalo, Ricardo; Stalport, Fabien; Brinckerhoff, William; Steininger, Harald; Goesmann, Fred; Mahaffy, Paul; Raulin, Francois

2014-11-01

The Mars Organic Molecule Analyzer (MOMA) aboard the ExoMars rover will be a key analytical tool in providing chemical (molecular) information from the solid samples collected by the rover, with a particular focus on the char-acterization of the organic content. The core of the MOMA instrument is a gas chromatograph coupled with a mass spectrometer (GC-MS) which provides the unique capability to characterize a broad range of compounds, including both of volatile and non-volatile species. Samples will be crushed and deposited into sample cups seated in a rotating carousel. Soil samples will be analyzed either by UV laser desorption / ionization (LDI) or pyrolysis gas chromatography ion trap mass spectrometry (pyr-GC-ITMS).The French GC brassboard was coupled to the US ion trap mass spectrometer brassboard in a flight-like con-figuration for several coupling campains. The MOMA GC setup is based on the SAM heritage design with a He reservoir and 4 separate analytical modules including traps, columns and Thermal Conductivity Detectors. Solid samples are sealed and heated in this setup using a manual tapping station, designed and built at MPS in Germany, for GC-MS analysis. The gaseous species eluting from the GC are then ionized by an electron impact ionization source in the MS chamber and analyzed by the linear ion trap mass spectrometer. Volatile and non-volatile compounds were injected in the MOMA instrumental suite. Both of these compounds classes were detected by the TCD and by the MS. MS signal (total ion current) and single mass spectra by comparison with the NIST library, gave us an unambiguous confirmation of these identifications. The mass spectra arise from an average of 10 mass spectra averaged around a given time point in the total ion chromatogram.Based on commercial instrument, the MOMA requirement for sensitivity in the GC-MS mode for organic molecules is 1 pmol. In this test, sensitivity was determined for the GC TCD and MS response to a dilution

Extraction of pure components from overlapped signals in gas chromatography-mass spectrometry (GC-MS)

PubMed Central

Likić, Vladimir A

2009-01-01

Gas chromatography-mass spectrometry (GC-MS) is a widely used analytical technique for the identification and quantification of trace chemicals in complex mixtures. When complex samples are analyzed by GC-MS it is common to observe co-elution of two or more components, resulting in an overlap of signal peaks observed in the total ion chromatogram. In such situations manual signal analysis is often the most reliable means for the extraction of pure component signals; however, a systematic manual analysis over a number of samples is both tedious and prone to error. In the past 30 years a number of computational approaches were proposed to assist in the process of the extraction of pure signals from co-eluting GC-MS components. This includes empirical methods, comparison with library spectra, eigenvalue analysis, regression and others. However, to date no approach has been recognized as best, nor accepted as standard. This situation hampers general GC-MS capabilities, and in particular has implications for the development of robust, high-throughput GC-MS analytical protocols required in metabolic profiling and biomarker discovery. Here we first discuss the nature of GC-MS data, and then review some of the approaches proposed for the extraction of pure signals from co-eluting components. We summarize and classify different approaches to this problem, and examine why so many approaches proposed in the past have failed to live up to their full promise. Finally, we give some thoughts on the future developments in this field, and suggest that the progress in general computing capabilities attained in the past two decades has opened new horizons for tackling this important problem. PMID:19818154

Challenges in GC-MS analysis: Case studies on phenibut and ethylphenidate.

PubMed

Lee, Hui Zhi Shirley; Ong, Mei Ching; Lim, Jong Lee Wendy; Yap, Tiong Whei Angeline

2017-08-01

The challenges associated with drug analysis using GC-MS such as thermal degradation, cyclisation or unwanted side reactions causing potential erroneous identification have become evident in view of the high surge in new drugs available in the market. Two case studies illustrated how alternative methods or modifications to existing techniques can help to circumvent the limitations. In the first case study, phenibut which is a GABA analogue, cyclises to 4-phenyl-2-pyrrolidinone under thermal conditions. The identification of phenibut was achieved through derivatisation and identification of its TMS derivative. The second case study, thermal degradation was minimised on drugs of interest methylphenidate and ethylphenidate by reducing the injector port temperature to 200°C and maintaining the GC oven temperature at below 190°C in order to prevent thermal degradation of the drugs of interest. Copyright © 2017 Elsevier B.V. All rights reserved.

Metabolite profiling in Trigonella seeds via UPLC-MS and GC-MS analyzed using multivariate data analyses.

PubMed

Farag, Mohamed A; Rasheed, Dalia M; Kropf, Matthias; Heiss, Andreas G

2016-11-01

Trigonella foenum-graecum is a plant of considerable value for its nutritive composition as well as medicinal effects. This study aims to examine Trigonella seeds using a metabolome-based ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) in parallel to gas chromatography-mass spectrometry (GC-MS) coupled with multivariate data analyses. The metabolomic differences of seeds derived from three Trigonella species, i.e., T. caerulea, T. corniculata, and T. foenum-graecum, were assessed. Under specified conditions, we were able to identify 93 metabolites including 5 peptides, 2 phenolic acids, 22 C/O-flavonoid conjugates, 26 saponins, and 9 fatty acids using UPLC-MS. Several novel dipeptides, saponins, and flavonoids were found in Trigonella herein for the first time. Samples were classified via unsupervised principal component analysis (PCA) followed by supervised orthogonal projection to latent structures-discriminant analysis (OPLS-DA). A distinct separation among the investigated Trigonella species was revealed, with T. foenum-graecum samples found most enriched in apigenin-C-glycosides, viz. vicenins 1/3 and 2, compared to the other two species. In contrast to UPLC-MS, GC-MS was less efficient to classify specimens, with differences among specimens mostly attributed to fatty acyl esters. GC-MS analysis of Trigonella seed extracts led to the identification of 91 metabolites belonging mostly to fatty acyl esters, free fatty acids followed by organic acids, sugars, and amino acids. This study presents the first report on primary and secondary metabolite compositional differences among Trigonella seeds via a metabolomics approach and reveals that, among the species examined, the official T. foenum-graecum presents a better source of Trigonella secondary bioactive metabolites.

[Study on supercritical CO2 extraction of xiaoyaosan and its GC-MS fingerprint].

PubMed

Zuo, Ya-Mei; Tian, Jun-Sheng; Guo, Xiao-Qing; Zhou, Yu-Zhi; Gao, Xiao-Xia; Qin, Xue-Mei

2014-02-01

To determine the optimum conditions of supercritical CO2 extraction of Xiaoyaosan, and establish its fingerprint by gas chromatography-mass spectrometry (GC-MS), the yield of extract were investigated, an orthogonal test was used to quantify the effects of extraction temperature, pressure, CO2 flow rate and time, and fingerprint analysis of different batches of extracts were by GC-MS. The optimal extraction conditions were determined as follows: extraction pressure 20 MPa, extraction temperature 50 degrees C, CO2 flow rate 25 kg x h(-1), extraction time 3 h, and average yield 2.2%. The GC-MS fingerprint was established and 27 common peaks were found, whose contents add up to 81.89% of the total peak area. Among them, 21 compounds were identified, accounting for 53.20% of the total extract. The extraction process is reasonable and favorable for industrial production. The GC-MS method is accurate, reliable, reproducible, and can be used for quality control of supercritical CO2 extract from Xiaoyaosan.

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

A gas chromatography-mass spectrometry (GC-MS) method for the detection and quantitation of monofluoroacetate in plants toxic to livestock

USDA-ARS?s Scientific Manuscript database

Monofluoroacetate (MFA) is a potent toxin that occurs in over 50 plant species in Africa, Australia, and South America and is responsible for significant livestock deaths in these regions. A gas chromatography–mass spectrometry (GC-MS) method for the analysis of MFA in plants based on the derivatiza...

A gas chromatography-mass spectrometry (GC-MS) method for the detection and quantitation of monofluoroacetate in plants toxic to livestock

USDA-ARS?s Scientific Manuscript database

Monofluoroacetate (MFA) is a potent toxin that occurs in over 50 plant species in Africa, Australia, and South America and is responsible for significant livestock deaths in these regions. A gas chromatography–mass spectrometry (GC-MS) method for the analysis of MFA in plants based on the derivatiz...

Comprehensive automation of the solid phase extraction gas chromatographic mass spectrometric analysis (SPE-GC/MS) of opioids, cocaine, and metabolites from serum and other matrices.

PubMed

Lerch, Oliver; Temme, Oliver; Daldrup, Thomas

2014-07-01

The analysis of opioids, cocaine, and metabolites from blood serum is a routine task in forensic laboratories. Commonly, the employed methods include many manual or partly automated steps like protein precipitation, dilution, solid phase extraction, evaporation, and derivatization preceding a gas chromatography (GC)/mass spectrometry (MS) or liquid chromatography (LC)/MS analysis. In this study, a comprehensively automated method was developed from a validated, partly automated routine method. This was possible by replicating method parameters on the automated system. Only marginal optimization of parameters was necessary. The automation relying on an x-y-z robot after manual protein precipitation includes the solid phase extraction, evaporation of the eluate, derivatization (silylation with N-methyl-N-trimethylsilyltrifluoroacetamide, MSTFA), and injection into a GC/MS. A quantitative analysis of almost 170 authentic serum samples and more than 50 authentic samples of other matrices like urine, different tissues, and heart blood on cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine, and 7-aminoflunitrazepam was conducted with both methods proving that the analytical results are equivalent even near the limits of quantification (low ng/ml range). To our best knowledge, this application is the first one reported in the literature employing this sample preparation system.

Enhanced Isotopic Ratio Outlier Analysis (IROA) Peak Detection and Identification with Ultra-High Resolution GC-Orbitrap/MS: Potential Application for Investigation of Model Organism Metabolomes.

PubMed

Qiu, Yunping; Moir, Robyn D; Willis, Ian M; Seethapathy, Suresh; Biniakewitz, Robert C; Kurland, Irwin J

2018-01-18

Identifying non-annotated peaks may have a significant impact on the understanding of biological systems. In silico methodologies have focused on ESI LC/MS/MS for identifying non-annotated MS peaks. In this study, we employed in silico methodology to develop an Isotopic Ratio Outlier Analysis (IROA) workflow using enhanced mass spectrometric data acquired with the ultra-high resolution GC-Orbitrap/MS to determine the identity of non-annotated metabolites. The higher resolution of the GC-Orbitrap/MS, together with its wide dynamic range, resulted in more IROA peak pairs detected, and increased reliability of chemical formulae generation (CFG). IROA uses two different 13 C-enriched carbon sources (randomized 95% 12 C and 95% 13 C) to produce mirror image isotopologue pairs, whose mass difference reveals the carbon chain length (n), which aids in the identification of endogenous metabolites. Accurate m/z, n, and derivatization information are obtained from our GC/MS workflow for unknown metabolite identification, and aids in silico methodologies for identifying isomeric and non-annotated metabolites. We were able to mine more mass spectral information using the same Saccharomyces cerevisiae growth protocol (Qiu et al. Anal. Chem 2016) with the ultra-high resolution GC-Orbitrap/MS, using 10% ammonia in methane as the CI reagent gas. We identified 244 IROA peaks pairs, which significantly increased IROA detection capability compared with our previous report (126 IROA peak pairs using a GC-TOF/MS machine). For 55 selected metabolites identified from matched IROA CI and EI spectra, using the GC-Orbitrap/MS vs. GC-TOF/MS, the average mass deviation for GC-Orbitrap/MS was 1.48 ppm, however, the average mass deviation was 32.2 ppm for the GC-TOF/MS machine. In summary, the higher resolution and wider dynamic range of the GC-Orbitrap/MS enabled more accurate CFG, and the coupling of accurate mass GC/MS IROA methodology with in silico fragmentation has great potential in

Comparative Analysis of Volatile Composition in Chinese Truffles via GC × GC/HR-TOF/MS and Electronic Nose

PubMed Central

Zhang, Ning; Chen, Haitao; Sun, Baoguo; Mao, Xueying; Zhang, Yuyu; Zhou, Ying

2016-01-01

To compare the volatile compounds of Chinese black truffle and white truffle from Yunnan province, this study presents the application of a direct solvent extraction/solvent-assisted flavor evaporation (DSE-SAFE) coupled with a comprehensive two-dimensional gas chromatography (GC × GC) high resolution time-of-flight mass spectrometry (HR-TOF/MS) and an electronic nose. Both of the analytical methods could distinguish the aroma profile of the two samples. In terms of the overall profile of truffle samples in this research, more kinds of acids were detected via the method of DSE-SAFE. Besides, compounds identified in black truffle (BT), but not in white truffle (WT), or vice versa, and those detected in both samples at different levels were considered to play an important role in differentiating the two samples. According to the analysis of electronic nose, the two samples could be separated, as well. PMID:27058524

Rapid analysis of 3,4-methylenedioxymethamphetamine: a comparison of nonaqueous capillary electrophoresis/fluorescence detection with GC/MS.

PubMed

Fang, Ching; Chung, Yu-Lin; Liu, Ju-Tsung; Lin, Cheng-Huang

2002-02-18

Because of the increasing use of 3,4-methylenedioxymethamphetamine (3,4-MDMA), a rapid and sensitive analytical technique is required for its detection and determination. Using nonaqueous capillary electrophoresis/fluorescence spectroscopy (NACE/FS) detection, it is possible to determine this drug at the level 0.5 ppm without any pre-treatment in less than 5 min. After liquid-liquid extraction, the sample can be condensed and a detection limit of 3,4-MDMA in urine of 50 ppb (S/N = 3) can be achieved. The precision of the method was evaluated by measuring the repeatability and intermediate precision of migration time and the corrected peak height by comparison with a 3,4-MDMA-D5 internal standard. With the conventional GC/MS method, it is necessary to derivatize the 3,4-MDMA before injection and the GC migration time also is in excess of 20 min. Therefore, NACE/FS represents a good complementary method to GC/MS for use in forensic analysis.

ADAP-GC 3.0: Improved Peak Detection and Deconvolution of Co-eluting Metabolites from GC/TOF-MS Data for Metabolomics Studies

PubMed Central

Ni, Yan; Su, Mingming; Qiu, Yunping; Jia, Wei

2017-01-01

ADAP-GC is an automated computational pipeline for untargeted, GC-MS-based metabolomics studies. It takes raw mass spectrometry data as input and carries out a sequence of data processing steps including construction of extracted ion chromatograms, detection of chromatographic peak features, deconvolution of co-eluting compounds, and alignment of compounds across samples. Despite the increased accuracy from the original version to version 2.0 in terms of extracting metabolite information for identification and quantitation, ADAP-GC 2.0 requires appropriate specification of a number of parameters and has difficulty in extracting information of compounds that are in low concentration. To overcome these two limitations, ADAP-GC 3.0 was developed to improve both the robustness and sensitivity of compound detection. In this paper, we report how these goals were achieved and compare ADAP-GC 3.0 against three other software tools including ChromaTOF, AnalyzerPro, and AMDIS that are widely used in the metabolomics community. PMID:27461032

ADAP-GC 3.0: Improved Peak Detection and Deconvolution of Co-eluting Metabolites from GC/TOF-MS Data for Metabolomics Studies.

PubMed

Ni, Yan; Su, Mingming; Qiu, Yunping; Jia, Wei; Du, Xiuxia

2016-09-06

ADAP-GC is an automated computational pipeline for untargeted, GC/MS-based metabolomics studies. It takes raw mass spectrometry data as input and carries out a sequence of data processing steps including construction of extracted ion chromatograms, detection of chromatographic peak features, deconvolution of coeluting compounds, and alignment of compounds across samples. Despite the increased accuracy from the original version to version 2.0 in terms of extracting metabolite information for identification and quantitation, ADAP-GC 2.0 requires appropriate specification of a number of parameters and has difficulty in extracting information on compounds that are in low concentration. To overcome these two limitations, ADAP-GC 3.0 was developed to improve both the robustness and sensitivity of compound detection. In this paper, we report how these goals were achieved and compare ADAP-GC 3.0 against three other software tools including ChromaTOF, AnalyzerPro, and AMDIS that are widely used in the metabolomics community.

Comprehensive Urine Drug Screen by Gas Chromatography/Mass Spectrometry (GC/MS).

PubMed

Ramoo, Bheemraj; Funke, Melissa; Frazee, Clint; Garg, Uttam

2016-01-01

Drug screening is an essential component of clinical toxicology laboratory service. Some laboratories use only automated chemistry analyzers for limited screening of drugs of abuse and few other drugs. Other laboratories use a combination of various techniques such as immunoassays, colorimetric tests, and mass spectrometry to provide more detailed comprehensive drug screening. Mass spectrometry, gas or liquid, can screen for hundreds of drugs and is often considered the gold standard for comprehensive drug screening. We describe an efficient and rapid gas chromatography/mass spectrometry (GC/MS) method for comprehensive drug screening in urine which utilizes a liquid-liquid extraction, sample concentration, and analysis by GC/MS.

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…

Analysis of volatiles in fire debris by combination of activated charcoal strips (ACS) and automated thermal desorption-gas chromatography-mass spectrometry (ATD/GC-MS).

PubMed

Martin Fabritius, Marie; Broillet, Alain; König, Stefan; Weinmann, Wolfgang

2018-06-04

Adsorption of volatiles in gaseous phase to activated charcoal strip (ACS) is one possibility for the extraction and concentration of ignitable liquid residues (ILRs) from fire debris in arson investigations. Besides liquid extraction using carbon dioxide or hexane, automated thermo-desorption can be used to transfer adsorbed residues to direct analysis by gas chromatography-mass spectrometry (GC-MS). We present a fire debris analysis work-flow with headspace adsorption of volatiles onto ACS and subsequent automated thermo-desorption (ATD) GC-MS analysis. Only a small portion of the ACS is inserted in the ATD tube for thermal desorption coupled to GC-MS, allowing for subsequent confirmation analysis with another portion of the same ACS. This approach is a promising alternative to the routinely used ACS method with solvent extraction of retained volatiles, and the application to fire debris analysis is demonstrated. Copyright © 2018 Elsevier B.V. All rights reserved.

Validation of an Analytical Method for the Determination of Pesticide Residues in Vine Leaves by GC-MS/MS.

PubMed

Maestroni, Britt; Abu Alnaser, Amer; Ghanem, Iyad; Islam, Marivil; Cesio, Veronica; Heinzen, Horacio; Kelly, Simon; Cannavan, Andrew

2018-06-27

A modified and miniaturized SweEt/QuEChERS method for pesticide residue analysis applied to vine leaves is presented. The deep-frozen plant material was cryogenically processed. A 2 g analytical portion was hydrated for 30 min and extracted with acidified ethyl acetate after buffering with NaHCO 3 and adding Na 2 SO 4 . A dispersive solid-phase (d-SPE) cleanup step with primary-secondary amine (PSA) was performed. The pesticide residues were determined using GC-MS/MS. The whole procedure was validated for 54-59 pesticides at 0.01, 0.02, 0.1, and 0.2 mg/kg in fresh vine leaves ( Vitis vinifera). The key method performance parameters investigated were specificity, linearity, trueness, within laboratory repeatability and reproducibility, limit of detection, limit of quantitation, and matrix effects. Recoveries for the 59 pesticides tested ranged from 60 to 110%, and the RSDs were lower than 20% for the majority of the pesticides studied.

Statistical analysis for improving data precision in the SPME GC-MS analysis of blackberry (Rubus ulmifolius Schott) volatiles.

PubMed

D'Agostino, M F; Sanz, J; Martínez-Castro, I; Giuffrè, A M; Sicari, V; Soria, A C

2014-07-01

Statistical analysis has been used for the first time to evaluate the dispersion of quantitative data in the solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis of blackberry (Rubus ulmifolius Schott) volatiles with the aim of improving their precision. Experimental and randomly simulated data were compared using different statistical parameters (correlation coefficients, Principal Component Analysis loadings and eigenvalues). Non-random factors were shown to significantly contribute to total dispersion; groups of volatile compounds could be associated with these factors. A significant improvement of precision was achieved when considering percent concentration ratios, rather than percent values, among those blackberry volatiles with a similar dispersion behavior. As novelty over previous references, and to complement this main objective, the presence of non-random dispersion trends in data from simple blackberry model systems was evidenced. Although the influence of the type of matrix on data precision was proved, the possibility of a better understanding of the dispersion patterns in real samples was not possible from model systems. The approach here used was validated for the first time through the multicomponent characterization of Italian blackberries from different harvest years. Copyright © 2014 Elsevier B.V. All rights reserved.

EIA and GC/MS analysis of 8-isoprostane in EBC of children with problematic asthma.

PubMed

Carraro, S; Cogo, P E; Isak, I; Simonato, M; Corradi, M; Carnielli, V P; Baraldi, E

2010-06-01

Asthmatic airways are characterised by enhanced oxidative stress, which can be studied by measuring biomarkers, such as 8-isoprostane. The aims of the present study were: 1) to measure the concentrations of 8-isoprostane in exhaled breath condensate (EBC) and urine of children with problematic and well-controlled asthma; 2) to compare the concentrations of 8-isoprostane measured by gas chromatographic/negative ion chemical ionisation mass spectrometry (GC/NICI-MS) and by an enzymatic immunoassay (EIA). We recruited 20 asthmatic allergic children, 13 with well-controlled asthma and seven with problematic asthma. They underwent exhaled nitric oxide measurements and spirometry, and both EBC and urine samples were collected. 8-isoprostane was measured in EBC by GC/NICI-MS and EIA. 8-isoprostane concentrations in EBC were significantly higher in children with problematic asthma than in children with well-controlled asthma (p = 0.01). An acceptable reproducibility emerged between GC/NICI-MS and EIA (coefficient of reproducibility 11.5 pg x mL(-1)). 8-isoprostane levels measured in urine did not correlate with those measured in EBC. We showed that 8-isoprostane in EBC was significantly increased in children with problematic asthma, suggesting a role for oxidative stress in this asthma phenotype. In addition we found an acceptable reproducibility of EIA compared to GC/NICI-MS, even if the latter method had higher accuracy.

Clandestine laboratory scene investigation and processing using portable GC/MS

NASA Astrophysics Data System (ADS)

Matejczyk, Raymond J.

1997-02-01

This presentation describes the use of portable gas chromatography/mass spectrometry for on-scene investigation and processing of clandestine laboratories. Clandestine laboratory investigations present special problems to forensic investigators. These crime scenes contain many chemical hazards that must be detected, identified and collected as evidence. Gas chromatography/mass spectrometry performed on-scene with a rugged, portable unit is capable of analyzing a variety of matrices for drugs and chemicals used in the manufacture of illicit drugs, such as methamphetamine. Technologies used to detect various materials at a scene have particular applications but do not address the wide range of samples, chemicals, matrices and mixtures that exist in clan labs. Typical analyses performed by GC/MS are for the purpose of positively establishing the identity of starting materials, chemicals and end-product collected from clandestine laboratories. Concerns for the public and investigator safety and the environment are also important factors for rapid on-scene data generation. Here is described the implementation of a portable multiple-inlet GC/MS system designed for rapid deployment to a scene to perform forensic investigations of clandestine drug manufacturing laboratories. GC/MS has long been held as the 'gold standard' in performing forensic chemical analyses. With the capability of GC/MS to separate and produce a 'chemical fingerprint' of compounds, it is utilized as an essential technique for detecting and positively identifying chemical evidence. Rapid and conclusive on-scene analysis of evidence will assist the forensic investigators in collecting only pertinent evidence thereby reducing the amount of evidence to be transported, reducing chain of custody concerns, reducing costs and hazards, maintaining sample integrity and speeding the completion of the investigative process.

Headspace GC-MS Analysis of Halogenated Volatile Organic Compounds in Aqueous Samples: An Experiment for General Chemistry Laboratory

ERIC Educational Resources Information Center

Keller, John W.; Fabbri, Cindy E.

2012-01-01

Analysis of halogenated volatile organic compounds (HVOCs) by GC-MS demonstrates the use of instrumentation in the environmental analysis of pollutant molecules and enhances student understanding of stable isotopes in nature. In this experiment, students separated and identified several HVOCs that have been implicated as industrial groundwater…

A characteristic biosignature for discrimination of gastric cancer from healthy population by high throughput GC-MS analysis

PubMed Central

Guo, Lei; Liu, Lei; Wen, Jingran; Xu, Lu; Yan, Min; Li, Zuofeng; Zhang, Xiaoyan; Nan, Peng; Jiang, Jinling; Ji, Jun; Zhang, Jianian; Cai, Wei; Zhuang, Huisheng; Wang, Yan; Zhu, Zhenggang; Yu, Yingyan

2016-01-01

Early diagnosis of gastric cancer is crucial to improve patient′ outcome. A good biomarker will function in early diagnosis for gastric cancer. In order to find practical and cost-effective biomarkers, we used gas chromatography combined mass spectrometer (GC-MS) to profile urinary metabolites on 293 urine samples. Ninety-four samples are taken as training set, others for validating study. Orthogonal partial least squares discriminant analysis (OPLS-DA), significance analysis of microarray (SAM) and Mann-Whitney U test are used for data analysis. The diagnostic value of urinary metabolites was evaluated by ROC curve. As results, Seventeen metabolites are significantly different between patients and healthy controls in training set. Among them, 14 metabolites show diagnostic value better than classic blood biomarkers by quantitative assay on validation set. Ten of them are amino acids and four are organic metabolites. Importantly, proline, p-cresol and 4-hydroxybenzoic acid disclose outcome-prediction value by means of survival analysis. Therefore, the examination of urinary metabolites is a promising noninvasive strategy for gastric cancer screening. PMID:27589838

Effect of Genetics, Environment, and Phenotype on the Metabolome of Maize Hybrids Using GC/MS and LC/MS.

PubMed

Tang, Weijuan; Hazebroek, Jan; Zhong, Cathy; Harp, Teresa; Vlahakis, Chris; Baumhover, Brian; Asiago, Vincent

2017-06-28

We evaluated the variability of metabolites in various maize hybrids due to the effect of environment, genotype, phenotype as well as the interaction of the first two factors. We analyzed 480 forage and the same number of grain samples from 21 genetically diverse non-GM Pioneer brand maize hybrids, including some with drought tolerance and viral resistance phenotypes, grown at eight North American locations. As complementary platforms, both GC/MS and LC/MS were utilized to detect a wide diversity of metabolites. GC/MS revealed 166 and 137 metabolites in forage and grain samples, respectively, while LC/MS captured 1341 and 635 metabolites in forage and grain samples, respectively. Univariate and multivariate analyses were utilized to investigate the response of the maize metabolome to the environment, genotype, phenotype, and their interaction. Based on combined percentages from GC/MS and LC/MS datasets, the environment affected 36% to 84% of forage metabolites, while less than 7% were affected by genotype. The environment affected 12% to 90% of grain metabolites, whereas less than 27% were affected by genotype. Less than 10% and 11% of the metabolites were affected by phenotype in forage and grain, respectively. Unsupervised PCA and HCA analyses revealed similar trends, i.e., environmental effect was much stronger than genotype or phenotype effects. On the basis of comparisons of disease tolerant and disease susceptible hybrids, neither forage nor grain samples originating from different locations showed obvious phenotype effects. Our findings demonstrate that the combination of GC/MS and LC/MS based metabolite profiling followed by broad statistical analysis is an effective approach to identify the relative impact of environmental, genetic and phenotypic effects on the forage and grain composition of maize hybrids.

Review: DNA oxidation, its consequences and efficacy of GC-MS and SPME-GC-MS for In Vitro quantification of DNA oxidative products

NASA Astrophysics Data System (ADS)

Singh, Himansha; Udawat, Abhishek; Franklin, Tony; Sarathi, Sai Partha

2012-10-01

DNA oxidation could be one of the main factors contributing to DNA damage, eventually leading to carcinogenesis, mutations or non-carcinogenic diseases such as Parkinsonís and Alzheimerís. Only recently has the focus turned towards identifying oxidative products of DNA and their consequences. Metabolism activities in vitro produce reactive radicals, which can break DNA strands to cause lesions. These lesions could also act as biomarkers for diagnostic purposes. This review provides an insight of the DNA oxidation mechanism, its harmful consequences and the advantages/disadvantages of available techniques to quantify such DNA oxidative products, focussing mainly on the use GC-MS along with derivatization reaction. In addition, the review also discusses the use of Solid Phase Micro Extraction (SPME) before conducting GC-MS as a potential assay to overcome the discrepancies involved in using GC-MS alone for the identification of DNA oxidative products.

Identification of 11-Nor-delta9-tetrahydrocannabinol-9-carboxylic acid in urine by ion trap GC-MS-MS in the context of doping analysis.

PubMed

Caballero, Gerardo M; D'Angelo, Carlos; Fraguío, Mariá Sol; Centurión, Osvaldo Teme

2004-01-01

The purpose of this study is to develop a sensitive and specific alternative to current gas chromatography (GC)-mass spectrometry (MS) selected ion monitoring confirmation methods of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (cTHC) in human urine samples, in the context of doping analysis. An identification procedure based on the comparison, among suspicious and control samples, of the relative abundances of cTHC selected product ions obtained by GC-tandem MS in an ion trap is presented. The method complies with the identification criteria for qualitative assays established by sports authorities; the comparison procedure is precise, reproducible, specific, and sensitive, thus indicating that it is fit for the purpose of identification accordingly to World Antidoping Agency requirements.

Analysis of inorganic and organic constituents of myrrh resin by GC-MS and ICP-MS: An emphasis on medicinal assets.

PubMed

Ahamad, Syed Rizwan; Al-Ghadeer, Abdul Rahman; Ali, Raisuddin; Qamar, Wajhul; Aljarboa, Suliman

2017-07-01

The aim of the present investigation was to explore the constituents of the Arabian myrrh resin obtained from Commiphora myrrha. The organic and inorganic composition of the myrrh gum resin has been investigated using gas chromatography-mass spectrometry (GC-MS) and inductively coupled plasma-mass spectrometry (ICP-MS). Analysis executed by ICP-MS reveals the presence of various inorganic elements in significant amount in the myrrh resin. The elements that were found to be present in large amounts include calcium, magnesium, aluminum, phosphorus, chlorine, chromium, bromine and scandium. The important organic constituents identified in the myrrh ethanolic extract include limonene, curzerene, germacrene B, isocericenine, myrcenol, beta selinene, and spathulenol,. The present work complements other myrrh associated investigations done in the past and provides additional data for the future researches.

Methods in endogenous steroid profiling - A comparison of gas chromatography mass spectrometry (GC-MS) with supercritical fluid chromatography tandem mass spectrometry (SFC-MS/MS).

PubMed

Teubel, Juliane; Wüst, Bernhard; Schipke, Carola G; Peters, Oliver; Parr, Maria Kristina

2018-06-15

In various fields of endocrinology, the determination of steroid hormones synthesised by the human body plays an important role. Research on central neurosteroids has been intensified within the last years, as they are discussed as biomarkers for various cognitive disorders. Their concentrations in cerebrospinal fluid (CSF) are considered to be regulated independently from peripheral fluids. For that reason, the challenging matrix CSF becomes a very interesting specimen for analysis. Concentrations are expected to be very low and available amount of CSF is limited. Thus, a comprehensive method for very sensitive quantification of a set of analytes as large as possible in one analytical aliquot is desired. However, high structural similarities of the selected panel of 51 steroids and steroid sulfates, including numerous isomers, challenges achievement of chromatographic selectivity. Since decades the analysis of endogenous steroids in various body fluids is mainly performed by gas chromatography (GC) coupled to (tandem) mass spectrometry (MS(/MS)). Due to the structure of the steroids of interest, derivatisation is performed to meet the analytical requirements for GC-MS(/MS). Most of the laboratories use a two-step derivatisation in multi-analyte assays that was already published in the 1980s. However, for some steroids this elaborate procedure yields multiple isomeric derivatives. Thus, some laboratories utilize (ultra) high performance liquid chromatography ((U)HPLC)-MS/MS as alternative but, even UHPLC is not able to separate some of the isomeric pairs. Supercritical fluid chromatography (SFC) as an orthogonal separation technique to GC and (U)HPLC may help to overcome these issues. Within this project the two most promising methods for endogenous steroid profiling were investigated and compared: the "gold standard" GC-MS and the orthogonal separation technique SFC-MS/MS. Different derivatisation procedures for gas chromatographic detection were explored and the

GC/MS determination of amines following exhaustive trifluoroacetylation

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

Thomson, J.S.; Green, J.B.; McWilliams, T.B.

An analytical method for trifluoroacetylation of aromatic amines and GC/MS of the resulting derivatives has been developed. The key feature of the method is its capability to differentiate d tertiary amines; since, using the conditions described in the report, most primary, secondary, an primary amines add two and secondary amines add one trifluoroacetyl group. In general, tertiary amines do not react. Since conventional trifluoroacetylation procedures introduce only a single trifluoroacetyl group into both primary and secondary aminess the procedure reported here improves GC/MS identification of the relatively large number of isomers of nitrogen compounds found in petroleum or similarly complexmore » mixtures. For example, using exhaustive trifluoroacetylation, it is possible to differentiate isomeric forms of C{sub 9}H{sub 11}N (e.g., cyclohexenopyridines, aminoindans, 1,2,3,4-tetrahydroquinoline and tetrahydroisoquinolines). Examples of the application of the method to petroleum and coal liquid products are provided. Because of the limited thermal stability of the derivatives of primary amines, the method is applicable only to distillates boiling below 370{degrees}C (700{degrees}F). To expedite utilization of the method by others, GC retention indices and relative GC/MS total ion current response factors for 102 trifluoroacetyl derivatives are included in the body of the report and their 70 ev mass spectra are reported in Appendix A.« less

Detection of virgin coconut oil adulteration with animal fats using quantitative cholesterol by GC × GC-TOF/MS analysis.

PubMed

Xu, Baocheng; Li, Peiwu; Ma, Fei; Wang, Xiuping; Matthäus, Bertrand; Chen, Ran; Yang, Qingqing; Zhang, Wen; Zhang, Qi

2015-07-01

A new method based on the cholesterol level was developed to detect the presence of animal fats in virgin coconut oil (VCO). In this study, the sterols in VCO and animal fats was separated using conventional one-dimensional gas chromatography (1D GC) and comprehensive two-dimensional gas chromatography (GC×GC). Compared with 1D GC, the GC×GC system could obtain a complete baseline separation of the sterol trimethylsilyl ethers derived from cholesterol and cholestanol, so that the cholesterol content in pure VCO and false VCO adulterated with animal fats could be accurately determined. Cholesterol, a main sterol found in animal fats, represented less than 5mg/kg of VCO. The study demonstrated that the determination of the cholesterol level in VCO could be used for reliable detection of the presence of lard, chicken fat, mutton tallow, beef tallow, or their mixture in VCO at a level as little as 0.25%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Advances in field-portable ion trap GC/MS instrumentation

NASA Astrophysics Data System (ADS)

Diken, Eric G.; Arno, Josep; Skvorc, Ed; Manning, David; Andersson, Greger; Judge, Kevin; Fredeen, Ken; Sadowski, Charles; Oliphant, Joseph L.; Lammert, Stephen A.; Jones, Jeffrey L.; Waite, Randall W.; Grant, Chad; Lee, Edgar D.

2012-06-01

The rapid and accurate detection and identification of chemical warfare agents and toxic industrial chemicals can be critical to the protection of military and civilian personnel. The use of gas chromatography (GC) - mass spectrometry (MS) can provide both the sensitivity and selectivity required to identify unknown chemicals in complex (i.e. real-world) environments. While most widely used as a laboratory-based technique, recent advances in GC, MS, and sampling technologies have led to the development of a hand-portable GC/MS system that is more practical for field-based analyses. The unique toroidal ion trap mass spectrometer (TMS) used in this instrument has multiple benefits related to size, weight, start-up time, ruggedness, and power consumption. Sample separation is achieved in record time (~ 3 minutes) and with high resolution using a state-of-the-art high-performance low-thermal-mass GC column. In addition to providing a system overview highlighting its most important features, the presentation will focus on the chromatographic and mass spectral performance of the system. Results from exhaustive performance testing of the new instrument will be introduced to validate its unique robustness and ability to identify targeted and unknown chemicals.

UPLC-MS/MS quantitative analysis and structural fragmentation study of five Parmotrema lichens from the Eastern Ghats.

PubMed

Kumar, K; Siva, Bandi; Sarma, V U M; Mohabe, Satish; Reddy, A Madhusudana; Boustie, Joel; Tiwari, Ashok K; Rao, N Rama; Babu, K Suresh

2018-07-15

Comparative phytochemical analysis of five lichen species [Parmotrema tinctorum (Delise ex Nyl.) Hale, P. andinum (Mull. Arg.) Hale, P. praesorediosum (Nyl.) Hale, P. grayanum (Hue) Hale, P. austrosinense (Zahlbr.) Hale] of Parmotrema genus were performed using two complementary UPLC-MS systems. The first system consists of high resolution UPLC-QToF-MS/MS spectrometer and the second system consisted of UPLC-MS/MS in Multiple Reaction Monitoring (MRM) mode for quantitative analysis of major constituents in the selected lichen species. The individual compounds (47 compounds) were identified using Q-ToF-MS/MS, via comparison of the exact molecular masses from their MS/MS spectra, the comparison of literature data and retention times to those of standard compounds which were isolated from crude extract of abundant lichen, P. tinctorum. The analysis also allowed us to identify unknown peaks/compounds, which were further characterized by their mass fragmentation studies. The quantitative MRM analysis was useful to have a better discrimination of species according to their chemical profile. Moreover, the determination of antioxidant activities (ABTS + inhibition) and Advance Glycation Endproducts (AGEs) inhibition carried out for the crude extracts revealed a potential antiglycaemic activity to be confirmed for P. austrosinense. Copyright © 2018 Elsevier B.V. All rights reserved.

Unraveling Molecular Differences of Gastric Cancer by Label-Free Quantitative Proteomics Analysis.

PubMed

Dai, Peng; Wang, Qin; Wang, Weihua; Jing, Ruirui; Wang, Wei; Wang, Fengqin; Azadzoi, Kazem M; Yang, Jing-Hua; Yan, Zhen

2016-01-21

Gastric cancer (GC) has significant morbidity and mortality worldwide and especially in China. Its molecular pathogenesis has not been thoroughly elaborated. The acknowledged biomarkers for diagnosis, prognosis, recurrence monitoring and treatment are lacking. Proteins from matched pairs of human GC and adjacent tissues were analyzed by a coupled label-free Mass Spectrometry (MS) approach, followed by functional annotation with software analysis. Nano-LC-MS/MS, quantitative real-time polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry were used to validate dysregulated proteins. One hundred forty-six dysregulated proteins with more than twofold expressions were quantified, 22 of which were first reported to be relevant with GC. Most of them were involved in cancers and gastrointestinal disease. The expression of a panel of four upregulated nucleic acid binding proteins, heterogeneous nuclear ribonucleoprotein hnRNPA2B1, hnRNPD, hnRNPL and Y-box binding protein 1 (YBX-1) were validated by Nano-LC-MS/MS, qRT-PCR, western blot and immunohistochemistry assays in ten GC patients' tissues. They were located in the keynotes of a predicted interaction network and might play important roles in abnormal cell growth. The label-free quantitative proteomic approach provides a deeper understanding and novel insight into GC-related molecular changes and possible mechanisms. It also provides some potential biomarkers for clinical diagnosis.

Characterizing fluorotelomer and polyfluoroalkyl substances in new and aged fluorotelomer-based polymers for degradation studies with GC/MS and LC/MS/MS.

PubMed

Washington, John W; Naile, Jonathan E; Jenkins, Thomas M; Lynch, David G

2014-05-20

Fluorotelomer-based polymers (FTPs), the dominant product of the fluorotelomer industry, are antistaining and antiwetting agents that permeate the products and surfaces of modern society. However, the degree to which these materials expose humans and the environment to fluorotelomer and perfluorinated compounds, including recalcitrant and toxic compounds such as perfluorooctanoic acid (PFOA), is ill-defined. The design intent of FTPs, to minimize interaction with other substances, including solvents, heretofore has stymied efforts to develop robust methods to characterize the content of monomers and associated compounds of new commercial FTPs, as well as commercial FTPs that have been aged in environmental media for degradation testing. Here we show that FTPs can be exhausted of these compounds and quantitated by (i) drying the FTP on a suitable substrate at elevated temperature to achieve low, constant monomer concentrations; (ii) serial extraction with MTBE for fluorotelomer-monomer analysis by GC/MS in PCI mode; followed by (iii) serial extraction with 90/10 ACN/H2O for polyfluorocompound analysis by LC/MS/MS in negative ESI mode. This approach yields exhaustive, internally consistent accounting of monomers and associated compounds for FTPs, either alone or in a soil matrix (representing an environmental medium), for both new and simulated-aged FTPs to allow degradation testing, and for fluorinated compounds at least as long as C12.

Migration from printing inks in multilayer food packaging materials by GC-MS analysis and pattern recognition with chemometrics.

PubMed

Clemente, Isabel; Aznar, Margarita; Nerín, Cristina; Bosetti, Osvaldo

2016-01-01

Inks and varnishes used in food packaging multilayer materials can contain different substances that are potential migrants when packaging is in contact with food. Although printing inks are applied on the external layer, they can migrate due to set-off phenomena. In order to assess food safety, migration tests were performed from two materials sets: set A based on paper and set B based on PET; both contained inks. Migration was performed to four food simulants (EtOH 50%, isooctane, EtOH 95% and Tenax(®)) and the volatile compounds profile was analysed by GC-MS. The effect of presence/absence of inks and varnishes and also their position in the material was studied. A total of 149 volatile compounds were found in migration from set A and 156 from set B materials, some of them came from inks. Quantitative analysis and a principal component analysis were performed in order to identify patterns among sample groups.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

PubMed

Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

2015-09-03

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. Copyright © 2015. Published by Elsevier B.V.

ANTIMICROBIAL AND ANTIBIOFILM EFFECTS OF EXTRACTS FROM TRAPA NATANS L., EVALUATION OF TOTAL PHENOLIC AND FLAVONOID CONTENTS AND GC-MS ANALYSIS.

PubMed

Radojevic, Ivana D; Vasic, Sava M; Dekic, Milan S; Radulovic, Niko S; Delic, Gorica T; Durdevic, Jelena S; Comic, Ljiljana R

2016-11-01

Research conducted in this study shows the applied in vitro antimicrobial and antibiofilm activity of the four extracts isolated from Trapa natans L. leaves. In this study, different methods were used (microdilution, tissue culture plate, different colorimetric methods, GC-FID and GC-MS analysis). While the water extract didn't show antibacterial activity, the acetone extract showed the strongest one. The same activity in the case of Pseudomonas aeruginosa (MIC was 313 μg/mL) was better than the activity of controls and it matched with antibiofilm activity. The effect of extracts was better on G+ bacteria (MICs were <78-625 μg/mL). For ethanol and ethyl acetate extracts all BIC values were better than MICs. Extracts showed a significant effect on Aspergillus restrictus (MICs were < 78/156 μg/mL). The GC and GC-MS analysis of the ethyl acetate extract revealed the identification of 22 compounds with (all E)-squalene (20.2%), n-alkanes and norlignan hinokiresinol among the most abundant ones. This is the first time that T. natans was studied using these methods.

Determination of Urinary PAH Metabolites Using DLLME Hyphenated to Injector Port Silylation and GC-MS-MS.

PubMed

Gupta, Manoj Kumar; Jain, Rajeev; Singh, Pratibha; Ch, Ratnasekhar; Mudiam, Mohana Krishna Reddy

2015-06-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and well-known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure, and there is a need to measure these metabolites at low concentrations. So, a precise and eco-friendly analytical method has been developed for rapid determination of PAH metabolites. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS-MS) analysis is reported for the analysis of seven urinary PAH metabolites. Factors affecting DLLME and IPS, such as type and volume of extraction and disperser solvent, pH, ionic strength, injector port temperature, volume of N,O-bis(trimethylsilyl)trifluoroacetamide and type of solvent were investigated. Under optimized conditions, the limit of detection and limit of quantification were found to be in the range of 1-9 and 3-29 ng/mL, respectively. Satisfactory recoveries of metabolites in urine samples in the range of 87-95% were found. The developed method has been successfully applied for the determination of PAH metabolites in urine samples of exposed workers. DLLME-auto-IPS-GC-MS-MS method is time, labor, solvent and reagent saving, which can be routinely used for the analysis of urinary PAH metabolites. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Experimental design-based isotope-dilution SPME-GC/MS method development for the analysis of smoke flavouring products.

PubMed

Giri, Anupam; Zelinkova, Zuzana; Wenzl, Thomas

2017-12-01

For the implementation of Regulation (EC) No 2065/2003 related to smoke flavourings used or intended for use in or on foods a method based on solid-phase micro extraction (SPME) GC/MS was developed for the characterisation of liquid smoke products. A statistically based experimental design (DoE) was used for method optimisation. The best general conditions to quantitatively analyse the liquid smoke compounds were obtained with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre, 60°C extraction temperature, 30 min extraction time, 250°C desorption temperature, 180 s desorption time, 15 s agitation time, and 250 rpm agitation speed. Under the optimised conditions, 119 wood pyrolysis products including furan/pyran derivatives, phenols, guaiacol, syringol, benzenediol, and their derivatives, cyclic ketones, and several other heterocyclic compounds were identified. The proposed method was repeatable (RSD% <5) and the calibration functions were linear for all compounds under study. Nine isotopically labelled internal standards were used for improving quantification of analytes by compensating matrix effects that might affect headspace equilibrium and extractability of compounds. The optimised isotope dilution SPME-GC/MS based analytical method proved to be fit for purpose, allowing the rapid identification and quantification of volatile compounds in liquid smoke flavourings.

Bromination of Aromatic Compounds by Residual Bromide in Sodium Chloride Matrix Modifier Salt During Heated Headspace GC/MS Analysis

EPA Science Inventory

Analytical artifacts attributed to the bromination of toluene, xylenes, and trimethylbenzenes were found during the heated headspace gas chromatography/mass spectrometry (GC/MS) analysis of aqueous samples. The aqueous samples were produced from Fenton-like chemical oxidation rea...

VOLATILE ORGANO-METALLOIDS IN BIO-SOLID MATERIALS: ANALYSIS BY VACUUM DISTILLATION-GC/MS

EPA Science Inventory

An analytical method based on vacuum distillation-gas chromatography-mass spectrometry (VD-GC-MS)

was developed for determining volatile organo-metalloid contaminants in bio-solid materials. Method

performance was evaluated for dimethylselenide (DMSe), dimethyldisel...

Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry

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

Owens, J; Hok, S; Alcaraz, A

Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limitmore » of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.« less

Preliminary study of urine metabolism in type two diabetic patients based on GC-MS

PubMed Central

Zhang, Ning; Geng, Fang; Hu, Zhong-Hua; Liu, Bin; Wang, Ye-Qiu; Liu, Jun-Cen; Qi, Yong-Hua; Li, Li-Jing

2016-01-01

Objective: Comparative study of type 2 diabetes and healthy controls by metabolomics methods to explore the pathogenesis of Type II diabetes. Methods: Gas chromatography - mass spectrometry (GC-MS) with a variety of multivariate statistical analysis methods to the healthy control group 58 cases, 68 cases of Type II diabetes group were analyzed. Chromatographic conditions: DB-5MS column; the carrier gas He; flow rate of 1 mL·min-1, the injection volume 1 uL; split ratio is 100: 1. MS conditions: electron impact (EI) ion source, an auxiliary temperature of 280°C, the ion source 230°C, quadrupole 150°C; mass scan range 30~600 mAu. Results: Established analytical method based on urine metabolomics GC-MS of Type II diabetes, determine the urine succinic acid, L-leucine, L-isoleucine, tyrosine, slanine, acetoace acid, mannose, L-isoleucine, L-threonine, Phenylalanine, fructose, D-glucose, palmi acid, oleic acid and arachidonic acid were significantly were significantly changed. Conclusion: Based on metabolomics of GC-MS detection and analysis metabolites can be found differences between type 2 diabetes and healthy control group, PCA diagram can effectively distinguish Type II diabetes and healthy control group, with load diagrams and PLS-DA VIP value metabolite screening, the resulting differences in metabolic pathways involved metabolites, including amino acid metabolism, lipid metabolism, glucose metabolism and energy metabolism. PMID:27508010

Bisphenol A release from an orthodontic resin composite: A GC/MS and LC/MS study.

PubMed

Deviot, Marc; Lachaise, Isabelle; Högg, Christof; Durner, Jürgen; Reichl, Franz-Xaver; Attal, Jean-Pierre; Dursun, Elisabeth

2018-02-01

First, to analyse the in vitro release of BPA and Bis-GMA from an orthodontic resin composite (Transbond XT, 3M Unitek), stored in various conditions, by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS); then to extrapolate the data to the clinical situation. Secondly, to explore the thermal stability of Bis-GMA. Cylinders of resin composite were prepared and stored according to 3 different protocols: (1) they were light-cured 20s, then placed in artificial saliva; (2) they were light-cured 2s, then placed in acetonitrile; (3) they were light-cured 2s, then placed in methanol. For each group, BPA and Bis-GMA release were determined with GC/MS and/or LC/MS at least after one week. Besides, 120 brackets (10 of each type) were bonded over metal teeth, then debonded, and the weight and the surface of resin composite residues were measured. BPA and Bis-GMA release of adhesive residues were extrapolated from the data obtained with the cylinders. Besides, BPA release from a heated Bis-GMA solution was measured. With GC/MC, BPA was detected in all samples. With LC/MS, BPA was detected only from samples immersed in MeOH; Bis-GMA was detected, in varying amount according to the extraction media and the light-curing time. BPA was found after heating of the Bis-GMA solution. Contamination risk and the heat applied in GC/MS may overestimate the BPA release from resin composite. Based on the LC/MS results, the risk of BPA release after orthodontic bonding would be more than 42000 times lower than the TDI for a 30-kg child. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Quality evaluation of LC-MS/MS-based E. coli H antigen typing (MS-H) through label-free quantitative data analysis in a clinical sample setup.

PubMed

Cheng, Keding; Sloan, Angela; McCorrister, Stuart; Peterson, Lorea; Chui, Huixia; Drebot, Mike; Nadon, Celine; Knox, J David; Wang, Gehua

2014-12-01

The need for rapid and accurate H typing is evident during Escherichia coli outbreak situations. This study explores the transition of MS-H, a method originally developed for rapid H antigen typing of E. coli using LC-MS/MS of flagella digest of reference strains and some clinical strains, to E. coli isolates in clinical scenario through quantitative analysis and method validation. Motile and nonmotile strains were examined in batches to simulate clinical sample scenario. Various LC-MS/MS batch run procedures and MS-H typing rules were compared and summarized through quantitative analysis of MS-H data output for a standard method development. Label-free quantitative data analysis of MS-H typing was proven very useful for examining the quality of MS-H result and the effects of some sample carryovers from motile E. coli isolates. Based on this, a refined procedure and protein identification rule specific for clinical MS-H typing was established and validated. With LC-MS/MS batch run procedure and database search parameter unique for E. coli MS-H typing, the standard procedure maintained high accuracy and specificity in clinical situations, and its potential to be used in a clinical setting was clearly established. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DETERMINATION OF 16 LARGEST PEAKS IN COMMERCIAL TECHNICAL TOXAPHENE BY GC/MS

EPA Science Inventory

Under typical temperature and high vacuum associated with GC/MS technique, Toxaphene decomposes and produces countless fragments which are impractical to quantify. A GC/MS method has been developed using the lowest possible temperature to resolve more peaks and lower the interfer...

Forensic Drug Identification, Confirmation, and Quantification Using Fully Integrated Gas Chromatography with Fourier Transform Infrared and Mass Spectrometric Detection (GC-FT-IR-MS).

PubMed

Lanzarotta, Adam; Lorenz, Lisa; Voelker, Sarah; Falconer, Travis M; Batson, JaCinta S

2018-05-01

This manuscript is a continuation of a recent study that described the use of fully integrated gas chromatography with direct deposition Fourier transform infrared detection and mass spectrometric detection (GC-FT-IR-MS) to identify and confirm the presence of sibutramine and AB-FUBINACA. The purpose of the current study was to employ the GC-FT-IR portion of the same instrument to quantify these compounds, thereby demonstrating the ability to identify, confirm, and quantify drug substances using a single GC-FT-IR-MS unit. The performance of the instrument was evaluated by comparing quantitative analytical figures of merit to those measured using an established, widely employed method for quantifying drug substances, high performance liquid chromatography with ultraviolet detection (HPLC-UV). The results demonstrated that GC-FT-IR was outperformed by HPLC-UV with regard to sensitivity, precision, and linear dynamic range (LDR). However, sibutramine and AB-FUBINACA concentrations measured using GC-FT-IR were not significantly different at the 95% confidence interval compared to those measured using HPLC-UV, which demonstrates promise for using GC-FT-IR as a semi-quantitative tool at the very least. The most significant advantage of GC-FT-IR compared to HPLC-UV is selectivity; a higher level of confidence regarding the identity of the analyte being quantified is achieved using GC-FT-IR. Additional advantages of using a single GC-FT-IR-MS instrument for identification, confirmation, and quantification are efficiency, increased sample throughput, decreased consumption of laboratory resources (solvents, chemicals, consumables, etc.), and thus cost.

De novo synthesis of trideuteromethyl esters of amino acids for use in GC-MS and GC-tandem MS exemplified for ADMA in human plasma and urine: standardization, validation, comparison and proof of evidence for their aptitude as internal standards.

PubMed

Tsikas, Dimitrios

2009-08-01

Asymmetric dimethylarginine (ADMA, N(G),N(G)-dimethyl-L-arginine) is an endogenous inhibitor of nitric oxide (NO) synthesis, a potential risk factor for cardiovascular diseases and a powerful biochemical parameter in clinical studies. In our previous work we have reported on a GC-tandem MS method for the accurate and precise quantification of ADMA in biological fluids using de novo synthesized [(2)H(3)]-methyl ester ADMA (d(3)Me-ADMA) as internal standard (IS). This method provides basal ADMA concentrations in biological fluids that agree with those obtained by other groups using other validated methods for ADMA. Unanimously, de novo synthesized stable-isotope labeled analogues are considered not ideal IS, because they must be prepared in a matrix different from the biological sample. Recently, [2,3,3,4,4,5,5-(2)H(7)]-ADMA (d(7)-ADMA) has become commercially available and we took this opportunity to test the reliability of the de novo synthesized d(3)Me-ADMA as an IS for ADMA in GC-tandem MS. In this article, we report on the re-validation of the previously reported GC-tandem MS method for ADMA in human plasma and urine using d(7)-ADMA as IS, and on comparative quantitative analyses of ADMA by GC-tandem MS using d(7)-ADMA and d(3)Me-ADMA. After thorough standardization of d(7)-ADMA and methods validation, we obtained by GC-tandem MS very similar ADMA concentrations in plasma and urine using d(7)-ADMA and d(3)Me-ADMA. The present study gives a proof of evidence for the aptitude of (2)H(3)-ADMA as IS in GC-tandem MS and suggests that de novo synthesis of stable-isotope labeled alkyl esters of amino acids and amino acid derivates may be a generally applicable method in mass spectrometry-based methods for amino acids. This approach is especially useful for amino acids for which no stable-isotope labeled analogues are commercially available.

Analysis of cannabis in oral fluid specimens by GC-MS with automatic SPE.

PubMed

Choi, Hyeyoung; Baeck, Seungkyung; Kim, Eunmi; Lee, Sooyeun; Jang, Moonhee; Lee, Juseon; Choi, Hwakyung; Chung, Heesun

2009-12-01

Methamphetamine (MA) is the most commonly abused drug in Korea, followed by cannabis. Traditionally, MA analysis is carried out on both urine and hair samples and cannabis analysis in urine samples only. Despite the fact that oral fluid has become increasingly popular as an alternative specimen in the field of driving under the influence of drugs (DUID) and work place drug testing, its application has not been expanded to drug analysis in Korea. Oral fluid is easy to collect and handle and can provide an indication of recent drug abuse. In this study, we present an analytical method using GC-MS to determine tetrahydrocannabinol (THC) and its main metabolite 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in oral fluid. The validated method was applied to oral fluid samples collected from drug abuse suspects and the results were compared with those in urine. The stability of THC and THC-COOH in oral fluid stored in different containers was also investigated. Oral fluid specimens from 12 drug abuse suspects, submitted by the police, were collected by direct expectoration. The samples were screened with microplate ELISA. For confirmation they were extracted using automated SPE with mixed-mode cation exchange cartridge, derivatized and analyzed by GC-MS using selective ion monitoring (SIM). The concentrations ofTHC and THC-COOH in oral fluid showed a large variation and the results from oral fluid and urine samples from cannabis abusers did not show any correlation. Thus, detailed information about time interval between drug use and sample collection is needed to interpret the oral fluid results properly. In addition, further investigation about the detection time window ofTHC and THC-COOH in oral fluid is required to substitute oral fluid for urine in drug testing.

GC-MS analysis of aroma of Medemia argun (mama-n-khanen or mama-n-xanin), an ancient Egyptian fruit palm.

PubMed

Hamed, Arafa I; Leonardi, Michele; Stochmal, Anna; Oleszek, Wieslaw; Pistelli, Luisa

2012-05-01

The fruits of the edible and medicinal Egyptian palm, Medemia argun, were collected from Aswan in Egypt and the essential oil (EO) from fruits and headspace (HS) of the seeds and fleshy mesocarps were analyzed by GC and GC-MS. Results obtained by GC-MS analysis indicated a high variability in the oil and in the headspace from seeds and mesocarps. Sesquiterpene derivatives were the main group of volatiles in the EO from fruits and in the HS from seeds (45.0 and 64.0%, respectively), while oxygenated hydrocarbon derivatives were the main constituents in the HS obtained from fleshy mesocarps (96.5%). The different chemical composition of the headspace obtained from the seeds and mesocarps of M. argun can be correlated with the different roles that the different constituents play in the prevention of dehydration of the fruits in the desert region from where the plant was collected.

GC-MS olfactometric and LC-DAD-ESI-MS/MS characterization of key odorants and phenolic compounds in black dry-salted olives.

PubMed

Selli, Serkan; Kelebek, Hasim; Kesen, Songul; Sonmezdag, Ahmet Salih

2018-02-01

Olives are processed in different ways depending on consumption habits, which vary between countries. Different de-bittering methods affect the aroma and aroma-active compounds of table olives. This study focused on analyzing the aroma and aroma-active compounds of black dry-salted olives using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) techniques. Thirty-nine volatile compounds which they have a total concentration of 29 459 µg kg -1 , were determined. Aroma extract dilution analysis (AEDA) was used to determine key aroma compounds of table olives. Based on the flavor dilution (FD) factor, the most powerful aroma-active compounds in the sample were methyl-2-methyl butyrate (tropical, sweet; FD: 512) and (Z)-3-hexenol (green, flowery; FD: 256). Phenolic compounds in table olives were also analyzed by LC-DAD-ESI-MS/MS. A total of 20 main phenolic compounds were identified and the highest content of phenolic compound was luteolin-7-glucoside (306 mg kg -1 ), followed by verbascoside (271 mg kg -1 ), oleuropein (231 mg kg -1 ), and hydroxytyrosol (3,4-DHPEA) (221 mg kg -1 ). Alcohols, carboxylic acids, and lactones were qualitatively and quantitatively the dominant volatiles in black dry-salted olives. Results indicated that esters and alcohols were the major aroma-active compounds. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Anticholinesterase and antioxidant potentials of Nonea micrantha Bioss. & Reut along with GC-MS analysis.

PubMed

Imran, Muhammad; Ullah, Farhat; Ayaz, Muhammad; Sadiq, Abdul; Shah, Muhammad Raza; Jan, Muhammad Saeed; Ullah, Farman

2017-11-23

Nonea micrantha Boiss. & Reut . being an unexplored member of Boraginaceae was investigated for GC/MS analysis, acetylcholinesterase (AChE), butyrylcholinesterase (BChE) inhibitory and antioxidant activities in an attempt to find its effectiveness in neurological disorders. The AChE and BChE inhibitory activities of crude methanolic extract (Nm.Cr), subsequent fractions; n-hexane (Nm.Hex), chloroform (Nm.Cf), ethyl acetate (Nm.EtAc), aqueous (Nm.Aq) and crude saponins (Nm.Sp) from N. micrantha were conducted using Ellman's assay. The antioxidant activity of the plant samples using DPPH and ABTS free radical scavenging potential following quantitative spectrophotometric and qualitative TLC method were also studied. Moreover the total reducing power (TRP) of all the samples was also figured out. The GC/Ms analysis confirmed that the plant is rich in bioactive molecules. Among different fractions, Nm.Hex, Nm.EtAc and Nm.Cf exhibited highest AChE inhibitory activities causing 75.51 ± 0.73, 68.54 ± 0.59 and 63.48 ± 0.59% enzyme inhibition respectively and IC 50 of 44, 100 and 144 μg/mL respectively. In BChE inhibiton assay, Nm.Aq, Nm.Sp and Nm.Cr showed highest activity causing 83.49 ± 0.27, 81.49 ± 0.89 and 75.31 ± 0.56% enzyme inhibition with IC 50 of 90, 110 and 44 μg/mL respectively. In DPPH assay, Nm.Aq, Nm.Cf, Nm.Hex and Nm.Cr were most potent exhibiting IC 50 values of 3, 5, 93 and 120 μg/ml respectively. In ABTS assay Nm.EtAc, Nm.Aq, Nm.Sp and Nm.Cr showed IC 50 values of 60, 95, 100 and 150 μg/mL respectively. Likewise ABTS inhibition was most prominent for Nm.Sp, Nm.EtAc and Nm.Aq causing 78.26 ± 0.49, 67.67 ± 0.73 and 63.58 ± 0.45% inhibition respectively at 1 mg/mL. These results were further confirmed by qualitative screening using DPPH and ABTS staining. Our anticholinesterase and antioxidant results signify the N. micrantha as a potential source of natural bioactive compounds. Moreover isolation of

Thiazolidine peracetates: Novel carbohydrate derivatives that assign cis-2,3- from trans-2,3- monosaccharides by GC/MS analysis

USDA-ARS?s Scientific Manuscript database

A new type of carbohydrate derivative is described that is suitable for analysis by GC/MS. Reaction of free aldoses (pentoses or hexoses), or the component aldoses arising from acid hydrolysis of polysaccharides or oligosaccharides, with excess cysteamine hydrochloride in pyridine, results in the qu...

Identification of Volatile Flavor Components by Headspace Analysis: A Quick and Easy Experiment for Introducing GC/MS

NASA Astrophysics Data System (ADS)

Kjonaas, Richard; Soller, Jean L.; McCoy, Leslee A.

1997-09-01

By placing a piece of chewing gum (Wrigley's) or a crushed piece of hard candy (LifeSavers or Runts) into a vial, followed by GC/MS analysis of a five microliter sample of the headspace, students are able to identify several of the volatile flavoring components which are present. The experiment has been used successfully with sophomore organic chemistry students, and with visiting groups of talented high school students over a three year period. Identification is simplified by handing out a list of the structural formulas of some likely candidates. Some of the components that these students easily identity include ethyl acetate, isobutyl acetate, isoamyl acetate, ethyl butyrate, benzaldehyde, benzyl alcohol, limonene, and cinnamaldehyde. Some of the more difficult to identify components include menthol, menthone, carvone, cineole, myrcene, alpha-pinene, beta-pinene, para-cymene, and gama-terpinene. Most of the major headspace components give signals whose size is comparable to that of the carbon dioxide which is present in each injection. Even with split injection, the background noise is trivial compared to the signals from the major components. The experiments were carried out with a commercially available tabletop GC/MS (Varian 3400 with Saturn MS).

Analysis of volatile flavor compounds influencing Chinese-type soy sauces using GC-MS combined with HS-SPME and discrimination with electronic nose.

PubMed

Gao, Lihua; Liu, Ting; An, Xinjing; Zhang, Jinlan; Ma, Xiaoran; Cui, Jinmei

2017-01-01

Soy sauce contains a variety of volatiles that are highly valuable to its quality with regard to sensory characteristics. This paper describes the analysis of volatile compounds influencing the flavor quality of Chinese-type soy sauces. Gas chromatography-mass spectrometry (GC-MS) combined with headspace-solid phase microextraction and electronic nose (E-nose) were applied for identifying the volatile flavor compounds as well as determining their volatile profiles of 12 soy sauces manufactured by different fermentation process. Forty one key volatile components of these 12 soy sauce products, a pure soy sauce and an acid-hydrolyzed vegetable protein sample, were compared in semi-quantitative form, and their volatile flavor profiles were analyzed by E-nose. The substantially similar results between hierarchical cluster analysis based on GC-MS data and E-nose analysis suggested that both techniques may be useful in evaluating the flavor quality of soy sauces and differentiating soy sauce products. The study also showed that there were less volatile flavor compounds in soy sauces produced through low-salt solid-state fermentation process, a traditional manufacturing technology and a widely adopted technology in Chinese soy sauce industries. In addition, the investigation suggested that the flavor quality of soy sauce varied widely in Chinese domestic market, and that the present Chinese national standards of soy sauce should be further perfected by the addition of flavor grades of soy sauce in the physical and chemical index. Meanwhile, this research provided valuable information to manufacturers and government regulators, which have practical significance to improve quality of soy sauces.

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.

[Study on rapid analysis method of pesticide contamination in processed foods by GC-MS and GC-FPD].

PubMed

Kobayashi, Maki; Otsuka, Kenji; Tamura, Yasuhiro; Tomizawa, Sanae; Kamijo, Kyoko; Iwakoshi, Keiko; Sato, Chizuko; Nagayama, Toshihiro; Takano, Ichiro

2011-01-01

A simple and rapid method using GC-MS and GC-FPD for the determination of pesticide contamination in processed food has been developed. Pesticides were extracted from a sample with ethyl acetate in the presence of anhydrous sodium sulfate, then cleaned up with a combination of mini-columns, such as macroporous diatomaceous earth, C18, GCB (graphite carbon black) and PSA. Recovery tests of 57 pesticides (known to be toxic or harmful) from ten kinds of processed foods (butter, cheese, corned beef, dried shrimp, frozen Chinese dumplings, grilled eels, instant noodles, kimchi, retort-packed curry and wine) were performed, and the recovery rates were mostly between 70% and 120%. This method can be used to judge whether or not processed foods are contaminated with pesticides at potentially harmful levels.

Determination of Cinnamaldehyde in Cinnamon by SPME-GC-MS: An Instrumental Analysis Experiment

ERIC Educational Resources Information Center

Wang, Yimin; Ocariz, Jessica; Hammersand, Jennifer; MacDonald, Evan; Bartczak, Ashley; Kero, Frank; Young, Vaneica Y.; Williams, Kathryn R.

2008-01-01

Students analyze "trans"-cinnamaldehyde in commercial cinnamon using solid-phase microextraction and GC-MS with ethyl benzoate as the internal standard. Aside from the instrumentation, the experiment utilizes readily available low hazard materials and can be completed within one four-hour laboratory period. (Contains 2 figures.)

Evaluation of EMIT and RIA high volume test procedures for THC metabolites in urine utilizing GC/MS confirmation.

PubMed

Abercrombie, M L; Jewell, J S

1986-01-01

Results of EMIT, Abuscreen RIA, and GC/MS tests for THC metabolites in a high volume random urinalysis program are compared. Samples were field tested by non-laboratory personnel with an EMIT system using a 100 ng/mL cutoff. Samples were then sent to the Army Forensic Toxicology Drug Testing Laboratory (WRAMC) at Fort Meade, Maryland, where they were tested by RIA (Abuscreen) using a statistical 100 ng/mL cutoff. Confirmations of all RIA positives were accomplished using a GC/MS procedure. EMIT and RIA results agreed for 91% of samples. Data indicated a 4% false positive rate and a 10% false negative rate for EMIT field testing. In a related study, results for samples which tested positive by RIA for THC metabolites using a statistical 100 ng/mL cutoff were compared with results by GC/MS utilizing a 20 ng/mL cutoff for the THCA metabolite. Presence of THCA metabolite was detected in 99.7% of RIA positive samples. No relationship between quantitations determined by the two tests was found.

Characterizing Vaccinium berry Standard Reference Materials by GC-MS using NIST spectral libraries.

PubMed

Lowenthal, Mark S; Andriamaharavo, Nirina R; Stein, Stephen E; Phinney, Karen W

2013-05-01

A gas chromatography-mass spectrometry (GC-MS)-based method was developed for qualitative characterization of metabolites found in Vaccinium fruit (berry) dietary supplement Standard Reference Materials (SRMs). Definitive identifications are provided for 98 unique metabolites determined among six Vaccinium-related SRMs. Metabolites were enriched using an organic liquid/liquid extraction, and derivatized prior to GC-MS analysis. Electron ionization (EI) fragmentation spectra were searched against EI spectra of authentic standards compiled in the National Institute of Standards and Technology's mass spectral libraries, as well as spectra selected from the literature. Metabolite identifications were further validated using a retention index match along with prior probabilities and were compared with results obtained in a previous effort using collision-induced dissociation (CID) MS/MS datasets from liquid chromatography coupled to mass spectrometry experiments. This manuscript describes a nontargeted metabolite profile of Vaccinium materials, compares results among related materials and from orthogonal experimental platforms, and discusses the feasibility and development of using mass spectral library matching for nontargeted metabolite identification.

Hair testing for cocaine and metabolites by GC/MS: criteria to quantitatively assess cocaine use.

PubMed

López-Guarnido, O; Álvarez, I; Gil, F; Rodrigo, L; Cataño, H C; Bermejo, A M; Tabernero, M J; Pla, A; Hernández, A F

2013-08-01

A simple, rapid and sensitive method has been developed and validated for the determination of cocaine and its main metabolites (benzoylecgonine and cocaethylene) in human hair. The method involved solid-phase extraction with an Oasis HLB extraction cartridge and subsequent analysis by GC/MS. The limit of detection was 0.01 ng mg(-1) for cocaine, 0.04 for benzoylecgonine and 0.03 for cocaethylene. The method validation included linearity (with a correlation coefficient >0.99 over the range 0.2-50 ng mg(-1) ), intra- and inter-day precision (always lower than 12%) and accuracy (mean relative error always below 17%) to meet the bioanalytical acceptance criteria. The procedure was further applied to 40 hair samples from self-reported cocaine users arrested by the police who provided a positive urine-analysis for cocaine, and was demonstrated to be suitable for its application in forensic toxicology. New approaches were raised to detect false-negative results that allow a better interpretation of hair testing results. Copyright © 2012 John Wiley & Sons, Ltd.

Lippia origanoides chemotype differentiation based on essential oil GC-MS and principal component analysis.

PubMed

Stashenko, Elena E; Martínez, Jairo R; Ruíz, Carlos A; Arias, Ginna; Durán, Camilo; Salgar, William; Cala, Mónica

2010-01-01

Chromatographic (GC/flame ionization detection, GC/MS) and statistical analyses were applied to the study of essential oils and extracts obtained from flowers, leaves, and stems of Lippia origanoides plants, growing wild in different Colombian regions. Retention indices, mass spectra, and standard substances were used in the identification of 139 substances detected in these essential oils and extracts. Principal component analysis allowed L. origanoides classification into three chemotypes, characterized according to their essential oil major components. Alpha- and beta-phellandrenes, p-cymene, and limonene distinguished chemotype A; carvacrol and thymol were the distinctive major components of chemotypes B and C, respectively. Pinocembrin (5,7-dihydroxyflavanone) was found in L. origanoides chemotype A supercritical fluid (CO(2)) extract at a concentration of 0.83+/-0.03 mg/g of dry plant material, which makes this plant an interesting source of an important bioactive flavanone with diverse potential applications in cosmetic, food, and pharmaceutical products.

Comparison of common components analysis with principal components analysis and independent components analysis: Application to SPME-GC-MS volatolomic signatures.

PubMed

Bouhlel, Jihéne; Jouan-Rimbaud Bouveresse, Delphine; Abouelkaram, Said; Baéza, Elisabeth; Jondreville, Catherine; Travel, Angélique; Ratel, Jérémy; Engel, Erwan; Rutledge, Douglas N

2018-02-01

The aim of this work is to compare a novel exploratory chemometrics method, Common Components Analysis (CCA), with Principal Components Analysis (PCA) and Independent Components Analysis (ICA). CCA consists in adapting the multi-block statistical method known as Common Components and Specific Weights Analysis (CCSWA or ComDim) by applying it to a single data matrix, with one variable per block. As an application, the three methods were applied to SPME-GC-MS volatolomic signatures of livers in an attempt to reveal volatile organic compounds (VOCs) markers of chicken exposure to different types of micropollutants. An application of CCA to the initial SPME-GC-MS data revealed a drift in the sample Scores along CC2, as a function of injection order, probably resulting from time-related evolution in the instrument. This drift was eliminated by orthogonalization of the data set with respect to CC2, and the resulting data are used as the orthogonalized data input into each of the three methods. Since the first step in CCA is to norm-scale all the variables, preliminary data scaling has no effect on the results, so that CCA was applied only to orthogonalized SPME-GC-MS data, while, PCA and ICA were applied to the "orthogonalized", "orthogonalized and Pareto-scaled", and "orthogonalized and autoscaled" data. The comparison showed that PCA results were highly dependent on the scaling of variables, contrary to ICA where the data scaling did not have a strong influence. Nevertheless, for both PCA and ICA the clearest separations of exposed groups were obtained after autoscaling of variables. The main part of this work was to compare the CCA results using the orthogonalized data with those obtained with PCA and ICA applied to orthogonalized and autoscaled variables. The clearest separations of exposed chicken groups were obtained by CCA. CCA Loadings also clearly identified the variables contributing most to the Common Components giving separations. The PCA Loadings did not

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.

A field-deployable GC-EI-HRTOF-MS for in situ characterization of volatile organic compounds

NASA Astrophysics Data System (ADS)

Lerner, B. M.; Herndon, S. C.; Yacovitch, T. I.; Roscioli, J. R.; Fortner, E.; Knighton, W. B.; Sueper, D.; Isaacman-VanWertz, G. A.; Jayne, J. T.; Worsnop, D. R.

2017-12-01

Previous authors have demonstrated the value of coupling conventional gas chromatograph (GC) separation techniques with the new generation of electron-impact high-resolution time-of-flight mass spectrometry (EI-HR-ToF-MS) detectors for the measurement of halocarbons and semi-volatile organic species. Here, we present new instrumentation, analytical techniques and field data from the deployment of a GC-EI-HR-ToF-MS system in the mini Aerodyne mobile laboratory to sites upwind and downwind of San Antonio, Texas in May 2017. The instrument employed a multi-component adsorbent trap pre-concertation system followed by single-column separation. We will show results from the field work, including inter-comparison with other VOC measurements and characterization of C5-C10 hydrocarbon mixing ratios to distinguish urban and oil/gas emission sources in characterized air. We will discuss practical aspects of deployment of the GC-EI-HRTOF-MS in a mobile laboratory and system performance in the field. Will we also present further development of Aerodyne's TERN software package for chromatographic data analysis to processing of HRTOF-MS datasets.

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.

Gas chromatography-mass spectrometry (GC-MS) analysis of extractives of naturally durable wood

Treesearch

G.T. Kirker; A.B. Blodgett; S.T. Lebow; C.A. Clausen

2011-01-01

A preliminary study to evaluate naturally durable wood species in an above ground field trial using Gas Chromatography-Mass Spectrometry (GC-MS) detected differences in fatty acid extractives between species and within the same species over time. Fatty acids were extracted with chloroform: methanol mixture then methylated with sodium methoxide and fractionated using...

GC-MS-based metabolite profiling of Cosmos caudatus leaves possessing alpha-glucosidase inhibitory activity.

PubMed

Javadi, Neda; Abas, Faridah; Abd Hamid, Azizah; Simoh, Sanimah; Shaari, Khozirah; Ismail, Intan Safinar; Mediani, Ahmed; Khatib, Alfi

2014-06-01

Cosmos caudatus, which is known as "Ulam Raja," is an herbal plant used in Malaysia to enhance vitality. This study focused on the evaluation of the α-glucosidase inhibitory activity of different ethanolic extracts of C. caudatus. Six series of samples extracted with water, 20%, 40%, 60%, 80%, and 100% ethanol (EtOH) were employed. Gas chromatography-mass spectrometry (GC-MS) and orthogonal partial least-squares (OPLS) analysis was used to correlate bioactivity of different extracts to different metabolite profiles of C. caudatus. The obtained OPLS scores indicated a distinct and remarkable separation into 6 clusters, which were indicative of the 6 different ethanol concentrations. GC-MS can be integrated with multivariate data analysis to identify compounds that inhibit α-glucosidase activity. In addition, catechin, α-linolenic acid, α-D-glucopyranoside, and vitamin E compounds were identified and indicate the potential α-glucosidase inhibitory activity of this herb. GC-MS and multivariate data analysis was applied to discriminate Cosmos caudatus samples extracted with water and different ratio of ethanol. Orthogonal partial least-squares (OPLS) model developed was used to determine the major metabolites contributed to α-glucosidase inhibitory activity. This approach also has the ability to predict the bioactivity of a new set of extracts based on a developed validated regression model that is important for quality control of the herb preparation. © 2014 Institute of Food Technologists®

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.

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

High-throughput quantitation of amino acids in rat and mouse biological matrices using stable isotope labeling and UPLC-MS/MS analysis.

PubMed

Takach, Edward; O'Shea, Thomas; Liu, Hanlan

2014-08-01

Quantifying amino acids in biological matrices is typically performed using liquid chromatography (LC) coupled with fluorescent detection (FLD), requiring both derivatization and complete baseline separation of all amino acids. Due to its high specificity and sensitivity, the use of UPLC-MS/MS eliminates the derivatization step and allows for overlapping amino acid retention times thereby shortening the analysis time. Furthermore, combining UPLC-MS/MS with stable isotope labeling (e.g., isobaric tag for relative and absolute quantitation, i.e., iTRAQ) of amino acids enables quantitation while maintaining sensitivity, selectivity and speed of analysis. In this study, we report combining UPLC-MS/MS analysis with iTRAQ labeling of amino acids resulting in the elution and quantitation of 44 amino acids within 5 min demonstrating the speed and convenience of this assay over established approaches. This chromatographic analysis time represented a 5-fold improvement over the conventional HPLC-MS/MS method developed in our laboratory. In addition, the UPLC-MS/MS method demonstrated improvements in both specificity and sensitivity without loss of precision. In comparing UPLC-MS/MS and HPLC-MS/MS results of 32 detected amino acids, only 2 amino acids exhibited imprecision (RSD) >15% using UPLC-MS/MS, while 9 amino acids exhibited RSD >15% using HPLC-MS/MS. Evaluating intra- and inter-assay precision over 3 days, the quantitation range for 32 detected amino acids in rat plasma was 0.90-497 μM, with overall mean intra-day precision of less than 15% and mean inter-day precision of 12%. This UPLC-MS/MS assay was successfully implemented for the quantitative analysis of amino acids in rat and mouse plasma, along with mouse urine and tissue samples, resulting in the following concentration ranges: 0.98-431 μM in mouse plasma for 32 detected amino acids; 0.62-443 μM in rat plasma for 32 detected amino acids; 0.44-8590μM in mouse liver for 33 detected amino acids; 0.61-1241 �

LFQuant: a label-free fast quantitative analysis tool for high-resolution LC-MS/MS proteomics data.

PubMed

Zhang, Wei; Zhang, Jiyang; Xu, Changming; Li, Ning; Liu, Hui; Ma, Jie; Zhu, Yunping; Xie, Hongwei

2012-12-01

Database searching based methods for label-free quantification aim to reconstruct the peptide extracted ion chromatogram based on the identification information, which can limit the search space and thus make the data processing much faster. The random effect of the MS/MS sampling can be remedied by cross-assignment among different runs. Here, we present a new label-free fast quantitative analysis tool, LFQuant, for high-resolution LC-MS/MS proteomics data based on database searching. It is designed to accept raw data in two common formats (mzXML and Thermo RAW), and database search results from mainstream tools (MASCOT, SEQUEST, and X!Tandem), as input data. LFQuant can handle large-scale label-free data with fractionation such as SDS-PAGE and 2D LC. It is easy to use and provides handy user interfaces for data loading, parameter setting, quantitative analysis, and quantitative data visualization. LFQuant was compared with two common quantification software packages, MaxQuant and IDEAL-Q, on the replication data set and the UPS1 standard data set. The results show that LFQuant performs better than them in terms of both precision and accuracy, and consumes significantly less processing time. LFQuant is freely available under the GNU General Public License v3.0 at http://sourceforge.net/projects/lfquant/. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dehydration of Methylcyclohexanol Isomers in the Undergraduate Organic Laboratory and Product Analysis by Gas Chromatography-Mass Spectroscopy (GC-MS)

ERIC Educational Resources Information Center

Clennan, Malgorzata M.; Clennan, Edward L.

2011-01-01

Dehydrations of "cis"- and "trans"-2-methylcyclohexanol mixtures were carried out with 60% sulfuric acid at 78-80 [degrees]C as a function of time and the products were identified by gas chromatography-mass spectroscopy (GC-MS) analysis. The compounds identified in the reaction mixtures include alkenes, 1-, 3-, and 4-methylcyclohexenes and…

Rapid Quantification of Abscisic Acid by GC-MS/MS for Studies of Abiotic Stress Response.

PubMed

Verslues, Paul E

2017-01-01

Drought and low water potential induce large increases in Abscisic Acid (ABA ) content of plant tissue. This increased ABA content is essential to regulate downstream stress resistance responses; however, the mechanisms regulating ABA accumulation are incompletely known. Thus, the ability to accurately quantify ABA at high throughput and low cost is important for plant stress research. We have combined and modified several previously published protocols to establish a rapid ABA analysis protocol using gas chromatography-tandem mass spectrometry (GC-MS/MS). Derivatization of ABA is performed with (trimethylsilyl)-diazomethane rather than the harder to prepare diazomethane. Sensitivity of the analysis is sufficient that small samples of low water potential treated Arabidopsis thaliana seedlings can be routinely analyzed in reverse genetic studies of putative stress regulators as well as studies of natural variation in ABA accumulation.

Sterol Profile for Natural Juices Authentification by GC-MS

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

Culea, M.

A GC-MS analytical method is described for some natural juices analysis. The fingerprint of sterols was used to characterize the natural juice. A rapid liquid-liquid extraction method was used. The sterols were separated on a Rtx-5MS capillary column, 15mx0.25mm, 0.25{mu}m film thickness, in a temperature program from 50 deg. C for 1 min, then ramped at 15 deg. C/min to 300 deg. C and held for 15 min. Identification of sterols and their patterns were used for juice characterization. The sterol profile is a useful approach for confirming the presence of juices of orange, grapefruit, pineapple and passion fruit inmore » compounded beverages and for detecting of adulteration of fruit juices.« less

Sterol Profile for Natural Juices Authentification by GC-MS

NASA Astrophysics Data System (ADS)

Culea, M.

2007-04-01

A GC-MS analytical method is described for some natural juices analysis. The fingerprint of sterols was used to characterize the natural juice. A rapid liquid-liquid extraction method was used. The sterols were separated on a Rtx-5MS capillary column, 15m×0.25mm, 0.25μm film thickness, in a temperature program from 50°C for 1 min, then ramped at 15°C/min to 300°C and held for 15 min. Identification of sterols and their patterns were used for juice characterization. The sterol profile is a useful approach for confirming the presence of juices of orange, grapefruit, pineapple and passion fruit in compounded beverages and for detecting of adulteration of fruit juices.

Compound Specific Hydrogen Isotope Composition of Type II and III Kerogen Extracted by Pyrolysis-GC-MS-IRMS

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Pernia, Denet; Evans, Michael; Fu, Qi; Bissada, Kadry K.; Curiale, Joseph A.; Niles, Paul B.

2013-01-01

The use of Hydrogen (H) isotopes in understanding oil and gas resource plays is in its infancy. Described here is a technique for H isotope analysis of organic compounds pyrolyzed from oil and gas shale-derived kerogen. Application of this technique will progress our understanding. This work complements that of Pernia et al. (2013, this meeting) by providing a novel method for the H isotope analysis of specific compounds in the characterization of kerogen extracted by analytically diverse techniques. Hydrogen isotope analyses were carried out entirely "on-line" utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC Ultra interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make semi-quantitative compositional measurements of the extracted compounds. Kerogen samples from five different basins (type II and III) were dehydrated (heated to 80 C overnight in vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C) which quantitatively forms H2, following a modified method of Burgoyne and Hayes, (1998, Anal. Chem., 70, 5136-5141). Samples ranging from approximately 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. Compounds were separated on a Poraplot Q GC column. Hydrogen isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight compounds. Water (H2O) average deltaD = -215.2 (V-SMOW), ranging from -271.8 for the Marcellus Shale to -51.9 for the Polish Shale. Higher molecular weight compounds like toluene (C7H8) have an average deltaD of -89.7 0/00, ranging from -156.0 for the Barnett Shale to -50.0 for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during formation within each basin. Since hydrocarbon H isotopes

GC-MS analysis of headspace and liquid extracts for metabolomic differentiation of citrus Huanglongbing and zinc deficiency in leaves of 'Valencia' sweet orange from commercial groves.

PubMed

Cevallos-Cevallos, Juan Manuel; García-Torres, Rosalía; Etxeberria, Edgardo; Reyes-De-Corcuera, José Ignacio

2011-01-01

Citrus Huanglongbing (HLB) is considered the most destructive citrus disease worldwide. Symptoms-based detection of HLB is difficult due to similarities with zinc deficiency. To find metabolic differences between leaves from HLB-infected, zinc-deficient, and healthy 'Valencia' orange trees by using GC-MS based metabolomics. Analysis based on GC-MS methods for untargeted metabolite analysis of citrus leaves was developed and optimized. Sample extracts from healthy, zinc deficient, or HLB-infected sweet orange leaves were submitted to headspace solid phase micro-extraction (SPME) and derivatization treatments prior to GC-MS analysis. Principal components analysis achieved correct classification of all the derivatized liquid extracts. Analysis of variance revealed 6 possible biomarkers for HLB, of which 5 were identified as proline, β-elemene, (-)trans- caryophyllene, and α-humulene. Significant (P < 0.05) differences in oxo-butanedioic acid, arabitol, and neo-inositol were exclusively detected in samples from plants with zinc deficiency. Levels of isocaryophyllen, α-selinene, β-selinene, and fructose were significantly (P < 0.05) different in healthy leaves only. Results suggest the potential of using identified HLB biomarkers for rapid differentiation of HLB from zinc deficiency. Copyright © 2010 John Wiley & Sons, Ltd.

The GC-MS Observation of Intermediates in a Stepwise Grignard Addition Reaction

ERIC Educational Resources Information Center

Latimer, Devin

2007-01-01

Preparation of phenylmagnesium bromide described by Eckert, addition of three equivalents of Grignard reagent to diethyl carbonate to form triphenylmethanol and a series of GC-MS procedures that form intermediates. The analysis is consistent with a gas chromatogram and mass spectrum for each of the expected intermediates and final product of the…

Reference measurement procedure for total glycerides by isotope dilution GC-MS.

PubMed

Edwards, Selvin H; Stribling, Shelton L; Pyatt, Susan D; Kimberly, Mary M

2012-04-01

The CDC's Lipid Standardization Program established the chromotropic acid (CA) reference measurement procedure (RMP) as the accuracy base for standardization and metrological traceability for triglyceride testing. The CA RMP has several disadvantages, including lack of ruggedness. It uses obsolete instrumentation and hazardous reagents. To overcome these problems the CDC developed an isotope dilution GC-MS (ID-GC-MS) RMP for total glycerides in serum. We diluted serum samples with Tris-HCl buffer solution and spiked 200-μL aliquots with [(13)C(3)]-glycerol. These samples were incubated and hydrolyzed under basic conditions. The samples were dried, derivatized with acetic anhydride and pyridine, extracted with ethyl acetate, and analyzed by ID-GC-MS. Linearity, imprecision, and accuracy were evaluated by analyzing calibrator solutions, 10 serum pools, and a standard reference material (SRM 1951b). The calibration response was linear for the range of calibrator concentrations examined (0-1.24 mmol/L) with a slope and intercept of 0.717 (95% CI, 0.7123-0.7225) and 0.3122 (95% CI, 0.3096-0.3140), respectively. The limit of detection was 14.8 μmol/L. The mean %CV for the sample set (serum pools and SRM) was 1.2%. The mean %bias from NIST isotope dilution MS values for SRM 1951b was 0.7%. This ID-GC-MS RMP has the specificity and ruggedness to accurately quantify total glycerides in the serum pools used in the CDC's Lipid Standardization Program and demonstrates sufficiently acceptable agreement with the NIST primary RMP for total glyceride measurement.

Analysis of flavor compounds by GC/MS after liquid-liquid extraction from fruit juices

NASA Astrophysics Data System (ADS)

Tuşa, F. D.; Moldovan, Z.; Schmutzer, G.; Magdaş, D. A.; Dehelean, A.; Vlassa, M.

2012-02-01

In this work we describe a rapid method for analysis of volatile profiles of several commercial fruit juices using GC/MS instrument after liquid-liquid extraction. Volatile flavor compounds have been identified based on mass spectrum obtained in EI mode. This method allows to analyses a wide range of flavor compounds (esters, aldehydes, alcohols, terpenoids) the procedure was rapid, simple and inexpensive. Moreover, by means of volatile compounds it could be possible to distinguish between juices of organic and conventional production and those with flavorings addition. More of 20 compounds were identified and quantified as relative chromatogram area taken on larges ion in mass spectrum.

Analysis of ketamine and norketamine in urine by automatic solid-phase extraction (SPE) and positive ion chemical ionization-gas chromatography-mass spectrometry (PCI-GC-MS).

PubMed

Kim, Eun-mi; Lee, Ju-seon; Choi, Sang-kil; Lim, Mi-ae; Chung, Hee-sun

2008-01-30

-liquid extraction (LLE), and PCI-GC-MS can offer both qualitative and quantitative information for urinalysis of KT in forensic analysis.

[Analysis of chemical constituents of volatile components from Jia Ga Song Tang by GC-MS].

PubMed

Tan, Qing-long; Xiong, Tian-qin; Liao, Jia-yi; Yang, Tao; Zhao, Yu-min; Lin, Xi; Zhang, Cui-xian

2014-10-01

To analyze the chemical components of volatile components from Jia Ga Song Tang. The volatile oils were extracted by water steam distillation. The chemical components of essential oil were analyzed by GC-MS and quantitatively determined by a normalization method. 103 components were separated and 87 components were identified in the volatile oil of Zingiberis Rhizoma. 58 components were separated and 38 components were identified in the volatile oil of Myristicae Semen. 49 components were separated and 38 components were identified in the volatile oil of Amomi Rotundus Fructus. 89 components were separated and 63 components were identified in the volatile oil of Jia Ga Song Tang. Eucalyptol, β-phellandrene and other terpenes were the main compounds in the volatile oil of Jia Ga Song Tang. Changes in the kinds and content of volatile components can provide evidences for scientific and rational compatibility for Jia Ga Song Tang.

In-tube extraction and GC-MS analysis of volatile components from wild and cultivated sea buckthorn (Hippophae rhamnoides L. ssp. Carpatica) berry varieties and juice.

PubMed

Socaci, Sonia A; Socaciu, Carmen; Tofană, Maria; Raţi, Ioan V; Pintea, Adela

2013-01-01

The health benefits of sea buckthorn (Hippophae rhamnoides L.) are well documented due to its rich content in bioactive phytochemicals (pigments, phenolics and vitamins) as well as volatiles responsible for specific flavours and bacteriostatic action. The volatile compounds are good biomarkers of berry freshness, quality and authenticity. To develop a fast and efficient GC-MS method including a minimal sample preparation technique (in-tube extraction, ITEX) for the discrimination of sea buckthorn varieties based on their chromatographic volatile fingerprint. Twelve sea buckthorn varieties (wild and cultivated) were collected from forestry departments and experimental fields, respectively. The extraction of volatile compounds was performed using the ITEX technique whereas separation and identification was performed using a GC-MS QP-2010. Principal component analysis (PCA) was applied to discriminate the differences among sample composition. Using GC-MS analysis, from the headspace of sea buckthorn samples, 46 volatile compounds were separated with 43 being identified. The most abundant derivatives were ethyl esters of 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid and butanoic acid, as well as 3-methylbutyl 3-methylbutanoate, 3-methylbutyl 2-methylbutanoate and benzoic acid ethyl ester (over 80% of all volatile compounds). Principal component analysis showed that the first two components explain 79% of data variance, demonstrating a good discrimination between samples. A reliable, fast and eco-friendly ITEX/GC-MS method was applied to fingerprint the volatile profile and to discriminate between wild and cultivated sea buckthorn berries originating from the Carpathians, with relevance to food science and technology. Copyright © 2013 John Wiley & Sons, Ltd.

Hyphenated GC-FTIR and GC-MS techniques applied in the analysis of bioactive compounds

NASA Astrophysics Data System (ADS)

Gosav, Steluta; Paduraru, Nicoleta; Praisler, Mirela

2014-08-01

The drugs of abuse, which affect human nature and cause numerous crimes, have become a serious problem throughout the world. There are hundreds of amphetamine analogues on the black market. They consist of various alterations of the basic amphetamine molecular structure, which are yet not yet included in the lists of forbidden compounds although they retain or slightly modify the hallucinogenic effects of their parent compound. It is their important variety that makes their identification quite a challenge. A number of analytical procedures for the identification of amphetamines and their analogues have recently been reported. We are presenting the profile of the main hallucinogenic amphetamines obtained with the hyphenated techniques that are recommended for the identification of illicit amphetamines, i. e. gas chromatography combined with mass spectrometry (GC-MS) and gas chromatography coupled with Fourier transform infrared spectrometry (GC-FTIR). The infrared spectra of the analyzed hallucinogenic amphetamines present some absorption bands (1490 cm-1, 1440 cm-1, 1245 cm-1, 1050 cm-1 and 940 cm-1) that are very stable as position and shape, while their intensity depends of the side-chain substitution. The specific ionic fragment of the studied hallucinogenic compounds is the 3,4-methylenedioxybenzyl cation (m/e = 135) which has a small relative abundance (lesser than 20%). The complementarity of the above mentioned techniques for the identification of hallucinogenic compounds is discussed.

Estimation of perimortal percent carboxy-heme in nonstandard postmortem specimens using analysis of carbon monoxide by GC/MS and iron by flame atomic absorption spectrophotometry.

PubMed

Middleberg, R A; Easterling, D E; Zelonis, S F; Rieders, F; Rieders, M F

1993-01-01

In decomposed, formalin-fixed, embalmed, exhumed, and some fire-dried cases in which normal blood is unavailable, the usual methods for determination of carboxyhemoglobin saturation frequently fail. To address these specimens, a method utilizing both gas chromatography/mass spectrometric (GC/MS) determination of carbon monoxide (CO) and flame atomic absorption spectrophotometry (FAAS) determination of iron (Fe), in the same specimen, was developed. The method is reported here, along with its application to seven pertinent forsensic death investigations. The CO analytical methodology involves acid liberation of the gas from the specimen aliquot in a headspace vial. After heating and equilibrating, a sample of the headspace vapor is injected into the GC/MS system with a gastight syringe. Quantitation is achieved by standard addition comparison utilizing the ideal gas law equation. Iron is quantified by FAAS analysis of the same aliquot used for the CO determination, following nitric acid digestion. The concentration is determined by comparison to a standard curve. A formula for determining the minimum percent carboxy-heme saturation was derived by using the ratio of the amount of CO to the amount of Fe in the aliquot analyzed. Tissue types analyzed include spleen, liver, muscle, dried blood, and unspecified decomposed tissue.

Steroids excreted in urine by neonates with 21-hydroxylase deficiency. 2. Characterization, using GC-MS and GC-MS/MS, of pregnanes and pregnenes with an oxo- group on the A- or B-ring.

PubMed

Christakoudi, Sofia; Cowan, David A; Taylor, Norman F

2012-04-01

Urine from neonates with 21-hydroxylase deficiency contains a large range of metabolites of 17-hydroxyprogesterone, 21-deoxycortisol and androgens but few have been previously described. We present the second part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal steroid metabolism. Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra were used together to determine the structure of the A- and B-rings containing an oxo group. Fragmentations indicating presence of 3-, 6-, and 7-oxo groups and also 1β-, 2α-, 4β-, and 6β-hydroxyls are presented and discussed for the first time. Interpretation was aided by comparison with spectra of available relevant standards, of oxidation products of standards and urinary metabolites and of deuterated derivatives. Endogenous 1-enes and 2(3)-ene artifacts of non-hydrolyzed 3α-sulfates are also reported. D-ring and side chain structure was determined according to our previously published criteria. Likely metabolic relationships were also explored. We conclude that GC-MS combined with GC-MS/MS allows identification of the A- and B-ring structure of pregnane and pregnenes in the presence of an oxo group on one of these rings. Major oxygenations are 1β, 15β, 16α and 21-hydroxy and 6- and 7-oxo groups. Minor positions of hydroxylation are those at 2α, 4β and 6β. Three major metabolic streams exist in affected neonates in addition to the classical 3α-hydroxy-5β-pregnane pathway, i.e. these of the 3-oxo-4-enes as well as 3α- and 3β-hydroxy-5α-anes. Copyright © 2011 Elsevier Inc. All rights reserved.

Mathematical Model Developed for Environmental Samples: Prediction of GC/MS Dioxin TEQ from XDS-CALUX Bioassay Data

PubMed Central

Brown, David J.; Orelien, Jean; Gordon, John D.; Chu, Andrew C.; Chu, Michael D.; Nakamura, Masafumi; Handa, Hiroshi; Kayama, Fujio; Denison, Michael S.; Clark, George C.

2010-01-01

Remediation of hazardous waste sites requires efficient and cost-effective methods to assess the extent of contamination by toxic substances including dioxin-like chemicals. Traditionally, dioxin-like contamination has been assessed by gas chromatography/high-resolution mass spectrometry (GC/MS) analysis for specific polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyl congeners. Toxic equivalency factors for these congeners are then used to estimate the overall dioxin toxic equivalency (TEQ) of complex mixtures found in samples. The XDS-CALUX bioassay estimates contamination by dioxin-like chemicals in a sample extract by measuring expression of a sensitive reporter gene in genetically engineered cells. The output of the XDS-CALUX assay is a CALUX-TEQ value, calibrated based on TCDD standards. Soil samples taken from a variety of hazardous waste sites were measured using the XDS-CALUX bioassay and GC/MS. TEQ and CALUX-TEQ from these methods were compared, and a mathematical model was developed describing the relationship between these two data sets: log(TEQ) = 0.654 × log(CALUX-TEQ) + 0.058-(log(CALUX-TEQ))2. Applying this equation to these samples showed that predicted and GC/MS measured TEQ values strongly correlate (R2 = 0.876) and that TEQ values predicted from CALUX-TEQ were on average nearly identical to the GC/MS-TEQ. The ability of XDS-CALUX bioassay data to predict GC/MS-derived TEQ data should make this procedure useful in risk assessment and management decisions. PMID:17626436

Identification of natural indigo in historical textiles by GC-MS.

PubMed

Degani, Laura; Riedo, Chiara; Chiantore, Oscar

2015-02-01

The possibility of successfully applying a common GC-MS procedure for identification in one step of all types of dyes from plants of unknown origin and from historical objects is particularly attractive due to the high separation efficiency of the capillary columns, the MS detection sensitivity and the reproducibility of results. In this work, GC-MS analysis, previously and successfully used for the characterization of anthraquinones, flavonoids and tannins from plant extracts and historical samples, has been tested on indigoid dyestuffs. An analytical procedure based on the silylating agent N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) was applied to pure molecules of indigotin and indirubin and to plant extracts of Indigofera tinctoria L. and Isatis tinctoria L. Preliminary tests have been done to establish the chromatographic conditions and the derivatization amounts most suitable for the simultaneous detection of indigoid molecules and of the other natural compounds, such as fatty acids, carboxylic acids and sugars, contained within the plant extracts. In order to assess the capacity and the sensitivity of the analytical procedure in typical archaeometric applications, wool samples dyed in the laboratory with indigo were analysed by mimicking the sample amounts typically available with historical objects. The electron ionization (EI) spectra of the main silylated derivatives of indigoid molecules obtained in this way constitute the necessary data set for the characterization of natural extracts and historical works of art. Subsequently, the procedure has been applied to historical samples for the detection of indigo and of other dyestuffs eventually contained in samples. Additional information, useful for restoration and preservation of works of art, could be also obtained on the nature of stains and smudges present on the sampled textile material. The GC-MS method turns out to be an efficient and fast analytical tool

TargetSearch--a Bioconductor package for the efficient preprocessing of GC-MS metabolite profiling data.

PubMed

Cuadros-Inostroza, Alvaro; Caldana, Camila; Redestig, Henning; Kusano, Miyako; Lisec, Jan; Peña-Cortés, Hugo; Willmitzer, Lothar; Hannah, Matthew A

2009-12-16

Metabolite profiling, the simultaneous quantification of multiple metabolites in an experiment, is becoming increasingly popular, particularly with the rise of systems-level biology. The workhorse in this field is gas-chromatography hyphenated with mass spectrometry (GC-MS). The high-throughput of this technology coupled with a demand for large experiments has led to data pre-processing, i.e. the quantification of metabolites across samples, becoming a major bottleneck. Existing software has several limitations, including restricted maximum sample size, systematic errors and low flexibility. However, the biggest limitation is that the resulting data usually require extensive hand-curation, which is subjective and can typically take several days to weeks. We introduce the TargetSearch package, an open source tool which is a flexible and accurate method for pre-processing even very large numbers of GC-MS samples within hours. We developed a novel strategy to iteratively correct and update retention time indices for searching and identifying metabolites. The package is written in the R programming language with computationally intensive functions written in C for speed and performance. The package includes a graphical user interface to allow easy use by those unfamiliar with R. TargetSearch allows fast and accurate data pre-processing for GC-MS experiments and overcomes the sample number limitations and manual curation requirements of existing software. We validate our method by carrying out an analysis against both a set of known chemical standard mixtures and of a biological experiment. In addition we demonstrate its capabilities and speed by comparing it with other GC-MS pre-processing tools. We believe this package will greatly ease current bottlenecks and facilitate the analysis of metabolic profiling data.

GC-TOF/MS-based metabolomic profiling of estrogen deficiency-induced obesity in ovariectomized rats

PubMed Central

Ma, Bo; Zhang, Qi; Wang, Guang-ji; A, Ji-ye; Wu, Di; Liu, Ying; Cao, Bei; Liu, Lin-sheng; Hu, Ying-ying; Wang, Yong-lu; Zheng, Ya-ya

2011-01-01

Aim: To explore the alteration of endogenous metabolites and identify potential biomarkers using metabolomic profiling with gas chromatography coupled a time-of-flight mass analyzer (GC/TOF-MS) in a rat model of estrogen-deficiency-induced obesity. Methods: Twelve female Sprague-Dawley rats six month of age were either sham-operated or ovariectomized (OVX). Rat blood was collected, and serum was analyzed for biomarkers using standard colorimetric methods with commercial assay kits and a metabolomic approach with GC/TOF-MS. The data were analyzed using multivariate statistical techniques. Results: A high body weight and body mass index inversely correlated with serum estradiol (E2) in the OVX rats compared to the sham rats. Estrogen deficiency also significantly increased serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol. Utilizing GC/TOF-MS-based metabolomic analysis and the partial least-squares discriminant analysis, the OVX samples were discriminated from the shams. Elevated levels of cholesterol, glycerol, glucose, arachidonic acid, glutamic acid, glycine, and cystine and reduced alanine levels were observed. Serum glucose metabolism, energy metabolism, lipid metabolism, and amino acid metabolism were involved in estrogen-deficiency-induced obesity in OVX rats. Conclusion: The series of potential biomarkers identified in the present study provided fingerprints of rat metabolomic changes during obesity and an overview of multiple metabolic pathways during the progression of obesity involving glucose metabolism, lipid metabolism, and amino acid metabolism. PMID:21293480

Field-portable Gas Chromatograph Mass Spectrometer (GC-MS) Unit for Semi-volatile Compound Analysis in Groundwater

DTIC Science & Technology

2011-09-01

of interest. Lack of bias with GC-MS method ........................................................ 12 3.1.1 Data requirements...14 3.2.1 Data ...3.3.1 Data requirements ....................................................................................................... 15 3.3.2 Success

GC-MS profile of antimicrobial and antioxidant fractions from Cordia rothii roots.

PubMed

Khan, Kehkashan; Firdous, Sadiqa; Ahmad, Aqeel; Fayyaz, Nida; Nadir, Muhammad; Rasheed, Munawwer; Faizi, Shaheen

2016-11-01

An ethnobotanical survey of Cordia rothii Roem. & Schult. (Boraginaceae) reveals it as a medicinal plant. Antimicrobial and antioxidant potential evaluation and identification of chemical constituents via GC-MS of C. rothii roots fractions. To the best of our knowledge, this is the first systematic investigation of the roots exploiting GC-MS. Extraction and fractionation of C. rothii roots furnished various fractions using solvents of varying polarity, i.e., n-hexane, chloroform, ethyl acetate, acetone and methanol. In vitro antimicrobial and antioxidant screening was performed using disk diffusion and DPPH methods, respectively. MIC of active fractions was also determined using disk diffusion method. GC-MS was used to identify constituents which may be responsible for these activities. Among various fractions from C. rothii roots, fraction KA-C showed strong antibacterial activity against 17 microorganisms tested, with MIC ranging from 250-31.25 μg/mL. Fractions KA-A, KM and KM-A exhibited significant antioxidant potential with EC 50 46.875 μg/mL, while fractions KEA-PE, KM-PE and KM-M were good with EC 50 93.750 μg/mL. Forty-five phytochemicals were identified in GC-MS studies including eight hydrocarbons, six free fatty acids, 11 fatty acids esters, two phenylpropanoids, four aromatics, four terpenoid quinones/hydroquinones, three triterpenes, four phytosterols, two hexose metabolites and a DNA base. Of these, 32 constituents have been reported for the first time from C. rothii, 24 from genus Cordia and 15 from Boraginaceae. Strong antibacterial and antioxidant potential of C. rothii roots may be due to the contribution of phytoconstituents identified through GC-MS studies.

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

GC and GC-MS determination of fluoroacetic acid and phenoxy acid herbicides via triphasal extractive pentafluorobenzylation using a polymer-bound phase-transfer catalyst.

PubMed

Miki, A; Tsuchihashi, H; Yamashita, M

1998-01-01

A simple and sensitive gas chromatography and gas chromatography-mass spectrometry (GC-MS) procedure has been developed for fluoroacetic acid (FA) and phenoxy acid herbicides (PAHs) via triphasal extractive pentafluorobenzylation. The triphasal system consisted of an aqueous sample, the extraction solvent toluene containing pentafluorobenzyl bromide as the derivatization reagent, and polymer-bound tri-n-butyl-methylphosphonium bromide as a phase-transfer catalyst, FA spiked in beverages, such as orange juice and milk, was extracted as its pentafluorobenzyl (PFB) derivative under moderate conditions (i.e., at a pH value of 6.5 at 60 degrees C). The detection limits were 0.10-0.20 microgram/mL by GC with electron-capture detection (GC-ECD), and 0.42-0.50 microgram/mL by full-scan GC-MS. PAHs were also detectable in the same manner within the detection limits of 0.05-0.10 microgram/mL by GC-ECD and 0.13-0.25 microgram/mL by full-scan GC-MS. Urine and serum which both contained 2,4-dichlorophenoxyacetic acid could also be analyzed by GC-MS after the triphasal pentafluorobenzylation. The detection limit was 0.20 microgram/mL in the full-scan mode and 10 ng/mL in the selected ion monitoring mode both for the urine and serum.

Development and validation of an universal interface for compound-specific stable isotope analysis of chlorine (37Cl/35Cl) by GC-high-temperature conversion (HTC)-MS/IRMS.

PubMed

Renpenning, Julian; Hitzfeld, Kristina L; Gilevska, Tetyana; Nijenhuis, Ivonne; Gehre, Matthias; Richnow, Hans-Hermann

2015-03-03

A universal application of compound-specific isotope analysis of chlorine was thus far limited by the availability of suitable analysis techniques. In this study, gas chromatography in combination with a high-temperature conversion interface (GC-HTC), converting organic chlorine in the presence of H2 to gaseous HCl, was coupled to a dual-detection system, combining an ion trap mass spectrometer (MS) and isotope-ratio mass spectrometer (IRMS). The combination of the MS/IRMS detection enabled a detailed characterization, optimization, and online monitoring of the high-temperature conversion process via ion trap MS as well as a simultaneous chlorine isotope analysis by the IRMS. Using GC-HTC-MS/IRMS, chlorine isotope analysis at optimized conversion conditions resulted in very accurate isotope values (δ(37)Cl(SMOC)) for measured reference material with known isotope composition, including chlorinated ethylene, chloromethane, hexachlorocyclohexane, and trichloroacetic acids methyl ester. Respective detection limits were determined to be <15 nmol Cl on column with achieved precision of <0.3‰.

Using BPCA and pyrolysis-GC/MS patterns as a measure of charring intensity

NASA Astrophysics Data System (ADS)

Kaal, Joeri; Schneider, Maximilian P. W.; Schmidt, Michael W. I.

2010-05-01

. 30 % between 250 and 450 °C. Thus, with regard to estimating the charring intensity of Black C, the BPCA method is more suitable for high T chars (> 450 °C) while pyrolysis-GC/MS seems more appropriate in the lower T range (< 500 °C). This is not surprising as larger clusters of polyaromatic domains (high T) can be assessed by the BPCA method but are resistant against pyrolysis. On the other hand, smaller clusters and non-polycondensed portions of Black C (low T) are amenable to pyrolysis-GC/MS but escape the analytical window of the BPCA method. The two methods may therefore be considered complementary, with BPCA giving reliable quantitative data on Black C content and charring degree of high T chars while pyrolysis-GC/MS is quantitatively weak but provides highly detailed information on the molecular properties of especially lower T chars. References [1] Brodowski, S., Rodionov, A., Haumeier L., Glaser, B., Amelung, W. (2005) Org. Geochem. 36, 1299-1310. [2] Glaser, B., Haumeier, L., Guggenberger, G., Zech, W. (1998) Org. Geochem. 29, 811-819. [3] Schneider, M.P.W., Hilf, M., Vogt, U.F., Schmidt, M.W.I., Org. Geochem. (submitted) [4] Kaal, J., Rumpel, C. (2009) Org. Geochem. 40, 1179-1187. [5] Hammes, K., Schmidt, M.W.I., Smernik, R.J. et al. (2007) Global Biogeochemical Cycles 21, 1-18.

Technical Note: Fast two-dimensional GC-MS with thermal extraction for anhydro-sugars in fine aerosols

EPA Science Inventory

A fast two-dimensional gas chromatography (GC-MS) method that uses heart-cutting and thermal extraction (TE) and requires no chemical derivatization is developed for the determination of anhydro-sugars in fine aerosols. Evaluation of the TE-GC-GC-MS method shows high average rela...

Development of a headspace GC/MS analysis for carbonyl compounds (aldehydes and ketones) in household products after derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine.

PubMed

Sugaya, Naeko; Sakurai, Katsumi; Nakagawa, Tomoo; Onda, Nobuhiko; Onodera, Sukeo; Morita, Masatoshi; Tezuka, Masakatsu

2004-05-01

Carbonyl compounds (aldehydes and ketones) are suspected to be among the chemical compounds responsible for Sick Building Syndrome and Multiple Chemical Sensitivities. A headspace gas chromatography/mass spectrometry (GC/MS) analysis for these compounds was developed using derivatization of the compounds into volatile derivatives with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA). For GC/MS detection, two ionization modes including electron impact ionization (EI) and negative chemical ionization (NCI) were compared. The NCI mode seemed to be better because of its higher selectivity and sensitivity. This headspace GC/MS (NCI mode) was employed as analysis for aldehydes and ketones in materials (fiber products, adhesives, and printed materials). Formaldehyde was detected in the range of N.D. (not detected) to 39 microg/g; acetaldehyde, N.D. to 4.1 microg/g; propionaldehyde, N.D. to 1.0 microg/g; n-butyraldehyde, N.D. to 0.10 microg/g; and acetone, N.D. to 3.1 microg/g in the samples analyzed.

Similarity Evaluation of Different Origins and Species of Dendrobiums by GC-MS and FTIR Analysis of Polysaccharides

PubMed Central

Chen, Nai-Dong; Chen, Nai-Fu; Li, Jun; Cao, Cai-Yun; Wang, Jin-Mei; Huang, He-Ping

2015-01-01

GC-MS method combined with FTIR techniques by the analysis of polysaccharide was applied to evaluate the similarity between wild (W) and tissue-cultured (TC) Dendrobium huoshanense (DHS), Dendrobium officinale (DO), and Dendrobium moniliforme (DM) as well as 3 wild Dendrobium spp.: Dendrobium henanense (DHN), Dendrobium loddigesii (DL), and Dendrobium crepidatum (DC). Eight monosaccharides involving xylose, arabinose, rhamnose, glucose, mannose, fructose, galactose, and galacturonic acid were identified in the polysaccharide from each Dendrobium sample while the contents of the monosugars varied remarkably across origins and species. Further similarity evaluation based on GC-MS data showed that the r cor values of different origins of DHS, DO, and DM were 0.831, 0.865, and 0.884, respectively, while the r cor values ranged from 0.475 to 0.837 across species. FTIR files of the polysaccharides revealed that the similarity coefficients between W and TC-DHS, DO, and DM were 88.7%, 86.8%, and 88.5%, respectively, in contrast to the similarity coefficients varying from 57.4% to 82.6% across species. These results suggested that the structures of polysaccharides between different origins of the investigated Dendrobiums might be higher than what we had supposed. PMID:26539215

Trapping of NAPQI, the intermediate toxic paracetamol metabolite, by aqueous sulfide (S²⁻) and analysis by GC-MS/MS.

PubMed

Trettin, Arne; Batkai, Sandor; Thum, Thomas; Jordan, Jens; Tsikas, Dimitrios

2014-07-15

NAPQI, i.e., N-acetyl-p-benzoquinone imine, is considered the toxic metabolite of the widely used analgesic drug paracetamol (acetaminophen, APAP). Due to its high reactivity towards nucleophiles both in low- and high-molecular-mass biomolecules, NAPQI is hardly detectable in its native form. Upon conjugation with glutathione, NAPQI is finally excreted in the urine as the paracetamol mercapturic acid. Thus, determination of paracetamol mercapturate may provide a measure of in vivo NAPQI formation. In this work, we propose the use of Na2S in aqueous solution to trap NAPQI and to analyze the reaction product, i.e., 3-thio-paracetamol, together with paracetamol by GC-MS/MS in the electron-capture negative-ion chemical ionization mode after solvent extraction with ethyl acetate and derivatization with pentafluorobenzyl bromide. In mechanistic studies, we used newly synthesized N-acetyl-p-[2,3,5,6-(2)H4]benzoquinone imine (d4-NAPQI). In quantitative analyses, N-(4-hydroxyphenyl)-[2,3,5,6-(2)H4]acetamide (d4-APAP) was used as the internal standard both for NAPQI and APAP. 3-Thio-d3-paracetamol, prepared from d4-NAPQI and Na2S, may also be useful as an internal standard. We showed NAPQI in vitro formation from APAP by recombinant cyclooxygenase-1 as well as by dog liver homogenate. In vivo formation of NAPQI was demonstrated in mice given paracetamol intraperitoneally (about 150 mg/kg). Copyright © 2014 Elsevier B.V. All rights reserved.

HS-GC-MS-O analysis and sensory acceptance of passion fruit during maturation.

PubMed

Janzantti, Natália S; Monteiro, Magali

2017-07-01

The odor-active compounds of the conventional yellow passion fruit influence the aroma during ripeness and the acceptance of the juice. HS-GC-MS and GC-OSME analysis and sensory acceptance of the conventional passion fruit from different stages of ripeness were studied to characterize the aroma of the fruit and, aroma and flavor of the juice. Ethyl butanoate, ethyl hexanoate and propyl acetate showed high odoriferous importance in the passion fruit from the 1/3 yellow skin color. C is -3-hexen-1-ol and diethyl carbonate plus the odor-active compounds from the 1/3 yellow skin color showed high odoriferous importance in the 2/3 yellow skin color, and butyl acetate and alpha-terpineol plus the same odor-active compounds from 2/3 were the most important for the 3/3 yellow skin color. There was difference in the aroma and flavor of the juices, with higher acceptance means for the passion fruit from the 3/3 yellow skin color. The passion fruit volatile compounds peak area, odoriferous intensity and sensory acceptance of the juices increased during ripeness, indicating that the conventional passion fruit characteristic aroma is completely expressed when the fruit reaches the whole maturation, at the 3/3 yellow skin color.

Simultaneous determination of creatinine and creatine in human serum by double-spike isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Fernández-Fernández, Mario; Rodríguez-González, Pablo; Añón Álvarez, M Elena; Rodríguez, Felix; Menéndez, Francisco V Álvarez; García Alonso, J Ignacio

2015-04-07

This work describes the first multiple spiking isotope dilution procedure for organic compounds using (13)C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine-creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled (13)C analogues ((13)C1-creatinine and (13)C2-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine-creatinine interconversion during LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography-isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine-creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors

TargetSearch - a Bioconductor package for the efficient preprocessing of GC-MS metabolite profiling data

PubMed Central

2009-01-01

Background Metabolite profiling, the simultaneous quantification of multiple metabolites in an experiment, is becoming increasingly popular, particularly with the rise of systems-level biology. The workhorse in this field is gas-chromatography hyphenated with mass spectrometry (GC-MS). The high-throughput of this technology coupled with a demand for large experiments has led to data pre-processing, i.e. the quantification of metabolites across samples, becoming a major bottleneck. Existing software has several limitations, including restricted maximum sample size, systematic errors and low flexibility. However, the biggest limitation is that the resulting data usually require extensive hand-curation, which is subjective and can typically take several days to weeks. Results We introduce the TargetSearch package, an open source tool which is a flexible and accurate method for pre-processing even very large numbers of GC-MS samples within hours. We developed a novel strategy to iteratively correct and update retention time indices for searching and identifying metabolites. The package is written in the R programming language with computationally intensive functions written in C for speed and performance. The package includes a graphical user interface to allow easy use by those unfamiliar with R. Conclusions TargetSearch allows fast and accurate data pre-processing for GC-MS experiments and overcomes the sample number limitations and manual curation requirements of existing software. We validate our method by carrying out an analysis against both a set of known chemical standard mixtures and of a biological experiment. In addition we demonstrate its capabilities and speed by comparing it with other GC-MS pre-processing tools. We believe this package will greatly ease current bottlenecks and facilitate the analysis of metabolic profiling data. PMID:20015393

Quantitative Analysis by Isotopic Dilution Using Mass Spectroscopy: The Determination of Caffeine by GC-MS.

ERIC Educational Resources Information Center

Hill, Devon W.; And Others

1988-01-01

Describes a laboratory technique for quantitative analysis of caffeine by an isotopic dilution method for coupled gas chromatography-mass spectroscopy. Discusses caffeine analysis and experimental methodology. Lists sample caffeine concentrations found in common products. (MVL)

Discovering Electronic Effects of Substituents in Nitrations of Benzene Derivatives Using GC-MS Analysis

ERIC Educational Resources Information Center

Clennan, Malgorzata M.; Clennan, Edward L.

2007-01-01

The nitration of six benzene derivatives having a range of substituents that differ in electronic effects were followed by GC-MS analyses of the crude reaction mixtures and adapted for the second-year organic laboratory. Students pool their results and identify the products by analyzing the mass spectral data of the isomers and by comparing them…

Potential Health Benefits and Metabolomics of Camel Milk by GC-MS and ICP-MS.

PubMed

Ahamad, Syed Rizwan; Raish, Mohammad; Ahmad, Ajaz; Shakeel, Faiyaz

2017-02-01

None of the research reports reveals the metabolomics and elemental studies on camel milk. Recent studies showed that camel milk possesses anticancer and anti-inflammatory activity. Metabolomics and elemental studies were carried out in camel milk which showed us the pathways and composition that are responsible for the key biological role of camel milk. Camel milk was dissolved in methanol and chloroform fraction and then vortexed and centrifuged. Both the fractions were derivatized by N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) and TMCS after nitrogen purging and analyzed by GC-MS. Camel milk was also analyzed by ICP-MS after microwave digestion. We found that higher alkanes and fatty acids are present in the chloroform fraction and amino acids, sugars and fatty acid derivatives are present in aqueous fractions. All the heavy metals like As, Pb, Cd, Co, Cu, and Ni were in the safe limits in terms of maximum daily intake of these elements. Na, K, Mg, and Ca were also present in the safe limits in terms of maximum daily intake of these elements. These results suggested that the camel milk drinking is safe and there is no health hazard. The present data of GC-MS and ICP-MS correlate the activities related to camel milk.

Quantitative analysis of major dibenzocyclooctane lignans in Schisandrae fructus by online TLC-DART-MS.

PubMed

Kim, Hye Jin; Oh, Myung Sook; Hong, Jongki; Jang, Young Pyo

2011-01-01

Direct analysis in real time (DART) ion source is a powerful ionising technique for the quick and easy detection of various organic molecules without any sample preparation steps, but the lack of quantitation capacity limits its extensive use in the field of phytochemical analysis. To improvise a new system which utilize DART-MS as a hyphenated detector for quantitation. A total extract of Schisandra chinensis fruit was analyzed on a TLC plate and three major lignan compounds were quantitated by three different methods of UV densitometry, TLC-DART-MS and HPLC-UV to compare the efficiency of each method. To introduce the TLC plate into the DART ion source at a constant velocity, a syringe pump was employed. The DART-MS total ion current chromatogram was recorded for the entire TLC plate. The concentration of each lignan compound was calculated from the calibration curve established with standard compound. Gomisin A, gomisin N and schisandrin were well separated on a silica-coated TLC plate and the specific ion current chromatograms were successfully acquired from the TLC-DART-MS system. The TLC-DART-MS system for the quantitation of natural products showed better linearity and specificity than TLC densitometry, and consumed less time and solvent than conventional HPLC method. A hyphenated system for the quantitation of phytochemicals from crude herbal drugs was successfully established. This system was shown to have a powerful analytical capacity for the prompt and efficient quantitation of natural products from crude drugs. Copyright © 2010 John Wiley & Sons, Ltd.

Analysis of PBDEs in soil, dust, spiked lake water, and human serum samples by hollow fiber-liquid phase microextraction combined with GC-ICP-MS.

PubMed

Xiao, Qin; Hu, Bin; Duan, Jiankun; He, Man; Zu, Wanqing

2007-10-01

A novel method for the analysis of four polybrominated diphenyl ethers (PBDEs) in environmental and human serum samples based on hollow fiber-liquid phase microextraction (HF-LPME) followed by gas chromatography-inductively coupled plasma mass spectrometric (GC-ICP-MS) detection has been developed. The organic solvent in the porous hollow fiber was first dipped into the sample for extraction at a given time, and the retracted organic phase was introduced into the GC-ICP-MS for analysis. The addition of methanol has a strong effect on the HF-LPME extraction efficiency. Other significant parameters affecting the extraction efficiency of HF-LPME were also studied. HF-LPME was effective to isolate the analytes from the complex matrix. Under the optimized conditions, the detection limits of the proposed method varied from 15.2 to 40.5 ng/L. In general, the relative standard deviations (RSDs) were less than 10%. Good linearity was obtained with the correlation coefficients all better than 0.999. The proposed method is simple, quick, few microliters of organic solvent required, and is especially suitable for the analysis of the real sample with small amount available. The overall process of HF-LPME with GC-ICP-MS was applied successfully for the determination of polybrominated diphenyl ethers (PBDEs) in environmental and spiked human serum samples, and the results were satisfactory.

Microwave heating causes rapid degradation of antioxidants in polypropylene packaging, leading to greatly increased specific migration to food simulants as shown by ESI-MS and GC-MS.

PubMed

Alin, Jonas; Hakkarainen, Minna

2011-05-25

Microwave heating of commercial microwavable polypropylene packaging in contact with fatty food simulants caused significant antioxidant degradation and increased specific migration as shown by electrospray ionization-mass spectrometry (ESI-MS) and gas chromatography-mass spectrometry (GC-MS). Degradation of the antioxidants Irgafos 168 and Irganox 1010 was not detected during conventional heating of polypropylene packaging at the same temperature. The migration into aqueous food simulants was primarily restricted by the water solubility of the migrants. Using isooctane as fatty food simulant caused significant swelling and greatly enhanced overall migration values compared to the other fatty food simulant, 99.9% ethanol, or the aqueous food simulants 10% ethanol, 3% acetic acid, or water. ESI-MS spectra clearly reflected the overall migration values, and the number and amount of compounds detected decreased as the hydrophilicity of the food simulant increased. ESI-MS was shown to be an excellent tool for the analysis of semivolatile migrants and a good complement to GC-MS analysis of volatile migrants.

Application of Sensory Evaluation, HS-SPME GC-MS, E-Nose, and E-Tongue for Quality Detection in Citrus Fruits.

PubMed

Qiu, Shanshan; Wang, Jun

2015-10-01

In this study, electronic tongue (E-tongue), headspace solid-phase microextraction gas chromatography-mass spectrometer (GC-MS), electronic nose (E-nose), and quantitative describe analysis (QDA) were applied to describe the 2 types of citrus fruits (Satsuma mandarins [Citrus unshiu Marc.] and sweet oranges [Citrus sinensis {L.} Osbeck]) and their mixing juices systematically and comprehensively. As some aroma components or some flavor molecules interacted with the whole juice matrix, the changes of most components in the fruit juice were not in proportion to the mixing ratio of the 2 citrus fruits. The potential correlations among the signals of E-tongue and E-nose, volatile components, and sensory attributes were analyzed by using analysis of variance partial least squares regression. The result showed that the variables from the sensor signals (E-tongue system and E-nose system) had significant and positive (or negative) correlations to the most variables of volatile components (GC-MS) and sensory attributes (QDA). The simultaneous utilization of E-tongue and E-nose obtained a perfect classification result with 100% accuracy rate based on linear discriminant analysis and also attained a satisfying prediction with high coefficient association for the sensory attributes (R(2) > 0.994 for training sets and R(2) > 0.983 for testing sets) and for the volatile components (R(2) > 0.992 for training sets and R(2) > 0.990 for testing sets) based on random forest. Being easy-to-use, cost-effective, robust, and capable of providing a fast analysis procedure, E-nose and E-tongue could be used as an alternative detection system to traditional analysis methods, such as GC-MS and sensory evaluation by human panel in the fruit industry. Being easy-to-use, cost-effective, robust, and capable of providing a fast analysis procedure, E-nose and E-tongue could be used as an alternative detection system to traditional analysis methods for characterizing food flavors. Based on those

Quantitation of Mycotoxins Using Direct Analysis in Real Time Mass Spectrometry (DART-MS).

PubMed

Busman, Mark

2018-05-01

Ambient ionization represents a new generation of MS ion sources and is used for the rapid ionization of small molecules under ambient conditions. The combination of ambient ionization and MS allows the analysis of multiple food samples with simple or no sample treatment or in conjunction with prevailing sample preparation methods. Two ambient ionization methods, desorptive electrospray ionization (DESI) and direct analysis in real time (DART) have been adapted for food safety application. Both ionization techniques provide unique advantages and capabilities. DART has been used for a variety of qualitative and quantitative applications. In particular, mycotoxin contamination of food and feed materials has been addressed by DART-MS. Applications to mycotoxin analysis by ambient ionization MS and particularly DART-MS are summarized.

Comparison of GC-MS and FTIR methods for quantifying naphthenic acids in water samples.

PubMed

Scott, Angela C; Young, Rozlyn F; Fedorak, Phillip M

2008-11-01

The extraction of bitumen from the oil sands in Canada releases toxic naphthenic acids into the process-affected waters. The development of an ideal analytical method for quantifying naphthenic acids (general formula C(n)H(2n+Z)O(2)) has been impeded by the complexity of these mixtures and the challenges of differentiating naphthenic acids from other naturally-occurring organic acids. The oil sands industry standard FTIR method was compared with a newly-developed GC-MS method. Naphthenic acids concentrations were measured in extracts of surface and ground waters from locations within the vicinity of and away from the oil sands deposits and in extracts of process-affected waters. In all but one case, FTIR measurements of naphthenic acids concentrations were greater than those determined by GC-MS. The detection limit of the GC-MS method was 0.01 mg L(-1) compared to 1 mg L(-1) for the FTIR method. The results indicated that the GC-MS method is more selective for naphthenic acids, and that the FTIR method overestimates their concentrations.

Determination of Detection Limits and Quantitation Limits for Compounds in a Database of GC/MS by FUMI Theory

PubMed Central

Nakashima, Shinya; Hayashi, Yuzuru

2016-01-01

The aim of this paper is to propose a stochastic method for estimating the detection limits (DLs) and quantitation limits (QLs) of compounds registered in a database of a GC/MS system and prove its validity with experiments. The approach described in ISO 11843 Part 7 is adopted here as an estimation means of DL and QL, and the decafluorotriphenylphosphine (DFTPP) tuning and retention time locking are carried out for adjusting the system. Coupled with the data obtained from the system adjustment experiments, the information (noise and signal of chromatograms and calibration curves) stored in the database is used for the stochastic estimation, dispensing with the repetition measurements. Of sixty-six pesticides, the DL values obtained by the ISO method were compared with those from the statistical approach and the correlation between them was observed to be excellent with the correlation coefficient of 0.865. The accuracy of the method proposed was also examined and concluded to be satisfactory as well. The samples used are commercial products of pesticides mixtures and the uncertainty from sample preparation processes is not taken into account. PMID:27162706

Power of Orbitrap-based LC-high resolution-MS/MS for comprehensive drug testing in urine with or without conjugate cleavage or using dried urine spots after on-spot cleavage in comparison to established LC-MSn or GC-MS procedures.

PubMed

Michely, Julian A; Meyer, Markus R; Maurer, Hans H

2018-01-01

Reliable, sensitive, and comprehensive urine screening procedures by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) with low or high resolution (HR) are of high importance for drug testing, adherence monitoring, or detection of toxic compounds. Besides conventional urine sampling, dried urine spots are of increasing interest. In the present study, the power of LC-HR-MS/MS was investigated for comprehensive drug testing in urine with or without conjugate cleavage or using dried urine spots after on-spot cleavage in comparison to established LC-MS n or GC-MS procedures. Authentic human urine samples (n = 103) were split in 4 parts. One aliquot was prepared by precipitation (UP), one by UP with conjugate cleavage (UglucP), one spot on filter paper cards and prepared by on-spot cleavage followed by liquid extraction (DUSglucE), and one worked-up by acid hydrolysis, liquid-liquid extraction, and acetylation for GC-MS analysis. The 3 series of LC-HR-MS/MS results were compared among themselves, to corresponding published LC-MS n data, and to screening results obtained by conventional GC-MS. The reference libraries used for the 3 techniques contained over 4500 spectra of parent compounds and their metabolites. The number of all detected hits (770 drug intakes) was set to 100%. The LC-HR-MS/MS approach detected 80% of the hits after UP, 89% after UglucP, and 77% after DUSglucE, which meant over one-third more hits in comparison to the corresponding published LC-MS n results with ≤49% detected hits. The GC-MS approach identified 56% of all detected hits. In conclusion, LC-HR-MS/MS provided the best screening results after conjugate cleavage and precipitation. Copyright © 2017 John Wiley & Sons, Ltd.

Design and analysis of quantitative differential proteomics investigations using LC-MS technology.

PubMed

Bukhman, Yury V; Dharsee, Moyez; Ewing, Rob; Chu, Peter; Topaloglou, Thodoros; Le Bihan, Thierry; Goh, Theo; Duewel, Henry; Stewart, Ian I; Wisniewski, Jacek R; Ng, Nancy F

2008-02-01

Liquid chromatography-mass spectrometry (LC-MS)-based proteomics is becoming an increasingly important tool in characterizing the abundance of proteins in biological samples of various types and across conditions. Effects of disease or drug treatments on protein abundance are of particular interest for the characterization of biological processes and the identification of biomarkers. Although state-of-the-art instrumentation is available to make high-quality measurements and commercially available software is available to process the data, the complexity of the technology and data presents challenges for bioinformaticians and statisticians. Here, we describe a pipeline for the analysis of quantitative LC-MS data. Key components of this pipeline include experimental design (sample pooling, blocking, and randomization) as well as deconvolution and alignment of mass chromatograms to generate a matrix of molecular abundance profiles. An important challenge in LC-MS-based quantitation is to be able to accurately identify and assign abundance measurements to members of protein families. To address this issue, we implement a novel statistical method for inferring the relative abundance of related members of protein families from tryptic peptide intensities. This pipeline has been used to analyze quantitative LC-MS data from multiple biomarker discovery projects. We illustrate our pipeline here with examples from two of these studies, and show that the pipeline constitutes a complete workable framework for LC-MS-based differential quantitation. Supplementary material is available at http://iec01.mie.utoronto.ca/~thodoros/Bukhman/.

Comparison of tire and road wear particle concentrations in sediment for watersheds in France, Japan, and the United States by quantitative pyrolysis GC/MS analysis.

PubMed

Unice, Ken M; Kreider, Marisa L; Panko, Julie M

2013-08-06

Impacts of surface runoff to aquatic species are an ongoing area of concern. Tire and road wear particles (TRWP) are a constituent of runoff, and determining accurate TRWP concentrations in sediment is necessary in order to evaluate the likelihood that these particles present a risk to the aquatic environment. TRWP consist of approximately equal mass fractions of tire tread rubber and road surface mineral encrustations. Sampling was completed in the Seine (France), Chesapeake (U.S.), and Yodo-Lake Biwa (Japan) watersheds to quantify TRWP in the surficial sediment of watersheds characterized by a wide diversity of population densities and land uses. By using a novel quantitative pyrolysis-GC/MS analysis for rubber polymer, we detected TRWP in 97% of the 149 sediment samples collected. The mean concentrations of TRWP were 4500 (n = 49; range = 62-11 600), 910 (n = 50; range = 50-4400) and 770 (n = 50; range = 26-4600) μg/g d.w. for the characterized portions of the Seine, Chesapeake and Yodo-Lake Biwa watersheds, respectively. A subset of samples from the watersheds (n = 45) was pooled to evaluate TRWP metals, grain size and organic carbon correlations by principal components analysis (PCA), which indicated that four components explain 90% of the variance. The PCA components appeared to correspond to (1) metal alloys possibly from brake wear (primarily Cu, Pb, Zn), (2) crustal minerals (primarily Al, V, Fe), (3) metals mediated by microbial immobilization (primarily Co, Mn, Fe with TOC), and (4) TRWP and other particulate deposition (primarily TRWP with grain size and TOC). This study should provide useful information for assessing potential aquatic effects related to tire service life.

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

GC-MS analyses of the volatiles of Houttuynia cordata Thunb.

PubMed

Yang, Zhan-Nan; Luo, Shi-Qiong; Ma, Jing; Wu, Dan; Hong, Liang; Yu, Zheng-Wen

2016-09-01

GC-MS is the basis of analysis of plant volatiles. Several protocols employed for the assay have resulted in inconsistent results in the literature. We developed a GC-MS method, which were applied to analyze 25 volatiles (α-pinene, camphene, β-pinene, 2-methyl-2-pentenal, myrcene, (+)-limonene, eucalyptol, trans-2-hexenal, γ-terpinene, cis-3-hexeneyl-acetate, 1-hexanol, α-pinene oxide, cis-3-hexen-1-ol, trans-2-hexen-1-ol, decanal, linalool, acetyl-borneol, β-caryophyllene, 2-undecanone, 4-terpineol, borneol, decanol, eugenol, isophytol and phytol) of Houttuynia cordata Thunb. Linear behaviors for all analytes were observed with a linear regression relationship (r2>0.9991) at the concentrations tested. Recoveries of the 25 analytes were 98.56-103.77% with RSDs <3.0%. Solution extraction (SE), which involved addition of an internal standard, could avoid errors for factors in sample preparation by steam distillation (SD) and solidphase micro extraction (SPME). Less sample material (≍0.05g fresh leaves of H. cordata) could be used to determine the contents of 25 analytes by our proposed method and, after collection, did not affect the normal physiological activity or growth of H. cordata. This method can be used to monitor the metabolic accumulation of H. cordata volatiles.

In situ Analysis of Organic Matter in Martian Soil: Laboratory Measurements Under Martian Operating Conditions Supporting Treatment and Interpretation of SAM GC-MS Data

NASA Astrophysics Data System (ADS)

Millan, M.; Szopa, C.; Coll, P.; Buch, A.; Cabane, M.; Coscia, D.; Glavin, D. P.; Freissinet, C.

2014-07-01

This work presents laboratory measurements under martian operating conditions in comparison with the SAM GC-MS data provided by the Curiosity rover. Their treatment and interpretation supports the in situ analysis of organic matter on Mars.

Rapid determination of residues of pesticides in honey by µGC-ECD and GC-MS/MS: Method validation and estimation of measurement uncertainty according to document No. SANCO/12571/2013.

PubMed

Paoloni, Angela; Alunni, Sabrina; Pelliccia, Alessandro; Pecorelli, Ivan

2016-01-01

A simple and straightforward method for simultaneous determination of residues of 13 pesticides in honey samples (acrinathrin, bifenthrin, bromopropylate, cyhalothrin-lambda, cypermethrin, chlorfenvinphos, chlorpyrifos, coumaphos, deltamethrin, fluvalinate-tau, malathion, permethrin and tetradifon) from different pesticide classes has been developed and validated. The analytical method provides dissolution of honey in water and an extraction of pesticide residues by n-Hexane followed by clean-up on a Florisil SPE column. The extract was evaporated and taken up by a solution of an injection internal standard (I-IS), ethion, and finally analyzed by capillary gas chromatography with electron capture detection (GC-µECD). Identification for qualitative purpose was conducted by gas chromatography with triple quadrupole mass spectrometer (GC-MS/MS). A matrix-matched calibration curve was performed for quantitative purposes by plotting the area ratio (analyte/I-IS) against concentration using a GC-µECD instrument. According to document No. SANCO/12571/2013, the method was validated by testing the following parameters: linearity, matrix effect, specificity, precision, trueness (bias) and measurement uncertainty. The analytical process was validated analyzing blank honey samples spiked at levels equal to and greater than 0.010 mg/kg (limit of quantification). All parameters were satisfactorily compared with the values established by document No. SANCO/12571/2013. The analytical performance was verified by participating in eight multi-residue proficiency tests organized by BIPEA, obtaining satisfactory z-scores in all 70 determinations. Measurement uncertainty was estimated according to the top-down approaches described in Appendix C of the SANCO document using the within-laboratory reproducibility relative standard deviation combined with laboratory bias using the proficiency test data.

Quantitative Silylation Speciations of Primary Phenylalkyl Amines, Including Amphetamine and 3,4-Methylenedioxyamphetamine Prior to Their Analysis by GC/MS.

PubMed

Molnár, Borbála; Fodor, Blanka; Boldizsár, Imre; Molnár-Perl, Ibolya

2015-10-20

A novel, quantitative trimethylsilylation approach derivatizing 11 primary phenylalkyl amines (PPAAs), including amphetamine (A) and 3,4-methylenedioxyamphetamine (MDA), was noted. Triggering the fully derivatized ditrimethylsilyl (diTMS) species with the N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) reagent, a new principle was recognized followed by GC/MS. In the course of method optimization, the complementary impact of solvents (acetonitrile, ACN; ethyl acetate, ETAC; pyridine, PYR) and catalysts (trimethylchlorosilane, TMCS; trimethyliodosilane, TMIS) was studied: the role of solvent and catalyst proved to be equally crucial. Optimum, proportional, huge responses were obtained with the MSTFA/PYR = 2/1-9/1 (v/v) reagent applying catalysts; A and MDA needed the TMIS, while the rest of PPAAs provided the diTMS products also with TMCS. Similar to derivatives generated with hexamethyldisilazane and perfluorocarboxylic acid (HMDS and PFCA) ( Molnár et al. Anal. Chem. 2015 , 87 , 848 - 852 ), the fully silylated PPAAs offer several advantages. Both of our methods save time and cost by allowing for direct injection of analytes into the column; this is in stark contrast with the requirement to evaporate acid anhydrides by nitrogen prior to their injection. Efficiences of the novel catalyzed trimethylsilylation (MSTFA) and our recently introduced (now, for A and MDA extended) acylation principle were contrasted. Catalyzed trimethylsilylation led to diTMS derivatives resulting in on average a 1.7 times larger response compared to the corresponding acylated species. Catalyzed trimethylsilylation of PPAAs, A, and MDA were characterized with retention, mass fragmentation, and analytical performance properties (R(2), LOQ values). The practical utility of ditrimethylsilyation was shown by analyzing A in urine and mescaline (MSC) in cactus samples.

Identification of unknown impurity of azelaic acid in liposomal formulation assessed by HPLC-ELSD, GC-FID, and GC-MS.

PubMed

Han, Stanisław; Karłowicz-Bodalska, Katarzyna; Potaczek, Piotr; Wójcik, Adam; Ozimek, Lukasz; Szura, Dorota; Musiał, Witold

2014-02-01

The identification of new contaminants is critical in the development of new medicinal products. Many impurities, such as pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid, have been identified in samples of azelaic acid. The aim of this study was to identify impurities observed during the stability tests of a new liposomal dosage form of azelaic acid that is composed of phosphatidylcholine and a mixture of ethyl alcohol and water, using high-performance liquid chromatography with evaporative light-scattering detector (HPLC-ELSD), gas chromatography-flame ionisation detection (GC-FID), and gas chromatography-mass spectrometry (GC-MS) methods. During the research and development of a new liposomal formulation of azelaic acid, we developed a method for determining the contamination of azelaic acid using HPLC-ELSD. During our analytical tests, we identified a previously unknown impurity of a liposomal preparation of azelaic acid that appeared in the liposomal formulation of azelaic acid during preliminary stability studies. The procedure led to the conclusion that the impurity was caused by the reaction of azelaic acid with one of the excipients that was applied in the product. The impurity was finally identified as an ethyl monoester of azelaic acid. The identification procedure of this compound was carried out in a series of experiments comparing the chromatograms that were obtained via the following chromatographic methods: HPLC-ELSD, GC-FID, and GC-MS. The final identification of the compound was carried out by GC with MS.

Differentiating organically and conventionally grown oregano using ultraperformance liquid chromatography mass spectrometry (UPLC-MS), headspace gas chromatography with flame ionization detection (headspace-GC-FID), and flow injection mass spectrum (FIMS) fingerprints combined with multivariate data analysis.

PubMed

Gao, Boyan; Qin, Fang; Ding, Tingting; Chen, Yineng; Lu, Weiying; Yu, Liangli Lucy

2014-08-13

Ultraperformance liquid chromatography mass spectrometry (UPLC-MS), flow injection mass spectrometry (FIMS), and headspace gas chromatography (headspace-GC) combined with multivariate data analysis techniques were examined and compared in differentiating organically grown oregano from that grown conventionally. It is the first time that headspace-GC fingerprinting technology is reported in differentiating organically and conventionally grown spice samples. The results also indicated that UPLC-MS, FIMS, and headspace-GC-FID fingerprints with OPLS-DA were able to effectively distinguish oreganos under different growing conditions, whereas with PCA, only FIMS fingerprint could differentiate the organically and conventionally grown oregano samples. UPLC fingerprinting provided detailed information about the chemical composition of oregano with a longer analysis time, whereas FIMS finished a sample analysis within 1 min. On the other hand, headspace GC-FID fingerprinting required no sample pretreatment, suggesting its potential as a high-throughput method in distinguishing organically and conventionally grown oregano samples. In addition, chemical components in oregano were identified by their molecular weight using QTOF-MS and headspace-GC-MS.

Untargeted Metabolomic Analysis of Capsicum spp. by GC-MS.

PubMed

Aranha, Bianca Camargo; Hoffmann, Jessica Fernanda; Barbieri, Rosa Lia; Rombaldi, Cesar Valmor; Chaves, Fábio Clasen

2017-09-01

In order to conserve the biodiversity of Capsicum species and find genotypes with potential to be utilised commercially, Embrapa Clima Temperado maintains an active germplasm collection (AGC) that requires characterisation, enabling genotype selection and support for breeding programmes. The objective of this study was to characterise pepper accessions from the Embrapa Clima Temperado AGC and differentiate species based on their metabolic profile using an untargeted metabolomics approach. Cold (-20°C) methanol extraction residue of freeze-dried fruit samples was partitioned into water/methanol (A) and chloroform (B) fractions. The polar fraction (A) was derivatised and both fractions (A and B) were analysed by gas chromatography coupled to mass spectrometry (GC-MS). Data from each fraction was analysed using a multivariate principal component analysis (PCA) with XCMS software. Amino acids, sugars, organic acids, capsaicinoids, and hydrocarbons were identified. Outlying accessions including P116 (C. chinense), P46, and P76 (C. annuum) were observed in a PCA plot mainly due to their high sucrose and fructose contents. PCA also indicated a separation of P221 (C. annuum) and P200 (C. chinense), because of their high dihydrocapsaicin content. Although the metabolic profiling did not allow for grouping by species, it permitted the simultaneous identification and quantification of several compounds complementing and expanding the metabolic database of the studied Capsicum spp. in the AGC. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Metabolomics Characterization of Two Apocynaceae Plants, Catharanthus roseus and Vinca minor, Using GC-MS and LC-MS Methods in Combination.

PubMed

Chen, Qi; Lu, Xueyan; Guo, Xiaorui; Guo, Qingxi; Li, Dewen

2017-06-17

Catharanthus roseus ( C. roseus ) and Vinca minor ( V. minor ) are two common important medical plants belonging to the family Apocynaceae. In this study, we used non-targeted GC-MS and targeted LC-MS metabolomics to dissect the metabolic profile of two plants with comparable phenotypic and metabolic differences. A total of 58 significantly different metabolites were present in different quantities according to PCA and PLS-DA score plots of the GC-MS analysis. The 58 identified compounds comprised 16 sugars, eight amino acids, nine alcohols and 18 organic acids. We subjected these metabolites into KEGG pathway enrichment analysis and highlighted 27 metabolic pathways, concentrated on the TCA cycle, glycometabolism, oligosaccharides, and polyol and lipid transporter (RFOS). Among the primary metabolites, trehalose, raffinose, digalacturonic acid and gallic acid were revealed to be the most significant marker compounds between the two plants, presumably contributing to species-specific phenotypic and metabolic discrepancy. The profiling of nine typical alkaloids in both plants using LC-MS method highlighted higher levels of crucial terpenoid indole alkaloid (TIA) intermediates of loganin, serpentine, and tabersonine in V. minor than in C. roseus . The possible underlying process of the metabolic flux from primary metabolism pathways to TIA synthesis was discussed and proposed. Generally speaking, this work provides a full-scale comparison of primary and secondary metabolites between two medical plants and a metabolic explanation of their TIA accumulation and phenotype differences.

Authentication of Polygonati Odorati Rhizoma and other two Chinese Materia Medica of the Liliaceae family by pharmacognosy technique with GC-MS analysis.

PubMed

Liu, Yingjiao; Liu, Canhuang; Yu, Yafei; Xu, Bei; Gong, Limin; Zeng, Xiaoyan; Xiao, Lan; Cheng, Qilai; Liu, Tasi

2015-02-01

Yuzhu (Polygonati Odorati Rhizoma), Kangdingyuzhu (Polygonati Prattii Rhizoma), and zhugenqiyuzhu (Disporopsis Fuscopictae Rhizoma) are of the same family, but of different genera. They have all often used in Chinese Materia Medica (CMM) as Polygonati Odorati Rhizoma in China market. Three species of CMM are confused. For better application, we need to identify these plants accurately. This study use pharmacognosy technique and GC-MS analysis, three species of CMM were authenticated. In macroscopic characteristics, the fruit of Polygonati Odorati Rhizoma is blue-black, while the other two are maroon and dark purple orderly. Nodes of Polygonati Odorati Rhizoma are upward and light uplift, about 1 cm spacing, while the other are not. As for microscopic characteristics, the cortex of Polygonati Odorati Rhizoma only occupies about 1/5 of the radius of the transverse section with inconspicuous endodermis, which is much smaller than others. The type of vascular bundles of Polygonati Odorati Rhizoma is closed collateral, but the other is amphivasal. Raphides of calcium oxalate are scattered, but Raphides of the other two are like brooms and neat rows. GC-MS analysis of essential oil could provide different characteristics to distinguish three species. Twenty-three compounds were identified from essential oil of Polygonati Odorati Rhizoma and the main components were n-hexadecanoic acid (49.45%), while n-hexadecanoic acid of the other two are 23.92% and 9.45%. The content of n-hexadecanoic is strongly different. This research was aimed to establish a method by pharmacognosy and GC-MS analysis to identify three CMM and for providing scientifical data to ensure accuracy of origin of three species. © 2014 Wiley Periodicals, Inc.

EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

EPA Science Inventory

Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

Speciation of organotin compounds in urine by GC-MIP-AED and GC-MS after ethylation and liquid-liquid extraction.

PubMed

Zachariadis, G A; Rosenberg, E

2009-04-15

A method for the determination of organotin compounds in urine samples based on liquid-liquid extraction (LLE) in hexane and gas chromatographic separation was developed and optimized. Seven organotin species, namely monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), tetrabutyltin (TeBT), monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT), were in situ derivatized by sodium tetraethylborate (NaBEt(4)) to form ethylated less polar derivatives directly in the urine matrix. The critical parameters which have a significant effect on the yield of the successive liquid-liquid extraction procedure were examined, by using standard solutions of tetrabutyltin in hexane. The method was optimized for use in direct analysis of undiluted human urine samples and ways to overcome practical problems such as foam formation during extraction, due to various constituents of urine are discussed. After thorough optimization of the extraction procedure, all examined species could be determined after 3 min of simultaneous derivatization and extraction at room temperature and 5 min phase separation by centrifugation. Gas chromatography with a microwave-induced plasma atomic emission detector (MIP-AED) as element specific detector was employed for quantitative measurements, while a quadrupole mass spectrometric detector (MS) was used as molecular specific detector. The detection limits were between 0.42 and 0.67 microg L(-1) (as Sn) for the quantitative LLE-GC-MIP-AED method and the precision between 4.2% and 11.7%, respectively.

Quantitative analysis of fatty-acid-based biofuels produced by wild-type and genetically engineered cyanobacteria by gas chromatography-mass spectrometry.

PubMed

Guan, Wenna; Zhao, Hui; Lu, Xuefeng; Wang, Cong; Yang, Menglong; Bai, Fali

2011-11-11

Simple and rapid quantitative determination of fatty-acid-based biofuels is greatly important for the study of genetic engineering progress for biofuels production by microalgae. Ideal biofuels produced from biological systems should be chemically similar to petroleum, like fatty-acid-based molecules including free fatty acids, fatty acid methyl esters, fatty acid ethyl esters, fatty alcohols and fatty alkanes. This study founded a gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of seven free fatty acids, nine fatty acid methyl esters, five fatty acid ethyl esters, five fatty alcohols and three fatty alkanes produced by wild-type Synechocystis PCC 6803 and its genetically engineered strain. Data obtained from GC-MS analyses were quantified using internal standard peak area comparisons. The linearity, limit of detection (LOD) and precision (RSD) of the method were evaluated. The results demonstrated that fatty-acid-based biofuels can be directly determined by GC-MS without derivation. Therefore, rapid and reliable quantitative analysis of fatty-acid-based biofuels produced by wild-type and genetically engineered cyanobacteria can be achieved using the GC-MS method founded in this work. Copyright © 2011 Elsevier B.V. All rights reserved.

Assaying Alpha-Dicarbonyl Compounds in Wine: A Complementary GC-MS, HPCL, and Visible Spectrophotometric Analysis

ERIC Educational Resources Information Center

Dwyer, Tammy J.; Fillo, Jeremiah D.

2006-01-01

The analytical system to teach the subtleties of assaying alpha-dicarbonyl compounds in wine is described. Spectrophotometry is determined to be minimally useful in the experiment where the GC-MS (methyglyoxal) method proved to be ideal to confirm that the compounds analyzed in the wine samples were indeed the glyoxals based on the formation of…

Analysis of emerging organic contaminants in water, fish and suspended particulate matter (SPM) in the Joint Danube Survey using solid-phase extraction followed by UHPLC-MS-MS and GC-MS analysis.

PubMed

Loos, Robert; Tavazzi, Simona; Mariani, Giulio; Suurkuusk, Gert; Paracchini, Bruno; Umlauf, Gunther

2017-12-31

In the third Joint Danube Survey (JDS3), emerging organic contaminants were analysed in the dissolved water phase of samples from the Danube River and its major tributaries. Analyses were performed using solid-phase extraction (SPE) followed by ultra-high-pressure liquid chromatography triple-quadrupole mass spectrometry (UHPLC-MS-MS) and gas chromatography-mass spectrometry (GC-MS). The polar organic compounds analysed by UHPLC-MS-MS were 1H-benzotriazole, methylbenzotriazoles, carbamazepine, 10,11-dihydro-10,11-dihydroxy-carbamazepine, diclofenac, sulfamethox-azole, 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA (2-methyl-4-chlorophenoxyacetic acid), metolachlor, cybutryne (irgarol), terbutryn, DEET (N,N-diethyl-m-toluamide), and several perfluoroalkyl acids (C 6 -C 9 ; C 8 =perfluorooctanoic acid (PFOA)) and perfluorooctansulfonic acid (PFOS). In addition, several organophosphorus flame retardants were analysed by GC-MS. The most relevant compounds identified in the 71 water samples, in terms of highest median and maximum concentrations, were 1H-benzotriazole, tris(1-chloro-2-propyl)phosphate (TCPP), methylbenzotriazoles, carbama-zepine and its metabolite, DEET, sulfamethoxazole, tris(isobutyl)phosphate (TiBP), tris(2-chloroethyl)phosphate (TCEP), PFOA, PFOS and diclofenac. The concentrations of these compounds in the samples were generally below the environmental quality standard (EQS) threshold values, with the exception of PFOS, the concentration of which exceeded the annual average water EQS limit of 0.65ng/L along the whole river, and also exceeded the fish biota EQS of 9.1μg/kg. In addition, the proposed EQS for diclofenac, of 0.1μg/L, was exceeded in the Arges River in Romania (255ng/L). Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

The optimization of phthalate analysis from plastic matrices by using GC/MS related techniques

NASA Astrophysics Data System (ADS)

Pusfitasari, Eka Dian; Hendarsyah, Hendris; Athaillah, Zatil Afrah

2017-11-01

Indication of malicious acts conducted by food vendors has been reported in many places in Indonesia and has been worrying the population. One of the issues is the indication that frying oil used by the vendors has been added with food packaging plastic to impart more crispy texture of the fried foods. One of the challenges for the monitoring process is to find suitable analytical method to identify this type of food adulteration. Because some food packaging, particularly from polyethylene group, contains plasticizer diethylhexylphthalate (DEHP), we intended to investigate the adulteration by detecting the phthalate compound. In this preliminary study, we focused on the optimization of GC equipment as well as the optimization of plastic extraction process with various types of solvents (hexane, dichloromethane, and acetonitrile) and extraction time (24, 48, and 72 hours). For 72-hour duration, treatment with solvent refreshment was also conducted to minimize solvent saturation effect. Our findings suggested that LOD and LOQ of the GC/MS instrument used for the DEHP analysis were 19.6 ng and 65.5 ng, respectively. In addition, it could be concluded that the process of plastic extraction through sonication for five minutes with n-hexane as a solvent resulted in the optimal value.

Catalytic pyrolysis-GC/MS of lignin from several sources

USDA-ARS?s Scientific Manuscript database

Lignin from four different sources extracted by various methods were pyrolyzed at 650 degree C using analytical pyrolysis methods, py-GC/MS. Pyrolysis was carried out in the absence and presence of two heterogeneous catalysts , an acidic zeolite (HZSM-5) catalyst and a mixed metal oxide catalyst (Co...

Analysis of munitions constituents in groundwater using a field-portable GC-MS.

PubMed

Bednar, A J; Russell, A L; Hayes, C A; Jones, W T; Tackett, P; Splichal, D E; Georgian, T; Parker, L V; Kirgan, R A; MacMillan, D K

2012-05-01

The use of munitions constituents (MCs) at military installations can produce soil and groundwater contamination that requires periodic monitoring even after training or manufacturing activities have ceased. Traditional groundwater monitoring methods require large volumes of aqueous samples (e.g., 2-4 L) to be shipped under chain of custody, to fixed laboratories for analysis. The samples must also be packed on ice and shielded from light to minimize degradation that may occur during transport and storage. The laboratory's turn-around time for sample analysis and reporting can be as long as 45 d. This process hinders the reporting of data to customers in a timely manner; yields data that are not necessarily representative of current site conditions owing to the lag time between sample collection and reporting; and incurs significant shipping costs for samples. The current work compares a field portable Gas Chromatograph-Mass Spectrometer (GC-MS) for analysis of MCs on-site with traditional laboratory-based analysis using High Performance Liquid Chromatography with UV absorption detection. The field method provides near real-time (within ~1 h of sampling) concentrations of MCs in groundwater samples. Mass spectrometry provides reliable confirmation of MCs and a means to identify unknown compounds that are potential false positives for methods with UV and other non-selective detectors. Published by Elsevier Ltd.

Characterization of Estrogen and Androgen Activity of Food Contact Materials by Different In Vitro Bioassays (YES, YAS, ERα and AR CALUX) and Chromatographic Analysis (GC-MS, HPLC-MS)

PubMed Central

Osorio, Veronica; Grininger, Angelika; Richter, Alexander; Bergmair, Johannes; Pyerin, Michael; Washüttl, Michael; Tacker, Manfred

2014-01-01

Endocrine active substances (EAS) show structural similarities to natural hormones and are suspected to affect the human endocrine system by inducing hormone dependent effects. Recent studies with in vitro tests suggest that EAS can leach from packaging into food and may therefore pose a risk to human health. Sample migrates from food contact materials were tested for estrogen and androgen agonists and antagonists with different commonly used in vitro tests. Additionally, chemical trace analysis by GC-MS and HPLC-MS was used to identify potential hormone active substances in sample migrates. A GC-MS method to screen migrates for 29 known or potential endocrine active substances was established and validated. Samples were migrated according to EC 10/2011, concentrated by solid phase extraction and tested with estrogen and androgen responsive reporter gene assays based on yeast cells (YES and YAS) or human osteoblast cells (ERα and AR CALUX). A high level of agreement between the different bioassays could be observed by screening for estrogen agonists. Four out of 18 samples tested showed an estrogen activity in a similar range in both, YES and ERα CALUX. Two more samples tested positive in ERα CALUX due to the lower limits of detection in this assay. Androgen agonists could not be detected in any of the tested samples, neither with YAS nor with AR CALUX. When testing for antagonists, significant differences between yeast and human cell-based bioassays were noticed. Using YES and YAS many samples showed a strong antagonistic activity which was not observed using human cell-based CALUX assays. By GC-MS, some known or supposed EAS were identified in sample migrates that showed a biological activity in the in vitro tests. However, no firm conclusions about the sources of the observed hormone activity could be obtained from the chemical results. PMID:25000404

Large-Scale and Deep Quantitative Proteome Profiling Using Isobaric Labeling Coupled with Two-Dimensional LC-MS/MS

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

Gritsenko, Marina A.; Xu, Zhe; Liu, Tao

Comprehensive, quantitative information on abundances of proteins and their post-translational modifications (PTMs) can potentially provide novel biological insights into diseases pathogenesis and therapeutic intervention. Herein, we introduce a quantitative strategy utilizing isobaric stable isotope-labelling techniques combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) for large-scale, deep quantitative proteome profiling of biological samples or clinical specimens such as tumor tissues. The workflow includes isobaric labeling of tryptic peptides for multiplexed and accurate quantitative analysis, basic reversed-phase LC fractionation and concatenation for reduced sample complexity, and nano-LC coupled to high resolution and high mass accuracy MS analysis for high confidence identification andmore » quantification of proteins. This proteomic analysis strategy has been successfully applied for in-depth quantitative proteomic analysis of tumor samples, and can also be used for integrated proteome and PTM characterization, as well as comprehensive quantitative proteomic analysis across samples from large clinical cohorts.« less

Large-Scale and Deep Quantitative Proteome Profiling Using Isobaric Labeling Coupled with Two-Dimensional LC-MS/MS.

PubMed

Gritsenko, Marina A; Xu, Zhe; Liu, Tao; Smith, Richard D

2016-01-01

Comprehensive, quantitative information on abundances of proteins and their posttranslational modifications (PTMs) can potentially provide novel biological insights into diseases pathogenesis and therapeutic intervention. Herein, we introduce a quantitative strategy utilizing isobaric stable isotope-labeling techniques combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) for large-scale, deep quantitative proteome profiling of biological samples or clinical specimens such as tumor tissues. The workflow includes isobaric labeling of tryptic peptides for multiplexed and accurate quantitative analysis, basic reversed-phase LC fractionation and concatenation for reduced sample complexity, and nano-LC coupled to high resolution and high mass accuracy MS analysis for high confidence identification and quantification of proteins. This proteomic analysis strategy has been successfully applied for in-depth quantitative proteomic analysis of tumor samples and can also be used for integrated proteome and PTM characterization, as well as comprehensive quantitative proteomic analysis across samples from large clinical cohorts.

MS-MS Approaches for the Analysis of Environmental Pollutants

EPA Science Inventory

Concern about the environment and the start of environmental analysis coincided with the rise of gas chromatography-mass spectrometry (GC-MS). The United States Environmental Protection Agency (U.S. EPA) was founded in 1970, and as the need for techniques to analyze environmental...

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

2012-01-01

We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

GC-MS (GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC) SUITABILITY TESTING OF RCRA APPENDIX VIII AND MICHIGAN LIST ANALYTES

EPA Science Inventory

As a first step in a hierarchical scheme to demonstrate the suitability of present U.S. Environmental Protection Agency (USEPA) analysis methods and/or develop new methodology, the gas chromatographic (GC) separation and mass spectrometric (MS) detection characteristics of 328 to...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF SOIL/HOUSE DUST FOR GC/MS ANALYSIS OF PESTICIDES (BCO-L-14.0)

EPA Science Inventory

The purpose of this SOP is to describe procedures for extracting and preparing dust or soil samples for gas chromatography/mass spectrometry (GC/MS) analysis of pesticides. This procedure was followed to ensure consistent data retrieval during the Arizona NHEXAS project and the "...

Elimination of chromatographic and mass spectrometric problems in GC-MS analysis of Lavender essential oil by multivariate curve resolution techniques: Improving the peak purity assessment by variable size moving window-evolving factor analysis.

PubMed

Jalali-Heravi, Mehdi; Moazeni-Pourasil, Roudabeh Sadat; Sereshti, Hassan

2015-03-01

In analysis of complex natural matrices by gas chromatography-mass spectrometry (GC-MS), many disturbing factors such as baseline drift, spectral background, homoscedastic and heteroscedastic noise, peak shape deformation (non-Gaussian peaks), low S/N ratio and co-elution (overlapped and/or embedded peaks) lead the researchers to handle them to serve time, money and experimental efforts. This study aimed to improve the GC-MS analysis of complex natural matrices utilizing multivariate curve resolution (MCR) methods. In addition, to assess the peak purity of the two-dimensional data, a method called variable size moving window-evolving factor analysis (VSMW-EFA) is introduced and examined. The proposed methodology was applied to the GC-MS analysis of Iranian Lavender essential oil, which resulted in extending the number of identified constituents from 56 to 143 components. It was found that the most abundant constituents of the Iranian Lavender essential oil are α-pinene (16.51%), camphor (10.20%), 1,8-cineole (9.50%), bornyl acetate (8.11%) and camphene (6.50%). This indicates that the Iranian type Lavender contains a relatively high percentage of α-pinene. Comparison of different types of Lavender essential oils showed the composition similarity between Iranian and Italian (Sardinia Island) Lavenders. Published by Elsevier B.V.

Volatile compound changes during shelf life of dried Boletus edulis: comparison between SPME-GC-MS and PTR-ToF-MS analysis.

PubMed

Aprea, Eugenio; Romano, Andrea; Betta, Emanuela; Biasioli, Franco; Cappellin, Luca; Fanti, Marco; Gasperi, Flavia

2015-01-01

Drying process is commonly used to allow long time storage of valuable porcini mushrooms (Boletus edulis). Although considered a stable product dried porcini flavour changes during storage. Monitoring of volatile compounds during shelf life may help to understand the nature of the observed changes. In the present work two mass spectrometric techniques were used to monitor the evolution of volatile compounds during commercial shelf life of dried porcini. Solid phase microextraction (SPME) coupled to gas chromatography - mass spectrometry (GC-MS) allowed the identification of 66 volatile compounds, 36 of which reported for the first time, monitored during the commercial shelf life of dried porcini. Proton transfer reaction - time of flight - mass spectrometry (PTR-ToF-MS) , a direct injection mass spectrometric technique, was shown to be a fast and sensitive instrument for the general monitoring of volatile compound evolution during storage of dried porcini. Furthermore, PTR-ToF-MS grants access to compounds whose determination would otherwise require lengthy pre-concentration and/or derivatization steps such as ammonia and small volatile amines. The two techniques, both used for the first time to study dried porcini, provided detailed description of time evolution of volatile compounds during shelf life. Alcohols, aldehydes, ketones and monoterpenes diminish during the storage while carboxylic acids, pyrazines, lactones and amines increase. The storage temperature modifies the rate of the observed changes influencing the final quality of the dried porcini. We showed the advantages of both techniques, suggesting a strategy to be adopted to follow time evolution of volatile compounds in food products during shelf life, based on the identification of compounds by GC-MS and the rapid time monitoring by PTR-ToF-MS measurements in order to maximize the advantages of both techniques. Copyright © 2015 John Wiley & Sons, Ltd.

GC-MS analysis of polybrominated diphenyl ethers in Lake Erie

NASA Astrophysics Data System (ADS)

Vagula, Mary C.; Vartak, Marissa; Tallmadge, Weslene

2012-06-01

Lake Erie is one of the five great lakes of North America. It is the shallowest, the warmest, and the most biologically productive of the Great Lakes producing more fish than all of the other four lakes combined. It is also a source of drinking water for 11 million people and a recreational asset. On the flipside, it is also very vulnerable and troubled with environmental challenges because it has the smallest water volume, but the greatest pressures from the human settlement. One of the many issues faced by the Lake is pollution. It receives larger loads of many pollutants than any other Great Lake. Even with the best pollution controls many pesticides and organohalogens continue to enter the lake. Polybrominated diphenyl ethers (PBDEs) are a class of flame-retardants that have been used in a variety of consumer products since the 1970s. They are added to many commercial and household products such as computers, foam mattresses, carpets, etc. Being largely non-polar and chemically stable, these chemicals are extremely lipophilic and resist degradation in the environment, thus giving them a high affinity for their bioaccumulation. Due to these properties PBDEs have become ubiquitous environmental contaminants. These compounds are reported to be endocrine disruptors and could cause oxidative damage. This report presents the sample preparation protocol, the GC-MS analysis of PBDEs in Lake Erie sediment samples.

The measurement of muscle protein synthesis in broilers with a flooding dose technique: use of 15N-labelled phenylalanine, GC-MS and GC-C-IRMS.

PubMed

Dänicke, S; Böttcher, W; Simon, O; Jeroch, H

2001-01-01

An experiment was carried out to measure fractional muscle protein synthesis rates (k(s)) in broilers with injection of a flooding dose of phenylalanine (1 ml/100 g body weight of 150 mM phenylalanine; 38 atom percent excess (APE) [15N]phenylalanine). K(s) was calculated from the [15N] enrichment in phenylalanine of tissue-free and protein-bound phenylalanine using both gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) for measurements after a 10 min isotope incorporation period. The tertiary-butyldimethylsilyl (t-BDMS) derivatives of phenylalanine were used for gas chromatographic separation in both systems. GC-MS and GC-C-IRMS were calibrated for a range of 7 to 37 [15N]APE and 0 to 0.62 [15N]APE, respectively, and for sample sizes of 0.45 to 4.5 nmol phenylalanine and 7 to 40 nmol phenylalanine, respectively. Reproducibility of standards as a measure of precision varied from 0.06 to 0.29 [15N]APE and from 0.0004 to 0.0018 [15N]APE in GC-MS and GC-C-IRMS, respectively. K(s) was measured in the m. pectoralis major of broilers fed rye based diets (56%) which were provided either unsupplemented (-) or supplemented (+) with an enzyme preparation containing xylanase. K(s) in breast muscles was significantly increased from 21.8%/d to 23.9%/d due to enzyme supplementation. It can be concluded from the study that the measurement of protein synthesis in broilers with the flooding dose technique can be carried out by using [15N]phenylalanine, GC-MS and GC-C-IRMS.

Identification of tamoxifen and metabolites in human male urine by GC/MS.

PubMed

Mihailescu, R; Aboul-Enein, H Y; Efstatide, M D

2000-05-01

Tamoxifen is an antiestrogenic drug which is used in the treatment of breast cancer and nonmalignant breast disorders. It also has a stimulating effect on the secretion of hypofisar gonadotropic hormones and is generally used in the treatment of infertility. In males, tamoxifen causes an increase of endogenous production of androgenic steroids, and therefore is used by athletes. A method for identification of tamoxifen and metabolites in urine, using the gas chromatography and mass spectrometry system (GC/MS) is described. This study also reports the extraction methodology of tamoxifen and metabolites in urine samples of healthy male volunteers and the GC/MS conditions used to identify tamoxifen and its metabolites.

Analysis of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its brominated analogues in chlorine-treated water by gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS).

PubMed

Planas, Carles; Ventura, Francesc; Caixach, Josep; Martín, Jordi; Boleda, M Rosa; Paraira, Miquel

2015-11-01

A simple, selective and sensitive method for the analysis of the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its brominated analogues (BMXs) in chlorine-treated water has been developed. The method is based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS), previous liquid-liquid extraction (LLE) of a smaller sample volume compared to other methods and on-line derivatization with a silylation reactive. GC-QqQ-MS/MS has been raised as an alternative easier to perform than gas chromatography coupled to high resolution mass spectrometry (GC-HRMS) for the analysis of MX and BMXs, and it allows to achieve low LODs (0.3 ng/L for MX and 0.4-0.9 ng/L for BMXs). This technique had not been previously described for the analysis of MX and BMXs. Quality parameters were calculated and real samples related to 3 drinking water treatment plants (DWTPs), tap water and both untreated and chlorinated groundwater were analyzed. Concentrations of 0.3-6.6 ng/L for MX and 1.0-7.3 ng/L for BMXs were detected. Results were discussed according to five of the main factors affecting MX and BMXs formation in chlorine-treated water (organic precursors, influence of bromide ions, evolution of MX and BMXs in the drinking water distribution system, groundwater chlorination and infiltration of water coming from chlorination processes in groundwater). Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative Profiling of Ester Compounds Using HS-SPME-GC-MS and Chemometrics for Assessing Volatile Markers of the Second Fermentation in Bottle.

PubMed

Muñoz-Redondo, José Manuel; Cuevas, Francisco Julián; León, Juan Manuel; Ramírez, Pilar; Moreno-Rojas, José Manuel; Ruiz-Moreno, María José

2017-04-05

A quantitative approach using HS-SPME-GC-MS was performed to investigate the ester changes related to the second fermentation in bottle. The contribution of the type of base wine to the final wine style is detailed. Furthermore, a discriminant model was developed based on ester changes according to the second fermentation (with 100% sensitivity and specificity values). The application of a double-check criteria according to univariate and multivariate analyses allowed the identification of potential volatile markers related to the second fermentation. Some of them presented a synthesis-ratio around 3-fold higher after this period and they are known to play a key role in wine aroma. Up to date, this is the first study reporting the role of esters as markers of the second fermentation. The methodology described in this study confirmed its suitability for the wine aroma field. The results contribute to enhance our understanding of this fermentative step.

Guilty by dissociation-development of gas chromatography-mass spectrometry (GC-MS) and other rapid screening methods for the analysis of 13 diphenidine-derived new psychoactive substances (NPSs).

PubMed

Geyer, Pierre M; Hulme, Matthew C; Irving, Joseph P B; Thompson, Paul D; Ashton, Ryan N; Lee, Robert J; Johnson, Lucy; Marron, Jack; Banks, Craig E; Sutcliffe, Oliver B

2016-11-01

The prevalence of new psychoactive substances (NPSs) in forensic casework has increased prominently in recent years. This has given rise to significant legal and analytical challenges in the identification of these substances. The requirement for validated, robust and rapid testing methodologies for these compounds is obvious. This study details the analysis of 13 synthesised diphenidine derivatives encountered in casework using presumptive testing, thin layer chromatography and gas chromatography-mass spectrometry (GC-MS). Specifically, the validated GC-MS method provides, for the first time, both a general screening method and quantification of the active components for seized solid samples, both in their pure form and in the presence of common adulterants. Graphical Abstract Chemical synthesis and forensic analysis of 13 diphenidine-derived new psychoactive substance(s).

Bromination of aromatic compounds by residual bromide in sodium chloride matrix modifier salt during heated headspace GC/MS analysis.

PubMed

Fine, Dennis D; Ko, Saebom; Huling, Scott

2013-12-15

Analytical artifacts attributed to the bromination of toluene, xylenes, and trimethylbenzenes were found during the heated headspace gas chromatography/mass spectrometry (GC/MS) analysis of aqueous samples. The aqueous samples were produced from Fenton-like chemical oxidation reactions and contained aromatic compounds, hydrogen peroxide (H2O2), and ferric sulfate. Prior to GC/MS headspace analysis, the samples were acidified (pH<2), and sodium chloride was amended to the headspace vial as a matrix modifier. The brominated artifacts were generated during heated headspace analysis. Further, when samples were spiked with a mixture of volatile chlorinated and aromatic compounds (50 µg/L), poor spike recoveries of toluene and xylenes occurred, and in some cases complete loss of trimethylbenzenes and naphthalene resulted. Where poor recovery of aromatic spike compounds occurred, brominated aromatic compounds were found. The only significant source of bromine in the reaction scheme is the bromide typically present (<0.01% w/w) in the sodium chloride amended to the samples. Conversely, brominated artifacts were absent when a buffered salt mixture composed of sodium chloride and potassium phosphate dibasic/monobasic was used as a matrix modifier and raised the sample pH (pH~6). This indicated that the brominated artifacts resulted from the reaction of the aromatic compounds with BrCl, which was formed by the reaction of H2O2, chloride, and bromide under acidic conditions. An alternative matrix modifier salt is recommended that prevents the bromination reaction and avoids these deleterious effects on sample integrity during headspace analysis. Published by Elsevier B.V.

Biofilm inhibition formation of clinical strains of Pseudomonas aeruginosa mutans, photocatalytic activity of azo dye and GC-MS analysis of leaves of Lagerstroemia speciosa.

PubMed

Sai Saraswathi, V; Kamarudheen, Neethu; Bhaskara Rao, K V; Santhakumar, K

2017-04-01

The investigation was conducted to analyse the bioactive compounds from the leaf extracts of L. speciosa by GC-MS. The extracts were screened for antibacterial and antibiofilm activities against potential clinical strains. The bioactive compounds from the leaves of L. speciosa were extracted by soxhlet continuous extraction method and their chemical composition was analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). The antibacterial activity was evaluated against clinical strain like Staphylococcus aureus, Escherichia coli, P. aeruginosa and Salmonella typhi by well diffusion technique. We also screened for antibacterial property against common food borne pathogens namely Listeria monocytogenes and Bacillus cereus at varied concentration 250μml -1 to 1000μml -1 . Thereafter antibiofilm assay was carried out at from 250 to 1000μg/ml against P. aeruginosa (high biofilm forming pathogen) clinical strain by cover slip technique and the morphology of the pathogen was observed using Scanning Electron Microscopy-(SEM). It was observed that diverse class of secondary metabolites were found by GC-MS analysis for all the extracts upon the continuous extraction. It was found that only minimum inhibition was seen in alcoholic extract for antibacterial activity, whereas all other extracts showed negligible activity. P. aeruginosa biofilm inhibited to 93.0±2% and 91±2% at higher concentration (1000μg/ml) for methanolic and ethanolic extract respectively. Absence of extracellular matrix structure and the surface cracking of biofilm were viewed by SEM, which confirmed the antibiofilm activity. Hence this study reveals that L. speciosa showed significant antibiofilm activity against P. aeruginosa due to the phytoconstituents present in the leaf extracts which was well documented in the alcoholic extracts by GC-MS analysis. The methanolic and ethanolic extract showed good photocatalytic activity of 77.44% and 96.66% against azo dye degradation respectively. Further

Classification of Coffee Beans by GC-C-IRMS, GC-MS, and (1)H-NMR.

PubMed

Arana, Victoria Andrea; Medina, Jessica; Esseiva, Pierre; Pazos, Diego; Wist, Julien

2016-01-01

In a previous work using (1)H-NMR we reported encouraging steps towards the construction of a robust expert system for the discrimination of coffees from Colombia versus nearby countries (Brazil and Peru), to assist the recent protected geographical indication granted to Colombian coffee in 2007. This system relies on fingerprints acquired on a 400 MHz magnet and is thus well suited for small scale random screening of samples obtained at resellers or coffee shops. However, this approach cannot easily be implemented at harbour's installations, due to the elevated operational costs of cryogenic magnets. This limitation implies shipping the samples to the NMR laboratory, making the overall approach slower and thereby more expensive and less attractive for large scale screening at harbours. In this work, we report on our attempt to obtain comparable classification results using alternative techniques that have been reported promising as an alternative to NMR: GC-MS and GC-C-IRMS. Although statistically significant information could be obtained by all three methods, the results show that the quality of the classifiers depends mainly on the number of variables included in the analysis; hence NMR provides an advantage since more molecules are detected to obtain a model with better predictions.

Classification of Coffee Beans by GC-C-IRMS, GC-MS, and 1H-NMR

PubMed Central

Arana, Victoria Andrea; Esseiva, Pierre; Pazos, Diego

2016-01-01

In a previous work using 1H-NMR we reported encouraging steps towards the construction of a robust expert system for the discrimination of coffees from Colombia versus nearby countries (Brazil and Peru), to assist the recent protected geographical indication granted to Colombian coffee in 2007. This system relies on fingerprints acquired on a 400 MHz magnet and is thus well suited for small scale random screening of samples obtained at resellers or coffee shops. However, this approach cannot easily be implemented at harbour's installations, due to the elevated operational costs of cryogenic magnets. This limitation implies shipping the samples to the NMR laboratory, making the overall approach slower and thereby more expensive and less attractive for large scale screening at harbours. In this work, we report on our attempt to obtain comparable classification results using alternative techniques that have been reported promising as an alternative to NMR: GC-MS and GC-C-IRMS. Although statistically significant information could be obtained by all three methods, the results show that the quality of the classifiers depends mainly on the number of variables included in the analysis; hence NMR provides an advantage since more molecules are detected to obtain a model with better predictions. PMID:27516919

24-HOUR DIFFUSIVE SAMPLING OF 1,3-BUTADIENE IN AIR ONTO CARBONPAK X SOLID ADSORBENT WITH THEMAL DESORPTION/GC/MS ANALYSIS - FEASIBILITY STUDIES

EPA Science Inventory

Diffusive sampling of 1,3-butadiene for 24 hours onto the graphitic adsorbent Carbopack X contained in a stainless steel tube badge (6.3 mm OD, 5 mm ID, and 90 mm in length) with analysis by thermal desorption/GC/MS has been evaluated in controlled tests. A test matrix of 42 tr...

Identification (GC and GC-MS) of unsaturated acetates in Elasmopalpus lignosellus and their biological activity (GC-EAD and EAG).

PubMed

Jham, Gulab N; da Silva, Alexsandro A; Lima, Eraldo R; Viana, Paulo

2005-02-01

Two insect colonies of Elasmopalpus lignosellus were reared in our laboratory, the first being initiated from pupae obtained from a cornfield in the region of Sete Lagoas, Minas Gerais and the second from a cornfield in the region of Goiânia, Goiás. From the two colonies, two extracts were prepared from the pheromone glands of virgin E. lignosellus females. The extract obtained from the first colony was designated as extract 1 while the extract obtained from the second colony was designated as extract 2. Extract 1 was analyzed by gas chromatography-mass spectrometry (GC-MS) with (Z)-9-hexadecenyl acetate [(Z)-9-HDA] and (Z)-11-hexadecenyl acetate [(Z)-11-HDA] being identified and confirmed by the formation of DMDS derivatives. In addition, a third acetate, which could be either (E)-8-hexadecenyl acetate [(E)-8-HDA] or (E)-9-hexadecenyl acetate [(E)-9-HDA] was detected by GC-MS. Extract 2 was analyzed by gas chromatography (GC) and gas chromatography-electroannetography (GC-EAD) revealing the presence of (Z)-11-HDA and (Z)-9-TDA. In addition, the same compounds elicited a response with the E. lignosellus male antenna obtained from the second insect colony. Electroantennography (EAG) screening with the male E. lignosellus antenna (obtained from the second insect colony) was conducted with the 23 possible tetradecenyl acetates (TDA) and 22 hexadecenyl acetates (HDA) as standards. Out of the 23 TDA isomers evaluated, only (Z)-9-TDA elicited a response and out of the 22 HDA [(Z) and (E) isomers gamma2 to delta13] evaluated only (Z)-11-HDA elicited a response. The acetate compositions of two extracts obtained from insects originating from the two states (Minas Gerais and Goiás) of Brazil were different from one another as well as from that obtained from insects in Tifton, GA, USA. The bioactivity data (GC-EAD) of the extract 2 differed from those reported for the Tifton, GA, USA population. These data suggest polymorphism in relation to the insect populations found in

Improved sample preparation for GC-MS-SIM analysis of ethyl carbamate in wine.

PubMed

Nóbrega, Ian C C; Pereira, Giuliano E; Silva, Marileide; Pereira, Elainy V S; Medeiros, Marcelo M; Telles, Danuza L; Albuquerque, Eden C; Oliveira, Juliane B; Lachenmeier, Dirk W

2015-06-15

An improved sample preparation procedure for analysis of carcinogenic ethyl carbamate (EC) in wine by GC-MS-SIM is proposed. Differences over AOAC reference procedure were: (1) use of EC-d5 as internal standard instead of less similar propyl carbamate; (2) extraction by diethyl ether instead of more toxic dichloromethane, and (3) concentration by vacuum automated parallel evaporation instead of more time and work consuming rotary evaporation. Mean recovery was 104.4%, intraday precision was 6.7% (3.4 μg L(-)(1)) and 1.7% (88.5 μg L(-)(1)), regression coefficient was 0.999 in the linear working range of 3-89 μg L(-)(1), and limits of detection and quantification were 0.4 and 1.2 μg L(-)(1). Applicability was demonstrated by analysis (in triplicate) of 5 wine samples. EC concentration ranged from 5.2 ± 0.2 to 29.4 ± 1.5 μg L(-)(1). The analytical method is selective, accurate, repeatable, linear, and has similar method performance as the reference method along with the several mentioned advantages. Copyright © 2015 Elsevier Ltd. All rights reserved.

Rapid qualitative and quantitative analysis of proanthocyanidin oligomers and polymers by ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS)

USDA-ARS?s Scientific Manuscript database

We developed a rapid method with ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS) for the qualitative and quantitative analysis of plant proanthocyanidins (PAs) directly from crude plant extracts. The method utilizes a range of cone voltages to achieve the depolymeriza...

Differentiation of wines according to grape variety and geographical origin based on volatiles profiling using SPME-MS and SPME-GC/MS methods.

PubMed

Ziółkowska, Angelika; Wąsowicz, Erwin; Jeleń, Henryk H

2016-12-15

Among methods to detect wine adulteration, profiling volatiles is one with a great potential regarding robustness, analysis time and abundance of information for subsequent data treatment. Volatile fraction fingerprinting by solid-phase microextraction with direct analysis by mass spectrometry without compounds separation (SPME-MS) was used for differentiation of white as well as red wines. The aim was to differentiate between varieties used for wine production and to also differentiate wines by country of origin. The results obtained were compared to SPME-GC/MS analysis in which compounds were resolved by gas chromatography. For both approaches the same type of statistical procedure was used to compare samples: principal component analysis (PCA) followed by linear discriminant analysis (LDA). White wines (38) and red wines (41) representing different grape varieties and various regions of origin were analysed. SPME-MS proved to be advantageous in use due to better discrimination and higher sample throughput. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization and differentiation of high energy cyclic organic peroxides by GC/FT-IR, GC-MS, FT-IR, and Raman microscopy

NASA Astrophysics Data System (ADS)

Pena, Alvaro J.; Pacheco-Londono, Leonardo; Figueroa, Javier; Rivera-Montalvo, Luis A.; Roman-Velazquez, Felix R.; Hernandez-Rivera, Samuel P.

2005-05-01

The characterization of Tetracetone Tetraperoxide (TRATRP), Triacetone Triperoxide (TATP), Diacetone Diperoxide (DADP), Tricyclohexylidene Triperoxide and Dibenzo Diperoxide using GC-MS, GC-FTIR, FTIR, FT-NMR and Raman Spectroscopy is reported. These compounds were synthesized, purified and characterized in the laboratory in order to develop methodologies for their trace detection. During this study, TATP has been synthesized by different methods obtaining high purity and good yields, even using common household products. DADP synthetic routes reported in the literature were verified. The methods described, including those that produce mixtures with TATP and other peroxides forms were also tested. This study will also focused in the preparation of other cyclic peroxides, including Hexamethelene Triperoxide Diamine (HMTD) and different forms of cyclic peroxides from ketones. This issue of thermodynamic versus kinetic control of secondary products of all syntheses and the effect of temperature in the distribution sub products of the syntheses was also addressed. A vibrational differentiation study of was carried out. Differences were found computationally in the υ(O-O), υ(C-O), δ(CH3-C) and δ(C-O) for Raman and IR bands and retention time and fragment patron for GC-MS and GC-FT-IR.

GC/MS analysis of pesticides in the Ferrara area (Italy) surface water: a chemometric study.

PubMed

Pasti, Luisa; Nava, Elisabetta; Morelli, Marco; Bignami, Silvia; Dondi, Francesco

2007-01-01

The development of a network to monitor surface waters is a critical element in the assessment, restoration and protection of water quality. In this study, concentrations of 42 pesticides--determined by GC-MS on samples from 11 points along the Ferrara area rivers--have been analyzed by chemometric tools. The data were collected over a three-year period (2002-2004). Principal component analysis of the detected pesticides was carried out in order to define the best spatial locations for the sampling points. The results obtained have been interpreted in view of agricultural land use. Time series data regarding pesticide contents in surface waters has been analyzed using the Autocorrelation function. This chemometric tool allows for seasonal trends and makes it possible to optimize sampling frequency in order to detect the effective maximum pesticide content.

Simultaneous analysis of psychotropic phenylalkylamines in oral fluid by GC-MS with automated SPE and its application to legal cases.

PubMed

Choi, Hyeyoung; Baeck, Seungkyung; Jang, Moonhee; Lee, Sooyeun; Choi, Hwakyung; Chung, Heesun

2012-02-10

Phenylalkylamine derivatives, such as methamphetamine (MA), amphetamine (AM), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), phentermine (PT), fenfluramine (FFA) and phenmetrazine (PM), and ketamine (KT) are widely abused recreational or anorectic drugs in Korea and are regulated under the Controlled Substance Act in Korea. Phenylalkylamines and ketamine analysis is normally performed using both urine and hair samples but there is no established method for the simultaneous analysis of all these phenylalkylamines and ketamine in oral fluids. Oral fluid is easy to collect/handle and can provide an indication of recent drug abuse. In this study, to confirm the presence of phenylalkylamine derivatives and ketamine in oral fluid after screening with an immunoassay, an analytical method using automated solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) was developed and fully validated according to international guidelines. The applicability of the assay was demonstrated by analyzing of authentic oral fluid samples and the results of oral fluid analysis were compared with those in urine and hair to to evaluate the feasibility of oral fluid in forensic cases. The recovery of phenylalkylamines and ketamine from oral fluid collection devices was also assessed. Oral fluid specimens from 23 drug abuse suspects submitted by the police were collected using Salivette (Sarstedt, Nümbrecht, Germany), Quantisal (Immunalysis, Pomona, CA) or direct expectoration. The samples were screened using a biochip array analyzer (Evidence Investigator, Randox, Antrim, UK). For confirmation, the samples were analyzed by GC-MS in selected-ion monitoring (SIM) mode after extraction using automated SPE (RapidTrace, Zymark, MA, USA) with a mixed-mode cation exchange cartridge (CLEAN SCREEN, 130 mg/3 ml, UCT, PA, USA) and derivatization with trifluoroacetic anhydride (TFA). The results from the immunoassay were consistent with those from GC-MS

A study on the GC-MS analysis of bioactive components and pancreato-protective effect of methanolic extract of Brassica oleracea L. var. botrytis.

PubMed

Rajapriya, Sadanandan; Geetha, Arumugam; Ganesan Kripa, Kavasseri

2017-09-01

The ever-increasing problem of pancreatitis due to alcohol abuse demands evaluation of novel drugs of plant origin. This study explores the therapeutic effects of the methanolic extract of Brassica oleraceae (MEBO) on ethanol and cerulein induced pancreatitis in rats. The MEBO was subjected to GC-MS and HPLC analysis. Male albino Wistar rats were divided into various groups, fed with alcohol (36% of total calories for 5 weeks) and cerulein (20 μg/kg b.wt i.p, weekly thrice for last three weeks) with or without MEBO (40 mg/kg b.wt). Serum lipase, amylase, IL-1β, IL-18, caspase-1, lipid peroxides, oxidative stress index and antioxidant status were assessed in pancreas. Six compounds were identified in GC-MS analysis. Co-administration of MEBO reduced the pancreatic marker enzymes in serum, IL-1β, IL-18 and caspase-1 and increased the antioxidant status of pancreas. The pancreato-protective effect of Brassica oleraceae may be attributed to well-known anti-inflammatory flavonoids, luteolin, quercetin and myricetin.

Determination of low ppm levels of dimethyl sulfate in an aqueous soluble API intermediate using liquid-liquid extraction and GC-MS.

PubMed

Zheng, Jie; Pritts, Wayne A; Zhang, Shuhong; Wittenberger, Steve

2009-12-05

Dimethyl sulfate (DMS) is an alkylating reagent commonly used in organic syntheses and pharmaceutical manufacturing processes. Due to its potential carcinogenicity, the level of DMS in the API process needs to be carefully monitored. However, in-process testing for DMS is challenging because of its reactivity and polarity as well as complex matrix effects. In this short communication, we report a GC-MS method for determination of DMS in an API intermediate that is a methyl sulfate salt. To overcome the complex matrix interference, DMS and an internal standard, d6-DMS, were extracted from the matrix with methyl tert-butyl ether. GC separation was conducted on a DB-624 column (30 m long, 0.32 mm ID, 1.8 microm film thickness). MS detection was performed on a single-quad Agilent MSD equipped with an electron impact source while the MSD signal was acquired in selected ion monitoring mode. This GC/MS method showed a linear response for DMS equivalent from 1.0 to 60 ppm. The practical quantitation limit for DMS was 1.0 ppm and the practical detection limit was 0.3 ppm. The relative standard derivation for analyte response was found as 0.1% for six injections of a working standard equivalent to 18.6 ppm of DMS. The spike recovery was ranged from 102.1 to 108.5% for a sample of API intermediate spiked with 8.0 ppm of DMS. In summary, the GC/MS method showed adequate specificity, linearity, sensitivity, repeatability and accuracy for determination of DMS in the API intermediate. This method has been successfully applied to study the efficiency of removing DMS from the process.

Amphetamine concentrations in human urine following single-dose administration of the calcium antagonist prenylamine-studies using fluorescence polarization immunoassay (FPIA) and GC-MS.

PubMed

Kraemer, Thomas; Roditis, Susanne K; Peters, Frank T; Maurer, Hans H

2003-03-01

Prenylamine (R,S-N-(3,3-diphenylpropyl-methyl-2-phenethylamine), a World Health Organization class V calcium antagonist, is known to be metabolized to amphetamine. In this study, amphetamine concentrations after a single-dose administration of prenylamine were determined to check if they reached values that could be of analytical and/or pharmacological importance in clinical and forensic toxicology. Enantiomeric composition of amphetamine was also studied. Five volunteers received a single 120-mg oral dose of prenylamine. Urine samples were analyzed using the Abbott TDx immunoassay Amphetamine/Methamphetamine II and using our routine systematic toxicological analysis (STA) gas chromatography-mass spectrometry (GC-MS) procedure. For quantitation purposes, GC-MS was used in the selected-ion monitoring (SIM) mode (ions m/z 118, 122, 240, 244) after solid-phase extraction (Isolute Confirm HCX) and derivatization (heptafluorobutyric anhydride). Amphetamine-d5 was used as internal standard (IS). Chiral separation of the heptafluorobutyrated amphetamine enantiomers was achieved using an Astec Chiraldex G-PN column. The TDx results showed a great variability for the different volunteers. A urine sample of one volunteer showed results as high as 3200 ng/mL, whereas the urine samples of another volunteer never gave results greater than the TDx detection limit (100 ng/mL). Using the STA procedure, the presence of amphetamine could be confirmed in all urine samples with TDx results greater than the cutoff value (300 ng/mL). Using the GC-MS SIM method, amphetamine concentrations up to 1280 ng/mL were determined. Chiral analysis revealed that both enantiomers of amphetamine were present in the samples with a surplus of the S(+)-enantiomer in the early phase of excretion. Forensic implications are discussed.

Multiresidue method for pesticide residue analysis in food of animal and plant origin based on GC or LC and MS or MS/MS.

PubMed

Muñoz, Eva; Muñoz, Gloria; Pineda, Laura; Serrahima, Eulalia; Centrich, Francesc

2012-01-01

A multiresidue method based on GC or LC and MS or MS/MS for the determination of 204 pesticides in diverse food matrixes of animal and plant origin is described. The method can include different stages of cleanup according to the chemical characteristics of each sample. Samples were extracted using accelerated solvent extraction. Those with a high fat content or that contained chlorophyll required further purification by gel permeation chromatography and/or SPE (ENVI-Carb). The methodology developed here was fully validated; the LOQs for the 204 pesticides are presented. The LOQ values lie between 0.01 to 0.02 mg/kg. However, in some cases, mainly in baby food, they were as low as 0.003 mg/kg, thereby meeting European Union requirements on maximum residue levels for pesticides, as outlined in European regulation 396/2005 and the Commission Directive 2003/13/EC. The procedure has been accredited for a wide scope of pesticides and matrixes by the Spanish Accreditation Body (ENAC) following ISO/IEC 17025:2005, as outlined in ENAC technical note NT-19.

GC-MS Analysis: In Vivo Hepatoprotective and Antioxidant Activities of the Essential Oil of Achillea biebersteinii Afan. Growing in Saudi Arabia.

PubMed

Al-Said, Mansour S; Mothana, Ramzi A; Al-Yahya, Mohammed M; Rafatullah, Syed; Al-Sohaibani, Mohammed O; Khaled, Jamal M; Alatar, Abdulrahman; Alharbi, Naiyf S; Kurkcuoglu, Mine; Baser, Husnu C

2016-01-01

Liver disease is a worldwide problem. It represents one of the main causes of morbidity and mortality in humans. Achillea biebersteinii is used as herbal remedy for various ailments including liver diseases. But the scientific basis for its medicinal use remains unknown. Thus, this research was undertaken to evaluate the efficiency of A. biebersteinii essential oil (ABEO) (0.2 mL/kg) in the amelioration of CCl4-induced hepatotoxicity in rodent model. Moreover, the chemical content of the oil was investigated using GC and GC-MS. The following biochemical parameters were evaluated: serum glutamic oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), gamma-glutamyl-transpeptidase (γ-GGT), alkaline phosphatase (ALP), and total bilirubin. Furthermore, lipid profile, malondialdehyde (MDA), nonprotein sulfhydryl (NP-SH), and total protein (TP) contents in liver tissue were estimated. 44 components (92.0%) of the total oil have been identified by GC-MS analysis where α-terpinene and p-cymene were the most abundant. The high serum enzymatic (GOT, GPT, GGT, and ALP) and bilirubin concentrations as well as the level of MDA, NP-SH, and TP contents in liver tissues were significantly reinstated towards normalization by the ABEO. Histopathological study further confirmed these findings. In addition, ABEO showed mild antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid assays.

Hydrogen (H) Isotope Composition of Type II Kerogen Extracted by Pyrolysis-GC-MS-IRMS: Terrestrial Shale Deposits as Martian Analogs

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Pernia, Denet; Evans, Michael; Fu, Qi; Bissada, Kadry K.; Curiale, Joseph A.; Niles, Paul B.

2014-01-01

Described here is a technique for H isotope analysis of organic compounds pyrolyzed from kerogens isolated from gas- and liquids-rich shales. Application of this technique will progress the understanding of the use of H isotopes not only in potential kerogen occurrences on Mars, but also in terrestrial oil and gas resource plays. H isotope extraction and analyses were carried out utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make qualitative and semi-quantitative compositional measurements of these products. Kerogen samples from five different basins (type II and II-S) were dehydrated (heated to 80 C overnight under vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C), which quantitatively forms H2. Samples ranging from 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. and separated on a Poraplot Q GC column. H isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight. H2O average delta D = -215.2 per mille (V-SMOW), ranging from - 271.8 per mille for the Marcellus Shale to -51.9 per mille for a Polish shale. Higher molecular weight compounds like toluene (C7H8) have an average delta D of -89.7 per mille, ranging from -156.0 per mille for the Barnett Shale to -50.0 per mille for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during basin formation. Since hydrocarbon H isotopes readily exchange with water, these data may provide some useful information on gas-water or oil-water interaction in resource plays, and further as a possible indicator of paleoenvironmental conditions. Alternatively, our data may be an indication of H isotope exchange with

Sensitivity, specificity, and efficiency in detecting opiates in oral fluid with the Cozart Opiate Microplate EIA and GC-MS following controlled codeine administration.

PubMed

Barnes, Allan J; Kim, Insook; Schepers, Raf; Moolchan, Eric T; Wilson, Lisa; Cooper, Gail; Reid, Claire; Hand, Chris; Huestis, Marilyn A

2003-10-01

Oral fluid specimens (N = 1406) were collected from 19 subjects prior to and up to 72 h following controlled administration of oral codeine. Volunteers provided informed consent to participate in this National Institute on Drug Abuse Institutional Review Board-approved protocol. A modification of Cozart Microplate Opiate EIA Oral Fluid Kit (Opiate ELISA), employing codeine calibrators, was used for semiquantitative analysis of opiates, followed by gas chromatography-mass spectrometry (GC-MS) for the confirmation and quantitation of codeine, norcodeine, morphine, and normorphine in oral fluid. GC-MS limits of detection and quantitation were 2.5 microg/L for all analytes. The Substance Abuse and Mental Health Services Administration (SAMHSA) has proposed a 40-microg/L opiate screening and a 40-microg/L morphine or codeine confirmation cutoff for the detection of opiate use. Oral fluid opiate screening and confirmation cutoffs of 30 micro g/L are in use in the U.K. Utilizing 2.5-, 20-, 30-, and 40-microg/L GC-MS cutoffs, 26%, 20%, 19%, and 18% of the oral fluid specimens were positive for codeine or one of its metabolites. Six Opiate ELISA/confirmation cutoff criteria (2.5/2.5, 10/2.5, 20/20, 30/20, 30/30, and 40/40 microg/L) were evaluated. Calculations for Opiate ELISA sensitivity, specificity, and efficiency were determined from the number of true-positive, true-negative, false-positive, and false-negative results at each screening/confirmation cutoff. Sensitivity, specificity, and efficiency for the lowest cutoff were 91.5%, 88.6%, and 89.3%. Application of the cutoff currently used in the U.K. yielded sensitivity, specificity, and efficiency results of 79.7%, 99.0%, and 95.4% and similar results of 76.7%, 99.1%, and 95.1% when applying the SAMHSA criteria. These data indicate that the Opiate ELISA efficiently detects oral codeine use. In addition, the data, collected following controlled oral codeine administration, may aid in the interpretation of opiate oral

Analysis of 34S in Individual Organic Compounds by Coupled GC-ICP-MS

NASA Astrophysics Data System (ADS)

Sessions, A. L.; Amrani, A.; Adkins, J. F.

2009-12-01

The abundances of 2H, 13C, and 15N in organic compounds have been extremely useful in many aspects of biogeochemistry. While sulfur plays an equally important role in many earth-surface processes, the isotopes of sulfur in organic matter have not been extensively employed in large part because there has been no direct route to the analysis of 34S in individual organic compounds. To remedy this, we have developed a highly sensitive and robust method for the analysis of 34S in individual organic compounds by coupled gas chromatography (GC) and multicollector inductively-coupled plasma mass spectrometry (ICP-MS). Isobaric interference from O2+ is minimized by employing dry plasma conditions, and is cleanly resolved at all masses using medium resolution on the Thermo Neptune ICP-MS. Correction for mass bias is accomplished using standard-sample bracketing with peaks of SF6 reference gas. The precision of measured δ34S values approaches 0.1‰ for analytes containing >40 pmol S, and is better than 0.5‰ for those containing as little as 6 pmol S. External accuracy is better than 0.3‰. Integrating only the center of chromatographic peaks, rather than the entire peak, offers significant gain in precision and chromatographic resolution with minimal effect on accuracy, but requires further study for verification as a routine method. Coelution of organic compounds that do not contain S can cause degraded analytical precision and accuracy. As a demonstration of the potential for this new method, we will present data from 3 sample types: individual organosulfur compounds from crude oil, dimethyl sulfide from seawater, and trace H2S from bacterial culture headspace.

A GC-MS method for the detection and quantitation of ten major drugs of abuse in human hair samples.

PubMed

Orfanidis, A; Mastrogianni, O; Koukou, A; Psarros, G; Gika, H; Theodoridis, G; Raikos, N

2017-03-15

A sensitive analytical method has been developed in order to identify and quantify major drugs of abuse (DOA), namely morphine, codeine, 6-monoacetylmorphine, cocaine, ecgonine methyl ester, benzoylecgonine, amphetamine, methamphetamine, methylenedioxymethamphetamine and methylenedioxyamphetamine in human hair. Samples of hair were extracted with methanol under ultrasonication at 50°C after a three step rinsing process to remove external contamination and dirt hair. Derivatization with BSTFA was selected in order to increase detection sensitivity of GC/MS analysis. Optimization of derivatization parameters was based on experiments for the selection of derivatization time, temperature and volume of derivatising agent. Validation of the method included evaluation of linearity which ranged from 2 to 350ng/mg of hair mean concentration for all DOA, evaluation of sensitivity, accuracy, precision and repeatability. Limits of detection ranged from 0.05 to 0.46ng/mg of hair. The developed method was applied for the analysis of hair samples obtained from three human subjects and were found positive in cocaine, and opiates. Published by Elsevier B.V.

24-HOUR DIFFUSIVE SAMPLING OF 1,3-BUTADIENE IN AIR ONTO CARBOPACK X SOLID ADSORBENT FOLLOWED BY THERMAL DESORPTION/GC/MS ANALYSIS - FEASIBILITY STUDY

EPA Science Inventory

Diffusive sampling of 1,3-butadiene for 24 hr onto the graphitic adsorbent Carbopack X packed in a stainless steel tube badge (6.3 mm o.d., 5 mm i.d., and 90 mm in length) with analysis by thermal desorption/gas chromatography (GC)/mass spectrometry (MS) has been evaluated in con...

Genuineness assessment of mandarin essential oils employing gas chromatography-combustion-isotope ratio MS (GC-C-IRMS).

PubMed

Schipilliti, Luisa; Tranchida, Peter Quinto; Sciarrone, Danilo; Russo, Marina; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

2010-03-01

Cold-pressed mandarin essential oils are products of great economic importance in many parts of the world and are used in perfumery, as well as in food products. Reconstituted mandarin oils are easy to find on the market; useful information on essential oil authenticity, quality, extraction technique, geographic origin and biogenesis can be attained through high-resolution GC of the volatile fraction, or enantioselective GC, using different chiral stationary phases. Stable isotope ratio analysis has gained considerable interest for the unveiling of citrus oil adulteration, detecting small differences in the isotopic carbon composition and providing plenty of information concerning the discrimination among products of different geographical origin and the adulteration of natural essential oils with synthetic or natural compounds. In the present research, the authenticity of several mandarin essential oils was assessed through the employment of GC hyphenated to isotope ratio MS, conventional GC flame ionization detector, enantioselective GC and HPLC. Commercial mandarin oils and industrial natural (declared as such) mandarin essential oils, characterized by different harvest periods and geographic origins, were subjected to analysis. The results attained were compared with those of genuine cold-pressed Italian mandarin oils, obtained during the 2008-2009 harvest season.

Simultaneous stable-isotope dilution GC-MS measurement of homoarginine, guanidinoacetate and their common precursor arginine in plasma and their interrelationships in healthy and diseased humans.

PubMed

Hanff, Erik; Kayacelebi, Arslan Arinc; Yanchev, Georgi Radoslavov; Maassen, Norbert; Haghikia, Arash; Tsikas, Dimitrios

2016-03-01

Low concentrations of L-homoarginine (hArg) in plasma or serum and urine have recently emerged as a novel cardiovascular risk factor. Previously, we reported gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) methods for the quantitative determination of hArg and Arg in plasma, serum, urine and other biological samples. In these methods, plasma and serum are ultrafiltered by means of commercially available cartridges (10 kDa), and 10-µL ultrafiltrate aliquots are subjected to a two-step derivatization procedure, yielding the methyl ester tri(N-pentafluoropropionyl) derivatives. De novo prepared trideuteromethyl ester hArg (d3Me-hArg) was used as an internal standard. To make the hArg analysis in plasma more convenient, straightforward and cheaper we performed two key modifications: (1) precipitation of plasma proteins by methanol and (2) use of newly prepared and d3Me-hArg as the internal standard. The method was validated and used for the quantitative determination of hArg in human plasma by GC-MS after electron-capture negative-ion chemical ionization (ECNICI) using methane as the reactant gas. Intra-assay accuracy (recovery) and imprecision (relative standard deviation) were within generally accepted ranges (93-109 and 2.3-10 %, respectively). Furthermore, we extended the applicability of this method to guanidinoacetate (GAA). This is of particular importance because hArg and GAA are produced from Arg by the catalytic action of arginine:glycine amidinotransferase (AGAT) also known as glycine:arginine transamidinase (GATM). Using this method, we quantitated simultaneously hArg, Arg and GAA in the selected-ion monitoring mode in 10-µL aliquots of plasma. In plasma samples of 17 non-medicated healthy young men, the concentration of hArg, GAA and Arg was determined to be (mean ± SD) 1.7 ± 0.6, 2.6 ± 0.8, 91 ± 29 µM, respectively. The correlation between hArg and Arg was borderline (r = 0.47, P = 0.06). GAA strongly correlated with Arg (r

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR PREPARATION OF CALIBRATION AND SURROGATE RECOVERY SOLUTIONS FOR GC/MS ANALYSIS OF PESTICIDES (BCO-L-21.1)

EPA Science Inventory

The purpose of this SOP is to describe procedures for preparing calibration curve solutions used for gas chromatography/mass spectrometry (GC/MS) analysis of chlorpyrifos, diazinon, malathion, DDT, DDE, DDD, a-chlordane, and g-chlordane in dust, soil, air, and handwipe sample ext...

A solid-phase microextraction GC/MS/MS method for rapid quantitative analysis of food and beverages for the presence of legally restricted biologically active flavorings.

PubMed

Bousova, Katerina; Mittendorf, Klaus; Senyuva, Hamide

2011-01-01

A method was developed using automated headspace solid-phase microextraction coupled with GC/MS/MS to simultaneously determine the presence of seven biologically active flavoring substances whose levels of use in processed foods is controlled by statutory limits. The method can be applied to identify and quantify the presence of 1,2-benzopyrone (coumarin), beta-asarone, 1-allyl-4-methoxybenzene (estragole), menthofuran, 4-allyl-1 ,2-dimethoxybenzene (methyl eugenol), pulegone, and thujone at levels ranging from 0.5 to 3000 mg/kg. The method has been optimized and validated for three different generic food types categorized on the basis of composition and anticipated use levels of flavorings and food ingredients. The food categories are alcoholic and nonalcoholic beverages; semisolid processed foods (e.g., soups, sauces, confectionary, etc.); and solid foods (muesli, bakery products, etc.). The method is simple, inexpensive, and rapid, and eliminates the use of flammable and toxic solvents. There is no sample preparation, and using MSIMS, unequivocal confirmation of identification is achieved even in highly complex matrixes containing many potential interfering volatiles. The method precision for spiked samples ranged from 2 to 21%, with the greatest variability associated with solid matrixes. The LOD and LOQ values were well below 0.1 and 0.5 mg/kg, respectively, in all cases for individual substances, fulfilling requirements for enforcement purposes. The robustness of the method was demonstrated in a small survey of retail samples of four spirits, five flavored milks, three energy drinks, five liqueurs, five soups, 10 sauces, five herbal teas, and three breakfast cereals.

GC-MS analysis of the antioxidant active fractions of Micromeria juliana with anticholinesterase activity.

PubMed

Oztürk, Mehmet; Kolak, Ufuk; Duru, Mehmet Emin; Harmandar, Mansur

2009-09-01

The aerial parts of Micromeria juliana (L.) Bentham ex Reichb. were extracted with light petroleum, acetone and methanol, successively. The antioxidant activity of different concentrations of the extracts was evaluated using different antioxidant tests, namely total antioxidant (lipid peroxidation inhibition activity), DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, ferric reducing power, and metal chelating. Total antioxidant activity was determined using the beta-carotene-linoleic acid assay. Unexpectedly, the light petroleum extract exhibited strong lipid peroxidation inhibition activity. The extract was fractionated on a silica gel column and the antioxidant activity of the fractions was determined by the beta-carotene-linoleic assay at 25 microg/mL concentration. The fractions that exhibited more than 50% inhibition activity were analysed by GC and GC/MS; thus, the structure of fourteen compounds were elucidated. In addition, acetyl- and butyryl-cholinesterase inhibitory activities of the extracts were also determined in vitro. The light petroleum and acetone extracts were found to have mild butyrylcholinesterase inhibitory activity.

Quantitative analysis of fragrance in selectable one dimensional or two dimensional gas chromatography-mass spectrometry with simultaneous detection of multiple detectors in single injection.

PubMed

Tan, Hui Peng; Wan, Tow Shi; Min, Christina Liew Shu; Osborne, Murray; Ng, Khim Hui

2014-03-14

A selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-mass spectrometry (GC-MS) system coupled with flame ionization detector (FID) and olfactory detection port (ODP) was employed in this study to analyze perfume oil and fragrance in shower gel. A split/splitless (SSL) injector and a programmable temperature vaporization (PTV) injector are connected via a 2-way splitter of capillary flow technology (CFT) in this selectable (1)D/(2)D GC-MS/FID/ODP system to facilitate liquid sample injections and thermal desorption (TD) for stir bar sorptive extraction (SBSE) technique, respectively. The dual-linked injectors set-up enable the use of two different injector ports (one at a time) in single sequence run without having to relocate the (1)D capillary column from one inlet to another. Target analytes were separated in (1)D GC-MS/FID/ODP and followed by further separation of co-elution mixture from (1)D in (2)D GC-MS/FID/ODP in single injection without any instrumental reconfiguration. A (1)D/(2)D quantitative analysis method was developed and validated for its repeatability - tR; calculated linear retention indices (LRI); response ratio in both MS and FID signal, limit of detection (LOD), limit of quantitation (LOQ), as well as linearity over a concentration range. The method was successfully applied in quantitative analysis of perfume solution at different concentration level (RSD≤0.01%, n=5) and shower gel spiked with perfume at different dosages (RSD≤0.04%, n=5) with good recovery (96-103% for SSL injection; 94-107% for stir bar sorptive extraction-thermal desorption (SBSE-TD). Copyright © 2014 Elsevier B.V. All rights reserved.

Authentication of meat products: determination of animal feeding by parallel GC-MS analysis of three adipose tissues.

PubMed

Sivadier, Guilhem; Ratel, Jérémy; Bouvier, Frédéric; Engel, Erwan

2008-11-12

Authentication of farm animal rearing conditions, especially the type of feeding, is a key issue in certification of meat quality and meat products. The purpose of this article was to analyze in parallel the volatile fraction of three adipose tissues excised from 16 lambs in order to authenticate two animal diets: pasture (n = 8) and concentrate (n = 8). On the basis of growth rate and anatomical location, three different lamb adipose tissues were analyzed: perirenal fat (PRF), caudal subcutaneous fat (CSCF), and heart fat (HF). An initial experiment was used to optimize the extraction of volatile compounds from the adipose tissues. Using a lipid liquid phase extraction, heating the ground tissue to 70 degrees C, was shown to be the best sample preparation mode before dynamic headspace-gas chromatography-mass spectrometry (DH-GC-MS) analysis to achieve a good representation of the starting material, while getting a good extraction and reproducibility. Next, the application of an instrumental drifts correction procedure to DH-GC-MS data enabled the identification of 130 volatile compounds that discriminate the two diets in one or several of the three tissues: 104 were found in PRF, 75 in CSCF, and 70 in HF. Forty-eight of these diet tracers, including 2,3-octanedione, toluene, terpenes, alkanes, alkenes, and ketones, had previously been identified as ruminant pasture-diet tracers and can be considered generic of this type of animal feeding. Moreover, 49 of the 130 compounds could identify diets in only one tissue, suggesting that complementary analysis of several tissues is superior for diet identification. Finally, multivariate discriminant analyses confirmed that the discrimination was improved when PRF, CSCF, and HF were considered simultaneously, even if HF contributed minimal information.

Comparative analysis of EPA and DHA in fish oil nutritional capsules by GC-MS.

PubMed

Yi, Tao; Li, Shuk-Man; Fan, Jia-Yi; Fan, Lan-Lan; Zhang, Zhi-Feng; Luo, Pei; Zhang, Xiao-Jun; Wang, Jian-Gang; Zhu, Lin; Zhao, Zhong-Zhen; Chen, Hu-Biao

2014-12-13

Fish oil is a popular nutritional product consumed in Hong Kong. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the two main bioactive components responsible for the health benefits of fish oil. Market survey in Hong Kong demonstrated that various fish oil capsules with different origins and prices are sold simultaneously. However, these capsules are labelled with same ingredient levels, namely EPA 180 mg/g and DHA 120 mg/g. This situation makes the consumers very confused. To evaluate the quality of various fish oil capsules, a comparative analysis of the contents of EPA and DHA in fish oil is crucial. A gas chromatography-mass spectrometry (GC-MS) method was developed for identification and determination of EPA and DHA in fish oil capsules. A comprehensive validation of the developed method was conducted. Ten batches of fish oil capsules samples purchased from drugstores of Hong Kong were analyzed by using the developed method. The present method presented good sensitivity, precision and accuracy. The limits of detection (LOD) for EPA and DHA were 0.08 ng and 0.21 ng, respectively. The relative standard deviation (RSD) values of EPA and DHA for repeatability tests were both less than 1.05%; and the recovery for accuracy test of EPA and DHA were 100.50% and 103.83%, respectively. In ten fish oil samples, the contents of EPA ranged from 39.52 mg/g to 509.16 mg/g, and the contents of DHA ranged from 35.14 mg/g to 645.70 mg/g. The present method is suitable for the quantitative analysis of EPA and DHA in fish oil capsules. There is a significant variation in the contents of the quantified components in fish oil samples, and there is not a linear relationship between price and contents of EPA and DHA. Strict supervision of the labelling of the fish oil capsules is urgently needed.

A comparative analysis of human plasma and serum proteins by combining native PAGE, whole-gel slicing and quantitative LC-MS/MS: Utilizing native MS-electropherograms in proteomic analysis for discovering structure and interaction-correlated differences.

PubMed

Wen, Meiling; Jin, Ya; Manabe, Takashi; Chen, Shumin; Tan, Wen

2017-12-01

MS identification has long been used for PAGE-separated protein bands, but global and systematic quantitation utilizing MS after PAGE has remained rare and not been reported for native PAGE. Here we reported on a new method combining native PAGE, whole-gel slicing and quantitative LC-MS/MS, aiming at comparative analysis on not only abundance, but also structures and interactions of proteins. A pair of human plasma and serum samples were used as test samples and separated on a native PAGE gel. Six lanes of each sample were cut, each lane was further sliced into thirty-five 1.1 mm × 1.1 mm squares and all the squares were subjected to standardized procedures of in-gel digestion and quantitative LC-MS/MS. The results comprised 958 data rows that each contained abundance values of a protein detected in one square in eleven gel lanes (one plasma lane excluded). The data were evaluated to have satisfactory reproducibility of assignment and quantitation. Totally 315 proteins were assigned, with each protein assigned in 1-28 squares. The abundance distributions in the plasma and serum gel lanes were reconstructed for each protein, named as "native MS-electropherograms". Comparison of the electropherograms revealed significant plasma-versus-serum differences on 33 proteins in 87 squares (fold difference > 2 or < 0.5, p < 0.05). Many of the differences matched with accumulated knowledge on protein interactions and proteolysis involved in blood coagulation, complement and wound healing processes. We expect this method would be useful to provide more comprehensive information in comparative proteomic analysis, on both quantities and structures/interactions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

THE ROLE OF GC/MS AND LC/MS IN THE DISCOVERY OF DRINKING WATER DISINFECTION BY-PRODUCTS

EPA Science Inventory

Gas chromatography/mass spectrometry (GC/MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide, or chloramine, react with natural organic matter in the ...

THE ROLE OF GC-MS AND LC-MS IN THE DISCOVERY OF DRINKING WATER DISINFECTION BY-PRODUCTS

EPA Science Inventory

Gas chromatography-mass spectrometry (GC-MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide or chloramine, react with natural organic matter in the wate...

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

Identification of volatile compounds in codfish ( Gadus) by a combination of two extraction Methods coupled with GC-MS analysis

NASA Astrophysics Data System (ADS)

Chang, Yufei; Hou, Hu; Li, Bafang

2016-06-01

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction (SPME) method and simultaneous distillation extraction (SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry (GC-MS) along with Kovats indices (KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols ( i.e., (E)-2-penten-1-ol and 2-octanol), esters ( i.e., ethyl butyrate and methyl geranate), aldehydes ( i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones ( i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.

Quantitative GC-MS assay of citric acid from humans and db/db mice blood serum to assist the diagnosis of diabetic nephropathy.

PubMed

Gao, Haoxue; Yu, Xiaoyi; Sun, Runbin; Yang, Na; He, Jun; Tao, Mingxue; Gu, Huilin; Yan, Caixia; Aa, Jiye; Wang, Guangji

2018-03-01

The early diagnosis of diabetic nephropathy (DN) is rather challenging. Our previous study suggested that citric acid is a potential marker for the early diagnosis of diabetic nephropathy in db/db mice. For the first time, in this study, a surrogate analyte of 13 C 6 -citric acid was employed to generate calibration curves for the quantitative measurement of the endogenous citric acid in the sera of db/db mice and diabetic nephropathy patients by GC/MS after the analytes were extracted, methoximated and trimethylsilylated. The constant response factor of 13 C 6 -citric acid versus citric acid over the linear range indicated the identical ionization efficiency of these two compounds. The full validation assessments suggested that the method is sensitive, specific, reliable, reproducible and has acceptable parameters. Statistical analysis revealed cut-off citric acid concentrations of 29.24 μg/mL with a 95% confidence interval between 32.75 and 39.16 μg/mL in the diabetic nephropathy patients and 16.74 and 22.57 μg/mL in the normal controls. The areas under the receiver operating characteristic curves indicated accuracies of over 90% for the diagnoses of early diabetic nephropathy in both humans and db/db mice, which suggests that the serum citric acid level is potentially a biomarker that could assist in the diagnosis of diabetic nephropathy. Copyright © 2018 Elsevier B.V. All rights reserved.

Secondary metabolite profiling of Curcuma species grown at different locations using GC/TOF and UPLC/Q-TOF MS.

PubMed

Lee, Jueun; Jung, Youngae; Shin, Jeoung-Hwa; Kim, Ho Kyoung; Moon, Byeong Cheol; Ryu, Do Hyun; Hwang, Geum-Sook

2014-07-04

Curcuma, a genus of rhizomatous herbaceous species, has been used as a spice, traditional medicine, and natural dye. In this study, the metabolite profile of Curcuma extracts was determined using gas chromatography-time of flight mass spectrometry (GC/TOF MS) and ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) to characterize differences between Curcuma aromatica and Curcuma longa grown on the Jeju-do or Jin-do islands, South Korea. Previous studies have performed primary metabolite profiling of Curcuma species grown in different regions using NMR-based metabolomics. This study focused on profiling of secondary metabolites from the hexane extract of Curcuma species. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) plots showed significant differences between the C. aromatica and C. longa metabolite profiles, whereas geographical location had little effect. A t-test was performed to identify statistically significant metabolites, such as terpenoids. Additionally, targeted profiling using UPLC/Q-TOF MS showed that the concentration of curcuminoids differed depending on the plant origin. Based on these results, a combination of GC- and LC-MS allowed us to analyze curcuminoids and terpenoids, the typical bioactive compounds of Curcuma, which can be used to discriminate Curcuma samples according to species or geographical origin.

Metabolomic analysis of avocado fruits by GC-APCI-TOF MS: effects of ripening degrees and fruit varieties.

PubMed

Hurtado-Fernández, E; Pacchiarotta, T; Mayboroda, O A; Fernández-Gutiérrez, A; Carrasco-Pancorbo, A

2015-01-01

In order to investigate avocado fruit ripening, nontargeted GC-APCI-TOF MS metabolic profiling analyses were carried out. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to explore the metabolic profiles from fruit samples of 13 varieties at two different ripening degrees. Mannoheptulose; pentadecylfuran; aspartic, malic, stearic, citric and pantothenic acids; mannitol; and β-sitosterol were some of the metabolites found as more influential for the PLS-DA model. The similarities among genetically related samples (putative mutants of "Hass") and their metabolic differences from the rest of the varieties under study have also been evaluated. The achieved results reveal new insights into avocado fruit composition and metabolite changes, demonstrating therefore the value of metabolomics as a functional genomics tool in characterizing the mechanism of fruit ripening development, a key developmental stage in most economically important fruit crops.

Simultaneous detection of seventeen drugs of abuse and metabolites in hair using solid phase micro extraction (SPME) with GC/MS.

PubMed

Aleksa, Katarina; Walasek, Paula; Fulga, Netta; Kapur, Bhushan; Gareri, Joey; Koren, Gideon

2012-05-10

The analysis of pediatric and adult hair is a useful non-invasive biomarker to effectively detect long term exposure to various xenobiotics, specifically drugs of abuse such as cocaine, opiates and amphetamines. Very often individuals are using, or are exposed to multiple drugs simultaneously and therefore it is important to be able to detect them in the same analysis. We have developed a sensitive and specific solid phase micro extraction (SPME) coupled with gas chromatography mass spectrometry (GC/MS) to detect 17 different analytes in hair using a single extraction method. Five milligrams of hair is extracted overnight, subjected to solid phase extraction (SPE) and then to SPME-GC/MS. The aimed analytes include amphetamine, methamphetamine, MDA, MDMA, cocaine, benzoylecognine, norcocaine, cocaethylene, methadone, codeine, morphine, 6-AM, oxycodone, oxymorphone, hydrocodone, hydromorphone and meperidone. The following are the LOD of the various drugs: 0.2ng/mg hair for amphetamine, methamphetamine, MDA, MDMA, morphine, codeine, 6-AM, oxycodone, oxymorphone, hydromorphone, hydrocodone, meperidine and 0.13ng/mg hair for cocaine, benzoylecognine, cocaethylene, norcocaine and methadone. This GC/MS method is sensitive and specific to detect the presence of these 17 analytes in as little as 5mg of hair and is especially useful for newborn and child hair analysis where the amount of hair is often very limited. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Detection and quantification of ochratoxin A and deoxynivalenol in barley grains by GC-MS and electronic nose.

PubMed

Olsson, J; Börjesson, T; Lundstedt, T; Schnürer, J

2002-02-05

Mycotoxin contamination of cereal grains can be detected and quantified using complex extraction procedures and analytical techniques. Normally, the grain odour, i.e. the presence of non-grain volatile metabolites, is used for quality classification of grain. We have investigated the possibility of using fungal volatile metabolites as indicators of mycotoxins in grain. Ten barley samples with normal odour, and 30 with some kind of off-odour were selected from Swedish granaries. The samples were evaluated with regard to moisture content, fungal contamination, ergosterol content, and levels of ochratoxin A (OA) and deoxynivalenol (DON). Volatile compounds were also analysed using both an electronic nose and gas chromatography combined with mass spectrometry (GC-MS). Samples with normal odour had no detectable ochratoxin A and average DON contents of 16 microg kg(-1) (range 0-80), while samples with off-odour had average OA contents of 76 microg kg(-1) (range 0-934) and DON contents of 69 microg kg(-1) (range 0-857). Data were evaluated by multivariate data analysis using projection methods such as principal component analysis (PCA) and partial least squares (PLS). The results show that it was possible to classify the OA level as below or above the maximum limit of 5 microg kg(-1) cereal grain established by the Swedish National Food Administration, and that the DON level could be estimated using PLS. Samples with OA levels below 5 microg kg(-1) had higher concentration of aldehydes (nonanal, 2-hexenal) and alcohols (1-penten-3-ol, 1-octanol). Samples with OA levels above 5 microg kg(-1) had higher concentrations of ketones (2-hexanone, 3-octanone). The GC-MS system predicted OA concentrations with a higher accuracy than the electronic nose, since the GC-MS misclassified only 3 of 37 samples and the electronic nose 7 of 37 samples. No correlation was found between odour and OA level, as samples with pronounced or strong off-odours had OA levels both below and above 5

Solid-phase extraction and GC-MS analysis of THC-COOH method optimized for a high-throughput forensic drug-testing laboratory.

PubMed

Stout, P R; Horn, C K; Klette, K L

2001-10-01

In order to facilitate the confirmation analysis of large numbers of urine samples previously screened positive for delta9-tetrahydrocannabinol (THC), an extraction, derivitization, and GC-MS analysis method was developed. This method utilized a positive pressure manifold anion-exchange polymer-based solid-phase extraction followed by elution directly into the automated liquid sampling (ALS) vials. Rapid derivitization was accomplished using pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFPOH). Recoveries averaged 95% with a limit of detection of 0.875 ng/mL with a 3-mL sample volume. Performance of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH)-d3 and THC-COOH-d9 internal standards were evaluated. The method was linear to 900 ng/mL THC-COOH using THC-COOH-d9 with negligible contribution from the internal standard to very weak samples. Excellent agreement was seen with previous quantitations of human urine samples. More than 1000 human urine samples were analyzed using the method with 300 samples analyzed using an alternate qualifier ion (m/z 622) after some interference was observed with a qualifier ion (m/z 489). The 622 ion did not exhibit any interference even in samples with interfering peaks present in the 489 ion. The method resulted in dramatic reductions in processing time, waste production, and exposure hazards to laboratory personnel.

Performance Evaluation of an Improved GC-MS Method to Quantify Methylmercury in Fish.

PubMed

Watanabe, Takahiro; Kikuchi, Hiroyuki; Matsuda, Rieko; Hayashi, Tomoko; Akaki, Koichi; Teshima, Reiko

2015-01-01

Here, we set out to improve our previously developed methylmercury analytical method, involving phenyl derivatization and gas chromatography-mass spectrometry (GC-MS). In the improved method, phenylation of methylmercury with sodium tetraphenylborate was carried out in a toluene/water two-phase system, instead of in water alone. The modification enabled derivatization at optimum pH, and the formation of by-products was dramatically reduced. In addition, adsorption of methyl phenyl mercury in the GC system was suppressed by co-injection of PEG200, enabling continuous analysis without loss of sensitivity. The performance of the improved analytical method was independently evaluated by three analysts using certified reference materials and methylmercury-spiked fresh fish samples. The present analytical method was validated as suitable for determination of compliance with the provisional regulation value for methylmercury in fish, set in the Food Sanitation haw.

Validation of an analytical method for nitrous oxide (N2O) laughing gas by headspace gas chromatography coupled to mass spectrometry (HS-GC-MS): forensic application to a lethal intoxication.

PubMed

Giuliani, N; Beyer, J; Augsburger, M; Varlet, V

2015-03-01

Drug abuse is a widespread problem affecting both teenagers and adults. Nitrous oxide is becoming increasingly popular as an inhalation drug, causing harmful neurological and hematological effects. Some gas chromatography-mass spectrometry (GC-MS) methods for nitrous oxide measurement have been previously described. The main drawbacks of these methods include a lack of sensitivity for forensic applications; including an inability to quantitatively determine the concentration of gas present. The following study provides a validated method using HS-GC-MS which incorporates hydrogen sulfide as a suitable internal standard allowing the quantification of nitrous oxide. Upon analysis, sample and internal standard have similar retention times and are eluted quickly from the molecular sieve 5Å PLOT capillary column and the Porabond Q column therefore providing rapid data collection whilst preserving well defined peaks. After validation, the method has been applied to a real case of N2O intoxication indicating concentrations in a mono-intoxication. Copyright © 2015 Elsevier B.V. All rights reserved.

Congener-specific extraction and separation of coplanar PCBs from soil using SPME and capillary GC/MS

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

Woolley, C.L.; Mani, V.; Shirey, R.E.

1995-12-31

The persistence and widespread environmental occurrence of polychlorinated biphenyls (PCBs) in the air, waterways and industrial facilities has created a need for quantitative and qualitative analysis of Aroclor-like mixtures. Although there are 209 possible PCB concerns, only a limited number have shown toxic activity similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The World Health Organization recently released a list of the 13 most toxic PCB congeners. Each was rated by its Toxic Equivalency Factor relative to TCDD. These 13 PCB congeners belong to the class of toxic coplanar compounds. These congeners commonly contain chlorosubstitutions in the 3,3{prime},4,4{prime} or 3,4,4{prime} or 3{prime},4,4{prime} positions andmore » either 0, 1, or 2 chloro-substituents in the ortho positions. A new capillary column containing a bonded octylmethyl polysiloxane stationary phase (SPB-Octyl) was evaluated for its propensity to separate coplanar PCB congeners. Solid phase microextraction (SPME), a solvent-free method for extracting volatiles and semi-volatiles from drinking water, waste water, soil and sludge was used to extract PCBs from soil. GC-ECD and GC-MS separations of PCB ladened soils were examined via SPME on the SPB-Octyl column. An approach for selective extraction of coplanar PCB congeners by SPME will be described.« less

Qualitative and quantitative analysis of the diuretic component ergone in Polyporus umbellatus by HPLC with fluorescence detection and HPLC-APCI-MS/MS.

PubMed

Zhao, Ying-Yong; Zhao, Ye; Zhang, Yong-Min; Lin, Rui-Chao; Sun, Wen-Ji

2009-06-01

Polyporus umbellatus is a widely used anti-aldosteronic diuretic in Traditional Chinese medicine (TCM). A new, sensitive and selective high-performance liquid chromatography-fluorescence detector (HPLC-FLD) and high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS/MS) method for quantitative and qualitative determination of ergosta-4,6,8(14),22-tetraen-3-one(ergone), which is the main diuretic component, was provided for quality control of P. umbellatus crude drug. The ergone in the ethanolic extract of P. umbellatus was unambiguously characterized by HPLC-APCI, and further confirmed by comparing with a standard compound. The trace ergone was detected by the sensitive and selective HPLC-FLD. Linearity (r2 > 0.9998) and recoveries of low, medium and high concentration (100.5%, 100.2% and 100.4%) were consistent with the experimental criteria. The limit of detection (LOD) of ergone was around 0.2 microg/mL. Our results indicated that the content of ergone in P. umbellatus varied significantly from habitat to habitat with contents ranging from 2.13 +/- 0.02 to 59.17 +/- 0.05 microg/g. Comparison among HPLC-FLD and HPLC-UV or HPLC-APCI-MS/MS demonstrated that the HPLC-FLD and HPLC-APCI-MS/MS methods gave similar quantitative results for the selected herb samples, the HPLC-UV methods gave lower quantitative results than HPLC-FLD and HPLC-APCI-MS/MS methods. The established new HPLC-FLD method has the advantages of being rapid, simple, selective and sensitive, and could be used for the routine analysis of P. umbellatus crude drug.

Characterization of oils and fats by 1H NMR and GC/MS fingerprinting: classification, prediction and detection of adulteration.

PubMed

Fang, Guihua; Goh, Jing Yeen; Tay, Manjun; Lau, Hiu Fung; Li, Sam Fong Yau

2013-06-01

The correct identification of oils and fats is important to consumers from both commercial and health perspectives. Proton nuclear magnetic resonance ((1)H NMR) spectroscopy, gas chromatography-mass spectrometry (GC/MS) fingerprinting and chemometrics were employed successfully for the quality control of oils and fats. Principal component analysis (PCA) of both techniques showed group clustering of 14 types of oils and fats. Partial least squares discriminant analysis (PLS-DA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) using GC/MS data had excellent classification sensitivity and specificity compared to models using NMR data. Depending on the availability of the instruments, data from either technique can effectively be applied for the establishment of an oils and fats database to identify unknown samples. Partial least squares (PLS) models were successfully established for the detection of as low as 5% of lard and beef tallow spiked into canola oil, thus illustrating possible applications in Islamic and Jewish countries. Copyright © 2012 Elsevier Ltd. All rights reserved.

IR and py/GC/MS examination of amber relics excavated from 6th century royal tomb in Korean Peninsula.

PubMed

Park, Jongseo; Yun, Eunyoung; Kang, Hyungtae; Ahn, Jooyoung; Kim, Gyuho

2016-08-05

Relics of amber were excavated from King Muryeong's tomb constructed in the 6th century on the Korean peninsula. To estimate the provenance, FTIR (Fourier transform infrared spectroscopy) and py/GC/MS (pyrolysis/gas chromatography/mass spectrometry) analysis were utilized. The reference Baltic amber sample was also analyzed with the same method for comparison. The relics were confirmed to be amber from the FTIR analysis where an absorption band near 1150cm(-1), characteristic one in Baltic amber, was also observed. In py/GC/MS analysis, pyrolyzed products like butanedioic acid and dehydroabietic acid, known constituents of amber, were observed. In addition, d-fenchyl alcohol, camphor, borneol and butanedioic acid, typical constituents of Baltic amber, were observed in some samples. From this, it appears that some of relics were made from Baltic amber and that Baltic amber was transported to the Korean peninsula in the time of tomb construction. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and application of GC-MS method for monitoring of long-term exposure to the pesticide cypermethrin.

PubMed

Kavvalakis, Matthaios P; Tzatzarakis, Manolis N; Alegakis, Athanasios K; Vynias, Dionysios; Tsakalof, Andreas K; Tsatsakis, Aristidis M

2014-06-01

Cypermethrin (CPMN) is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as for domestic purposes. In the present study a gas chromatography-mass spectrometry (GC-MS) based method was developed and validated for the quantitation of CPMN metabolites, 3-phenoxybenzoic acid (3-PBA) and cis- and trans- 3-(2,2-dichlorovinyl)-2,2-dimethyl-1-cyclopropane (cis- and trans- Cl2 CA). The developed method was applied for the monitoring of CPMN metabolites in hair of laboratory animals (rabbits) intentionally exposed per os to CPMN at 40 (low dose) and 80 (high dose) mg/kg weight/day for 16 weeks. The analytical method comprises three main steps: isolation of analytes from hair, analytes derivatization, and subsequent instrumental analysis by GC-MS. The limits of detection ensured by the method are 4.0, 3.9 and 1.0 pg/mg hair for cis-Cl2 CA, trans-Cl2 CA and 3-PBA, respectively. The instrument responce is linear (r(2)  > 0.99) in the investigated concentrations range from 25 to 1000 pg/mg. With and between-run precision as well as accuracy were estimated and found satisfactory. Analytes were efficiently isolated by solid-liquid extraction from hair with recoveries greater than 84.8% for cis-Cl2 CA, 87.2% for trans-Cl2 CA and 96.4% for 3-PBA. Rabbit's hair showed increasing levels for all metabolites (metabolites accumulation in a time and dose dependent manner) over time and in a dose-dependent manner. The developed experimental procedure could be used for biomonitoring of population exposure to CPMN. Copyright © 2014 John Wiley & Sons, Ltd.

Protocols for the measurement of the F2-isoprostane, 15(S)-8-iso-prostaglandin F2α, in biological samples by GC-MS or GC-MS/MS coupled with immunoaffinity column chromatography.

PubMed

Tsikas, Dimitrios; Suchy, Maria-Theresia

2016-04-15

Arachidonic acid, the origin of the eicosanoids family, occurs in biological samples as free acid and as ester in lipids. Free arachidonic acid is oxidized to numerous metabolites by means of enzymes including cyclooxygenase (COX). Arachidonic acid esterified to lipids is attacked by reactive oxygen species (ROS) to generate numerous oxidized arachidonic acid derivatives. Generally, it is assumed that ROS-derived arachidonic acid derivatives are distinct from those generated by enzymes such as COX. Therefore, ROS-generated eicosanoids are considered specific biomarkers of oxidative stress. However, there are serious doubts concerning a strict distinction between the enzyme-derived eicosanoids and the ROS-derived iso-eicosanoids. Prominent examples are prostaglandin F2α (PGF2α) and 15(S)-8-iso-prostaglandin F2α (15(S)-8-iso-PGF2α) which have been originally considered to exclusively derive from COX and ROS, respectively. There is convincing evidence that both COX and ROS can oxidize arachidonic acid to PGF2α and 15(S)-8-iso-PGF2α. Thus, many results previously reported for 15(S)-8-iso-PGF2α as exclusive ROS-dependent reaction product, and consequently as a specific biomarker of oxidative stress, require a careful re-examination which should also consider the analytical methods used to measure 15(S)-8-iso-PGF2α. This prominent but certainly not the only example underlines more than ever the importance of the analytical chemistry in basic and clinical research areas of oxidative stress. In the present work, we report analytical protocols for the reliable quantitative determination of 15(S)-8-iso-PGF2α in human biological samples including plasma and urine by mass spectrometry coupled to gas chromatography (GC-MS, GC-MS/MS) after specific isolation of endogenous 15(S)-8-iso-PGF2α and the externally added internal standard [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α by immunoaffinity column chromatography (IAC). 15(S)-8-iso-PGF2α esterified to plasma lipids is

Determination of Ethyl Carbamate in Chinese Yellow Rice Wine by Diatomaceous Earth Extraction and GC/MS Method.

PubMed

Wu, Pinggu; Zhang, Liqun; Shen, Xianghong; Wang, Liyuan; Zou, Yan; Zhang, Jing; Tan, Ying; Tang, Jun; Ma, Bingjie; Pan, Xiaodong; Jiang, Wei

2015-01-01

A sensitive and rapid analytical method based on alkaline diatomaceous earth extraction followed by GC/MS was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC) in yellow rice wines. The optimal extraction conditions were investigated. With the application of diatomaceous earth extraction, the damage of organic acids to the capillary column was greatly reduced. By using d5-EC as an internal standard for quantitative analysis of EC, the linearity of the calibration curves was good between 10 and 1000 ng/mL. The LOD and LOQ were 1.7 and 5.0 μg/kg, respectively. The spiked level of EC was 5.0-300 μg/kg, and the average recovery of the spikes was between 78.4 and 98.2%, with an RSD between 4.3 and 8.3%. Upon validation by five laboratories when spiked with 50, 100, and 300 μg/kg, the average respective recoveries were 102.9, 102.2, and 98.7% with a RSD between 0.7 and 8.1%. The validation results demonstrated that the method is fast, simple, selective, and suitable for the determination of EC in yellow rice wines.

Performances of the Mars Organic Molecule Analyzer (MOMA) GC-MS suite aboard ExoMars Mission

NASA Astrophysics Data System (ADS)

Buch, A.; Grand, N.; Pinnick, V. T.; Szopa, C.; Humeau, O.; Danell, R.; van Amerom, F. H. W.; Freissinet, C.; Glavin, D. P.; Belmahdi, I.; Coll, P. J.; Lustrement, B.; Brinckerhoff, W. B.; Arevalo, R. D., Jr.; Stalport, F.; Steininger, H.; Goesmann, F.; Raulin, F.; Mahaffy, P. R.

2014-12-01

The Mars Organic Molecule Analyzer (MOMA) aboard the ExoMars rover (Pasteur) will be a key analytical tool in providing chemical (molecular) information from the solid samples collected by the rover, with a particular focus on the characterization of the organic content. Samples will be extracted as deep as 2 meters below the martian surface to minimize effects of radiation and oxidation on organic materials. The core of the MOMA instrument is a dual source UV laser desorption / ionization (LDI) and pyrolysis gas chromatography (pyr-GC) ion trap mass spectrometer (ITMS) which provides the unique capability to characterize a broad range of compounds, including both of volatile and non-volatile species. Samples which undergo GC-ITMS analysis may be submitted to a derivatization process, consisting of the reaction of the sample components with specific reactants (MTBSTFA [1], DMF-DMA [2] or TMAH [3]) which increase the volatility of complex organic species. With the goal to optimize this instrumentation, and especially the GC-ITMS coupling, a series of tests is currently being carried out with prototypes of MOMA instrumentation and with the ETU models wich is similar to the flight model. The MOMA oven and tapping station are also part of these end-to-end experiments. Qualitative and quantitative tests has been done on gas, liquid and solid samples. The results obtained demonstrate the current status of the end-to-end performance of the gas chromatography-mass spectrometry mode of operation. Both prototypes individually meet the performance requirements, but this work particularly demonstrates the capabilities of the critical GC-MS interface. References: [1] Buch, A. et al. (2009) J chrom. A, 43, 143-151. [2] Freissinet et al. (2011) J Chrom A, 1306, 59-71. [3] Geffroy-Rodier, C. et al. (2009) JAAP, 85, 454-459. Acknowledgements: Funding provided by the Mars Exploration Program (point of contact, George Tahu, NASA/HQ). MOMA is a collaboration between NASA and ESA (PI

Create, run, share, publish, and reference your LC-MS, FIA-MS, GC-MS, and NMR data analysis workflows with the Workflow4Metabolomics 3.0 Galaxy online infrastructure for metabolomics.

PubMed

Guitton, Yann; Tremblay-Franco, Marie; Le Corguillé, Gildas; Martin, Jean-François; Pétéra, Mélanie; Roger-Mele, Pierrick; Delabrière, Alexis; Goulitquer, Sophie; Monsoor, Misharl; Duperier, Christophe; Canlet, Cécile; Servien, Rémi; Tardivel, Patrick; Caron, Christophe; Giacomoni, Franck; Thévenot, Etienne A

2017-12-01

Metabolomics is a key approach in modern functional genomics and systems biology. Due to the complexity of metabolomics data, the variety of experimental designs, and the multiplicity of bioinformatics tools, providing experimenters with a simple and efficient resource to conduct comprehensive and rigorous analysis of their data is of utmost importance. In 2014, we launched the Workflow4Metabolomics (W4M; http://workflow4metabolomics.org) online infrastructure for metabolomics built on the Galaxy environment, which offers user-friendly features to build and run data analysis workflows including preprocessing, statistical analysis, and annotation steps. Here we present the new W4M 3.0 release, which contains twice as many tools as the first version, and provides two features which are, to our knowledge, unique among online resources. First, data from the four major metabolomics technologies (i.e., LC-MS, FIA-MS, GC-MS, and NMR) can be analyzed on a single platform. By using three studies in human physiology, alga evolution, and animal toxicology, we demonstrate how the 40 available tools can be easily combined to address biological issues. Second, the full analysis (including the workflow, the parameter values, the input data and output results) can be referenced with a permanent digital object identifier (DOI). Publication of data analyses is of major importance for robust and reproducible science. Furthermore, the publicly shared workflows are of high-value for e-learning and training. The Workflow4Metabolomics 3.0 e-infrastructure thus not only offers a unique online environment for analysis of data from the main metabolomics technologies, but it is also the first reference repository for metabolomics workflows. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of plant gums and saccharide materials in paint samples: comparison of GC-MS analytical procedures and databases

PubMed Central

2012-01-01

Background Saccharide materials have been used for centuries as binding media, to paint, write and illuminate manuscripts and to apply metallic leaf decorations. Although the technical literature often reports on the use of plant gums as binders, actually several other saccharide materials can be encountered in paint samples, not only as major binders, but also as additives. In the literature, there are a variety of analytical procedures that utilize GC-MS to characterize saccharide materials in paint samples, however the chromatographic profiles are often extremely different and it is impossible to compare them and reliably identify the paint binder. Results This paper presents a comparison between two different analytical procedures based on GC-MS for the analysis of saccharide materials in works-of-art. The research presented here evaluates the influence of the analytical procedure used, and how it impacts the sugar profiles obtained from the analysis of paint samples that contain saccharide materials. The procedures have been developed, optimised and systematically used to characterise plant gums at the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). The main steps of the analytical procedures and their optimisation are discussed. Conclusions The results presented highlight that the two methods give comparable sugar profiles, whether the samples analysed are simple raw materials, pigmented and unpigmented paint replicas, or paint samples collected from hundreds of centuries old polychrome art objects. A common database of sugar profiles of reference materials commonly found in paint samples was thus compiled. The database presents data also from those materials that only contain a minor saccharide fraction. This database highlights how many sources of saccharides can be found in a paint sample, representing an important step forward in the problem of

Analysis of plant gums and saccharide materials in paint samples: comparison of GC-MS analytical procedures and databases.

PubMed

Lluveras-Tenorio, Anna; Mazurek, Joy; Restivo, Annalaura; Colombini, Maria Perla; Bonaduce, Ilaria

2012-10-10

Saccharide materials have been used for centuries as binding media, to paint, write and illuminate manuscripts and to apply metallic leaf decorations. Although the technical literature often reports on the use of plant gums as binders, actually several other saccharide materials can be encountered in paint samples, not only as major binders, but also as additives. In the literature, there are a variety of analytical procedures that utilize GC-MS to characterize saccharide materials in paint samples, however the chromatographic profiles are often extremely different and it is impossible to compare them and reliably identify the paint binder. This paper presents a comparison between two different analytical procedures based on GC-MS for the analysis of saccharide materials in works-of-art. The research presented here evaluates the influence of the analytical procedure used, and how it impacts the sugar profiles obtained from the analysis of paint samples that contain saccharide materials. The procedures have been developed, optimised and systematically used to characterise plant gums at the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). The main steps of the analytical procedures and their optimisation are discussed. The results presented highlight that the two methods give comparable sugar profiles, whether the samples analysed are simple raw materials, pigmented and unpigmented paint replicas, or paint samples collected from hundreds of centuries old polychrome art objects. A common database of sugar profiles of reference materials commonly found in paint samples was thus compiled. The database presents data also from those materials that only contain a minor saccharide fraction. This database highlights how many sources of saccharides can be found in a paint sample, representing an important step forward in the problem of identifying polysaccharide binders in

Diethylstilbestrol in fish tissue determined through subcritical fluid extraction and with GC-MS

NASA Astrophysics Data System (ADS)

Qiao, Qinghui; Shi, Nianrong; Feng, Xiaomei; Lu, Jie; Han, Yuqian; Xue, Changhu

2016-06-01

As the key point in sex hormone analysis, sample pre-treatment technology has attracted scientists' attention all over the world, and the development trend of sample preparation forwarded to faster and more efficient technologies. Taking economic and environmental concerns into account, subcritical fluid extraction as a faster and more efficient method has stood out as a sample pre-treatment technology. This new extraction technology can overcome the shortcomings of supercritical fluid and achieve higher extraction efficiency at relatively low pressures and temperatures. In this experiment, a simple, sensitive and efficient method has been developed for the determination of diethylstilbestrol (DES) in fish tissue using subcritical 1,1,1,2-tetrafluoroethane (R134a) extraction in combination with gas chromatography-mass spectrometry (GC-MS). After extraction, freezing-lipid filtration was utilized to remove fatty co-extract. Further purification steps were performed with C18 and NH2 solid phase extraction (SPE). Finally, the analyte was derived by heptafluorobutyric anhydride (HFBA), followed by GC-MS analysis. Response surface methodology (RSM) was employed to optimizing the extraction condition, and the optimized was as follows: extraction pressure, 4.3 MPa; extraction temperature, 26°C; amount of co-solvent volume, 4.7 mL. Under this condition, at a spiked level of 1, 5, 10 μg kg-1, the mean recovery of DES was more than 90% with relative standard deviations (RSDs) less than 10%. Finally, the developed method has been successfully used to analyzing the real samples.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF SOIL AND HOUSE DUST SAMPLES FOR GC/MS ANALYSIS OF PESTICIDE AND PAH (BCO-L-28.0)

EPA Science Inventory

The purpose of this SOP is to describe procedures for extracting and preparing a dust or soil sample for gas chromatography mass spectrometry (GC/MS) analysis of pesticides and polyaromatic hydrocarbons (PAHs). This procedure was followed to ensure consistent data retrieval durin...

Determination of 48 fragrance allergens in toys using GC with ion trap MS/MS.

PubMed

Lv, Qing; Zhang, Qing; Li, Wentao; Li, Haiyu; Li, Pi; Ma, Qiang; Meng, Xianshuang; Qi, Meiling; Bai, Hua

2013-11-01

This paper presents a method for the simultaneous determination of 48 fragrance allergens in four types of toys (plastic toys, play clays, plush toys, and paper toys) based on GC with ion trap MS/MS. Compared with single-stage MS, MS/MS is superior in terms of the qualification and quantification of a large range of compounds in complicated matrices. Procedures for extraction and purification were optimized for each toy type. The method proved to be linear over a wide range of concentrations for all analytes with correlation coefficients between 0.9768 and 0.9999. Validation parameters, namely, LODs and LOQs, ranged from 0.005-5.0 and from 0.02-20 mg/kg, respectively. Average recoveries of target compounds (spiked at three concentration levels) were in the range of 79.5-109.1%. Intraday and interday repeatabilities of the proposed method varied from 0.7-10.5% and from 3.1-13.4%, respectively. The proposed method was used to monitor fragrance allergens in commercial toy products. Our findings indicate that this method is an accurate and effective technique for analyzing fragrance allergens in materials composed of complex components. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HS-GC/MS volatile profile of different varieties of garlic and their behavior under heating.

PubMed

Molina-Calle, María; Priego-Capote, Feliciano; de Castro, María D Luque

2016-05-01

Garlic is one of the most used seasonings in the world whose beneficial health effects, mainly ascribed to organosulfur compounds, are shared with the rest of the Allium family. The fact that many of these compounds are volatile makes the evaluation of the volatile profile of garlic interesting. For this purpose, three garlic varieties-White, Purple, and Chinese-cultivated in the South of Spain were analyzed by a method based on a headspace (HS) device coupled to a gas chromatograph and mass detector (HS-GC/MS). The main temperatures in the HS were optimized to achieve the highest concentration of volatiles. A total number of 45 volatiles were tentatively identified (among them 17 were identified for the first time in garlic); then, all were classified, also for the first time, and their relative concentration in three garlic varieties was used to evaluate differences among them and to study their profiles according to the heating time. Chinese garlic was found to be the richest variety in sulfur volatiles, while the three varieties presented a similar trend under preset heating times allowing differentiation between varieties and heating time using principal component analysis. Graphical Abstract HS-GC/MS analysis of the volatile profile of garlic.

[Analysis of essential oil extracted from Lactuca sativa seeds growing in Xinjiang by GC-MS].

PubMed

Xu, Fang; Wang, Qiang; Haji, Akber Aisa

2011-12-01

To analyze the components of essential oil from Lactuca sativa seeds growing in Xinjiang. The components of essential oil from Lactuca sativa seeds were analyzed by gas chromatography-mass spectrometry (GC-MS). 62 components were identified from 71 separated peaks,amounting to total mass fraction 95.07%. The dominant compounds were n-Hexanol (36.31%), n-Hexanal (13.71%), trans-2-Octen-l-ol (8.09%) and 2-n-Pentylfuran (4.41%). The research provides a theoretical basis for the exploitation and use of Lactuca sativa seeds resource.

Two-dimensional on-line detection of brominated and iodinated volatile organic compounds by ECD and ICP-MS after GC separation.

PubMed

Schwarz, A; Heumann, K G

2002-09-01

Inductively coupled plasma-mass spectrometry (ICP-MS) was coupled to a gas chromatographic (GC) system with electron capture detector (ECD), which enables relatively easy characterization and quantification of brominated and iodinated (halogenated) volatile organic compounds (HVOCs) in aquatic and air samples. The GC-ECD system is connected in series with an ICP-MS by a directly heated transfer line and an outlet port-hole for elimination of the ECD make-up gas during ignition of the plasma. The hyphenated GC-ECD/ICP-MS system provides high selectivity and sensitivity for monitoring individual HVOCs under fast chromatographic conditions. The ECD is most sensitive for the detection of chlorinated and brominated but the ICP-MS for iodinated compounds. The greatest advantage of the use of an ICP-MS is its element-specific detection, which allows clear identification of compounds in most cases. The absolute detection limits for ICP-MS are 0.5 pg for iodinated, 10 pg for brominated, and 50 pg for chlorinated HVOCs with the additional advantage that calibration is almost independent on different compounds of the same halogen. In contrast to that detection limits for ECD vary for the different halogenated compounds and lie in the range of 0.03-11 pg. The two-dimensional GC-ECD/ICP-MS instrumentation is compared with electron impact mass spectrometry (EI-MS) and microwave induced plasma atomic emission detection (MIP-AED). Even if EI-MS has additional power in identifying unknown peaks by its scan mode, the detection limits are much higher compared with GC-ECD/ICP-MS, whereas the selective ion monitoring mode (SIM) reaches similar detection limits. The MIP-AED detection limits are at the same level as EI-MS in the scan mode.

Active and realistic passive marijuana exposure tested by three immunoassays and GC/MS in urine

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

Mule, S.J.; Lomax, P.; Gross, S.J.

Human urine samples obtained before and after active and passive exposure to marijuana were analyzed by immune kits (Roche, Amersham, and Syva) and gas chromatography/mass spectrometry (GC/MS). Seven of eight subjects were positive for the entire five-day test period with one immune kit. The latter correlated with GC/MS in 98% of the samples. Passive inhalation experiments under conditions likely to reflect realistic exposure resulted consistently in less than 10 ng/mL of cannabinoids. The 10-100-ng/mL cannabinoid concentration range essential for detection of occasional and moderate marijuana users is thus unaffected by realistic passive inhalation.

AUTOMATED ANALYSIS OF AQUEOUS SAMPLES CONTAINING PESTICIDES, ACIDIC/BASIC/NEUTRAL SEMIVOLATILES AND VOLATILE ORGANIC COMPOUNDS BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GC/MS

EPA Science Inventory

Data is presented on the development of a new automated system combining solid phase extraction (SPE) with GC/MS spectrometry for the single-run analysis of water samples containing a broad range of organic compounds. The system uses commercially available automated in-line 10-m...

Determination of 28 pesticides applied on two tomato cultivars with a different surface/weight ratio of the berries, using a multiresidue GC-MS/MS method.

PubMed

Dedola, Fabrizio; Cabizza, Maddalena; Satta, Maurizio

2014-01-01

The behavior of 28 pesticides on two tomato cultivars with a different surface/weight (S/W) ratio of the berries (S/W, Birikino vs. Tombola) was studied, in order to provide appropriate indications about their persistence on crops reaching the pre-harvest interval (PHI). Quantitative analysis was performed using a GC MS/MS method. Birikino cv. (BIR) was a "cherry type tomato" with a double S/W ratio compared with Tombola cv. (TOM). The results showed a different pesticide behavior. Azoxystrobin, Boscalid, Bupirimate, Difenoconazole, Etofenprox, Iprodione, Mepanipyrim, Myclobutanil, Tebuconazole, Zoxamide, Metalaxyl M, Pyrimethanil, Tetraconazole, Benalaxyl, Cyprodinil, Fenamidone, Famoxadone and Fludioxonil immediately after treatments showed residues on BIR higher than TOM, and this behavior is consistent with its greater exposed surface. BIR showed higher decay rates of these pesticides during the whole trial, nevertheless residue averages remained higher than TOM reaching the time of harvest. Residues at the PHI were all below their Maximum Residue Levels (MRLs), but data indicated that they could exceed their legal limits especially if the above-mentioned active ingredients were employed more than once per crop cycle on cherry type tomatoes. As regards to Chlorpyrifos, Chlorpyrifos methyl, Triadimenol, Pyridaben and Tebufenpyrad, no different residual behavior related to S/W ratio of the cultivars was observed. Even in this case, residues at the PHI were all below MRLs. As for Cyfluthrin, Deltamethrin, Lambda cyhalothrin, Etoxazole and Cyproconazole, residues were lower than the limit of quantitation (LOQ) of the analytical method just after the treatment, according to their low doses of employment.

Aroma characterization of chinese rice wine by gas chromatography-olfactometry, chemical quantitative analysis, and aroma reconstitution.

PubMed

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

2013-11-27

The aroma profile of Chinese rice wine was investigated in this study. The volatile compounds in a traditional Chinese rice wine were extracted using Lichrolut EN and further separated by silica gel normal phase chromatography. Seventy-three aroma-active compounds were identified by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). In addition to acids, esters, and alcohols, benzaldehyde, vanillin, geosmin, and γ-nonalactone were identified to be potentially important to Chinse rice wine. The concentration of these aroma-active compounds in the Chinese rice wine was further quantitated by combination of four different methods, including headsapce-gas chromatography, solid phase microextraction-gas chromatography (SPME)-GC-MS, solid-phase extraction-GC-MS, and SPME-GC-pulsed flame photometric detection (PFPD). Quantitative results showed that 34 aroma compounds were at concentrations higher than their corresponding odor thresholds. On the basis of the odor activity values (OAVs), vanillin, dimethyl trisulfide, β-phenylethyl alcohol, guaiacol, geosmin, and benzaldehyde could be responsible for the unique aroma of Chinese rice wine. An aroma reconstitution model prepared by mixing 34 aroma compounds with OAVs > 1 in an odorless Chinese rice wine matrix showed a good similarity to the aroma of the original Chinese rice wine.

Study of the rice straw biodegradation in mixed culture of Trichoderma viride and Aspergillus niger by GC-MS and FTIR.

PubMed

Chen, Yaoning; Huang, Jingxia; Li, Yuanping; Zeng, Guangming; Zhang, Jiachao; Huang, Aizhi; Zhang, Jie; Ma, Shuang; Tan, Xuebin; Xu, Wei; Zhou, Wei

2015-07-01

This study was conducted to investigate the biodegradation ability of the mixed culture of Trichoderma viride and Aspergillus niger through the study of the organic matter extracted from rice straw and the lignocellulose structure by using gas chromatography-mass spectrometer (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The results of the GC-MS showed that the mixed culture possessed shorter alkane (heptane) at the end of the incubation and more kinds of organic matter (except the alkanes, 29 kinds of organic matter were detected) than the pure cultures. It could be deduced that the organic matter could indicate the degradation degree of the lignocellulose to some extent. Moreover, pinene was detected in the mixed culture on days 5 and 10, which might represent the antagonistic relationship between T. viride and A. niger. The analysis of FTIR spectrums which indirectly verified the GC-MS results showed that the mixed culture possessed a better degradation of rice straw compared with the pure culture. Therefore, the methods used in this research could be considered as effective ones to investigate the lignocellulose degradation mechanism in mixed culture.

Differentiation of Volatile Profiles from Stockpiled Almonds at Varying Relative Humidity Levels Using Benchtop and Portable GC-MS.

PubMed

Beck, John J; Willett, Denis S; Gee, Wai S; Mahoney, Noreen E; Higbee, Bradley S

2016-12-14

Contamination by aflatoxin, a toxic metabolite produced by Aspergillus fungi ubiquitous in California almond and pistachio orchards, results in millions of dollars of lost product annually. Current detection of aflatoxin relies on destructive, expensive, and time-intensive laboratory-based methods. To explore an alternative method for the detection of general fungal growth, volatile emission profiles of almonds at varying humidities were sampled using both static SPME and dynamic needle-trap SPE followed by benchtop and portable GC-MS analysis. Despite the portable SPE/GC-MS system detecting fewer volatiles than the benchtop system, both systems resolved humidity treatments and identified potential fungal biomarkers at extremely low water activity levels. This ability to resolve humidity levels suggests that volatile profiles from germinating fungal spores could be used to create an early warning, nondestructive, portable detection system of fungal growth.

GC/GCMS analysis of the petroleum ether and dichloromethane extracts of Moringa oleifera roots

PubMed Central

Faizi, Shaheen; Sumbul, Saima; Versiani, Muhammed Ali; Saleem, Rubeena; Sana, Aisha; Siddiqui, Hira

2014-01-01

Objective To explore the phytochemical constituents from petroleum ether and dichloromethane extracts of Moringa oleifera (M. oleifera) roots using GC/GC-MS. Methods A total of 5.11 kg fresh and undried crushed root of M. oleifera were cut into small pieces and extracted with petroleum ether and dichloromethane (20 L each) at room temperature for 2 d. The concentrated extracts were subjected to their GC-MS analysis. Results The GC-MS analysis of the petroleum ether and dichloromethane extracts of M. oleifera roots, which showed promising biological activities, has resulted in the identification 102 compounds. These constituents belong to 15 classes of compounds including hydrocarbons, fatty acids, esters, alcohols, isothiocyanate, thiocyanate, pyrazine, aromatics, alkamides, cyanides, steroids, halocompounds, urea and N-hydroxyimine derivatives, unsaturated alkenamides, alkyne and indole. GC/GC-MS studies on petroleum ether extract of the roots revealed that it contained 39 compounds, belonging to nine classes. Cyclooctasulfur S8 has been isolated as a pure compound from the extract. The major compounds identified from petroleum ether extract were trans-13-docosene (37.9%), nonacosane (32.6%), cycloartenol (28.6%) nonadecanoic acid (13.9%) and cyclooctasulfur S8 (13.9%). Dichloromethane extract of the roots was composed of 63 compounds of which nasimizinol (58.8%) along with oleic acid (46.5%), N-benzyl-N-(7-cyanato heptanamide (38.3%), N-benzyl-N-(1-chlorononyl) amide (30.3%), bis [3-benzyl prop-2-ene]-1-one (19.5%) and N, N-dibenzyl-2-ene pent 1, 5-diamide (11.6%) were the main constituents. Conclusions This study helps to predict the formula and structure of active molecules which can be used as drugs. This result also enhances the traditional usage of M. oleifera which possesses a number of bioactive compounds. PMID:25183335

Determination of tramadol by dispersive liquid-liquid microextraction combined with GC-MS.

PubMed

Habibollahi, Saeed; Tavakkoli, Nahid; Nasirian, Vahid; Khani, Hossein

2015-01-01

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 µg L(-1), respectively. The linear range was between 0.26 and 220.00 µg L(-1) (R(2) = 0.9970). The relative standard deviation for 50.00 µg L(-1) of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood. Published by Oxford University Press 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Fast analysis of 4-tertoctylphenol, pentachlorophenol and 4-nonylphenol in river sediments by QuEChERS extraction procedure combined with GC-QqQ-MS/MS.

PubMed

Czech, T; Bonilla, N Barco; Gambus, F; González, R Romero; Marín-Sáez, J; Vidal, J L Martínez; Frenich, A Garrido

2016-07-01

A quick, easy, cheap, effective, rugged and safe (QuEChERS)-based extraction method has been optimized for the determination of pentachlorophenol, 4-tertoctylphenol and 4-nonylphenol in river sediments. The extraction method was followed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) analysis, which ensures the reliable identification of the target compounds. The proposed method has been validated allowing the successful determination of the selected compounds, with recoveries ranging from 72 to 96%, when three concentration levels were evaluated (10, 50 and 100μgkg(-1)) and inter-day and intra-day precision, expressed as relative standard deviation (RSD), were lower than 20%. The method showed limits of detection (LODs) and limits of quantification (LOQs) ranging from 0.1 to 2.0μgkg(-1) and from 0.5 to 5.0μgkg(-1), respectively. Finally, 25 real samples from Poland have been analyzed, and only 4-tertoctylphenol was detected at concentrations up to 8.9μgkg(-1) of soil dry weight. Copyright © 2016 Elsevier B.V. All rights reserved.

Elucidation of several neglected reactions in the GC-MS identification of sialic acids as heptafluorobutyrates calls for an urgent reassessment of previous claims.

PubMed

Rota, Paola; Anastasia, Luigi; Allevi, Pietro

2015-05-07

The current analytical protocol used for the GC-MS determination of free or 1,7-lactonized natural sialic acids (Sias), as heptafluorobutyrates, overlooks several transformations. Using authentic reference standards and by combining GC-MS and NMR analyses, flaws in the analytical protocol were pinpointed and elucidated, thus establishing the scope and limitations of the method. It was demonstrated that (a) Sias 1,7-lactones, even if present in biological samples, decompose under the acidic hydrolysis conditions used for their release; (b) Sias 1,7-lactones are unpredicted artifacts, accidentally generated from their parent acids; (c) the N-acetyl group is quantitatively exchanged with that of the derivatizing perfluorinated anhydride; (d) the partial or complete failure of the Sias esterification-step with diazomethane leads to the incorrect quantification and structure attribution of all free Sias. While these findings prompt an urgent correction and improvement of the current analytical protocol, they could be instrumental for a critical revision of many incorrect claims reported in the literature.

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.

Determination of the alkylpyrazine composition of coffee using stable isotope dilution-gas chromatography-mass spectrometry (SIDA-GC-MS).

PubMed

Pickard, Stephanie; Becker, Irina; Merz, Karl-Heinz; Richling, Elke

2013-07-03

A stable isotope dilution analysis based on gas chromatography-mass spectrometry analysis (SIDA-GC-MS) was developed for the quantitative analysis of 12 alkylpyrazines found in commercially available coffee samples. These compounds contribute to coffee flavor. The accuracy of this method was tested by analyzing model mixtures of alkylpyrazines. Comparisons of alkylpyrazine-concentrations suggested that water as extraction solvent was superior to dichloromethane. The distribution patterns of alkylpyrazines in different roasted coffees were quite similar. The most abundant alkylpyrazine in each coffee sample was 2-methylpyrazine, followed by 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, and 2,3,5-trimethylpyrazine, respectively. Among the alkylpyrazines tested, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine revealed the lowest concentrations in roasted coffee. By the use of isotope dilution analysis, the total concentrations of alkylpyrazines in commercially available ground coffee ranged between 82.1 and 211.6 mg/kg, respectively. Decaffeinated coffee samples were found to contain lower amounts of alkylpyrazines than regular coffee samples by a factor of 0.3-0.7, which might be a result of the decaffeination procedure.

Determining the degradation efficiency and mechanisms of ethyl violet using HPLC-PDA-ESI-MS and GC-MS

PubMed Central

2012-01-01

Background The discharge of wastewater that contains high concentrations of reactive dyes is a well-known problem associated with dyestuff activities. In recent years, semiconductor photocatalysis has become more and more attractive and important since it has a great potential to contribute to such environmental problems. One of the most important aspects of environmental photocatalysis is in the selection of semiconductor materials like ZnO and TiO2, which are close to being two of the ideal photocatalysts in several respects. For example, they are relatively inexpensive, and they provide photo-generated holes with high oxidizing power due to their wide band gap energy. In this work, nanostructural ZnO film on the Zn foil of the Alkaline-Manganese Dioxide-Zinc Cell was fabricated to degrade EV dye. The major innovation of this paper is to obtain the degradation mechanism of ethyl violet dyes resulting from the HPLC-PDA-ESI-MS analyses. Results The fabrication of ZnO nanostructures on zinc foils with a simple solution-based corrosion strategy and the synthesis, characterization, application, and implication of Zn would be reported in this study. Other objectives of this research are to identify the reaction intermediates and to understand the detailed degradation mechanism of EV dye, as model compound of triphenylmethane dye, with active Zn metal, by HPLC-ESI-MS and GC-MS. Conclusions ZnO nanostructure/Zn-foils had an excellent potential for future applications on the photocatalytic degradation of the organic dye in the environmental remediation. The intermediates of the degradation process were separated and characterized by the HPLC-PDA-ESI-MS and GC-MS, and twenty-six intermediates were characterized in this study. Based on the variation of the amount of intermediates, possible degradation pathways for the decolorization of dyes are also proposed and discussed. PMID:22748361

GC-MS analysis of clove (Syzygium aromaticum) bud essential oil from Java and Manado

NASA Astrophysics Data System (ADS)

Amelia, B.; Saepudin, E.; Cahyana, A. H.; Rahayu, D. U.; Sulistyoningrum, A. S.; Haib, J.

2017-07-01

The largest clove production contributors in Indonesia are mostly coming from Java and Manado. Different flavor among clove origins is caused by chemical constituents in clove oil. Unfortunately, scientific research and publications about flavor in clove from Indonesia's origin are still limited. The objective of this research is to determine significant differences of constituents in terms of flavor in clove oil originated from Java and Manado. The essential oils were isolated from cut clove bud samples by steam distillation method. The chemical constituents of clove bud oil were analyzed by using gas chromatography-mass spectrometry (GC-MS). Constituents were then identified by comparing the results of the chromatogram and reference retention time using Wiley mass spectra library (Wiley W9N11). Thirty-six and thirty-four chemical constituents were identified based on GC-MS from clove oil collected from Java and Manado, respectively. Major classes of compounds are sesquiterpenes, phenyl propanoid, oxygenated sesquiterpenes, and esters. Different compositions in major constituents were found between both origins. Clove Java contained eugenol (55.60 %), eugenyl acetate (20.54 %), caryophyllene (14.84 %), and α-humulene (2.75 %). While, in clove Manado, the composition were eugenol (74.64 %), caryophyllene (12.79 %), eugenyl acetate (8.70 %), and α-humulene (1.53 %). Moreover, minor constituents β-elemene (0.04 %), α-cadinene (0.05 %) and ledol (0.06 %) were existed only in clove Java, while clove Manado had some unique minor constituents which were not found in clove Java, i.e. β-gurjunene (0.04 %), γ-cadinene %), and humulene oxide (0.05 %). In conclusion, both clove oils from Java and Manado contained same major chemical constituents but different in their composition. In addition, some minor constituents existed only in specific origin.

High-resolution gas chromatography/mas spectrometry method for characterization and quantitative analysis of ginkgolic acids in ginkgo biloba plants, extracts, and dietary supplements

USDA-ARS?s Scientific Manuscript database

A high resolution GC/MS with Selected Ion Monitor (SIM) method focusing on the characterization and quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba L. plant materials, extracts and commercial products was developed and validated. The method involved sample extraction with (1:1) meth...

Characterization of ion processes in a GC/DMS air quality monitor by integration of the instrument to a mass spectrometer.

PubMed

Limero, T F; Nazarov, E G; Menlyadiev, M; Eiceman, G A

2015-02-07

The air quality monitor (AQM), which included a portable gas chromatograph (GC) and a detector was interfaced to a mass spectrometer (MS) by introducing flow from the GC detector to the atmospheric pressure ion source of the MS. This small GC system, with a gas recirculation loop for carrier and detector make-up gases, comprised an inlet to preconcentrate volatile organic compounds (VOCs) in air, a thermal desorber before the GC column, a differential mobility spectrometer (DMS), and another DMS as an atmospheric pressure ionization source for the MS. Return flow to the internally recirculated air system of the AQM's DMS was replenished using purified air. Although ions and unreacted neutral vapors flowed from the detector through Viton® tubing into the source of the MS, ions were not detected in the MS without the auxillary ion source, (63)Ni as in the mobility detector. The GC-DMS-MS instrument provided a 3-D measurement platform (GC, DMS, and MS analysis) to explore the gas composition inside the GC-DMS recirculation loop and provide DMS-MS measurement of the components of a complex VOC mixture with performance significantly enhanced by mass-analysis, either with mass spectral scans or with an extracted ion chromatogram. This combination of a mobility spectrometer and a mass spectrometer was possible as vapors and ions are carried together through the DMS analyzer, thereby preserving the chromatographic separation efficiency. The critical benefit of this instrument concept is that all flows in and through the thoroughly integrated GC-DMS analyzer are kept intact allowing a full measure of the ion and vapor composition in the complete system. Performance has been evaluated using a synthetic air sample and a sample of airborne vapors in a laboratory. Capabilities and performance values are described using results from AQM-MS analysis of purified air, ambient air from a research laboratory in a chemistry building, and a sample of synthetic air of known composition

Supercritical fluid chromatography applied to the highly selective isolation of urinary steroid hormones prior to GC/MS analysis.

PubMed

Doué, Mickael; West, Caroline; Bichon, Emmanuelle; Le Bizec, Bruno; Lesellier, Eric

2018-06-01

To assess the presence of prohibited anabolic substances used to promote growth in livestock, calf urine is the most relevant matrix. However, the sample preparation methods (required to remove unwanted matrix components and fractionate isobaric species that may be unresolved by gas chromatography- mass spectrometry GC/MS) are long and complex. In this context, semi-preparative supercritical fluid chromatography (SFC) was considered to possibly simplify the sample preparation in reducing the number of procedures. Fifteen stationary phases were screened with SFC combined with UV and evaporative light-scattering detection (ELSD), among which two columns (Cosmosil π-NAP and Princeton DIOL) were retained for their ability to isolate steroid hormones from other matrix components and, for the second column, for the additional possibility to fractionate steroid hormones into different families (estrogens, mono-hydroxylated and di-hydroxylated androgens). The fractions were further analysed with GC/MS showing the benefit of class fractionation. The final method allows for significant time, solvent and money savings compared to the previously widely used method (solid-phase extraction combined with semi-preparative high-performance liquid chromatography). Copyright © 2018 Elsevier B.V. All rights reserved.

Odor and odorous chemical emissions from animal buildings: Part 5 - Correlations between odor intensities and chemical concentrations (GC-MS/O)

USDA-ARS?s Scientific Manuscript database

Simultaneous chemical and sensory analysis based on gas chromatography-mass spectrometry-olfactometry (GC-MS-O) of air samples from livestock operations is a very useful approach for quantification of target odorous gases and also for ranking of odorous compounds. This information can help link spec...

GC-MS and LC-MS analysis of nerve agents in body fluids: intra-laboratory verification test using spiked plasma and urine samples.

PubMed

Koller, Marianne; Becker, Christian; Thiermann, Horst; Worek, Franz

2010-05-15

The purpose of this study was to check the applicability of different analytical methods for the identification of unknown nerve agents in human body fluids. Plasma and urine samples were spiked with nerve agents (plasma) or with their metabolites (urine) or were left blank. Seven random samples (35% of all samples) were selected for the verification test. Plasma was worked up for unchanged nerve agents and for regenerated nerve agents after fluoride-induced reactivation of nerve agent-inhibited butyrylcholinesterase. Both extracts were analysed by GC-MS. Metabolites were extracted from plasma and urine, respectively, and were analysed by LC-MS. The urinary metabolites and two blank samples could be identified without further measurements, plasma metabolites and blanks were identified in six of seven samples. The analysis of unchanged nerve agent provided five agents/blanks and the sixth agent after further investigation. The determination of the regenerated agents also provided only five clear findings during the first screening because of a rather noisy baseline. Therefore, the sample preparation was extended by a size exclusion step performed before addition of fluoride which visibly reduced baseline noise and thus improved identification of the two missing agents. The test clearly showed that verification should be performed by analysing more than one biomarker to ensure identification of the agent(s). Copyright (c) 2010 Elsevier B.V. All rights reserved.

OPTIMIZATION OF HIGH-SPEED GC/TOFMS FOR METHOD TO-14 ANALYSIS

EPA Science Inventory

A fast GC/MS system (FGCMS) consisting of a high-speed gas chromatograph equipped with a narrow bandwidth injection accessory and a time-of-flight mass spectrometer detector is being optimized for analysis of Method TO-14 target compounds. The system consists entirely of comm...

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 �

GC and GC-MS characterization of crude oil transformation in sediments and microbial mat samples after the 1991 oil spill in the Saudi Arabian Gulf coast.

PubMed

Garcia de Oteyza, T; Grimalt, J O

2006-02-01

The massive oil discharge in the Saudi Arabian coast at the end of the 1991 Gulf War is used here as a natural experiment to study the ability of microbial mats to transform oil residues after major spills. The degree of oil transformation has been evaluated from the analysis of the aliphatic and aromatic hydrocarbons by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The oil-polluted microbial mat samples from coastal environments exhibited an intermediate degree of transformation between that observed in superficial and deep sediments. Evaporation, photo-oxidation and water-washing seemed to lead to more effective and rapid elimination of hydrocarbons than cyanobacteria and its associated microorganisms. Furthermore, comparison of some compounds (e.g. regular isoprenoid hydrocarbons or alkylnaphthalenes) in the oil collected in the area after the spill or in the mixtures retained by cyanobacterial growth gave rise to an apparent effect of hydrocarbon preservation in the microbial mat ecosystems.

Application of survival analysis methodology to the quantitative analysis of LC-MS proteomics data.

PubMed

Tekwe, Carmen D; Carroll, Raymond J; Dabney, Alan R

2012-08-01

Protein abundance in quantitative proteomics is often based on observed spectral features derived from liquid chromatography mass spectrometry (LC-MS) or LC-MS/MS experiments. Peak intensities are largely non-normal in distribution. Furthermore, LC-MS-based proteomics data frequently have large proportions of missing peak intensities due to censoring mechanisms on low-abundance spectral features. Recognizing that the observed peak intensities detected with the LC-MS method are all positive, skewed and often left-censored, we propose using survival methodology to carry out differential expression analysis of proteins. Various standard statistical techniques including non-parametric tests such as the Kolmogorov-Smirnov and Wilcoxon-Mann-Whitney rank sum tests, and the parametric survival model and accelerated failure time-model with log-normal, log-logistic and Weibull distributions were used to detect any differentially expressed proteins. The statistical operating characteristics of each method are explored using both real and simulated datasets. Survival methods generally have greater statistical power than standard differential expression methods when the proportion of missing protein level data is 5% or more. In particular, the AFT models we consider consistently achieve greater statistical power than standard testing procedures, with the discrepancy widening with increasing missingness in the proportions. The testing procedures discussed in this article can all be performed using readily available software such as R. The R codes are provided as supplemental materials. ctekwe@stat.tamu.edu.

Comprehensive two-dimensional gas chromatography with flame ionization and time-of-flight mass spectrometry detection: qualitative and quantitative analysis of West Australian sandalwood oil.

PubMed

Shellie, Robert; Marriott, Philip; Morrison, Paul

2004-09-01

The use of gas chromatography (GC)-mass spectrometry (MS), GC-time-of-flight MS (TOFMS), comprehensive two-dimensional GC (GCxGC)-flame ionization detection (FID), and GCxGC-TOFMS is discussed for the characterization of the eight important representative components, including Z-alpha-santalol, epi-alpha-bisabolol, Z-alpha-trans-bergamotol, epi-beta-santalol, Z-beta-santalol, E,E-farnesol, Z-nuciferol, and Z-lanceol, in the oil of west Australian sandalwood (Santalum spicatum). Single-column GC-MS lacks the resolving power to separate all of the listed components as pure peaks and allow precise analytical measurement of individual component abundances. With enhanced peak resolution capabilities in GCxGC, these components are sufficiently well resolved to be quantitated using flame ionization detection, following initial characterization of components by using GCxGC-TOFMS.

Discrimination of smokeless powders by headspace SPME-GC-MS and SPME-GC-ECD, and the potential implications upon training canine detection of explosives

NASA Astrophysics Data System (ADS)

Harper, Ross J.; Almirall, Jose R.; Furton, Kenneth G.

2005-05-01

This presentation will provide an odour analysis of a variety of smokeless powders & communicate the rapid SPME-GC-ECD method utilized. This paper will also discuss the implications of the headspace analysis of Smokeless Powders upon the choice of training aids for Explosives Detection Canines. Canine detection of explosives relies upon the dogs" ability to equate finding a given explosive odour with a reward, usually in the form of praise or play. The selection of explosives upon which the dogs are trained thus determines which explosives the canines can and potentially cannot find. Commonly, the training is focussed towards high explosives such as TNT and Composition 4, and the low explosives such as Black and Smokeless Powders are added often only for completeness. Powder explosives constitute a major component of explosive incidents throughout the US, and canines trained to detect explosives must be trained across the entire range of powder products. Given the variability in the manufacture and product make-up many smokeless powders do not share common odour chemicals, giving rise to concerns over the extensiveness of canine training. Headspace analysis of a selection of Smokeless Powders by Solid Phase Microextraction Gas Chromatography using Mass Spectrometry (SPME-GC-MS) and Electron Capture Detectors (SPME-GC-ECD) has highlighted significant differences in the chemical composition of the odour available from different brands. This suggests that greater attention should be paid towards the choice of Powder Explosives when assigning canine training aids.

Composition of dissolved organic matter (DOM) from periodically submerged soils in the Three Gorges Reservoir areas as determined by elemental and optical analysis, infrared spectroscopy, pyrolysis-GC-MS and thermally assisted hydrolysis and methylation.

PubMed

Jiang, Tao; Kaal, Joeri; Liang, Jian; Zhang, Yaoling; Wei, Shiqiang; Wang, Dingyong; Green, Nelson W

2017-12-15

Soil-derived dissolved organic matter (DOM) has a major influence in biogeochemical processes related to contaminant dynamics and greenhouse gas emissions, due to its reactivity and its bridging role between the soil and aquatic systems. Within the Three Gorges Reservoir (TGR, China) area, an extensive water-fluctuation zone periodically submerges the surrounding soils. Here we report a characterization study of soil-derived DOM across the TGR areas, using elemental and optical analysis, infrared spectroscopy (FTIR), pyrolysis-GC-MS (Py-GC-MS) and thermally assisted hydrolysis and methylation (THM-GC-MS). The results showed that the soil DOM from the TGR area is a mixture of "allochthonous" (i.e., plant-derived/terrigenous) and "autochthonous" (i.e., microbial) origins. The terrigenous DOM is composed primarily of phenolic and aliphatic structures from lignin and aliphatic biopolymers (i.e. cutin, suberin), respectively. Multivariate statistics differentiated between two fractions of the microbial DOM, i.e. chitin-derived, perhaps from fungi and arthropods in soil, and protein-derived, partially sourced from algal or aquatic organisms. Molecular proxies of source and degradation state were in good agreement with optical parameters such as SUVA 254 , the fluorescence index (FI) and the humification index (HIX). The combined use of elemental analysis, fluorescence spectroscopy, and Py-GC-MS provides rigorous and detailed DOM characterization, whereas THM-GC-MS is useful for more precise but qualitative identification of the different phenolic (cinnamyl, p-hydroxyphenyl, guaiacyl, syringyl and tannin-derived) and aliphatic materials. With the multi-methodological approach used in this study, FTIR was the least informative, in part, because of the interference of inorganic matter in the soil DOM samples. The soil DOM from the TGR's water fluctuation zone exhibited considerable compositional diversity, mainly related to the balance between DOM source (microbial- or

Evaluation of petroleum heterogeneities in the Eldfish Chalk reservoir using thermal extraction and pyrolysis GC and thermal extraction GC-MS

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

Hall, P.B.; Bjory, M.; Stoddart, D.

1993-09-01

Petroleum geochemical research is being applied more and more to production-oriented problems such as improving recovery of oil from existing fields and identifying satellite fields. Recent studies by ourselves and others have suggested that compositional heterogeneities within the petroleum column of reservoirs can provide information relevant to these objectives. Some of the best data for distinguishing petroleum [open quotes]populations[close quotes] in reservoirs comes from conventional geochemical techniques, some of which are very time consuming (e.g., solvent extraction, EOM fractionation, and GC and GC-MS of saturated and aromatic hydrocarbon fractions). Furthermore, a large number of samples need to be analyzed onmore » order to detect the often slight heterogeneities present in a reservoir. The techniques employed in this study (particularly thermal extraction and pyrolysis GC and thermal extraction GC-MS) can be used to generate large amounts of relevant data quickly. In this study, data were acquired on core samples ([approximately]750) from the Paleocene/Cretaceous Eldfish Chalk reservoir (2/7 block Norwegian North Sea). The acquired data reveal distinct maturity gradients and also small, but still significant, variations in source of the oil within the different Eldfisk oil pools (Alpha, Bravo, and East). This indicates incomplete mixing of the hydrocarbons. These variations have been used to delineate lateral and vertical barriers to petroleum mixing. These observations, when integrated with geological data, can lead to an improved understanding of the possible field filling directions and the intrareservoir compartmentalization. The conclusions from this may also aid in exploration for satellite fields as well as influencing the production plan for the Eldfisk field.« less

Natural isotope correction of MS/MS measurements for metabolomics and (13)C fluxomics.

PubMed

Niedenführ, Sebastian; ten Pierick, Angela; van Dam, Patricia T N; Suarez-Mendez, Camilo A; Nöh, Katharina; Wahl, S Aljoscha

2016-05-01

Fluxomics and metabolomics are crucial tools for metabolic engineering and biomedical analysis to determine the in vivo cellular state. Especially, the application of (13)C isotopes allows comprehensive insights into the functional operation of cellular metabolism. Compared to single MS, tandem mass spectrometry (MS/MS) provides more detailed and accurate measurements of the metabolite enrichment patterns (tandem mass isotopomers), increasing the accuracy of metabolite concentration measurements and metabolic flux estimation. MS-type data from isotope labeling experiments is biased by naturally occurring stable isotopes (C, H, N, O, etc.). In particular, GC-MS(/MS) requires derivatization for the usually non-volatile intracellular metabolites introducing additional natural isotopes leading to measurements that do not directly represent the carbon labeling distribution. To make full use of LC- and GC-MS/MS mass isotopomer measurements, the influence of natural isotopes has to be eliminated (corrected). Our correction approach is analyzed for the two most common applications; (13)C fluxomics and isotope dilution mass spectrometry (IDMS) based metabolomics. Natural isotopes can have an impact on the calculated flux distribution which strongly depends on the substrate labeling and the actual flux distribution. Second, we show that in IDMS based metabolomics natural isotopes lead to underestimated concentrations that can and should be corrected with a nonlinear calibration. Our simulations indicate that the correction for natural abundance in isotope based fluxomics and quantitative metabolomics is essential for correct data interpretation. © 2015 Wiley Periodicals, Inc.

Analysis of Endocrine Disrupting Pesticides by Capillary GC with Mass Spectrometric Detection

PubMed Central

Matisová, Eva; Hrouzková, Svetlana

2012-01-01

Endocrine disrupting chemicals, among them many pesticides, alter the normal functioning of the endocrine system of both wildlife and humans at very low concentration levels. Therefore, the importance of method development for their analysis in food and the environment is increasing. This also covers contributions in the field of ultra-trace analysis of multicomponent mixtures of organic pollutants in complex matrices. With this fact conventional capillary gas chromatography (CGC) and fast CGC with mass spectrometric detection (MS) has acquired a real importance in the analysis of endocrine disrupting pesticide (EDP) residues. This paper provides an overview of GC methods, including sample preparation steps, for analysis of EDPs in a variety of matrices at ultra-trace concentration levels. Emphasis is put on separation method, mode of MS detection and ionization and obtained limits of detection and quantification. Analysis time is one of the most important aspects that should be considered in the choice of analytical methods for routine analysis. Therefore, the benefits of developed fast GC methods are important. PMID:23202677

Determination and production of antimicrobial compounds by Aspergillus clavatonanicus strain MJ31, an endophytic fungus from Mirabilis jalapa L. using UPLC-ESI-MS/MS and TD-GC-MS analysis

PubMed Central

Mishra, Vineet Kumar; Passari, Ajit Kumar; Chandra, Preeti; Leo, Vincent Vineeth; Kumar, Brijesh; Uthandi, Sivakumar; Thankappan, Sugitha; Gupta, Vijai Kumar

2017-01-01

Endophytic fungi associated with medicinal plants are reported as potent producers of diverse classes of secondary metabolites. In the present study, an endophytic fungi, Aspergillus clavatonanicus strain MJ31, exhibiting significant antimicrobial activity was isolated from roots of Mirabilis jalapa L., was identified by sequencing three nuclear genes i.e. internal transcribed spacers ribosomal RNA (ITS rRNA), 28S ribosomal RNA (28S rRNA) and translation elongation factor 1- alpha (EF 1α). Ethyl acetate extract of strain MJ31displayed significant antimicrobial potential against Bacillus subtilis, followed by Micrococccus luteus and Staphylococcus aureus with minimum inhibitory concentrations (MIC) of 0.078, 0.156 and 0.312 mg/ml respectively. In addition, the strain was evaluated for its ability to synthesize bioactive compounds by the amplification of polyketide synthase (PKS) and non ribosomal peptide synthetase (NRPS) genes. Further, seven antibiotics (miconazole, ketoconazole, fluconazole, ampicillin, streptomycin, chloramphenicol, and rifampicin) were detected and quantified using UPLC-ESI-MS/MS. Additionally, thermal desorption-gas chromatography mass spectrometry (TD-GC-MS) analysis of strain MJ31 showed the presence of 28 volatile compounds. This is the first report on A. clavatonanicus as an endophyte obtained from M. jalapa. We conclude that A. clavatonanicus strain MJ31 has prolific antimicrobial potential against both plant and human pathogens and can be exploited for the discovery of new antimicrobial compounds and could be an alternate source for the production of secondary metabolites. PMID:29049321

Determination and production of antimicrobial compounds by Aspergillus clavatonanicus strain MJ31, an endophytic fungus from Mirabilis jalapa L. using UPLC-ESI-MS/MS and TD-GC-MS analysis.

PubMed

Mishra, Vineet Kumar; Passari, Ajit Kumar; Chandra, Preeti; Leo, Vincent Vineeth; Kumar, Brijesh; Uthandi, Sivakumar; Thankappan, Sugitha; Gupta, Vijai Kumar; Singh, Bhim Pratap

2017-01-01

Endophytic fungi associated with medicinal plants are reported as potent producers of diverse classes of secondary metabolites. In the present study, an endophytic fungi, Aspergillus clavatonanicus strain MJ31, exhibiting significant antimicrobial activity was isolated from roots of Mirabilis jalapa L., was identified by sequencing three nuclear genes i.e. internal transcribed spacers ribosomal RNA (ITS rRNA), 28S ribosomal RNA (28S rRNA) and translation elongation factor 1- alpha (EF 1α). Ethyl acetate extract of strain MJ31displayed significant antimicrobial potential against Bacillus subtilis, followed by Micrococccus luteus and Staphylococcus aureus with minimum inhibitory concentrations (MIC) of 0.078, 0.156 and 0.312 mg/ml respectively. In addition, the strain was evaluated for its ability to synthesize bioactive compounds by the amplification of polyketide synthase (PKS) and non ribosomal peptide synthetase (NRPS) genes. Further, seven antibiotics (miconazole, ketoconazole, fluconazole, ampicillin, streptomycin, chloramphenicol, and rifampicin) were detected and quantified using UPLC-ESI-MS/MS. Additionally, thermal desorption-gas chromatography mass spectrometry (TD-GC-MS) analysis of strain MJ31 showed the presence of 28 volatile compounds. This is the first report on A. clavatonanicus as an endophyte obtained from M. jalapa. We conclude that A. clavatonanicus strain MJ31 has prolific antimicrobial potential against both plant and human pathogens and can be exploited for the discovery of new antimicrobial compounds and could be an alternate source for the production of secondary metabolites.

Non-targeted analysis of petroleum metabolites in groundwater using GC×GC-TOFMS.

PubMed

Mohler, Rachel E; O'Reilly, Kirk T; Zemo, Dawn A; Tiwary, Asheesh K; Magaw, Renae I; Synowiec, Karen A

2013-09-17

Groundwater at fuel release sites often contains nonpolar hydrocarbons that originate from both the fuel release and other environmental sources, as well as polar metabolites of petroleum biodegradation. These compounds, along with other polar artifacts, can be quantified as "total petroleum hydrocarbons" using USEPA Methods 3510/8015B, unless a silica gel cleanup step is used to separate nonpolar hydrocarbons from polar compounds prior to analysis. Only a limited number of these metabolites have been identified by traditional GC-MS methods, because they are difficult to resolve using single-column configurations. Additionally, the targeted use of derivatization limits the detection of many potential metabolites of interest. The objective of this research was to develop a nontargeted GC×GC-TOFMS approach to characterize petroleum metabolites in environmental samples gathered from fuel release sites. The method tentatively identified more than 760 unique polar compounds, including acids/esters, alcohols, phenols, ketones, and aldehydes, from 22 groundwater samples collected at five sites. Standards for 28 polar compounds indicate that effective limits of quantitation for most of these compounds in the groundwater samples range from 1 to 11 μg/L.

Validation of a GC-MS/MS method for simultaneous determination of 86 persistent organic pollutants in marine sediments by pressurized liquid extraction followed by stir bar sorptive extraction.

PubMed

Camino-Sánchez, F J; Zafra-Gómez, Alberto; Pérez-Trujillo, J P; Conde-González, J E; Marques, J C; Vílchez, José Luis

2011-08-01

A multiresidue method for the analysis of 86 persistent pollutants in marine sediments at ultra-trace level has been developed and validated using pressurized liquid extraction (PLE) and stir-bar sorptive extraction (SBSE) coupled with thermal desorption and gas chromatography-triple quadrupole mass spectrometry (TD-GC-MS/MS QqQ). The compounds analyzed belong to various families such as polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polybrominated diphenylethers, organophosphorus and organochlorine pesticides and other pesticides such as urons, and triazines. The analytes have very different polarities and log K(ow) values, which is an important parameter in the optimization of a SBSE method. Due to PLE high efficiency and throughput rates, along with the proven ability for multiresidue analysis and excellent sensitivity of SBSE, we present an efficient method. The limits of quantification obtained ranged from 0.014 to 1.0 ng g(-1), with detection limits below pg g(-1) levels. In order to validate the proposed methodology, quality parameters such as recovery, linearity and reproducibility were studied. Recoveries ranged from 63% to 119%, reproducibility (in terms of Relative Standard Deviation for ten determinations) was lower than 35% in all cases, and determination coefficients higher than 0.990 for all analytes. The main factors that affect PLE, SBSE and GC-MS/MS procedures were optimized. The method was applied to the analysis of nine marine sediments obtained from the nine main submarine wastewater discharge points (emissaries) presents along the coast of Tenerife Island (Canary Islands, Spain). Copyright © 2011 Elsevier Ltd. All rights reserved.

Quantitation of intracellular purine intermediates in different Corynebacteria using electrospray LC-MS/MS.

PubMed

Peifer, Susanne; Schneider, Konstantin; Nürenberg, Gudrun; Volmer, Dietrich A; Heinzle, Elmar

2012-11-01

Intermediates of the purine biosynthesis pathway play key roles in cellular metabolism including nucleic acid synthesis and signal mediation. In addition, they are also of major interest to the biotechnological industry as several intermediates either possess flavor-enhancing characteristics or are applied in medical therapy. In this study, we have developed an analytical method for quantitation of 12 intermediates from the purine biosynthesis pathway including important nucleotides and their corresponding nucleosides and nucleobases. The approach comprised a single-step acidic extraction/quenching procedure, followed by quantitative electrospray LC-MS/MS analysis. The assay was validated in terms of accuracy, precision, reproducibility, and applicability for complex biological matrices. The method was subsequently applied for determination of free intracellular pool sizes of purine biosynthetic pathway intermediates in the two Gram-positive bacteria Corynebacterium glutamicum and Corynebacterium ammoniagenes. Importantly, no ion pair reagents were applied in this approach as usually required for liquid chromatography analysis of large classes of diverse metabolites.

Systematic assessment of survey scan and MS2-based abundance strategies for label-free quantitative proteomics using high-resolution MS data.

PubMed

Tu, Chengjian; Li, Jun; Sheng, Quanhu; Zhang, Ming; Qu, Jun

2014-04-04

Survey-scan-based label-free method have shown no compelling benefit over fragment ion (MS2)-based approaches when low-resolution mass spectrometry (MS) was used, the growing prevalence of high-resolution analyzers may have changed the game. This necessitates an updated, comparative investigation of these approaches for data acquired by high-resolution MS. Here, we compared survey scan-based (ion current, IC) and MS2-based abundance features including spectral-count (SpC) and MS2 total-ion-current (MS2-TIC), for quantitative analysis using various high-resolution LC/MS data sets. Key discoveries include: (i) study with seven different biological data sets revealed only IC achieved high reproducibility for lower-abundance proteins; (ii) evaluation with 5-replicate analyses of a yeast sample showed IC provided much higher quantitative precision and lower missing data; (iii) IC, SpC, and MS2-TIC all showed good quantitative linearity (R(2) > 0.99) over a >1000-fold concentration range; (iv) both MS2-TIC and IC showed good linear response to various protein loading amounts but not SpC; (v) quantification using a well-characterized CPTAC data set showed that IC exhibited markedly higher quantitative accuracy, higher sensitivity, and lower false-positives/false-negatives than both SpC and MS2-TIC. Therefore, IC achieved an overall superior performance than the MS2-based strategies in terms of reproducibility, missing data, quantitative dynamic range, quantitative accuracy, and biomarker discovery.

Systematic Assessment of Survey Scan and MS2-Based Abundance Strategies for Label-Free Quantitative Proteomics Using High-Resolution MS Data

PubMed Central

2015-01-01

Survey-scan-based label-free method have shown no compelling benefit over fragment ion (MS2)-based approaches when low-resolution mass spectrometry (MS) was used, the growing prevalence of high-resolution analyzers may have changed the game. This necessitates an updated, comparative investigation of these approaches for data acquired by high-resolution MS. Here, we compared survey scan-based (ion current, IC) and MS2-based abundance features including spectral-count (SpC) and MS2 total-ion-current (MS2-TIC), for quantitative analysis using various high-resolution LC/MS data sets. Key discoveries include: (i) study with seven different biological data sets revealed only IC achieved high reproducibility for lower-abundance proteins; (ii) evaluation with 5-replicate analyses of a yeast sample showed IC provided much higher quantitative precision and lower missing data; (iii) IC, SpC, and MS2-TIC all showed good quantitative linearity (R2 > 0.99) over a >1000-fold concentration range; (iv) both MS2-TIC and IC showed good linear response to various protein loading amounts but not SpC; (v) quantification using a well-characterized CPTAC data set showed that IC exhibited markedly higher quantitative accuracy, higher sensitivity, and lower false-positives/false-negatives than both SpC and MS2-TIC. Therefore, IC achieved an overall superior performance than the MS2-based strategies in terms of reproducibility, missing data, quantitative dynamic range, quantitative accuracy, and biomarker discovery. PMID:24635752

GC-MS analysis and gastroprotective evaluations of crude extracts, isolated saponins and essential oil from Polygonum hydropiper L.

NASA Astrophysics Data System (ADS)

Ayaz, Muhammad; Junaid, Muhammad; Ullah, Farhat; Sadiq, Abdul; Shahid, Muhammad; Ahmad, Waqar; Ullah, Ihsan; Ahmad, Ashfaq; Syed, Nawazish-i.-Husain

2017-08-01

Peptic ulceration is among the most prevalent gastrointestinal disorders characterized by pepsin and gastric acid mediated mucosal damage, as result of imbalance between defensive and offensive processes. The main objective of the current study was to investigate the antiulcer potentials of Polygonum hydropiper crude methanolic ectract (Ph.Cr) in aspirin induced ulcerogenesis using pylorus ligated rat model. In-vitro urease and Proteus mirabilis inhibitory potentials were evaluated using standard protocols. All fractions were analyzed using GC-MS to identify major components. The aspirin induced ulcerogenesis in pylorus ligated rat model was associated with significant changes in the mean ulcer score (F5,30 = 7.141, P = 0.0002), gastric juice volume (F5,30 = 8.245, P < 0.0001), gastric juice pH (F5,30 = 5.715, P = 0.0008), free acidity (F5,30 = 4.544, P = 0.0033), total acidity (F5,30 = 2.740, P = 0.0373) and pepsin concentration (F5,30 = 2.335, P = 0.0664). Pre treatment with Ph.Cr at 100, 200 and 400 mg/kg dose exhibited marked gastroprotective and anti-ulcerogenic effect in the aspirin induced pyloric ligation ulcerogenesis model at 100, 200 and 400 mg/kg as indicated by ulcerative biochemical parameters. In urease inhibition assay, leaves essential oil (Ph.Lo), saponins (Ph.Sp) and chloroform extract (Ph.Chf) exhibited highest activities with IC50 of 90, 98 and 520 µg/ml respectively. Ph.Sp, Ph.Chf, ethyl acetate (Ph.EtAc) and Ph.Cr showed MICs of 25, 30, 32.25 and 40.50 µg/ml respectively against Proteus mirabilis. Several compounds were identified in GC-MS analysis of samples. Significant in-vivo antiulcer, urease inhibitory as well as anti-proteus potentials of P. hydropiper solvent extracts, signify its potential use for the management of peptic ulcers and may provide scientific bases for the traditional uses of the plant.

Dereplication of pentacyclic triterpenoids in plants by GC-EI/MS.

PubMed

Gu, Jian-Qiao; Wang, Yuehong; Franzblau, Scott G; Montenegro, Gloria; Timmermann, Barbara N

2006-01-01

Three common plant-derived pentacyclic triterpenoids, oleanolic acid (1), betulinic acid (2) and ursolic acid (3), have been found to exhibit moderate anti-tubercular activity in a microplate alamar blue assay. In order to facilitate the discovery of novel anti-tubercular leads with diverse chemical structures, a new and rapid GC-EI/MS method was developed simultaneously and unambiguously to dereplicate 1-3 as their methyl esters with limits of detection of 25.6, 26.9 and 26.8 ng, respectively.

Pushing quantitation limits in micro UHPLC-MS/MS analysis of steroid hormones by sample dilution using high volume injection.

PubMed

Márta, Zoltán; Bobály, Balázs; Fekete, Jenő; Magda, Balázs; Imre, Tímea; Mészáros, Katalin Viola; Szabó, Pál Tamás

2016-09-10

Ultratrace analysis of sample components requires excellent analytical performance in terms of limits of quantitation (LoQ). Micro UHPLC coupling with sensitive tandem mass spectrometry provides state of the art solutions for such analytical problems. Decreased column volume in micro LC limits the injectable sample volume. However, if analyte concentration is extremely low, it might be necessary to inject high sample volumes. This is particularly critical for strong sample solvents and weakly retained analytes, which are often the case when preparing biological samples (protein precipitation, sample extraction, etc.). In that case, high injection volumes may cause band broadening, peak distortion or even elution in dead volume. In this study, we evaluated possibilities of high volume injection onto microbore RP-LC columns, when sample solvent is diluted. The presented micro RP-LC-MS/MS method was optimized for the analysis of steroid hormones from human plasma after protein precipitation with organic solvents. A proper sample dilution procedure helps to increase the injection volume without compromising peak shapes. Finally, due to increased injection volume, the limit of quantitation can be decreased by a factor of 2-5, depending on the analytes and the experimental conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Quality profile determination of Chios mastic gum essential oil and detection of adulteration in mastic oil products with the application of chiral and non-chiral GC-MS analysis.

PubMed

Paraschos, Sotirios; Magiatis, Prokopios; Gikas, Evagelos; Smyrnioudis, Ilias; Skaltsounis, Alexios-Leandros

2016-10-01

The determination of mastic oil profile, with emphasis on its chiral characteristics, could serve as a method for detecting adulteration in products found in the market with a claim of mastic oil content aiming towards protecting it from counterfeiting. Furthermore the evaluation of the raw material is crucial, as the profile is potentially affected by factors as mastic origin and storage time. Thus 45 authentic mastic oil samples were analyzed by GC-MS employing a chiral column and content limits for all major constituents were determined. The chiral GC-MS analysis proved that selected concentration ratios between these constituents, namely those of (-)/(+)-α-pinene (≤1:100) and (-)-α-pinene/myrcene (1.9:100-11:100) could serve as markers for the determination of mastic oil authenticity. Employing this methodology, the analysis of 25 mastic oils contained in cosmetic and dietary products, as well as an artificial mastic oil sample, exhibited several differentiations that could indicate adulteration either with artificial essential oils or volatile compounds, or the use of aged mastic oil. Copyright © 2016 Elsevier B.V. All rights reserved.

Antidepressants detection and quantification in whole blood samples by GC-MS/MS, for forensic purposes.

PubMed

Truta, Liliana; Castro, André L; Tarelho, Sónia; Costa, Pedro; Sales, M Goreti F; Teixeira, Helena M

2016-09-05

Depression is among the most prevalent psychiatric disorders of our society, leading to an increase in antidepressant drug consumption that needs to be accurately determined in whole blood samples in Forensic Toxicology Laboratories. For this purpose, this work presents a new gas chromatography tandem mass spectrometry (GC-MS/MS) method targeting the simultaneous and rapid determination of 14 common Antidepressants in whole blood: 13 Antidepressants (amitriptyline, citalopram, clomipramine, dothiepin, fluoxetine, imipramine, mianserin, mirtazapine, nortryptiline, paroxetine, sertraline, trimipramine and venlafaxine) and 1 Metabolite (N-desmethylclomipramine). Solid-phase extraction was used prior to chromatographic separation. Chromatographic and MS/MS parameters were selected to improve sensitivity, peak resolution and unequivocal identification of the eluted analyte. The detection was performed on a triple quadrupole tandem MS in selected ion monitoring (SIM) mode in tandem, using electronic impact ionization. Clomipramine-D3 and trimipramine-D3 were used as deutered internal standards. The validation parameters included linearity, limits of detection, lower limit of quantification, selectivity/specificity, extraction efficiency, carry-over, precision and robustness, and followed internationally accepted guidelines. Limits of quantification and detection were lower than therapeutic and sub-therapeutic concentration ranges. Overall, the method offered good selectivity, robustness and quick response (<16min) for typical concentration ranges, both for therapeutic and lethal levels. Copyright © 2016 Elsevier B.V. All rights reserved.

Pistachio oil (Pistacia vera L. cv. Uzun): Characterization of key odorants in a representative aromatic extract by GC-MS-olfactometry and phenolic profile by LC-ESI-MS/MS.

PubMed

Sonmezdag, Ahmet Salih; Kelebek, Hasim; Selli, Serkan

2018-02-01

Volatile, aroma-active, and phenolic compounds of pistachio oil obtained from cv. Uzun were investigated in the current study. To obtain a representative aromatic extract, three of the most widely used extraction methods were compared using a representative test; the solvent-assisted flavour extraction (SAFE) aromatic extract from pistachio oil was found to be the most representative. A total of 50 aroma compounds were determined in pistachio oil and it was found that terpenes, aldehydes, and alcohols were the most abundant volatile compounds. Applying GC-MS-olfactometry and aroma extract dilution analysis (AEDA) resulted in a total of 14 aroma-active areas being detected in the extract of pistachio oil. In the phenolic fraction obtained by the LC-ESI-MS/MS method, a total of 12 phenolic compounds was found in the pistachio oil, of which seven compounds were reported for the first time. Eriodictyol-7-O-glucoside and protocatechuic acid were the most dominant phenolic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel assay of DGAT activity based on high temperature GC/MS of triacylglycerol.

PubMed

Greer, Michael S; Zhou, Ting; Weselake, Randall J

2014-08-01

Diacylglycerol acyltransferase (DGAT) catalyzes the final step in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG), a high-energy compound composed of three fatty acids esterified to a glycerol backbone. In vitro DGAT assays, which are usually conducted with radiolabeled substrate using microsomal fractions, have been useful in identifying compounds and genetic modifications that affect DGAT activity. Here, we describe a high-temperature gas chromatography (GC)/mass spectrometry (MS)-based method for monitoring molecular species of TAG produced by the catalytic action of microsomal DGAT. This method circumvents the need for radiolabeled or modified substrates, and only requires a simple lipid extraction prior to GC. The utility of the method is demonstrated using a recombinant type-1 Brassica napus DGAT produced in a strain of Saccharomyces cerevisae that is deficient in TAG synthesis. The GC/MS-based assay of DGAT activity was strongly correlated with the typical in vitro assay of the enzyme using [1-(14)C] acyl-CoA as an acyl donor. In addition to determining DGAT activity, the method is also useful for determining substrate specificity and selectivity properties of the enzyme.

MetaQuant: a tool for the automatic quantification of GC/MS-based metabolome data.

PubMed

Bunk, Boyke; Kucklick, Martin; Jonas, Rochus; Münch, Richard; Schobert, Max; Jahn, Dieter; Hiller, Karsten

2006-12-01

MetaQuant is a Java-based program for the automatic and accurate quantification of GC/MS-based metabolome data. In contrast to other programs MetaQuant is able to quantify hundreds of substances simultaneously with minimal manual intervention. The integration of a self-acting calibration function allows the parallel and fast calibration for several metabolites simultaneously. Finally, MetaQuant is able to import GC/MS data in the common NetCDF format and to export the results of the quantification into Systems Biology Markup Language (SBML), Comma Separated Values (CSV) or Microsoft Excel (XLS) format. MetaQuant is written in Java and is available under an open source license. Precompiled packages for the installation on Windows or Linux operating systems are freely available for download. The source code as well as the installation packages are available at http://bioinformatics.org/metaquant

Separation and Identification of a Mixture of Group 6 Transition-Metal Carbonyl Compounds Using GC-MS in the General Chemistry Curriculum

ERIC Educational Resources Information Center

Fong, Lawrence K.

2004-01-01

Students in the general chemistry course are advised to scrutinize data obtained by gas chromatograph (GC) for segregation, and mass spectroscopy (MS) for recognizing combination of group 6 transition-metal carbonyl compounds. The GC-MS method arouses students' interest, as it can be applied to real-world situations, such as the routine…

An analytical approach based on ESI-MS, LC-MS and PCA for the quali-quantitative analysis of cycloartane derivatives in Astragalus spp.

PubMed

Napolitano, Assunta; Akay, Seref; Mari, Angela; Bedir, Erdal; Pizza, Cosimo; Piacente, Sonia

2013-11-01

Astragalus species are widely used as health foods and dietary supplements, as well as drugs in traditional medicine. To rapidly evaluate metabolite similarities and differences among the EtOH extracts of the roots of eight commercial Astragalus spp., an approach based on direct analyses by ESI-MS followed by PCA of ESI-MS data, was carried out. Successively, quali-quantitative analyses of cycloartane derivatives in the eight Astragalus spp. by LC-ESI-MS(n) and PCA of LC-ESI-MS data were performed. This approach allowed to promptly highlighting metabolite similarities and differences among the various Astragalus spp. PCA results from LC-ESI-MS data of Astragalus samples were in reasonable agreement with both PCA results of ESI-MS data and quantitative results. This study affords an analytical method for the quali-quantitative determination of cycloartane derivatives in herbal preparations used as health and food supplements. Copyright © 2013 Elsevier B.V. All rights reserved.

Quantitative analysis of UV-A shock and short term stress using iTRAQ, pseudo selective reaction monitoring (pSRM) and GC-MS based metabolite analysis of the cyanobacterium Nostoc punctiforme ATCC 29133.

PubMed

Wase, Nishikant; Pham, Trong Khoa; Ow, Saw Yen; Wright, Phillip C

2014-09-23

A quantitative proteomics and metabolomics analysis was performed using iTRAQ, HPLC and GC-MS in the filamentous cyanobacterium Nostoc punctiforme ATCC 29133 to understand the effect of short and long term UV-A exposure. Changes in the proteome were measured for short-term stress (4-24h) using iTRAQ. Changes in the photosynthetic pigments and intracellular metabolites were observed at exposures of up to 7days (pigments) and up to 11days (intracellular metabolites). To assess iTRAQ measurement quality, pseudo selected reaction monitoring (pSRM) was used, with this confirming underestimation of protein abundance levels by iTRAQ. Our results suggest that short term UV-A radiation lowers the abundance of PS-I and PS-II proteins. We also observed an increase in abundance of intracellular redox homeostasis proteins and plastocyanin. Additionally, we observed statistically significant changes in scytonemin, Chlorophyll A, astaxanthin, zeaxanthin, and β-carotene. Assessment of intracellular metabolites showed significant changes in several, suggesting their potential role in the Nostoc's stress mitigation strategy. Cyanobacteria under UV-A radiation have reduced growth due to intensive damage to essential functions, but the organism shows a defense response by remodeling bioenergetics pathway, induction of the UV protection compound scytonemin and increased levels of proline and tyrosine as a mitigation response. The effect of UV-A radiation on the proteome and intracellular metabolites of N. punctiforme ATCC 29133 including photosynthetic pigments has been described. We also verify the expression of 13 iTRAQ quantified protein using LC-pSRM. Overall we observed that UV-A radiation has a drastic effect on the photosynthetic machinery, photosynthetic pigments and intracellular amino acids. As a mitigation strategy against UV-A radiation, proline, glycine, and tyrosine were accumulated. Copyright © 2014. Published by Elsevier B.V.

Isotope dilution-GC-MS/MS analysis of 16 polycyclic aromatic hydrocarbons in selected medicinal herbs used as health food additives.

PubMed

Yu, L; Cao, Y; Zhang, J; Cui, Z; Sun, H

2012-01-01

Medicinal herbs have a very important role in health protection and disease control, and have been used in health foods. Polycyclic aromatic hydrocarbons (PAHs) have carcinogenic, biological and mutagenic effects. In this paper, the content of 16 PAHs as representative contaminants in nine Chinese medicinal herbs, as additives for health foods, was investigated in order to ensure food safety from this source. A highly sensitive isotope dilution-gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method combined with gel permeation chromatography (GPC) and solid-phase extraction (SPE) was developed. Calibration curves showed good linearity for all PAHs (R² > 0.999), and the limit of quantification (LOQ) ranged from 0.42 to 2.7 µg kg⁻¹. Average recoveries for these compounds were in the range of 52.5-117%, 52.6-119% and 81.4-108% at the concentrations of 10, 50 and 250 µg kg⁻¹ with RSD of 1.8-15%, 0.9-15% and 1.0-15%, respectively. The proposed method was used for the analysis of nine Chinese medicinal herbs. Total levels of PAHs varied from 98.2 µg kg⁻¹ (cassia seed) to 2245 µg kg⁻¹ (eucommia bark). The highest level was found for phenanthrene (Phe) in liquorice root (631.3 µg kg⁻¹), indigowoad leaf (551.0 µg kg⁻¹), rose flower (435.2 µg kg⁻¹) and eucommia bark (432.3 µg kg⁻¹). The proposed method could provide a useful basis for safety monitoring of herbs and risk management for PAHs in the health food industry.

Chromatographic Characterization and GC-MS Evaluation of the Bioactive Constituents with Antimicrobial Potential from the Pigmented Ink of Loligo duvauceli

PubMed Central

Girija, Smiline; Duraipandiyan, Veeramuthu; Kuppusamy, Pandi Suba; Gajendran, Hariprasad; Rajagopal, Raghuraman

2014-01-01

Chromatographic characterization and the GC-MS evaluation of the black pigmented ink of Loligo duvauceli in the present study have yielded an array of bioactive compounds with potent antimicrobial property. Facing an alarm of antimicrobial resistance globally, a need for elucidating antimicrobial agents from natural sources will be the need for the hour. In this view, this study is aimed at characterizing the black pigmented ink of the Indian squid L. duvauceli. The squid ink was subjected to crude solvent extraction and was fractionated by silica gel column chromatography. TLC and HPTLC profiles were recorded. Antimicrobial bioassay of the squid ink fractions was done by agar well diffusion method. The antimicrobial fraction was then characterized using GC-MS analysis. The results showed that the n-hexane extract upon column fractionation yielded a total of 8 fractions with the mobile phase of Hex/EtOAc in different gradients. TLC and HPTLC profiles showed a single spot with a retention factor of 0.76. Fraction 1 showed significant antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Lactobacillus acidophilus and a promising antifungal activity against Candida albicans. The antimicrobial fraction upon GC-MS analysis of bis(2-ethylhexyl) phthalate (BEHP) possesses the highest percentage of area normalisation (91%) with other few minor constituents. The study is concluded by stating that the antimicrobial efficacy of the squid ink might be due to the synergistic effects of the phthalate derivative and the other minor volatile compounds analysed in the squid ink. PMID:27437466

Chromatographic Characterization and GC-MS Evaluation of the Bioactive Constituents with Antimicrobial Potential from the Pigmented Ink of Loligo duvauceli.

PubMed

Girija, Smiline; Duraipandiyan, Veeramuthu; Kuppusamy, Pandi Suba; Gajendran, Hariprasad; Rajagopal, Raghuraman

2014-01-01

Chromatographic characterization and the GC-MS evaluation of the black pigmented ink of Loligo duvauceli in the present study have yielded an array of bioactive compounds with potent antimicrobial property. Facing an alarm of antimicrobial resistance globally, a need for elucidating antimicrobial agents from natural sources will be the need for the hour. In this view, this study is aimed at characterizing the black pigmented ink of the Indian squid L. duvauceli. The squid ink was subjected to crude solvent extraction and was fractionated by silica gel column chromatography. TLC and HPTLC profiles were recorded. Antimicrobial bioassay of the squid ink fractions was done by agar well diffusion method. The antimicrobial fraction was then characterized using GC-MS analysis. The results showed that the n-hexane extract upon column fractionation yielded a total of 8 fractions with the mobile phase of Hex/EtOAc in different gradients. TLC and HPTLC profiles showed a single spot with a retention factor of 0.76. Fraction 1 showed significant antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Lactobacillus acidophilus and a promising antifungal activity against Candida albicans. The antimicrobial fraction upon GC-MS analysis of bis(2-ethylhexyl) phthalate (BEHP) possesses the highest percentage of area normalisation (91%) with other few minor constituents. The study is concluded by stating that the antimicrobial efficacy of the squid ink might be due to the synergistic effects of the phthalate derivative and the other minor volatile compounds analysed in the squid ink.

Development of a GC-MS-SPME Method for the Determination of Amines in Meteorites

NASA Astrophysics Data System (ADS)

Hilts, R. W.; Skelhorne, A. W.; Simkus, D.; Herd, C. D. K.

2016-08-01

A GC-MS-SPME analytical method for the direct determination of amines in aqueous solution has been developed. The key step in the procedure is the conversion of the amines into their non-volatile ammonium salts by protonation with HCl.

Modified Method for Detection of Benzoylecgonine in Human Urine by GC-MS: Derivatization Using Pentafluoropropanol/Acetic Anhydride.

PubMed

Serafin, Michelle C; Paulemon, Kasandra M; Fuller, Zachary J; Bronner, William E

2017-05-01

An existing GC-MS method for detecting benzoylecgonine (BZE) in urine was modified by changing derivatizing reagents. This method modification presents a cost-effective alternative derivatization procedure for the detection of BZE in urine by GC-MS. The combination of pentafluoropropanol and acetic anhydride was found to produce the same reaction product for BZE as pentafluoropropanol with pentafluoropropionic anhydride, while reducing reagent cost. With no anhydride present, derivatization of BZE by pentafluoropropanol did not occur. Published by Oxford University Press 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Application of Gas Chromatography-Tandem Mass Spectrometry (GC/MS/MS) for the Analysis of Deuterium Enrichment of Water

PubMed Central

Walker, Dillon K.; Thaden, John J.; Deutz, Nicolaas E.P.

2015-01-01

Incorporation of deuterium from deuterium oxide (2H2O) into biological components is a commonly used approach in metabolic studies. Determining the dilution of deuterium in the body water pool (BW) can be used to estimate body composition. We describe three sensitive GC-MS/MS methods to measure water enrichment in BW . Samples were reacted with NaOH and U-13C3-acetone in an autosampler vial to promote deuterium exchange with U-13C3-acetone hydrogens. Headspace injections were made of U-13C3-acetone-saturated air onto a 30m DB-1MS column in EI-mode. Subjects ingested 30ml 2H2O and plasma samples were collected. BW was determined by standard equation. DXA scans were performed to calculate body mass, body volume and bone mineral content. A 4 compartmental model was used to estimate body composition (fat and fat free mass). Full scan experiments generated a m/z 45 peak and to a lesser extent a m/z 61 peak. Product fragment ions further monitored included 45 and 46 using selected ion monitoring (SIM;Method1), the 61>45 and 62>46 transition using multiple reaction monitoring (MRM;Method2) and the Neutral Loss, 62>45, transition (Method3). MRM methods were optimized for collision energy (CE) and collision-induced dissociation (CID) argon gas pressure with 6eV CE and 1.5 mTorr CID gas being optimal. Method2 was used for finally determination of 2H2O enrichment of subjects due to lower natural background. We have developed a sensitive method to determine 2H2O enrichment in body water to enable measurement of FM and FFM. PMID:26169138

Comparative SIFT-MS, GC-MS and FTIR analysis of methane fuel produced in biogas stations and in artificial photosynthesis over acidic anatase TiO2 and montmorillonite

NASA Astrophysics Data System (ADS)

Knížek, Antonín; Dryahina, Ksenyia; Španěl, Patrik; Kubelík, Petr; Kavan, Ladislav; Zukalová, Markéta; Ferus, Martin; Civiš, Svatopluk

2018-06-01

The era of fossil fuels is slowly nearing its inevitable end and the urgency of alternative energy sources basic research, exploration and testing becomes ever more important. Storage and alternative production of energy from fuels, such as methane, represents one of the many alternative approaches. Natural gas containing methane represents a powerful source of energy producing large volume of greenhouse gases. However, methane can be also produced in closed, CO2-neutral cycles. In our study, we compare detailed chemical composition of CH4 fuel produced in two different processes: Classical production of biogas in a rendering station, industrial wastewater treatment station and landfill gas station together with novel approach of artificial photosynthesis from CO2 over acidic anatase TiO2 in experimental apparatus developed in our laboratory. The analysis of CH4 fuel produced in these processes is important. Trace gaseous traces can be for example corrosive or toxic, low quality of the mixture suppresses effectivity of energy production, etc. In this analysis, we present a combination of two methods: High resolution Fourier transform infrared spectroscopy (HR-FTIR) suitable for the main component analysis; and the complementary extremely sensitive method of Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and gas chromatography (GC-MS), which are in turn best suited for trace analysis. The combination of these methods provides more information than any single of them would be able to and promises a new possible analytical approach to fuel and gaseous mixture analysis.

A rapid assay for the simultaneous determination of nicotine, cocaine and metabolites in meconium using disposable pipette extraction and gas chromatography-mass spectrometry (GC-MS).

PubMed

Mozaner Bordin, Dayanne C; Alves, Marcela N R; Cabrices, Oscar G; de Campos, Eduardo G; De Martinis, Bruno Spinosa

2014-01-01

Drug abuse by pregnant women is considered a serious public health problem worldwide. Meconium is the first excretion in newborns and has been used as an alternative matrix to evaluate in utero drug exposure. Solid phase extraction (SPE) is widely employed to prepare and clean up samples in the field of forensic analysis. Most SPE products require large volumes of solvent, which culminates in longer sample processing times and increased cost per sample. Disposable pipette extraction (DPX) tips have been used as an alternative to traditional SPE cartridges. They combine efficient and rapid extraction with reduced solvent consumption. The purpose of this study was to develop and validate a method to determine nicotine, cotinine, cocaine, benzoylecgonine, cocaethylene and methyl ester anhydroecgonine in meconium using DPX and gas chromatography-mass spectrometry (GC-MS). Validation results indicated that extraction efficiency ranged 50-98%, accuracy 92-106%, intra-assay precision 4-12% and inter-assay precision 6-12%. Linear calibration curves resulted in R(2) values >0.99, limits of detection ranged from 2.5 to 15 ng/g and the limit of quantitation from 10 to 20 ng/g. The DPX-GC-MS method was shown to selectively analyze trace concentrations of drugs in meconium samples. Finally, the developed and validated method was applied to 50 meconium samples.

The comparison of solid phase microextraction-GC and static headspace-GC for determination of solvent residues in vegetable oils.

PubMed

Ligor, Magdalena; Buszewski, Bogusław

2008-02-01

The objective of these investigations has been the determination of volatile organic compounds including residue solvents present in vegetable oil samples. Some olive oil, rape oil, sunflower oil, soy-bean oil, pumpkin oil, grape oil, rice oil as well as hazel-nut oil samples were analysed. Among residue solvents the following compounds have been mentioned: acetone, n-hexane, benzene, and toluene. Some experiments for the solid phase microextraction (SPME)-GC-flame ionisation detection (FID) were performed to examine extraction conditions such as fiber exposure time, temperature of extraction, and temperature of desorption. Various SPME fibers such as polydimethylsiloxane, Carboxen/polydimethylsiloxane and polydimethylsiloxane/divinylbenzene coatings were used for the isolation of tested compounds from vegetable oil samples. After optimisation of SPME, real vegetable oil samples were examined using SPME-GC/MS. Based on preliminary experiments the qualitative and quantitative analyses for the determination of acetone, n-hexane, benzene and toluene were performed by SPME-GC-FID and static head-space (SHS)-GC-FID methods. The regression coefficients for calibration curves for the examined compounds were R(2) > or = 0.992. This shows that the used method is linear in the examined concentration range (0.005-0.119 mg/kg for SPME-GC-FID and 0.003-0.728 mg/kg for SHS-GC-FID). Chemical properties of analysed vegetable oils have been characterised by chemometric procedure (cluster analysis).

Metabolism of the new psychoactive substances N,N-diallyltryptamine (DALT) and 5-methoxy-DALT and their detectability in urine by GC-MS, LC-MSn, and LC-HR-MS-MS.

PubMed

Michely, Julian A; Helfer, Andreas G; Brandt, Simon D; Meyer, Markus R; Maurer, Hans H

2015-10-01

N,N-Diallyltryptamine (DALT) and 5-methoxy-DALT (5-MeO-DALT) are synthetic tryptamine derivatives commonly referred to as so-called new psychoactive substances (NPS). They have psychoactive effects that may be similar to those of other tryptamine derivatives. The objectives of this work were to study the metabolic fate and detectability, in urine, of DALT and 5-MeO-DALT. For metabolism studies, rat urine obtained after high-dose administration was prepared by precipitation and analyzed by liquid chromatography-high-resolution mass spectrometry (LC-HR-MS-MS). On the basis of the metabolites identified, several aromatic and aliphatic hydroxylations, N-dealkylation, N-oxidation, and combinations thereof are proposed as the main metabolic pathways for both compounds. O-Demethylation of 5-MeO-DALT was also observed, in addition to extensive glucuronidation or sulfation of both compounds after phase I transformation. The cytochrome P450 (CYP) isoenzymes predominantly involved in DALT metabolism were CYP2C19, CYP2D6, and CYP3A4; those mainly involved in 5-MeO-DALT metabolism were CYP1A2, CYP2C19, CYP2D6, and CYP3A4. For detectability studies, rat urine was screened by GC-MS, LC-MS(n), and LC-HR-MS-MS after administration of low doses. LC-MS(n) and LC-HR-MS-MS were deemed suitable for monitoring consumption of both compounds. The most abundant targets were a ring hydroxy metabolite of DALT, the N,O-bis-dealkyl metabolite of 5-MeO-DALT, and their glucuronides. GC-MS enabled screening of DALT by use of its main metabolites only.

On-site GC/MS analysis of Chapman gasification separator liquor. Final report Jul 80-Mar 81

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

Thielen, C.J.; Magee, R.A.; Collins, R.V.

1981-08-01

The report gives results of a characterization of a wastewater stream from a coal gasification plant, using on-site extraction and GC/MS analysis. Extractable material in the wastewater was primarily phenols and alkylphenols, accounting for about 99% of the total mass identified. Several polynuclear aromatic compounds were also identified. The composition of the sample deteriorated even though the water was held in amber bottles at 4C: this was most evident in the concentration of dimethylphenols which dropped about 75% during 2 weeks of refrigerated storage. Ambient sample storage produced a greater decrease in the concentration of phenol, but did not appearmore » to affect the alkylphenols or the base/neutral compounds as much. The observed changes in composition should hamper any off-site wastewater treatbility studies with waters of this type. Diisopropyl ether (DIPE) extraction confirmed the 99-plus % removal efficiency of phenol which had been demonstrated in previous studies. Wet oxidation removed organics almost as efficiently as DIPE extraction, but may have limited use because of its high operating cost.« less

Metabolic profiling and systematic identification of flavonoids and isoflavonoids in roots and cell suspension cultures of Medicago truncatula using HPLC-UV-ESI-MS and GC-MS.

PubMed

Farag, Mohamed A; Huhman, David V; Lei, Zhentian; Sumner, Lloyd W

2007-02-01

An integrated approach utilizing HPLC-UV-ESI-MS and GC-MS was used for the large-scale and systematic identification of polyphenols in Medicago truncatula root and cell culture. Under optimized conditions, we were able to simultaneously quantify and identify 35 polyphenols including 26 isoflavones, 3 flavones, 2 flavanones, 2 aurones and a chalcone. All identifications were based upon UV spectra, mass spectral characteristics of protonated molecules, tandem mass spectral data, mass measurements obtained using a quadrupole time-of-flight mass spectrometer (QtofMS), and confirmed through the co-characterization of authentic compounds. In specific instances where the stereochemistry of sugar conjugates was uncertain, subsequent enzymatic hydrolysis of the conjugate followed by GC-MS was used to assign the sugar stereochemical configuration. Comparative metabolic profiling of Medicago truncatula root and cell cultures was then performed and revealed significant differences in the isoflavonoid composition of these two tissues.

Toward best practices in data processing and analysis for intact biotherapeutics by MS in quantitative bioanalysis.

PubMed

Kellie, John F; Kehler, Jonathan R; Karlinsey, Molly Z; Summerfield, Scott G

2017-12-01

Typically, quantitation of biotherapeutics from biological matrices by LC-MS is based on a surrogate peptide approach to determine molecule concentration. Recent efforts have focused on quantitation of the intact protein molecules or larger mass subunits of monoclonal antibodies. To date, there has been limited guidance for large or intact protein mass quantitation for quantitative bioanalysis. Intact- and subunit-level analyses of biotherapeutics from biological matrices are performed at 12-25 kDa mass range with quantitation data presented. Linearity, bias and other metrics are presented along with recommendations made on the viability of existing quantitation approaches. This communication is intended to start a discussion around intact protein data analysis and processing, recognizing that other published contributions will be required.

Identification by GC-EAD of the two-component trail-following pheromone of Prorhinotermes simplex (Isoptera, Rhinotermitidae, Prorhinotermitinae).

PubMed

Sillam-Dussès, David; Kalinová, Blanka; Jiros, Pavel; Brezinová, Anna; Cvacka, Josef; Hanus, Robert; Sobotník, Jan; Bordereau, Christian; Valterová, Irena

2009-08-01

GC/MS analysis confirmed that neocembrene is the major component of the trail pheromone in the three species of the termite genus Prorhinotermes (P. simplex, P. canalifrons, P. inopinatus). In addition, EAG and GC-EAD experiments with P. simplex strongly suggest that dodecatrienol is a quantitatively minor component but a qualitatively important component of this trail pheromone. Trail-following bioassays confirmed the two-component nature of the trail pheromone. This is the first report of the use of the GC-EAD for the identification of trail pheromone in termites. These original results underline once again the special phylogenetic status of the Prorhinotermitinae among Rhinotermitidae.

Quali-quantitative characterization of the volatile constituents in Cordia verbenacea D.C. essential oil exploiting advanced chromatographic approaches and nuclear magnetic resonance analysis.

PubMed

Sciarrone, Danilo; Giuffrida, Daniele; Rotondo, Archimede; Micalizzi, Giuseppe; Zoccali, Mariosimone; Pantò, Sebastiano; Donato, Paola; Rodrigues-das-Dores, Rosana Goncalves; Mondello, Luigi

2017-11-17

Cordia verbenacea D.C. (Boraginaceae, Varronia curassavica Jacq. synonym) is a medicinal plant, native from Brazil, especially the leaves are used in folk medicine. The aim of this study was to extend the characterization of the volatile fraction of the essential oil obtained from this plant, by using GC-FID, GC-MS, and chiral GC. Moreover, to further clarify the composition of the volatile fraction, preparative multidimensional-GC (prep-MDGC) was used to collect unknown compounds, followed by NMR characterization. Specifically, the chemical characterization, both qualitative and quantitative, of the volatile fraction of the essential oil obtained from Cordia verbenacea cultivated in the Minas Gerais area (central area of Brazil) was investigated for the first time. The principal components from a quantitative point of view were α-pinene (25.32%; 24.48g/100g) and α-santalene (17.90%; 17.30g/100g), belonging to the terpenes family. Chiral-GC data are reported for the enantiomeric distribution of 7 different components. Last, to obtain the complete characterization of the essential oil constituents, prep-MDGC analysis was used to attain the isolation of two compounds, not present in the principal MS databases, which were unambiguously identified by NMR investigation as (E)-α-santalal and (E)-α-bergamotenal, reported for the first time in Cordia verbenacea essential oil. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of yohimbine alkaloid from Pausinystalia yohimbe by non-aqueous capillary electrophoresis and gas chromatography-mass spectrometry.

PubMed

Chen, Qinhua; Li, Peng; Zhang, Zhuo; Li, Kaijun; Liu, Jia; Li, Qiang

2008-07-01

In the present work, the qualitative and quantitative analysis of Pausinystalia yohimbe-type alkaloids in the barks of Rubiaceae species is presented using different analytical approaches. Extracts of P. yohimbe were first examined by GC-MS and the major alkaloids were identified. The quantitation of yohimbine was then accomplished by non-aqueous CE (NACE) with diode array detection. This approach was selected in order to use a running buffer fully compatible with samples in organic solvent. In particular, a mixture of methanol containing ammonium acetate (20 mM) and glacial acetic acid was used as a BGE. The same analytical sample was subjected to GC-MS and NACE analysis; the different selectivity displayed by these techniques allowed different separation profiles that can be useful in phytochemical characterization of the extracts. The linear calibration ranges were all 10-1000 microg/mL for yohimbine by GC-MS and NACE analysis. The recovery of yohimbine was 91.2-94.0% with RSD 1.4-4.3%. The LOD for yohimbine were 0.6 microg/mL by GC-MS and 1.0 microg/mL by NACE, respectively. The GC-MS and NACE methods were successfully validated and applied to the quantitation of yohimbine.

Fluorescence-labeled methylation-sensitive amplified fragment length polymorphism (FL-MS-AFLP) analysis for quantitative determination of DNA methylation and demethylation status.

PubMed

Kageyama, Shinji; Shinmura, Kazuya; Yamamoto, Hiroko; Goto, Masanori; Suzuki, Koichi; Tanioka, Fumihiko; Tsuneyoshi, Toshihiro; Sugimura, Haruhiko

2008-04-01

The PCR-based DNA fingerprinting method called the methylation-sensitive amplified fragment length polymorphism (MS-AFLP) analysis is used for genome-wide scanning of methylation status. In this study, we developed a method of fluorescence-labeled MS-AFLP (FL-MS-AFLP) analysis by applying a fluorescence-labeled primer and fluorescence-detecting electrophoresis apparatus to the existing method of MS-AFLP analysis. The FL-MS-AFLP analysis enables quantitative evaluation of more than 350 random CpG loci per run. It was shown to allow evaluation of the differences in methylation level of blood DNA of gastric cancer patients and evaluation of hypermethylation and hypomethylation in DNA from gastric cancer tissue in comparison with adjacent non-cancerous tissue.

Quantitation of sweet steviol glycosides by means of a HILIC-MS/MS-SIDA approach.

PubMed

Well, Caroline; Frank, Oliver; Hofmann, Thomas

2013-11-27

Meeting the rising consumer demand for natural food ingredients, steviol glycosides, the sweet principle of Stevia rebaudiana Bertoni (Bertoni), have recently been approved as food additives in the European Union. As regulatory constraints require sensitive methods to analyze the sweet-tasting steviol glycosides in foods and beverages, a HILIC-MS/MS method was developed enabling the accurate and reliable quantitation of the major steviol glycosides stevioside, rebaudiosides A-F, steviolbioside, rubusoside, and dulcoside A by using the corresponding deuterated 16,17-dihydrosteviol glycosides as suitable internal standards. This quantitation not only enables the analysis of the individual steviol glycosides in foods and beverages but also can support the optimization of breeding and postharvest downstream processing of Stevia plants to produce preferentially sweet and least bitter tasting Stevia extracts.

Detection of Δ6-methyltestosterone in a "dietary supplement" and GC-MS/MS investigations on its urinary metabolism.

PubMed

Parr, Maria K; Fusshöller, Gregor; Schlörer, Nils; Opfermann, Georg; Geyer, Hans; Rodchenkov, Grigory; Schänzer, Wilhelm

2011-03-05

Since a few years more and more products have appeared on the market for dietary supplements containing steroids that had never been marketed as approved drugs, mostly without proper labeling of the contents. Syntheses and few data on pharmacological effects are available dated back mainly to the 1950s or 1960s. Only little knowledge exists about effects and side effects of these steroids in humans. The present study reports the identification of Δ6-methyltestosterone in a product named "Jungle Warfare", which was obtained from a web-based supplement store. The main urinary metabolites, 17α-hydroxy-17β-methylandrosta-4,6-dien-3-one (Δ6-epimethyl-testosterone), 17α-methyl-5β-androstane-3α,17β-diol (3α,5β-THMT), and 17β-methyl-5β-androstane-3α,17α-diol, as well as the parent compound excreted after a single oral administration were monitored by GC-MS/MS. Δ6-Epimethyltestosterone and 3α,5β-THMT served for long-term detection (still present in the 181-189 h urine). 17α-Methyltestosterone and its 17-epimer were not detected in the urines (LOD 0.3ng/mL). The highest concentrations were found in the 14-20.5h urine for Δ6-epimethyltestosterone (600 ng/mL), and 3α,5β-THMT (240 ng/mL) and in the 36-44.5h urine for 17β-methyl-5β-androstane-3α,17α-diol (7 ng/mL). For reference methyltestosterone and epimethyltestosterone were dehydrogenated with chloranil. The characterization of the products was performed by GC-MS(/MS) and NMR. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Simple and rapid analytical method for detection of amino acids in blood using blood spot on filter paper, fast-GC/MS and isotope dilution technique.

PubMed

Kawana, Shuichi; Nakagawa, Katsuhiro; Hasegawa, Yuki; Yamaguchi, Seiji

2010-11-15

A simple and rapid method for quantitative analysis of amino acids, including valine (Val), leucine (Leu), isoleucine (Ile), methionine (Met) and phenylalanine (Phe), in whole blood has been developed using GC/MS. In this method, whole blood was collected using a filter paper technique, and a 1/8 in. blood spot punch was used for sample preparation. Amino acids were extracted from the sample, and the extracts were purified using cation-exchange resins. The isotope dilution method using ²H₈-Val, ²H₃-Leu, ²H₃-Met and ²H₅-Phe as internal standards was applied. Following propyl chloroformate derivatization, the derivatives were analyzed using fast-GC/MS. The extraction recoveries using these techniques ranged from 69.8% to 87.9%, and analysis time for each sample was approximately 26 min. Calibration curves at concentrations from 0.0 to 1666.7 μmol/l for Val, Leu, Ile and Phe and from 0.0 to 333.3 μmol/l for Met showed good linearity with regression coefficients=1. The method detection limits for Val, Leu, Ile, Met and Phe were 24.2, 16.7, 8.7, 1.5 and 12.9 μmol/l, respectively. This method was applied to blood spot samples obtained from patients with phenylketonuria (PKU), maple syrup urine disease (MSUD), hypermethionine and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), and the analysis results showed that the concentrations of amino acids that characterize these diseases were increased. These results indicate that this method provides a simple and rapid procedure for precise determination of amino acids in whole blood. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of water content on thermal oxidation of oleic acid investigated by combination of EPR spectroscopy and SPME-GC-MS/MS.

PubMed

Chen, Hongjian; Cao, Peirang; Li, Bo; Sun, Dewei; Wang, Yong; Li, Jinwei; Liu, Yuanfa

2017-04-15

Promotion of water to the thermal oxidation of oleic acid was detected by the combination of EPR, SPME-GC-MS/MS and GC. Spin-trapping technique was used to identify and quantify the radical species formed during thermal oxidation of oleic acid by using DMPO as electron spin trap. The most abundant radical species were identified as DMPO-alkyl radical adducts. EPR intensity plateau of the samples with 5% water content was 140% higher than the samples without water. It implies oleic acid samples with high water content had high level of oxidation rates. The proportion of aldehydes of the samples with 2% water content was the maximum about 59.97%. Among the formed products, (E,E)-2,4-decadienal has genotoxic and cytotoxic effects, whose percentage was nearly twice comparing with that of 5-0% water content. This study demonstrated that higher water content in frying systems would contribute to seriously oxidation and degradation of oleic acids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of Essential Oil Composition in Different Basil Species and Pot Cultures by a GC-MS Method.

PubMed

Muráriková, Andrea; Ťažký, Anton; Neugebauerová, Jarmila; Planková, Alexandra; Jampílek, Josef; Mučaji, Pavel; Mikuš, Peter

2017-07-20

Basil ( Ocimum L.) species are used as medicinal plants due to their essential oils exhibiting specific biological activity. The present work demonstrated that both the variety and season/conditions of cultivation had a significant effect on (i) the produced amount (extraction yield), (ii) qualitative, as well as (iii) quantitative profile of basil essential oil. Among studied basil varieties, a new variety, 'Mánes', was characterized for the first time. Based on our quantitative evaluation of GC-MS profiles, the following chemotypes and average concentrations of a main component were detected in the studied basil varieties: 'Ohře', 'Lettuce Leaf', 'Purple Opaal', 'Dark Green' (linalool, 5.99, 2.49, 2.34, 2.01 mg/mL, respectively), and 'Mammolo Genovese', 'Mánes', 'Red Rubin' (eucalyptol, 1.34, 0.96, 0.76 mg/mL, respectively). At the same time, when considering other compounds identified in GC-MS profiles, all the studied varieties, except from 'Lettuce Leaf', were methyl eugenol-rich with a strong dependence of the eugenol:methyl eugenol ratio on the seasonal changes (mainly solar irradiation, but also temperature and relative humidity). More complex and/or variable (depending on the season and cultivation) chemotypes were observed with 'Lettuce Leaf' (plus estragole, 2.27 mg/mL), 'Dark Green' (plus eucalyptol, 1.36 mg/mL), 'Mammolo Genovese' (plus eugenol, 1.19 mg/mL), 'Red Rubin' (plus linalool and eugenol, 0.46 and 0.56 mg/mL, respectively), and 'Mánes' (plus linalool and eugenol, 0.58 and 0.40 mg/mL, respectively). When considering superior extraction yield (ca. 17 mL·kg -1 , i.e., two to five times higher than other examined varieties) and consistent amounts (yields) of essential oil when comparing inter-seasonal or inter-year data (RSD and inter-year difference in mean yield values ˂2.5%), this new basil variety is very promising for use in the pharmaceutical, food, and cosmetic industries.

Multifamily determination of pesticide residues in soya-based nutraceutical products by GC/MS-MS.

PubMed

Páleníková, Agneša; Martínez-Domínguez, Gerardo; Arrebola, Francisco Javier; Romero-González, Roberto; Hrouzková, Svetlana; Frenich, Antonia Garrido

2015-04-15

An analytical method based on a modified QuEChERS extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was evaluated for the determination of 177 pesticides in soya-based nutraceutical products. The QuEChERS method was optimised and different extraction solvents and clean-up approaches were tested, obtaining the most efficient conditions with a mixture of sorbents (PSA, C18, GBC and Zr-Sep(+)). Recoveries were evaluated at 10, 50 and 100 μg/kg and ranged between 70% and 120%. Precision was expressed as relative standard deviation (RSD), and it was evaluated for more than 160 pesticides as intra and inter-day precision, with values always below 20% and 25%, respectively. Limits of detection (LODs) ranged from 0.1 to 10 μg/kg, whereas limits of quantification (LOQs) from 0.5 to 20 μg/kg. The applicability of the method was proved by analysing soya-based nutraceuticals. Two pesticides were found in these samples, malathion and pyriproxyfen, at 11.1 and 1.5 μg/kg respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative analysis of the volatile composition of honeys from Brazilian stingless bees by static headspace GC-MS.

PubMed

de Lima Morais da Silva, Patricia; de Lima, Liliane Schier; Caetano, Ísis Kaminski; Torres, Yohandra Reyes

2017-12-01

The volatile composition of honeys produced by eight species of stingless bees collected in three municipalities in the state of Paraná (Brazil) was compared by combining static headspace GC-MS and chemometrics methods. Forty-four compounds were identified using NIST library and linear retention index relative to n-alkanes (C 8 -C 40 ). Linalool derivatives were the most abundant peaks in most honeys regardless geographical or entomological origin. However, Principal Component Analysis discriminated honeys from different geographical origins considering their distinctive minor volatile components. Honey samples from Guaraqueçaba were characterized by the presence of hotrienol while those from Cambará showed epoxylinalol, benzaldehyde and TDN as minor discriminating compounds. Punctual species such as Borá showed similar fingerprints regardless geographical origin, with ethyl octanoate and ethyl decanoate as characteristic intense chromatographic peaks, which may suggest a specialized behavior for nectar collection. Discriminant Analysis allowed correct geographic discrimination of most honeys produced in the three spots tested. We concluded that volatile profile of stingless bee honeys can be used to attest authenticity related to regional origin of honeys. Copyright © 2017. Published by Elsevier Ltd.

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

Simultaneous determination of trace migration of phthalate esters in honey and royal jelly by GC-MS.

PubMed

Zhou, Jinhui; Qi, Yitao; Wu, Hongmei; Diao, Qingyun; Tian, Feifei; Li, Yi

2014-03-01

A simple, rapid, and reliable liquid-liquid extraction coupled to GC-MS method was developed and validated for the quantification of 22 phthalate esters (PAEs) in honey and royal jelly. Instrument parameters for GC-MS were tested to obtain the satisfactory separation between 22 PAEs with high sensitivity. The extraction procedure was optimized in order to achieve the best recovery. The following criteria were used to validate the developed method: linearity, LOD, lower LOQ, precision, accuracy, matrix effect and carry-over. Correlation coefficients were >0.999 by applying the linear regression model based on the least-squares method with a weighting factor (1/x). The intra- and interday precision were within 12.7% in terms of RSD, and the accuracy was within -11.8% in terms of relative error. The mean extraction recoveries ranged between 80.1 and 110.9% for honey and royal jelly. No significant matrix effect and carry-over for PAEs were observed for the analysis of honey and royal jelly samples. A total of 20 real samples were analyzed for a mini-survey using the developed method. Seven PAEs in honey samples and five PAEs in royal jelly samples were found, indicating potential contamination with several PAEs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analytical determination of bisphenol A (BPA) and bisphenol analogues in paper products by GC-MS/MS.

PubMed

Jurek, A; Leitner, E

2017-07-01

Bisphenol A (BPA; 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol), a suspected endocrine disruptor with a weak estrogenic activity, is used in a variety of consumer products, including food-contact materials made of paper and cardboard products. Due to restrictions on the use of BPA because of its potential health risks, BPA is gradually being replaced by other bisphenols because no limitations exist for these substances. This study presents a method for the simultaneous analysis of BPA, bisphenol AF (BPAF), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and bisphenol S (BPS) in paper and board products using gas chromatography-tandem mass spectrometry (GC-MS/MS). Paper samples were extracted by liquid extraction, as well as by Folch extraction, derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and the results compared. The developed method showed good linearity (R 2  > 0.9965) and precision, yielding relative standard deviations (RSDs) of less than 16.6% for reproducibility and 19.8% for repeatability. The limits of detection and limits of quantification for the different bisphenols ranged from 0.23 to 2.70 µg kg - 1 paper and from 0.78 to 9.10 µg kg - 1 paper, respectively. Analysis of different paper products (recycled, virgin fibre) showed that all the analysed bisphenols were present in the samples, except for BPAF and BPB. A calculation of the 'worst-case' scenario assuming a maximum potential migration of 100% of the analytes into food showed that the analysed products can be assumed to be safe regarding the migration of bisphenols.

The utility of ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) for clinically relevant steroid analysis.

PubMed

Storbeck, Karl-Heinz; Gilligan, Lorna; Jenkinson, Carl; Baranowski, Elizabeth S; Quanson, Jonathan L; Arlt, Wiebke; Taylor, Angela E

2018-05-15

Liquid chromatography tandem mass spectrometry (LC-MS/MS) assays are considered the reference standard for serum steroid hormone analyses, while full urinary steroid profiles are only achievable by gas chromatography (GC-MS). Both LC-MS/MS and GC-MS have well documented strengths and limitations. Recently, commercial ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) systems have been developed. These systems combine the resolution of GC with the high-throughput capabilities of UHPLC. Uptake of this new technology into research and clinical labs has been slow, possibly due to the perceived increase in complexity. Here we therefore present fundamental principles of UHPSFC-MS/MS and the likely applications for this technology in the clinical research setting, while commenting on potential hurdles based on our experience to date. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.

2011-01-01

One possible process responsible for methane generation on Mars is abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions. Measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane by tracing the geochemical pathway during formation. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible hydrogen isotope measurements. Reported here are results of experiments to characterize the hydrogen isotope composition of low molecular weight organic acids and alcohols. The presence of these organic compounds has been suggested by others as intermeadiary products made during mineral surface catalyzed reactions. This work compliments our previous study characterizing the carbon isotope composition of similar low molecular weight intermediary organic compounds (Socki, et al, American Geophysical Union Fall meeting, Abstr. #V51B-2189, Dec., 2010). Our hydrogen isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). Our technique is unique in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II? quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

Quantification of Complex Polycyclic Aromatic Hydrocarbon Mixtures in Standard Reference Materials Using GC×GC/ToF-MS

PubMed Central

Manzano, Carlos; Hoh, Eunha; Massey Simonich, Staci L.

2014-01-01

This research is the first to quantify complex PAH mixtures in NIST SRMs using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/ToF-MS), with and without extract cleanup, and reports previously unidentified PAH isomers in the NIST SRMs. We tested a novel, high orthogonality GC column combination (LC-50×NSP-35), as well as with a commonly used column combination (Rtx-5ms×Rxi-17) for the quantification of a complex mixture of 85 different PAHs, including parent (PAHs), alkyl- (MPAHs), nitro- (NPAHs), oxy- (OPAHs), thio- (SPAHs), bromo- (BrPAHs), and chloro-PAHs (ClPAHs) in extracts from two standard reference materials: NIST SRM1650b (diesel particulate matter), with cleanup and NIST SRM1975 (diesel particulate extract), with and without extract cleanup. The LC-50×NSP-35 column combination resulted in an average absolute percent difference of 33.8%, 62.2% and 30.8% compared to the NIST certified PAH concentrations for NIST SRM1650b, NIST SRM1975 with cleanup and NIST SRM1975 without cleanup, while the Rtx-5ms×Rxi-17 resulted in an absolute percent difference of 38.6%, 67.2% and 79.6% for NIST SRM1650b, NIST SRM1975 with cleanup and NIST SRM1975 without cleanup, respectively. This GC×GC/ToF-MS method increases the number of PAHs detected and quantified in complex environmental extracts using a single chromatographic run. Without clean-up, 7 additional compounds were detected and quantified in NIST SRM1975 using the LC-50×NSP-35 column combination. These results suggest that the use of the LC-50×NSP-35 column combination in GC×GC/ToF-MS not only results in better chromatographic resolution and greater orthogonality for the separation of complex PAH mixtures, but can also be used for the accurate quantification of complex PAH mixtures in environmental extracts without cleanup. PMID:23932031

GC-MS Analysis and Gastroprotective Evaluations of Crude Extracts, Isolated Saponins, and Essential Oil from Polygonum hydropiper L.

PubMed Central

Ayaz, Muhammad; Junaid, Muhammad; Ullah, Farhat; Sadiq, Abdul; Shahid, Muhammad; Ahmad, Waqar; Ullah, Ihsan; Ahmad, Ashfaq; Syed, Nawazish-i-Husain

2017-01-01

Peptic ulceration is among the most prevalent gastrointestinal disorders characterized by pepsin and gastric acid mediated mucosal damage, as result of imbalance between defensive and offensive processes. The main objective of the current study was to investigate the antiulcer potentials of Polygonum hydropiper crude methanolic ectract (Ph.Cr) in aspirin induced ulcerogenesis using pylorus ligated rat model. In-vitro urease and Proteus mirabilis inhibitory potentials were evaluated using standard protocols. All fractions were analyzed using GC-MS to identify major components. The aspirin induced ulcerogenesis in pylorus ligated rat model was associated with significant changes in the mean ulcer score [F(5, 30) = 7.141, P = 0.0002], gastric juice volume [F(5, 30) = 8.245, P < 0.0001], gastric juice pH [F(5, 30) = 5.715, P = 0.0008], free acidity [F(5, 30) = 4.544, P = 0.0033], total acidity [F(5, 30) = 2.740, P = 0.0373], and pepsin concentration [F(5, 30) = 2.335, P = 0.0664]. Pre-treatment with Ph.Cr at 100, 200, and 400 mg/kg dose exhibited marked gastroprotective and anti-ulcerogenic effect in the aspirin induced pyloric ligation ulcerogenesis model at 100, 200, and 400 mg/kg as indicated by ulcerative biochemical parameters. In urease inhibition assay, leaves essential oil (Ph.Lo), saponins (Ph.Sp), and chloroform extract (Ph.Chf) exhibited highest activities with IC50 of 90, 98, and 520 μg/ml, respectively. Ph.Sp, Ph.Chf, ethyl acetate (Ph.EtAc), and Ph.Cr showed MICs of 25, 30, 32.25, and 40.50 μg/ml, respectively against P. mirabilis. Several compounds were identified in GC-MS analysis of samples. Significant in-vivo antiulcer, urease inhibitory as well as anti-proteus potentials of P. hydropiper solvent extracts, signify its potential use for the management of peptic ulcers and may provide scientific bases for the traditional uses of the plant. PMID:28824906

Screening of Satureja subspicata Vis. Honey by HPLC-DAD, GC-FID/MS and UV/VIS: Prephenate Derivatives as Biomarkers.

PubMed

Jerković, Igor; Kranjac, Marina; Marijanović, Zvonimir; Zekić, Marina; Radonić, Ani; Tuberoso, Carlo Ignazio Giovanni

2016-03-21

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe(2+)/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)).

Second-order standard addition for deconvolution and quantification of fatty acids of fish oil using GC-MS.

PubMed

Vosough, Maryam; Salemi, Amir

2007-08-15

In the present work two second-order calibration methods, generalized rank annihilation method (GRAM) and multivariate curve resolution-alternating least square (MCR-ALS) have been applied on standard addition data matrices obtained by gas chromatography-mass spectrometry (GC-MS) to characterize and quantify four unsaturated fatty acids cis-9-hexadecenoic acid (C16:1omega7c), cis-9-octadecenoic acid (C18:1omega9c), cis-11-eicosenoic acid (C20:1omega9) and cis-13-docosenoic acid (C22:1omega9) in fish oil considering matrix interferences. With these methods, the area does not need to be directly measured and predictions are more accurate. Because of non-trilinear conditions of GC-MS data matrices, at first MCR-ALS and GRAM have been used on uncorrected data matrices. In comparison to MCR-ALS, biased and imprecise concentrations (%R.S.D.=27.3) were obtained using GRAM without correcting the retention time-shift. As trilinearity is the essential requirement for implementing GRAM, the data need to be corrected. Multivariate rank alignment objectively corrects the run-to-run retention time variations between sample GC-MS data matrix and a standard addition GC-MS data matrix. Then, two second-order algorithms have been compared with each other. The above algorithms provided similar mean predictions, pure concentrations and spectral profiles. The results validated using standard mass spectra of target compounds. In addition, some of the quantification results were compared with the concentration values obtained using the selected mass chromatograms. As in the case of strong peak-overlap and the matrix effect, the classical univariate method of determination of the area of the peaks of the analytes will fail, the "second-order advantage" has solved this problem successfully.

Quantitative LC-MS/MS analysis of seven ginsenosides and three aconitum alkaloids in Shen-Fu decoction

PubMed Central

2013-01-01

Background Shen-Fu decoction is a traditional Chinese medicine prescription with a 3:2 ratio of Radix Ginseng and Fuzi (Radix Aconiti lateralis praeparata). Ginsenosides and alkaloids are considered to be the main active components of Shen-Fu decoction. However, no analytical methods have been used to quantitatively analyse both components in Shen-Fu decoction simultaneously. Results We successfully developed a rapid resolution liquid chromatography coupled with tandem mass spectrometry (RRLC-MS/MS) method for the simultaneous analysis of seven ginsenosides and three aconitum alkaloids in Shen-Fu decoction, the decoction of Radix ginseng and Fuzi (Radix Aconiti lateralis praeparata). Chromatogrpahic separation by RPLC was achieved using a reversed-phase column and a water/acetonitrile mobile phase, containing 0.05% formic acid and using a gradient system. The method was optimized to allow for simultaneous analysis of all analytes in 11minutes without the need for baseline resolution of the components. Furthermore, the separation demonstrated good linearity (r > 0.9882), repeatability (RSD < 7.01%), intra- and inter-day precisions (RSD < 5.06%) and high yields of recovery (91.13-111.97%) for ten major constituents, namely ginsenoside-Re, Rg1, Rb1, Rc, Rb2, Rd, Rf, aconitine, hypacoitine and mesaconitine. Conclusions The developed method could be used as a rapid and reliable approach for assessment of the quantity of the major constituents in Shen-Fu decoction. PMID:24107599

[Quantitative determination of biogenic amine from Biomphalaria glabrata nervous system by UPLC MS/MS].

PubMed

Tao, Huang; Yun-Hai, Guo; He-Xiang, Liu; Yi, Zhang

2018-04-19

To establish a method for the quantitative determination of serotonin and dopamine in the nervous system of Biomphalaria glabrata by using ultra high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC MS/MS) . The B. glabrata nervous system was broken in the pure methanol solution after obtaining it by dissecting with microscope. Then, the supernatant containing the target substance after twice high speed centrifugation was got. The extraction was separated on an ACQUITY UPLC BEH Amide column with Waters TQ-XS series mass spectrometry detector, with ESI source and positive electrospray ionization mode when the machine testing. The detection limit of serotonin was 0.03 ng/ml and the limit of quantification was 0.1 ng/ml. The detection limit of dopamine was 0.05 ng/ml and the limit of quantification was 0.15 ng/ml. The recoveries of serotonin ranged from 90.68% to 94.72% over the range of 1 to 40 ng/ml. The recoveries of dopamine ranged from 91.68% to 96.12% over the range of 1.0 ng/ml to 40 ng/ml. The established UPLC MS/MS method is simple, stable and reproducible. It can be used for the quantitative analysis of serotonin and dopamine in the nervous system of B. glabrata snails.

Rugged LC-MS/MS survey analysis for acrylamide in foods.

PubMed

Roach, John A G; Andrzejewski, Denis; Gay, Martha L; Nortrup, David; Musser, Steven M

2003-12-17

The described liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the detection of acrylamide in food entails aqueous room temperature extraction, SPE cleanup, and analysis by LC-MS/MS. The method is applicable to a wide variety of foods. [(13)C(3)]acrylamide is the internal standard. The limit of quantitation is 10 ppb (microg/kg). Data were obtained in duplicate from >450 products representing >35 different food types. The variability in analyte levels in certain food types suggests that it may be possible to reduce acrylamide levels in those foods.

Assessment of the ion-trap mass spectrometer for routine qualitative and quantitative analysis of drugs of abuse extracted from urine.

PubMed

Vorce, S P; Sklerov, J H; Kalasinsky, K S

2000-10-01

The ion-trap mass spectrometer (MS) has been available as a detector for gas chromatography (GC) for nearly two decades. However, it still occupies a minor role in forensic toxicology drug-testing laboratories. Quadrupole MS instruments make up the majority of GC detectors used in drug confirmation. This work addresses the use of these two MS detectors, comparing the ion ratio precision and quantitative accuracy for the analysis of different classes of abused drugs extracted from urine. Urine specimens were prepared at five concentrations each for amphetamine (AMP), methamphetamine (METH), benzoylecgonine (BZE), delta9-carboxy-tetrahydrocannabinol (delta9-THCCOOH), phencyclidine (PCP), morphine (MOR), codeine (COD), and 6-acetylmorphine (6-AM). Concentration ranges for AMP, METH, BZE, delta9-THCCOOH, PCP, MOR, COD, and 6-AM were 50-2500, 50-5000, 15-800, 1.5-65, 1-250, 500-32000, 250-21000, and 1.5-118 ng/mL, respectively. Sample extracts were injected into a GC-quadrupole MS operating in selected ion monitoring (SIM) mode and a GC-ion-trap MS operating in either selected ion storage (SIS) or full scan (FS) mode. Precision was assessed by the evaluation of five ion ratios for n = 15 injections at each concentration using a single-point calibration. Precision measurements for SIM ion ratios provided coefficients of variation (CV) between 2.6 and 9.8% for all drugs. By comparison, the SIS and FS data yielded CV ranges of 4.0-12.8% and 4.0-11.2%, respectively. The total ion ratio failure rates were 0.2% (SIM), 0.7% (SIS), and 1.2% (FS) for the eight drugs analyzed. Overall, the SIS mode produced stable, comparable mean ratios over the concentration ranges examined, but had greater variance within batch runs. Examination of postmortem and quality-control samples produced forensically accurate quantitation by SIS when compared to SIM. Furthermore, sensitivity of FS was equivalent to SIM for all compounds examined except for 6-AM.

Determination of 17 kinds of banned organochlorine pesticides in water by activated carbon fiber-solid phase microextraction coupled with GC-MS.

PubMed

Sun, Tonghua; Jia, Jinping; Zhong, Dengjie; Wang, Yalin

2006-02-01

Activated carbon fiber (ACF) as extraction fiber for solid-phase microextraction (SPME) and its application for the analysis of banned organochlorine pesticides (OCPs) were investigated. Firstly, ACF was activated by different concentration of zinc chloride, which indicated that ACF activated by 60% zinc chloride had a reasonable specific surface area, pore volume and pore distribution. Secondly, the parameters for the ACF-SPME procedure, the adsorption and desorption conditions, were also optimized when coupled with gas chromatography-mass spectrometry (GC-MS). Thirdly, the ACF-SPME was used to analyze 17 kinds of OCPs in water. The linearity of most pesticides was found to be between 0.2 and 50 microg/l with GC-MS under the selected ion monitoring (SIM) acquisition mode. The limits of detection (LOD) at the sub microg/l were obtained. The work demonstrated here shows that ACF is a promising alternative for the SPME procedure.

High-resolution gas chromatography/mass spectrometry method for characterization and quantitative analysis of ginkgolic acids in Ginkgo biloba plants, extracts, and dietary supplements.

PubMed

Wang, Mei; Zhao, Jianping; Avula, Bharathi; Wang, Yan-Hong; Avonto, Cristina; Chittiboyina, Amar G; Wylie, Philip L; Parcher, Jon F; Khan, Ikhlas A

2014-12-17

A high-resolution gas chromatography/mass spectrometry (GC/MS) with selected ion monitor method focusing on the characterization and quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba L. plant materials, extracts, and commercial products was developed and validated. The method involved sample extraction with (1:1) methanol and 10% formic acid, liquid-liquid extraction with n-hexane, and derivatization with trimethylsulfonium hydroxide (TMSH). Separation of two saturated (C13:0 and C15:0) and six unsaturated ginkgolic acid methyl esters with different positional double bonds (C15:1 Δ8 and Δ10, C17:1 Δ8, Δ10, and Δ12, and C17:2) was achieved on a very polar (88% cyanopropyl) aryl-polysiloxane HP-88 capillary GC column. The double bond positions in the GAs were determined by ozonolysis. The developed GC/MS method was validated according to ICH guidelines, and the quantitation results were verified by comparison with a standard high-performance liquid chromatography method. Nineteen G. biloba authenticated and commercial plant samples and 21 dietary supplements purported to contain G. biloba leaf extracts were analyzed. Finally, the presence of the marker compounds, terpene trilactones and flavonol glycosides for Ginkgo biloba in the dietary supplements was determined by UHPLC/MS and used to confirm the presence of G. biloba leaf extracts in all of the botanical dietary supplements.

Comparison of PTR-MS and GC-MS measurements of oxidized VOC and aromatic VOC concentrations at a boreal forest

NASA Astrophysics Data System (ADS)

Kajos, M.

2013-12-01

M.K. Kajos1, M. Hill2, H. Hellén3, P. Rantala1, C. C Hoerger2, S. Reimann2, H. Hakola3, T. Petäjä1, T.M. Ruuskanen1 1 Department of Physics, University of Helsinki, P.O.Box 64, 00014 University of Helsinki, Finland 2 Empa, Laboratory for Air Pollution/ Environmental Technology, Ueberlandstr. 129, 8600 Duebendorf, Switzerland 3 Finnish Metorological Institute, P.O.Box 503, 00101 Helsinki, Finland Oxidized volatile organic compounds (OVOCs) such as acetaldehyde and acetone and aromatic VOCs such as benzene and toluene originate from various natural and anthropogenic sources. The lifetimes of these compounds are relatively long, from hundreds of days in the winter to a few days in summer thus they are effectively transported. Some of them are continuously monitored e.g. benzene due to it being carcinogenic. In this study the volume mixing ratios of acetaldehyde, acetone, benzene and toluene, were measured with two different methods; Gas Chromatography-Mass Spectrometry (GC-MS) and Proton Transfer Reaction-Mass Spectrometry (PTR-MS). GC-MS is a well-established and old method to measure these compounds with a low, often one hour, time resolution. However it is rather labor intensive method and often used in short term campaigns. The other method, PTR-MS has a sub-minute time resolution and it is suitable for long term continuous measurements. The disadvantage of the PTR-MS is that the identification of the compounds is based on mass only, thus compounds with the same nominal mass cannot be distinguished. Both methods are widely used at atmospheric measurement stations around the world. The concentrations were measured with two GC-MSs and two PTR-MSs (Ionicon Analytik, Austria) at SMEAR II site (Station for Measuring Forest Ecosystem-Atmosphere Relations, 61°51'N, 24°17'E, 181 m a.s.l.) in Hyytiälä, Southern Finland in April-May 2012. The site is a well characterized atmosphere flagship station located in a rural boreal forest (Hari and Kulmala, 2005). The

Disentangling oil weathering using GC x GC. 1. chromatogram analysis.

PubMed

Arey, J Samuel; Nelson, Robert K; Reddy, Christopher M

2007-08-15

Historically, the thousands of compounds found in oils constituted an "unresolved complex mixture" that frustrated efforts to analyze oil weathering. Moreover, different weathering processes inflict rich and diverse signatures of compositional change in oil, and conventional methods do not effectively decode this elaborate record. Using comprehensive two-dimensional gas chromatography (GC x GC), we can separate thousands of hydrocarbon components and simultaneously estimate their chemical properties. We investigated 13 weathered field samples collected from the Bouchard 120 heavy fuel oil spill in Buzzards Bay, Massachusetts in 2003. We first mapped hydrocarbon vapor pressures and aqueous solubilities onto the compositional space explored by GC x GC chromatograms of weathered samples. Then we developed methods to quantitatively decouple mass loss patterns associated with evaporation and dissolution. The compositional complexity of oil, traditionally considered an obstacle, was now an advantage. We exploited the large inventory of chemical information encoded in oil to robustly differentiate signatures of mass transfer to air and water. With this new approach, we can evaluate mass transfer models (the Part 2 companion to this paper) and more properly account for evaporation, dissolution, and degradation of oil in the environment.

Metabolite profiling of a NIST Standard Reference Material for human plasma (SRM 1950): GC-MS, LC-MS, NMR, and clinical laboratory analyses, libraries, and web-based resources.

PubMed

Simón-Manso, Yamil; Lowenthal, Mark S; Kilpatrick, Lisa E; Sampson, Maureen L; Telu, Kelly H; Rudnick, Paul A; Mallard, W Gary; Bearden, Daniel W; Schock, Tracey B; Tchekhovskoi, Dmitrii V; Blonder, Niksa; Yan, Xinjian; Liang, Yuxue; Zheng, Yufang; Wallace, William E; Neta, Pedatsur; Phinney, Karen W; Remaley, Alan T; Stein, Stephen E

2013-12-17

Recent progress in metabolomics and the development of increasingly sensitive analytical techniques have renewed interest in global profiling, i.e., semiquantitative monitoring of all chemical constituents of biological fluids. In this work, we have performed global profiling of NIST SRM 1950, "Metabolites in Human Plasma", using GC-MS, LC-MS, and NMR. Metabolome coverage, difficulties, and reproducibility of the experiments on each platform are discussed. A total of 353 metabolites have been identified in this material. GC-MS provides 65 unique identifications, and most of the identifications from NMR overlap with the LC-MS identifications, except for some small sugars that are not directly found by LC-MS. Also, repeatability and intermediate precision analyses show that the SRM 1950 profiling is reproducible enough to consider this material as a good choice to distinguish between analytical and biological variability. Clinical laboratory data shows that most results are within the reference ranges for each assay. In-house computational tools have been developed or modified for MS data processing and interactive web display. All data and programs are freely available online at http://peptide.nist.gov/ and http://srmd.nist.gov/ .

Qualitative analysis of seized cocaine samples using desorption electrospray ionization- mass spectrometry (DESI-MS).

PubMed

Stojanovska, Natasha; Tahtouh, Mark; Kelly, Tamsin; Beavis, Alison; Fu, Shanlin

2015-05-01

Desorption electrospray ionization - mass spectrometry (DESI-MS) is a useful technique for the qualitative analysis of compounds found in seized drug material. In this study, DESI-MS was utilized in the screening analysis of illicit cocaine samples. The technique was also applied to the geographical origin determination of these samples. The limit of detection was determined to be 24.3 µg (or 3.47 µg/mm(2) ) and the analysis time was less than 1 minute per sample. The intra-day and inter-day precision for the detection of cocaine was 11 % and 42 %, respectively; therefore the quantitative data provided by DESI-MS was limited in its use for accurate determination of cocaine concentration in a sample. Using the quadrupole time-of-flight (QTOF) mass spectrometer, the presence of cocaine and impurities detected were confirmed by accurate tandem MS data. The qualitative chemical profiles obtained using DESI-MS were compared to two popular analysis techniques, GC-MS and LC-MS. The effects of a range of adulterants including caffeine, procaine, levamisole, lignocaine, paracetamol, and atropine on the detectability of cocaine were also investigated. It was found that the addition of these adulterants in a cocaine sample did not prevent the detection of the analyte itself (there was slight enhancement in some samples), which was useful in drug detection. The detection of truxillines in the seized samples by DESI-MS aided in the preliminary determination of geographical origin, i.e., Bolivian, Peruvian or Colombian leaf origin. The application of DESI-MS to the qualitative analysis and screening of seized cocaine samples demonstrates the potential and applicability of the technique to the fast chemical profiling of illicit samples. Copyright © 2014 John Wiley & Sons, Ltd.

Differentiation of Toxic Molds via Headspace SPME-GC/MS and Canine Detection

PubMed Central

Griffith, Robert T.; Jayachandran, Krishnaswamy; Shetty, Kateel G.; Whitstine, William; Furton, Kenneth G.

2007-01-01

Indoor mold growth has recently become a concern in the legal world in regards to insurance litigation. Hazardous mold exposure to humans has been linked to many acute and chronic adverse health effects including death. As it grows, mold produces several types of primary and secondary metabolites, including microbial volatile organic compounds (MVOCs). Microbial volatile organic compound emission may be used as a preliminary indication of a mold infestation that is invisible to the unaided eye. The objective of the study is to identify the unique odor signatures of three species of molds, Aspergillus versicolor, Penicillium chrysogenum, and Stachybotrys chartarum by SPME-GC/MS analysis. Determining the compounds that are emitted by the selected species has made it possible to conduct validation studies of canine detection of these mold species through a series of field tests.

Identification of keto- and hydroxy-dicarboxylic acids in remote marine aerosols from the western North Pacific: GC and GC/TOF-MS measurements

NASA Astrophysics Data System (ADS)

Vani, D.; Kawamura, K.; Tachibana, E.; Boreddy, S. K. R.

2015-12-01

Dicarboxylic acids (diacids) are dominant components of organic aerosols in the atmosphere. They contribute significantly to the total aerosol mass and have a serious impacts on global climate changes. However, studies on keto- and hydroxy-diacids in marine aerosols are limited. Compare to diacids, keto- and hydroxy-diacids are more hygroscopic due to the additional polar groups (OH and CO) and, hence, acts as cloud condensation nuclei (CCN). Molecular characterization of these compounds provides insight into organic aerosols sources and transformation pathways. We collected marine aerosols from remote Chichijima Island in the western North Pacific from December 2010 to November 2011 and studied for water-soluble keto- and hydroxy-diacids. Carboxyl groups were derivatized to dibutyl esters with 14% boron trifluoride/n-butanol, whereas hydroxyl groups were derivatized to trimethylsilyl ethers using N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA). After two-step derivatization, samples were injected to GC, GC/MS and GC/TOF-MS. In the GC chromatogram, we detected several new peaks after BSTFA derivatization of dibutyl ester fraction. Based on mass spectral interpretation, we found these peaks as homologues series of hydroxy-diacids and keto-diacids. Some of these hydroxy-diacids have been individually reported in literature in the laboratory photo-oxidation experiments and forest environments samples. But, there are no evidences to prove their sources and formation mechanism in the atmosphere. Here, we report for the first time homologous series of hydroxy-diacids (hC3di-hC6di) and keto-diacid (oxaloacetic acid, enol and keto forms) in remote marine atmosphere. Molecular distributions of hydroxy-diacids generally showed the predominance of malic acid followed by tartronic acid. Both hydroxy- and keto-diacids show significant positive correlation with oxalic acid and SO42-, suggesting that they are generated in the atmosphere and play an important role in the

Direct immersion single drop micro-extraction method for multi-class pesticides analysis in mango using GC-MS.

PubMed

Pano-Farias, Norma S; Ceballos-Magaña, Silvia G; Muñiz-Valencia, Roberto; Jurado, Jose M; Alcázar, Ángela; Aguayo-Villarreal, Ismael A

2017-12-15

Due the negative effects of pesticides on environment and human health, more efficient and environmentally friendly methods are needed. In this sense, a simple, fast, free from memory effects and economical direct-immersion single drop micro-extraction (SDME) method and GC-MS for multi-class pesticides determination in mango samples was developed. Sample pre-treatment using ultrasound-assisted solvent extraction and factors affecting the SDME procedure (extractant solvent, drop volume, stirring rate, ionic strength, time, pH and temperature) were optimized using factorial experimental design. This method presented high sensitive (LOD: 0.14-169.20μgkg -1 ), acceptable precision (RSD: 0.7-19.1%), satisfactory recovery (69-119%) and high enrichment factors (20-722). Several obtained LOQs are below the MRLs established by the European Commission; therefore, the method could be applied for pesticides determination in routing analysis and custom laboratories. Moreover, this method has shown to be suitable for determination of some of the studied pesticides in lime, melon, papaya, banana, tomato, and lettuce. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fast quantitative analysis of boric acid by gas chromatography-mass spectrometry coupled with a simple and selective derivatization reaction using triethanolamine.

PubMed

Zeng, Li-Min; Wang, Hao-Yang; Guo, Yin-Long

2010-03-01

A fast, selective, and sensitive GC-MS method has been developed and validated for the determination of boric acid in the drinking water by derivatization with triethanolamine. This analytic strategy successfully converts the inorganic, nonvolatile boric acid B(OH)(3) present in the drinking water to a volatile triethanolamine borate B(OCH(2)CH(2))(3)N in a quantitative manner, which facilitates the GC measurement. The SIM mode was applied in the analysis and showed high accuracy, specificity, and reproducibility, as well as reducing the matrix effect effectively. The calibration curve was obtained from 0.01 microg/mL to 10.0 microg/mL with a satisfactory correlation coefficient of 0.9988. The limit of detection for boric acid was 0.04 microg/L. Then the method was applied for detection of the amount of boric acid in bottled drinking water and the results are in accordance with the reported concentration value of boric acid. This study offers a perspective into the utility of GC-MS as an alternate quantitative tool for detection of B(OH)(3), even for detection of boron in various other samples by digesting the boron compounds to boric acid. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Carbon Isotope Characterization of Organic Intermediaries in Hydrothermal Hydrocarbon Synthesis by Pyrolysis-GC-MS-C-IRMS

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.

2010-01-01

We report results of experiments designed to characterize the carbon isotope composition of intermediate organic compounds produced as a result of mineral surface catalyzed reactions. The impetus for this work stems from recently reported detection of methane in the Martian atmosphere coupled with evidence showing extensive water-rock interaction during Martian history. Abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions may be one possible process responsible for methane generation on Mars, and measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible isotope measurements. Our isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-Combustion-Isotope Ratio Mass Specrometry (Py-GC-MS-C-IRMS). Others have conducted similar pyrolysis-IRMS experiments on low molecular weight organic acids (Dias, et al, Organic Geochemistry, 33 [2002]). Our technique differs in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of the organic compounds. A sample of carboxylic acid (mixture of C1 through C6) was pyrolyzed at 100 XC and passed through the GC-MS-C-IRMS (combusted at 940 XC). In order to test the reliability of our technique we compared the _13C composition of different molecular weight organic acids (from C1 through C6) extracted individually by the traditional sealed-tube cupric oxide combustion (940 XC) method with the _13C produced by our pyrolysis technique. Our data indicate that an average 4.3. +/-0.5. (V

Exposure assessment approach through mycotoxin/creatinine ratio evaluation in urine by GC-MS/MS.

PubMed

Rodríguez-Carrasco, Yelko; Moltó, Juan Carlos; Mañes, Jordi; Berrada, Houda

2014-10-01

In this pilot survey human urine samples were analyzed for presence of 15 mycotoxins and some of their metabolites using a novel urinary multi-mycotoxin GC-MS/MS method following salting-out liquid-liquid extraction. Fifty-four urine samples from children and adults residents in Valencia were analyzed for presence of urinary mycotoxin and expressed in gram of creatinine. Three out of 15 mycotoxins were detected namely, HT-2 toxin, nivalenol and deoxynivalenol (DON). 37 samples showed quantifiable values of mycotoxins. Co-occurrence of these contaminants was also observed in 20.4% of assayed samples. DON was the most frequently detected mycotoxin (68.5%) with mean levels of 23.3 μg/g creatinine (range: 2.8-69.1 μg/g creatinine). The levels of urinary DON were used to carry out an exposure assessment approach. 8.1% of total subjects were estimated to exceed the DON provisional maximum tolerable daily intake (PMTDI) (1 μg/kg b.w.). Two out of 9 exposed children exceeded the DON PMTDI thus, making them the most exposed based on the urinary results. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

[Analysis and research on the degradation and migration of organic pollutants in textile wastewater treatment process by GC-MS].

PubMed

Liu, Wei-jing; Zhang, Long; Wu, Wei; Tu, Yong

2010-04-01

In order to analyze the advantages/disadvantages of the combined treatment process between "physicochemical + biochemical" and "biochemical + physicochemical" in treatment of textile wastewater, gas chromatography-mass spectrometry (GC-MS) was used to determine the degradation process of organic pollutants in this two totally different treatment processes. The same analysis was also conducted to the sludge and discharged water. The results showed that the "physicochemical + biochemical" process displayed a poorer effect than "biochemical + physicochemical" in degrading the organic pollutants. The latter was 6.2% higher than the former in removing the organic pollutants averagely. The difference was mainly manifested in the efficiency of anaerobic hydrolysis in the two coupled processes. Moreover, the implement of "physicochemical + biochemical" process resulted in the migration of plenty of typical organic pollutants to sludge from primary coagulation sedimentation process and to the discharged water, which would cause secondary pollution easily.

Microplastic Abundance and Composition in Western Lake Superior As Determined via Microscopy, Pyr-GC/MS, and FTIR.

PubMed

Hendrickson, Erik; Minor, Elizabeth C; Schreiner, Kathryn

2018-02-20

While plastic pollution in marine and freshwater systems is an active area of research, there is not yet an in-depth understanding of the distributions, chemical compositions, and fates of plastics in aquatic environments. In this study, the magnitude, distribution, and common polymers of microplastic pollution in surface waters in western Lake Superior are determined. Analytical methodology, including estimates of ambient contamination during sample collection and processing, are described and employed. Microscopy, pyrolysis-gas chromatography/mass spectrometry (Pyr-GC/MS), and Fourier transform infrared spectroscopy (FTIR) were used to quantify and identify microplastic particles. In surface waters, fibers were the most frequently observed morphology, and, based upon PyGC/MS analysis,  polyvinyl chloride was the most frequently observed polymer, followed by polypropylene and polyethylene. The most common polymer identified by FTIR was polyethylene. Despite the low human population in Lake Superior's watershed, microplastic particles (particularly fibers, fragments, and films) were identified in western-lake surface waters at levels comparable to average values reported in studies within Lake Michigan, the North Atlantic Ocean, and the South Pacific Ocean. This study provides insight into the magnitude of microplastic pollution in western Lake Superior, and describes in detail methodology to improve future microplastics studies in aquatic systems.

Part 3: Solid phase extraction of Russian VX and its chemical attribution signatures in food matrices and their detection by GC-MS and LC-MS.

PubMed

Williams, Audrey M; Vu, Alexander K; Mayer, Brian P; Hok, Saphon; Valdez, Carlos A; Alcaraz, Armando

2018-08-15

Chemical attribution signatures indicative of O-isobutyl S-(2-diethylaminoethyl) methylphosphonothioate (Russian VX) synthetic routes were investigated in spiked food samples. Attribution signatures were identified using a multifaceted approach: Russian VX was synthesized using six synthetic routes and the chemical attribution signatures identified by GC-MS and LC-MS. Three synthetic routes were then down selected and spiked into complex matrices: bottled water, baby food, milk, liquid eggs, and hot dogs. Sampling and extraction methodologies were developed for these materials and used to isolate the attribution signatures and Russian VX from each matrix. Recoveries greater than 60% were achieved for most signatures in all matrices; some signatures provided recoveries greater than 100%, indicating some degradation during sample preparation. A chemometric model was then developed and validated with the concatenated data from GC-MS and LC-MS analyses of the signatures; the classification results of the model were > 75% for all samples. This work is part three of a three-part series in this issue of the United States-Sweden collaborative efforts towards the understanding of the chemical attribution signatures of Russian VX in crude materials and in food matrices. Copyright © 2018 Elsevier B.V. All rights reserved.

Development of a GC/Quadrupole-Orbitrap Mass Spectrometer, Part I: Design and Characterization

PubMed Central

2015-01-01

Identification of unknown compounds is of critical importance in GC/MS applications (metabolomics, environmental toxin identification, sports doping, petroleomics, and biofuel analysis, among many others) and remains a technological challenge. Derivation of elemental composition is the first step to determining the identity of an unknown compound by MS, for which high accuracy mass and isotopomer distribution measurements are critical. Here, we report on the development of a dedicated, applications-grade GC/MS employing an Orbitrap mass analyzer, the GC/Quadrupole-Orbitrap. Built from the basis of the benchtop Orbitrap LC/MS, the GC/Quadrupole-Orbitrap maintains the performance characteristics of the Orbitrap, enables quadrupole-based isolation for sensitive analyte detection, and includes numerous analysis modalities to facilitate structural elucidation. We detail the design and construction of the instrument, discuss its key figures-of-merit, and demonstrate its performance for the characterization of unknown compounds and environmental toxins. PMID:25208235

Extraction and derivatization of polar herbicides for GC-MS analyses.

PubMed

Ranz, Andreas; Maier, Eveline; Motter, Herbert; Lankmayr, Ernst

2008-09-01

A sample preparation procedure including a simultaneous microwave-assisted (MA) extraction and derivatization for the determination of chlorophenoxy acids in soil samples is presented. For a selective and sensitive measurement, an analytical technique such as GC coupled with MS needs to be adopted. For GC analyses, chlorophenoxy acids have to be converted into more volatile and thermally stable derivatives. Derivatization by means of microwave radiation offers new alternatives in terms of shorter derivatization time and reduces susceptibility for the formation of artefacts. Extraction and derivatization into methyl esters (ME) were performed with sulphuric acid and methanol. Due to the novelty of the simultaneous extraction and derivatization assisted by means of microwave radiation, a careful investigation and optimization of influential reaction parameters was necessary. It could be shown that the combination of sulphuric acid and methanol provides a fast sample preparation including an efficient clean up procedure. The data obtained by the described method are in good agreement with those published for the reference material. Finally, compared to conventional heating and also to the standard procedure of the EPA, the sample preparation time could be considerably shortened.

GC and GC/MS Analysis of Essential Oil Composition of the Endemic Soqotraen Leucas virgata Balf.f. and Its Antimicrobial and Antioxidant Activities

PubMed Central

Mothana, Ramzi A.; Al-Said, Mansour S.; Al-Yahya, Mohammed A.; Al-Rehaily, Adnan J.; Khaled, Jamal M.

2013-01-01

Leucas virgata Balf.f. (Lamiaceae) was collected from the Island Soqotra (Yemen) and its essential oil was obtained by hydrodistillation. The chemical composition of the oil was investigated by GC and GC-MS. Moreover, the essential oil was evaluated for its antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria, and one yeast species by using broth micro-dilution assay for minimum inhibitory concentrations (MIC) and antioxidant activity by measuring the scavenging activity of the DPPH radical. The investigation led to the identification of 43 constituents, representing 93.9% of the total oil. The essential oil of L. virgata was characterized by a high content of oxygenated monoterpenes (50.8%). Camphor (20.5%) exo-fenchol (3.4%), fenchon (5.4%), and borneol (3.1%) were identified as the main components. Oxygenated sesquiterpenes were found as the second major group of compounds (21.0%). β-Eudesmol (6.1%) and caryophyllene oxide (5.1%) were the major compounds among oxygenated sesquiterpenes. The results of the antimicrobial assay showed that the oil exhibited a great antibacterial activity against the tested S. aureus, B. subtilis, and E. coli. No activity was found against P. aeruginosa and C. albicans. Moreover, the DPPH-radical scavenging assay exhibited only a moderate antioxidant activity (31%) for the oil at the highest concentration tested (1 mg/mL). PMID:24284402

Application of the Reference Method Isotope Dilution Gas Chromatography Mass Spectrometry (ID/GC/MS) to Establish Metrological Traceability for Calibration and Control of Blood Glucose Test Systems

PubMed Central

Andreis, Elisabeth; Küllmer, Kai

2014-01-01

Self-monitoring of blood glucose (BG) by means of handheld BG systems is a cornerstone in diabetes therapy. The aim of this article is to describe a procedure with proven traceability for calibration and evaluation of BG systems to guarantee reliable BG measurements. Isotope dilution gas chromatography mass spectrometry (ID/GC/MS) is a method that fulfills all requirements to be used in a higher-order reference measurement procedure. However, this method is not applicable for routine measurements because of the time-consuming sample preparation. A hexokinase method with perchloric acid (PCA) sample pretreatment is used in a measurement procedure for such purposes. This method is directly linked to the ID/GC/MS method by calibration with a glucose solution that has an ID/GC/MS-determined target value. BG systems are calibrated with whole blood samples. The glucose levels in such samples are analyzed by this ID/GC/MS-linked hexokinase method to establish traceability to higher-order reference material. For method comparison, the glucose concentrations in 577 whole blood samples were measured using the PCA-hexokinase method and the ID/GC/MS method; this resulted in a mean deviation of 0.1%. The mean deviation between BG levels measured in >500 valid whole blood samples with BG systems and the ID/GC/MS was 1.1%. BG systems allow a reliable glucose measurement if a true reference measurement procedure, with a noninterrupted traceability chain using ID/GC/MS linked hexokinase method for calibration of BG systems, is implemented. Systems should be calibrated by means of a traceable and defined measurement procedure to avoid bias. PMID:24876614

Determination of cocaine and its derivatives in hair samples by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Pego, A M F; Roveri, F L; Kuninari, R Y; Leyton, V; Miziara, I D; Yonamine, M

2017-05-01

Hair testing is a recognized approach when it comes to accessing historical drug use. According to the World Drug Report of United Nations Office on Drugs and Crime (UNODC) 2015, Brazil is the largest cocaine (COC) market in South America. New analytical methodologies to detect crack/cocaine analytes in hair samples are highly desirable. Here, a method consisting of a liquid-phase microextraction (LPME) as a clean-up step, followed by gas chromatography-mass spectrometry (GC-MS) analysis has been proposed. The new validated method consisted of a washing step; an overnight incubation with methanol and a quick derivatization with butylchloroformate. Once derivatized, the samples were then submitted to the LPME procedure. Limits of detection (LoD) and quantitation (LoQ) obtained were of 0.1 and 0.5ng/mg for COC 0.4 and 0.5ng/mg for anhydroecgonine methyl ester (AEME); 0.03 and 0.05 for cocaethylene (CE), respectively and 0.05ng/mg for both LoD and LoQ for benzoylecgonine (BZE). All calibration curves were linear over the scope applied, from LoQ up to 20ng/mg, with a r 2 >0.99. Precision and accuracy assays showed acceptable %RSD values, according to international guidelines. Twelve postmortem head hair samples stemming from the Institute of Legal Medicine of Sao Paulo (IML-SP) have been analyzed, from which seven have shown to be positive for COC (0.75->20ng/mg) and BZE (0.1->20ng/mg). Apart from COC's main metabolite, four samples were also positive for CE (0.1-3.9ng/mg) and three samples for AEME (0.5-4.9ng/mg). To conclude, the LPME technique together with GC-MS analysis have shown promising results and were able to meet the demand of the laboratory of analyzing postmortem hair samples to look for all four analytes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Simple and Fast Sample Preparation Followed by Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS) for the Analysis of 2- and 4-Methylimidazole in Cola and Dark Beer.

PubMed

Choi, Sol Ji; Jung, Mun Yhung

2017-04-01

We have developed a simple and fast sample preparation technique in combination with a gas chromatography-tandem mass spectrometry (GC-MS/MS) for the quantification of 2-methylimidazole (2-MeI) and 4-methylimidazole (4-MeI) in colas and dark beers. Conventional sample preparation technique for GC-MS requires laborious and time-consuming steps consisting of sample concentration, pH adjustment, ion pair extraction, centrifugation, back-extraction, centrifugation, derivatization, and extraction. Our sample preparation technique consists of only 2 steps (in situ derivation and extraction) which requires less than 3 min. This method provided high linearity, low limit of detection and limit of quantification, high recovery, and high intra- and interday repeatability. It was found that internal standard method with diluted stable isotope (4-MeI-d 6 ) and 2-ethylimidazole (2-EI) could not correctly compensate the matrix effects. Thus, standard addition technique was used for the quantification of 2- and 4-MeI. The established method was successfully applied to colas and dark beers for the determination of 2-MeI and 4-MeI. The 4-MeI contents in colas and dark beers ranged from 8 to 319 μg/L and from trace to 417 μg/L, respectively. Small quantity (0 to 8 μg/L) of 2-MeI was found only in dark beers. The contents of 4-MeI (22 μg/L) in colas obtained from fast food restaurants were significantly lower than those (177 μg/L) in canned or bottled colas. © 2017 Institute of Food Technologists®.

Analysis of 13C-mixed triacylglycerol in stool by bulk (EA-IRMS) and compound specific (GC/MS) methods.

PubMed

Slater, C; Ling, S C; Preston, T; Weaver, L T

2002-06-01

This paper was presented in poster form at the 17th International Congress of Nutrition, August 27-31, Vienna, Austria (Annals of Nutrition & Metabolism 2001; 45(Suppl.1):349). Some of the data were also presented in poster form at the British Society of Gastroenterology Meeting, March 18-21, Glasgow, UK (Gut 2001; 48(Suppl.1):A91). The 13C-mixed triacylglycerol (MTG) breath test is used to measure intraluminal fat digestion. In normal digestion, 20-40% of the ingested 13C label is recovered in breath CO2. We aimed to identify the proportions of ingested label excreted in stool, as well as breath following ingestion of 13C-MTG by children with impaired exocrine pancreatic function and healthy controls. 13C enrichment of breath samples was measured by continuous flow isotope ratio mass spectrometry (IRMS) and cumulative percent dose recovered (cPDR) in 10 h was calculated. Total 13C of a faecal fat extract from each stool was measured by elemental analyser-IRMS, and 13C enrichment and concentration of the TBDMS derivative of octanoic acid was measured by GC/MS after hydrolysis of the fat extract. Stool 5-day cPDR was calculated. Mean breath cPDR was 35%. Mean cPDR in stool by combustion-IRMS and GC/ MS, respectively, was 0.8% and 1.0%. Therefore, the remaining 64% of the 13C label must remain in the body and variability in breath cPDR is due to postabsorptive rather than predigestive factors.

Identification of metabolites of malathion in plant, water and soil by GC-MS.

PubMed

Kaur, I; Mathur, R P; Tandon, S N; Dureja, P

1997-01-01

Metabolism of malathion (O,O,-dimethyl S-[1,2-bis(ethoxy carbonyl)-ethyl]phosphorodithioate) has been studied in plants, water and soil. A number of products identified by gas chromatography-mass spectrometry (GC-MS), have been formed by de-esterification, oxidation and hydrolysis of malathion. Hydrolysis of the P-S and C-S bonds occur in alkaline pH 8.0 and acidic pH 5.5, respectively.

Trace-Level Volatile Quantitation by Direct Analysis in Real Time Mass Spectrometry following Headspace Extraction: Optimization and Validation in Grapes.

PubMed

Jastrzembski, Jillian A; Bee, Madeleine Y; Sacks, Gavin L

2017-10-25

Ambient ionization mass spectrometric (AI-MS) techniques like direct analysis in real time (DART) offer the potential for rapid quantitative analyses of trace volatiles in food matrices, but performance is generally limited by the lack of preconcentration and extraction steps. The sensitivity and selectivity of AI-MS approaches can be improved through solid-phase microextraction (SPME) with appropriate thin-film geometries, for example, solid-phase mesh-enhanced sorption from headspace (SPMESH). This work improves the SPMESH-DART-MS approach for use in food analyses and validates the approach for trace volatile analysis for two compounds in real samples (grape macerates). SPMESH units prepared with different sorbent coatings were evaluated for their ability to extract a range of odor-active volatiles, with poly(dimethylsiloxane)/divinylbenzene giving the most satisfactory results. In combination with high-resolution mass spectrometry (HRMS), detection limits for SPMESH-DART-MS under 4 ng/L in less than 30 s acquisition times could be achieved for some volatiles [3-isobutyl-2-methoxypyrazine (IBMP) and β-damascenone]. A comparison of SPMESH-DART-MS and SPME-GC-MS quantitation of linalool and IBMP demonstrates excellent agreement between the two methods for real grape samples (r 2 ≥ 0.90), although linalool measurements appeared to also include isobaric interference.

Development of a HS-SPME-GC-MS/MS Method for the Quantitation of Thymol and Carvacrol in Bovine Matrices and To Determine Residue Depletion in Milk and Tissues.

PubMed

Armorini, Sara; Yeatts, James E; Mullen, Keena A E; Mason, Sharon E; Mehmeti, Elmira; Anderson, Kevin L; Washburn, Steve P; Baynes, Ronald E

2016-10-11

Thymol and carvacrol may be present in several phytoceutical products but there are no well-defined methods to measure these compounds in meat and milk from treated animals. U.S. regulatory authorities deem their presence as an adulteration of food. A rapid and sensitive HS-SPME-GC-MS/MS method was developed for the detection of thymol and carvacrol in bovine milk, plasma, liver, kidney, and fat. Inter- and intraday precision values were all less than 15.7 and 20.2% for thymol and carvacrol, respectively. The accuracy was in ranges of 69.9-111.8% for thymol and 74.0-119.2% for carvacrol. With the exception of fat tissue, stability studies showed that both compounds are stable over a 2 month period. A pilot pharmacokinetic study was conducted to evaluate the developed analytical method and to provide initial estimates of thymol and carvacrol depletion in plasma, milk, and several tissues. Treatment of lactating dairy cattle with phytoceutical products containing these substances resulted in low but measurable residue levels at 96 h for liver and 36 h for milk with very short apparent plasma and milk half-lives (<3.0 h).

Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC.

PubMed

Negahdar, Leila; Gonzalez-Quiroga, Arturo; Otyuskaya, Daria; Toraman, Hilal E; Liu, Li; Jastrzebski, Johann T B H; Van Geem, Kevin M; Marin, Guy B; Thybaut, Joris W; Weckhuysen, Bert M

2016-09-06

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13 C nuclear magnetic resonance ( 13 C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13 C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

PubMed Central

2016-01-01

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil. PMID:27668136

A New Algorithm Using Cross-Assignment for Label-Free Quantitation with LC/LTQ-FT MS

PubMed Central

Andreev, Victor P.; Li, Lingyun; Cao, Lei; Gu, Ye; Rejtar, Tomas; Wu, Shiaw-Lin; Karger, Barry L.

2008-01-01

A new algorithm is described for label-free quantitation of relative protein abundances across multiple complex proteomic samples. Q-MEND is based on the denoising and peak picking algorithm, MEND, previously developed in our laboratory. Q-MEND takes advantage of the high resolution and mass accuracy of the hybrid LTQFT MS mass spectrometer (or other high resolution mass spectrometers, such as a Q-TOF MS). The strategy, termed “cross-assignment”, is introduced to increase substantially the number of quantitated proteins. In this approach, all MS/MS identifications for the set of analyzed samples are combined into a master ID list, and then each LC/MS run is searched for the features that can be assigned to a specific identification from that master list. The reliability of quantitation is enhanced by quantitating separately all peptide charge states, along with a scoring procedure to filter out less reliable peptide abundance measurements. The effectiveness of Q-MEND is illustrated in the relative quantitative analysis of E.coli samples spiked with known amounts of non-E.coli protein digests. A mean quantitation accuracy of 7% and mean precision of 15% is demonstrated. Q-MEND can perform relative quantitation of a set of LC/MS datasets without manual intervention and can generate files compatible with the Guidelines for Proteomic Data Publication. PMID:17441747

A new algorithm using cross-assignment for label-free quantitation with LC-LTQ-FT MS.

PubMed

Andreev, Victor P; Li, Lingyun; Cao, Lei; Gu, Ye; Rejtar, Tomas; Wu, Shiaw-Lin; Karger, Barry L

2007-06-01

A new algorithm is described for label-free quantitation of relative protein abundances across multiple complex proteomic samples. Q-MEND is based on the denoising and peak picking algorithm, MEND, previously developed in our laboratory. Q-MEND takes advantage of the high resolution and mass accuracy of the hybrid LTQ-FT MS mass spectrometer (or other high-resolution mass spectrometers, such as a Q-TOF MS). The strategy, termed "cross-assignment", is introduced to increase substantially the number of quantitated proteins. In this approach, all MS/MS identifications for the set of analyzed samples are combined into a master ID list, and then each LC-MS run is searched for the features that can be assigned to a specific identification from that master list. The reliability of quantitation is enhanced by quantitating separately all peptide charge states, along with a scoring procedure to filter out less reliable peptide abundance measurements. The effectiveness of Q-MEND is illustrated in the relative quantitative analysis of Escherichia coli samples spiked with known amounts of non-E. coli protein digests. A mean quantitation accuracy of 7% and mean precision of 15% is demonstrated. Q-MEND can perform relative quantitation of a set of LC-MS data sets without manual intervention and can generate files compatible with the Guidelines for Proteomic Data Publication.

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.

Larvicidal activity and GC-MS analysis of flavonoids of Vitex negundo and Andrographis paniculata against two vector mosquitoes Anopheles stephensi and Aedes aegypti.

PubMed

Gautam, Keerti; Kumar, Padma; Poonia, Sawitri

2013-09-01

Development of insect resistance to synthetic pesticides, high operational cost and environmental pollution have created the need for developing alternative approaches to control vector-borne diseases. In the present study, larvicidal activity of flavonoid extracts of different parts of Vitex negundo (Linnaeus) and Andrographis paniculata (Nees) have been studied against the late III or early IV instar larvae of Aedes aegypti and Anopheles stephensi (Liston). Flavonoids were extracted from different parts of the selected plants using standard method. Bioassay test was carried out by WHO method for determination of larvicidal activity against mosquitoes. Different compounds of the most active extract were identified by the gas chromatography-mass spectrometry (GC-MS) analysis. Flavonoid extract of whole aerial part of A. paniculata was found to be inactive against the selected larvae of Ae. aegypti even at the concentration of 600 ppm, whereas it caused 70% mortality in An. stephensi at the concentration of 200 ppm. Flavonoid extract of flower-buds produced highest mortality (100%) at the concentration of 600 ppm for the late III or early IV instar larvae of Ae. aegypti and at the concentration of 200 ppm for the larvae of An. stephensi. GC-MS analysis of the most active flavonoid extract from flower-buds of Vitex showed 81 peaks. Phenol (26.83% area), naphthalene (4.95% area), 2,3-dihydrobenzofuran (6.79% area), Phenol-2,4-Bis (1,1-dimethyl) (4.49% area), flavones 4'-OH,5-OH,7-di-O-glucoside (0.25% area) and 5-hydroxy- 3,6,7,3',4'-pentamethoxy flavones (0.80% area) were present in major amount. Flavonoid extracts from different parts of two selected plants possess larvicidal activity against two selected mosquito species, hence, could be utilized for developing flavonoid-based, eco-friendly insecticide as an alternative to synthetic insecticides.

Determination of musks and other fragrance compounds at ng/L levels using CLSA (closed loop stripping analysis) and GC/MS detection.

PubMed

Mitjans, D; Ventura, F

2004-01-01

Closed loop stripping analysis (CLSA), a suitable tool for the determination of volatile and semivolatile compounds at low trace levels (ng/l), has been used to determine and quantify seven selected musks and two fragrances (Acetyl cedrene and Amberonne). The obtained extracts are analyzed by high resolution gas chromatography coupled to mass spectrometry (GC/MS) operating in the SIM mode. Quality parameters such as limit of detection; matrix effects; precision expressed as repeatability and reproducibility relative standard deviations of the method and an estimation of the uncertainty have been evaluated. The method has been applied to the analysis of wastewater effluents, surface water and tap water from different places in Europe. All samples contained differents musks at ng/l levels with the polycyclic musks Galaxolide and Tonalide and both fragrances, Amberonne and Acetyl cedrene, being the most abundant. These results suggest the importance of studying and controlling the presence of these ubiquitous environmental compounds in water systems.

Nanodetection of the disinfection by-products on GC-MS techniques

NASA Astrophysics Data System (ADS)

Ristoiu, Dumitru; Haydee, Melinda; Ristoiu, Tania

2009-01-01

Exposures to disinfection by-products (DBPs) in residential drinking water occur through multiple routes and vary across the population because of differences in the amount and ways people use water. Municipal water in the Romania is disinfected, with chlorine being the most common disinfectant agent. Disinfection of water, in additional to having the benefit of destroying microbes that can transmit diseases, has the drawback of producing a series of compounds known as disinfection by-products (DBPs). Chlorination produces many compounds containing chlorine and/or bromine, some of which have been shown to be carcinogenic, mutagenic, and/or teratogenic in animal studies. The most abundant class of DBPs that result from chlorination of drinking water are trihalomethanes (THMs) - chloroform (CHCl3), dichlorobromomethane (CHCl2Br), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3). The most predominant THM species was CHCl3 and it highest concentration was 85•106 ng/m3. The others THMs compounds concentration were lower, between 65•104 ng/m3 and 12•106 ng/m3. THMs compounds were analyzed on gas chromatography coupled with mass spectrometer detector (GC-MS) and head space technique (HS) was used for all analysis.

Determination of n-alkanes in C. annuum (bell pepper) fruit and seed using GC-MS: comparison of extraction methods and application to samples of different geographical origin.

PubMed

de Rijke, E; Fellner, C; Westerveld, J; Lopatka, M; Cerli, C; Kalbitz, K; de Koster, C G

2015-07-01

An efficient extraction and analysis method was developed for the isolation and quantification of n-alkanes from bell peppers of different geographical locations. Five extraction techniques, i.e., accelerated solvent extraction (ASE), ball mill extraction, ultrasonication, rinsing, and shaking, were quantitatively compared using gas chromatography coupled to mass spectrometry (GC-MS). Rinsing of the surface wax layer of freeze-dried bell peppers with chloroform proved to be a relatively quick and easy method to efficiently extract the main n-alkanes C27, C29, C31, and C33. A combined cleanup and fractionation approach on Teflon-coated silica SPE columns resulted in clean chromatograms and gave reproducible results (recoveries 90-95 %). The GC-MS method was reproducible (R(2) = 0.994-0.997, peak area standard deviation = 2-5%) and sensitive (LODs, S/N = 3, 0.05-0.15 ng/μL). The total main n-alkane concentrations were in the range of 5-50 μg/g dry weight. Seed extractions resulted in much lower total amounts of extracted n-alkanes compared to flesh and surface extractions, demonstrating the need for further improvement of pre-concentration and cleanup. The method was applied to 131 pepper samples from four different countries, and by using the relative n-alkane concentration ratios, Dutch peppers could be discriminated from those of the other countries, with the exception of peppers from the same cultivar. Graphical Abstract Procedure for pepper origin determination.