Rapid determination of amino acids in neonatal blood samples based on derivatization with isobutyl chloroformate followed by solid-phase microextraction and gas chromatography/mass spectrometry.

PubMed

Deng, Chunhui; Li, Ning; Zhang, Xiangmin

2004-01-01

The purpose of this study was to develop a simple, rapid and sensitive analytical method for determination of amino acids in neonatal blood samples. The developed method involves the employment of derivatization and a solid-phase microextraction (SPME) technique together with gas chromatography/mass spectrometry (GC/MS). Amino acids in blood samples were derivatized by a mixture of isobutyl chloroformate, methanol and pyridine, and the N(O,S)-alkoxycarbonyl alkyl esters thus formed were headspace extracted by a SPME fiber. Finally, the extracted analytes on the fiber were desorbed and detected by GC/MS in electron impact (EI) mode. L-Valine, L-leucine, L-isoleucine, L-phenylanaline and L-tyrosine in blood samples were quantitatively analyzed by measurement of the corresponding N(O,S)-alkoxycarbonyl alkyl esters using an external standard method. SPME conditions were optimized, and the method was validated. The method was applied to diagnosis of neonatal phenylkenuria (PKU) and maple syrup urine disease (MSUD) by the analyses of five amino acids in blood samples. The results showed that the proposed method is a potentially powerful tool for simultaneous screening for neonatal PKU and MSUD. Copyright (c) 2004 John Wiley & Sons, Ltd.

Quantitation of fumonisin B1 and B2 in feed using FMOC pre-column derivatization with HPLC and fluorescence detection.

PubMed

Smith, Lori L; Francis, Kyle A; Johnson, Joseph T; Gaskill, Cynthia L

2017-11-01

Pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) was determined to be effective for quantitation of fumonisins B 1 and B 2 in feed. Liquid-solid extraction, clean-up using immunoaffinity solid phase extraction chromatography, and FMOC-derivatization preceded analysis by reverse phase HPLC with fluorescence. Instrument response was unchanged in the presence of matrix, indicating no need to use matrix-matched calibrants. Furthermore, high method recoveries indicated calibrants do not need to undergo clean-up to account for analyte loss. Established method features include linear instrument response from 0.04-2.5µg/mL and stable derivatized calibrants over 7days. Fortified cornmeal method recoveries from 0.1-30.0μg/g were determined for FB 1 (75.1%-109%) and FB 2 (96.0%-115.2%). Inter-assay precision ranged from 1.0%-16.7%. Method accuracy was further confirmed using certified reference material. Inter-laboratory comparison with naturally-contaminated field corn demonstrated equivalent results with conventional derivatization. These results indicate FMOC derivatization is a suitable alternative for fumonisins B 1 and B 2 quantitation in corn-based feeds. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization].

PubMed

Wang, Xiaoyan; Qi, Weimei; Zhao, Xian'en; Lü, Tao; Wang, Xiya; Zheng, Longfang; Yan, Yehao; You, Jinmao

2014-06-01

To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 microL chloroform as extraction solvent, 400 microL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na2CO3-NaHCO3 buffer/acetonitrile at 50 degrees C for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc.

Liquid chromatography coupled to quadrupole-time of flight tandem mass spectrometry based quantitative structure-retention relationships of amino acid analogues derivatized via n-propyl chloroformate mediated reaction.

PubMed

Kritikos, Nikolaos; Tsantili-Kakoulidou, Anna; Loukas, Yannis L; Dotsikas, Yannis

2015-07-17

In the current study, quantitative structure-retention relationships (QSRR) were constructed based on data obtained by a LC-(ESI)-QTOF-MS/MS method for the determination of amino acid analogues, following their derivatization via chloroformate esters. Molecules were derivatized via n-propyl chloroformate/n-propanol mediated reaction. Derivatives were acquired through a liquid-liquid extraction procedure. Chromatographic separation is based on gradient elution using methanol/water mixtures from a 70/30% composition to an 85/15% final one, maintaining a constant rate of change. The group of examined molecules was diverse, including mainly α-amino acids, yet also β- and γ-amino acids, γ-amino acid analogues, decarboxylated and phosphorylated analogues and dipeptides. Projection to latent structures (PLS) method was selected for the formation of QSRRs, resulting in a total of three PLS models with high cross-validated coefficients of determination Q(2)Y. For this reason, molecular structures were previously described through the use of descriptors. Through stratified random sampling procedures, 57 compounds were split to a training set and a test set. Model creation was based on multiple criteria including principal component significance and eigenvalue, variable importance, form of residuals, etc. Validation was based on statistical metrics Rpred(2),QextF2(2),QextF3(2) for the test set and Roy's metrics rm(Av)(2) and rm(δ)(2), assessing both predictive stability and internal validity. Based on aforementioned models, simplified equivalent were then created using a multi-linear regression (MLR) method. MLR models were also validated with the same metrics. The suggested models are considered useful for the estimation of retention times of amino acid analogues for a series of applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Indirect enantioseparation of fluoxetine in mouse serum by derivatization with 1R-(-)-menthyl chloroformate followed by ultra high performance liquid chromatography and quadrupole time-of-flight mass spectrometry.

PubMed

Zhao, Jing; Jin, Yan; Shin, Yujin; Jeong, Kyung Min; Lee, Jeongmi

2016-03-01

Here we describe a simple and sensitive analytical method for the enantioselective quantification of fluoxetine in mouse serum using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry. The sample preparation method included a simple deproteinization with acetonitrile in 50 μL of serum, followed by derivatization of the extracts in 50 μL of 2 mM 1R-(-)-menthyl chloroformate at 45ºC for 55 min. These conditions were statistically optimized through response surface methodology using a central composite design. Under the optimized conditions, neither racemization nor kinetic resolution occurred. The derivatized diastereomers were readily resolved on a conventional sub-2 μm C18 column under a simple gradient elution of aqueous methanol containing 0.1% formic acid. The established method was validated and found to be linear, precise, and accurate over the concentration range of 5.0-1000.0 ng/mL for both R and S enantiomers (r(2) > 0.993). Stability tests of the prepared samples at three different concentration levels showed that the R- and S-fluoxetine derivatives were relatively stable for 48 h. No significant matrix effects were observed. Last, the developed method was successfully used for enantiomeric analysis of real serum samples collected at a number of time points from mice administered with racemic fluoxetine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Estrogens determination in wastewater samples by automatic in-syringe dispersive liquid-liquid microextraction prior silylation and gas chromatography.

PubMed

González, Alba; Avivar, Jessica; Cerdà, Víctor

2015-09-25

A new procedure for the extraction, preconcentration and simultaneous determination of the estrogens most used in contraception pharmaceuticals (estrone, 17β-estradiol, estriol, and 17α-ethynylestradiol), cataloged as Contaminants of Emergent Concern by the Environmental Protection Agency of the United States (US-EPA), is proposed. The developed system performs an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction (in-syringe-MSA-DLLME) prior derivatization and gas chromatography (GC-MS). Different extraction (carbon tetrachloride, ethyl acetate, chloroform and trichloroethylene) and disperser solvents (acetone, acetonitrile and methanol) were tested. Chloroform and acetone were chosen as extraction and disperser solvent, respectively, as they provided the best extraction efficiency. Then, a multivariate optimization of the extraction conditions was carried out. Derivatization conditions were also studied to ensure the conversion of the estrogens to their respective trimethylsilyl derivatives. Low LODs and LOQs were achieved, i.e. between 11 and 82ngL(-1), and 37 and 272ngL(-1), respectively. Good values for intra and inter-day precision were obtained (RSDs≤7.06% and RSD≤7.11%, respectively). The method was successfully applied to wastewater samples. Copyright © 2015 Elsevier B.V. All rights reserved.

In matrix derivatization of trichloroethylene metabolites in human plasma with methyl chloroformate and their determination by solid-phase microextraction-gas chromatography-electron capture detector.

PubMed

Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Varshney, Meenu; Ch, Ratnasekhar; Chauhan, Abhishek; Goyal, Sudhir Kumar; Khan, Haider A; Murthy, R C

2013-04-15

Trichloroethylene (TCE) is a common industrial chemical that has been widely used as metal degreaser and for many industrial purposes. In humans, TCE is metabolized into dichloroacetic acid (DCA), trichloroacetic acid (TCA) and trichloroethanol (TCOH). A simple and rapid method has been developed for the quantitative determination of TCE metabolites. The procedure involves the in situ derivatization of TCE metabolites with methyl chloroformate (MCF) directly in diluted plasma samples followed by extraction and analysis with solid-phase microextraction (SPME) coupled to gas chromatography-electron capture detector (GC-ECD). Factors which can influence the efficiency of derivatization such as amount of MCF and pyridine (PYR), ratio of water/methanol were optimized. The factors which can affect the extraction efficiencies of SPME were screened using 2(7-4) Placket-Burman Design (PBD). A central composite design (CCD) was then applied to further optimize the most significant factors for optimum SPME extraction. The optimum factors for the SPME extraction were found to be 562.5mg of NaCl, pH at 1 and an extraction time of 22 min. Recoveries and detection limits of all three analytes in plasma were found to be in the range of 92.69-97.55% and 0.036-0.068 μg mL(-1) of plasma, respectively. The correlation coefficients were found to be in the range of 0.990-0.995. The intra- and inter-day precisions for TCE metabolites were found to be in the range of 2.37-4.81% and 5.13-7.61%, respectively. The major advantage of this method is that MCF derivatization allows conversion of TCE metabolites into their methyl esters in very short time (≤30 s) at room temperature directly in the plasma samples, thus makes it a solventless analysis. The method developed was successfully applied to the plasma samples of humans exposed to TCE. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of efficacy of fingermark enhancement reagents; the use of propyl chloroformate for the derivatization of fingerprint amino acids extracted from paper.

PubMed

Mink, Tineke; Voorhaar, Annelies; Stoel, Reinoud; de Puit, Marcel

2013-09-01

The analysis of the constituents of fingerprints has been described numerous times, mainly with the purpose of determining the aging effect on fingerprints or showing the differences between donors or groups of donors. In this paper we describe the use of derivatized amino acids to determine the efficacy of the visualization reagents 1,8-diazafluoren-9-one (DFO) and ninhydrin. At present certain conditions are used for the application of these reagents, as determined by trial-and-error investigations, to the effect on fingerprints. The recovery of amino acids from a porous surface can be used as a measure for the efficacy of a visualization agent. In this paper we describe a method for the determination of the amount of amino acid left after reaction with well known fingerprint visualization reagents. This will allow a more scientific approach to method development for fingermark enhancement techniques. Furthermore, investigations on the influence of the concentration of fingermark amino acids, the order of application of and exposure time to reagents and the influence of age of the amino acids were carried out. These studies have resulted in a broader understanding of the mechanism involved in visualization of fingermarks using DFO and ninhydrin. Copyright © 2013 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

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

Li, Feng; Cooper, S.F.

A novel gas chromatography-mass spectrometric (GC-MS) method was developed to confirm and identify metoprolol and its metabolites by double derivatization with S-(-)menthyl chloroformate [(-)-MCF] and N-methyl(trimethylsilyl-trifluoroacetamide) (MSTFA). This is the first report, which describes the simultaneous identification of metoprolol, its one major acidc and other basic metabolites in human urine based on solid-phase extraction with C{sub 18} reversed-phase cartridges. 12 refs., 4 figs.

Development of New Decon Green (registered trademark): A How-To Guide for the Rapid Decontamination of CARC Paint

DTIC Science & Technology

2008-09-01

sodium carbonate, and extracted with 2-mL chloroform. The chloroform layer was analyzed for residual agent by Gas Chromatography /Atomic Emission...agent remaining on the panel. Solutions were analyzed by Gas Chromatography /Flame-Ionization Detector (GC/FID) to determine the amounts of agent...transferred to glass scintillation vials. A 100-µL aliquot of the DEP was diluted with 900-µL chloroform (1:10 dilution) in a Gas Chromatography

A new agent for derivatizing carbonyl species used to investigate limonene ozonolysis

NASA Astrophysics Data System (ADS)

Wells, J. R.; Ham, Jason E.

2014-12-01

A new method for derivatizing carbonyl compounds is presented. The conversion of a series of dicarbonyls to oximes in aqueous solution and from gas-phase sampling was achieved using O-tert-butylhydroxylamine hydrochloride (TBOX). Some advantages of using this derivatization agent include: aqueous reactions, lower molecular weight oximes, and shortened oxime-formation reaction time. Additionally, the TBOX derivatization technique was used to investigate the carbonyl reaction products from limonene ozonolysis. With ozone (O3) as the limiting reagent, four carbonyl compounds were detected: 7-hydroxy-6-oxo-3-(prop-1-en-2-yl)heptanal; 3-Isopropenyl-6-oxoheptanal (IPOH), 3-acetyl-6-oxoheptanal (3A6O) and one carbonyl of unknown structure. Using cyclohexane as a hydroxyl (OHrad) radical scavenger, the relative yields (peak area) of the unknown carbonyl, IPOH, and 3A6O were reduced indicating the influence secondary OH radicals have on limonene ozonolysis products. The relative yield of the hydroxy-dicarbonyl based on the chromatogram was unchanged suggesting it is only made by the limonene + O3 reaction. The detection of 3A6O using TBOX highlights the advantages of a smaller molecular weight derivatization agent for the detection of multi-carbonyl compounds. The use of TBOX derivatization if combined with other derivatization agents may address a recurring need to simply and accurately detect multi-functional oxygenated species in air.

Determining the fatty acid composition in plasma and tissues as fatty acid methyl esters using gas chromatography – a comparison of different derivatization and extraction procedures.

PubMed

Ostermann, Annika I; Müller, Maike; Willenberg, Ina; Schebb, Nils Helge

2014-12-01

Analysis of the fatty acid (FA) composition in biological samples is commonly carried out using gas liquid chromatography (GC) after transesterification to volatile FA methyl esters (FAME). We compared the efficacy of six frequently used protocols for derivatization of different lipid classes as well as for plasma and tissue samples. Transesterification with trimethylsulfonium hydroxide (TMSH) led to insufficient derivatization efficacies for polyunsaturated FAs (PUFA, <50%). Derivatization in presence of potassium hydroxide (KOH) failed at derivatizing free FAs (FFAs). Boron trifluoride (BF3) 7% in hexane/MeOH (1:1) was insufficient for the transesterification of cholesterol ester (CE) as well as triacylglycerols (TGs). In contrast, methanolic hydrochloric acid (HCl) as well as a combination of BF3 with methanolic sodium hydroxide (NaOH+BF3) were suitable for the derivatization of FFAs, polar lipids, TGs, and CEs (derivatization rate >80% for all tested lipids). Regarding plasma samples, all methods led to an overall similar relative FA pattern. However, significant differences were observed, for example, for the relative amount of EPA+DHA (n3-index). Absolute FA plasma concentrations differed considerably among the methods, with low yields for KOH and BF3. We also demonstrate that lipid extraction with tert-butyl methyl ether/methanol (MTBE/MeOH) is as efficient as the classical method according to Bligh and Dyer, making it possible to replace (environmentally) toxic chloroform.We conclude that HCl-catalyzed derivatization in combination with MeOH/MTBE extraction is the most appropriate among the methods tested for the analysis of FA concentrations and FA pattern in small biological samples. A detailed protocol for the analysis of plasma and tissues is included in this article.

Derivatization coupled to headspace programmed-temperature vaporizer gas chromatography with mass spectrometry for the determination of amino acids: Application to urine samples.

PubMed

González Paredes, Rosa María; García Pinto, Carmelo; Pérez Pavón, José Luis; Moreno Cordero, Bernardo

2016-09-01

A new method based on headspace programmed-temperature vaporizer gas chromatography with mass spectrometry has been developed and validated for the determination of amino acids (alanine, sarcosine, ethylglycine, valine, leucine, and proline) in human urine samples. Derivatization with ethyl chloroformate was employed successfully to determine the amino acids. The derivatization reaction conditions as well as the variables of the headspace sampling were optimized. The existence of a matrix effect was checked and the analytical characteristics of the method were determined. The limits of detection were 0.15-2.89 mg/L, and the limits of quantification were 0.46-8.67 mg/L. The instrumental repeatability was 1.6-11.5%. The quantification of the amino acids in six urine samples from healthy subjects was performed with the method developed with the one-point standard additions protocol, with norleucine as the internal standard. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biochemical surface modification of Co-Cr-Mo.

PubMed

Puleo, D A

1996-01-01

Because of the limited mechanical properties of tissue substitutes formed by culturing cells on polymeric scaffolds, other approaches to tissue engineering must be explored for applications that require complete and immediate ability to bear weight, e.g. total joint replacements. Biochemical surface modification offers a way to partially regulate events at the bone-implant interface to obtain preferred tissue responses. Tresyl chloride, gamma-aminopropyltriethoxysilane (APS) and p-nitrophenyl chloroformate (p-NPC) immobilization schemes were used to couple a model enzyme, trypsin, on bulk samples of Co-Cr-Mo. For comparison, samples were simply adsorbed with protein. The three derivatization schemes resulted in different patterns and levels of activity. Tresyl chloride was not effective in immobilizing active enzyme on Co-Cr-Mo. Aqueous silanization with 12.5% APS resulted in optimal immobilized activity. Activity on samples derivatized with 0.65 mg p-NPC cm-2 was four to five times greater than that on samples simple adsorbed with enzyme or optimally derivatized with APS and was about eight times that on tresylated samples. This work demonstrates that, although different methods have different effectiveness, chemical derivatization can be used to alter the amount and/or stability of biomolecules immobilized on the surface of Co-Cr-Mo.

Urinary Amino Acid Analysis: A Comparison of iTRAQ®-LC-MS/MS, GC-MS, and Amino Acid Analyzer

PubMed Central

Kaspar, Hannelore; Dettmer, Katja; Chan, Queenie; Daniels, Scott; Nimkar, Subodh; Daviglus, Martha L.; Stamler, Jeremiah; Elliott, Paul; Oefner, Peter J.

2009-01-01

Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino acid standard, we compared the precision and accuracy of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of propyl chloroformate and iTRAQ® derivatized amino acids, respectively, to conventional amino acid analysis. The GC-MS method builds on the direct derivatization of amino acids in diluted urine with propyl chloroformate, GC separation and mass spectrometric quantification of derivatives using stable isotope labeled standards. The LC-MS/MS method requires prior urinary protein precipitation followed by labeling of urinary and standard amino acids with iTRAQ® tags containing different cleavable reporter ions distinguishable by MS/MS fragmentation. Means and standard deviations of percent technical error (%TE) computed for 20 amino acids determined by amino acid analyzer, GC-MS, and iTRAQ®-LC-MS/MS analyses of 33 duplicate and triplicate urine specimens were 7.27±5.22, 21.18±10.94, and 18.34±14.67, respectively. Corresponding values for 13 amino acids determined in a second batch of 144 urine specimens measured in duplicate or triplicate were 8.39±5.35, 6.23±3.84, and 35.37±29.42. Both GC-MS and iTRAQ®-LC-MS/MS are suited for high-throughput amino acid analysis, with the former offering at present higher reproducibility and completely automated sample pretreatment, while the latter covers more amino acids and related amines. PMID:19481989

Urinary amino acid analysis: a comparison of iTRAQ-LC-MS/MS, GC-MS, and amino acid analyzer.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Chan, Queenie; Daniels, Scott; Nimkar, Subodh; Daviglus, Martha L; Stamler, Jeremiah; Elliott, Paul; Oefner, Peter J

2009-07-01

Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino acid standard, we compared the precision and accuracy of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of propyl chloroformate and iTRAQ derivatized amino acids, respectively, to conventional amino acid analysis. The GC-MS method builds on the direct derivatization of amino acids in diluted urine with propyl chloroformate, GC separation and mass spectrometric quantification of derivatives using stable isotope labeled standards. The LC-MS/MS method requires prior urinary protein precipitation followed by labeling of urinary and standard amino acids with iTRAQ tags containing different cleavable reporter ions distinguishable by MS/MS fragmentation. Means and standard deviations of percent technical error (%TE) computed for 20 amino acids determined by amino acid analyzer, GC-MS, and iTRAQ-LC-MS/MS analyses of 33 duplicate and triplicate urine specimens were 7.27+/-5.22, 21.18+/-10.94, and 18.34+/-14.67, respectively. Corresponding values for 13 amino acids determined in a second batch of 144 urine specimens measured in duplicate or triplicate were 8.39+/-5.35, 6.23+/-3.84, and 35.37+/-29.42. Both GC-MS and iTRAQ-LC-MS/MS are suited for high-throughput amino acid analysis, with the former offering at present higher reproducibility and completely automated sample pretreatment, while the latter covers more amino acids and related amines.

Identification of fentanyl metabolites in rat urine by gas chromatography-mass spectrometry with stable-isotope tracers

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

Goromaru, T.; Matsuura, H.; Furuta, T.

The metabolites of fentanyl (l), which has been widely used as a neuroleptic analgesic agent, were identified in urine of rats by gas chromatography-mass spectrometry combined with a stable-isotope tracer technique. After the oral administration of an equimolar mixture of l and deuterium-labeled l (l/l-d5), the urinary metabolites were extracted with chloroform at pH 9.0. Extracts were derivatized and analyzed by GC/MS. Metabolites were identified by the presence of doublet ion peaks separated by 5 amu, and chemical structures were established from analyses of fragmentation pathways. The metabolites were identified as 4-N-(N-propionylanilino)-piperidine, 4-N-(N-hydroxypropionylanilino)piperidine, 4-N-(N-propionylanilino) hydroxypiperidine, 1-(2-phenethyl)-4-N-(N-hydroxypropionylanilino)piperidine and 1-(2-phenethyl)-4-N-(N-propionylanilino)hydroxypiperidine. These metabolites,more » together with unchanged l, were also detected in urine of rats receiving l/l-d5 intravenously, by selected-ion monitoring of the specific cluster ions.« less

Development of a simple and rapid solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry method for the analysis of dopamine, serotonin and norepinephrine in human urine.

PubMed

Naccarato, Attilio; Gionfriddo, Emanuela; Sindona, Giovanni; Tagarelli, Antonio

2014-01-31

The work aims at developing a simple and rapid method for the quantification of dopamine (DA), serotonin (5-HT) and norepinephrine (NE) in human urine. The urinary levels of these biogenic amines can be correlated with several pathological conditions concerning heart disease, stress, neurological disorders and cancerous tumors. The proposed analytical approach is based on the use of solid phase microextraction (SPME) combined with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) after a fast derivatization of both aliphatic amino and phenolic moieties by propyl chloroformate. The variables influencing the derivatization reaction were reliably optimized by the multivariate approach of "Experimental design". The optimal conditions were obtained by performing derivatization with 100μL of propyl chloroformate and 100μL of pyridine. The extraction ability of five commercially available SPME fibers was evaluated in univariate mode and the best results were obtained using the polyacrylate fiber. The variables affecting the efficiency of SPME analysis were again optimized by the multivariate approach of "Experimental design" and, in particular, a central composite design (CCD) was applied. The optimal values were extraction in 45min at room temperature, desorption temperature at 300°C, no addition of NaCl. Assay of derivatized analytes was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) system in selected reaction monitoring (SRM) acquisition. An evaluation of all analytical parameters demonstrates that the developed method provides satisfactory results. Indeed, very good linearities were achieved in the tested calibration range with correlation coefficient values of 0.9995, 0.9999 and 0.9997 for DA, 5-HT and NE, respectively. Accuracies and RSDs calculated for between-run and tested at concentrations of 30, 200, and 800μg L(-1) were in the range from 92.8% to 103.0%, and from 0.67 to 4.5%, respectively. Finally, the LOD values obtained can be considered very good (0.587, 0.381 and 1.23μg L(-1) for DA, 5-HT and NE, respectively). Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

PubMed

López-Nogueroles, Marina; Chisvert, Alberto; Salvador, Amparo

2014-05-15

A new analytical method based on simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC-MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid-liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample solution, free of the low polar matrix from the essential oils, as donor phase. Different parameters, such as the nature and volume of both the extraction and disperser solvents, the ionic strength of the aqueous donor phase or the effect of the derivatization reagent volume, were optimized. Under the selected conditions (injection of a mixture of 750μL of acetone as disperser solvent, 100μL of chloroform as extraction solvent and 100μL of anhydride acetic as derivatization reagent) the figures of merit of the proposed method were evaluated. Limits of detection in the low ngmL(-1) range were obtained. Matrix effect was observed in real perfume samples and thus, standard addition calibration is recommended. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of oxidized coal surfaces: Quarterly report, May 1988--September 1988

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

Hercules, D. M.

1988-01-01

Laser mass spectra have been obtained of 2-fluoro-1-methylpyridinium (FMP) derivatized coal consistent with a prime objective of this research. This reagent, specific for the hydroxy functionality, produced major peaks at m/z 184 and 199 in the spectra of Pocahontas coal following derivatization. A gas phase reactor was built in order to enhance coal derivatization. Gas phase derivatization was accomplished on model compounds. Derivatization was carried out on Illinois No. 6 coal and analyzed with DRIFTS to determine the extent of derivatization. Oxidation indices of the oxidized coal decreased upon reacting with 2,4-dinitrophenylhydrazine, a derivatizing agent specific for carbonyl groups, confirmingmore » that the derivatization reaction had taken place. 5 refs., 5 figs.« less

Analysis of psilocybin and psilocin in Psilocybe subcubensis Guzmán by ion mobility spectrometry and gas chromatography-mass spectrometry.

PubMed

Keller, T; Schneider, A; Regenscheit, P; Dirnhofer, R; Rücker, T; Jaspers, J; Kisser, W

1999-01-11

A new method has been developed for the rapid analysis of psilocybin and/or psilocin in fungus material using ion mobility spectrometry. Quantitative analysis was performed by gas chromatography-mass spectrometry after a simple one-step extraction involving homogenization of the dried fruit bodies of fungi in chloroform and derivatization with MSTFA. The proposed methods resulted in rapid procedures useful in analyzing psychotropic fungi for psilocybin and psilocin.

Enhancement of Drug Detection and Identification by Use of Various Derivatizing Reagents on GC-FTIR Analysis.

DTIC Science & Technology

1992-07-01

pseudoephedrine and L- studied the effects of five different phenylpropanolamine ephedrine, which are stereoisomers of each other, infrared...FIGURE 2. IR spectrum of D- pseudoephedrine . dard because it does not derivatize with any of the derivatizing agents chosen for this study and it has a

Determination of trace amino acids in human serum by a selective and sensitive pre-column derivatization method using HPLC-FLD-MS/MS and derivatization optimization by response surface methodology.

PubMed

Li, Guoliang; Cui, Yanyan; You, Jinmao; Zhao, Xianen; Sun, Zhiwei; Xia, Lian; Suo, Yourui; Wang, Xiao

2011-04-01

Analysis of trace amino acids (AA) in physiological fluids has received more attention, because the analysis of these compounds could provide fundamental and important information for medical, biological, and clinical researches. More accurate method for the determination of those compounds is highly desirable and valuable. In the present study, we developed a selective and sensitive method for trace AA determination in biological samples using 2-[2-(7H-dibenzo [a,g]carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC) as labeling reagent by HPLC-FLD-MS/MS. Response surface methodology (RSM) was first employed to optimize the derivatization reaction between DBCEC and AA. Compared with traditional single-factor design, RSM was capable of lessening laborious, time and reagents consumption. The complete derivatization can be achieved within 6.3 min at room temperature. In conjunction with a gradient elution, a baseline resolution of 20 AA containing acidic, neutral, and basic AA was achieved on a reversed-phase Hypersil BDS C(18) column. This method showed excellent reproducibility and correlation coefficient, and offered the exciting detection limits of 0.19-1.17 fmol/μL. The developed method was successfully applied to determinate AA in human serum. The sensitive and prognostic index of serum AA for liver diseases has also been discussed.

Rapid and simultaneous determination of twenty amino acids in complex biological and food samples by solid-phase microextraction and gas chromatography-mass spectrometry with the aid of experimental design after ethyl chloroformate derivatization.

PubMed

Mudiam, Mohana Krishna Reddy; Ratnasekhar, Ch; Jain, Rajeev; Saxena, Prem Narain; Chauhan, Abhishek; Murthy, R C

2012-10-15

Amino acids play a vital role as intermediates in many important metabolic pathways such as the biosynthesis of nucleotides, vitamins and secondary metabolites. A sensitive and rapid analytical method has been proposed for the first time for the simultaneous determination of twenty amino acids using solid-phase microextraction (SPME). The protein samples were hydrolyzed by 6M HCl under microwave radiation for 120 min. Then the amino acids were derivatized by ethyl chloroformate (ECF) and the ethoxy carbonyl ethyl esters of amino acids formed were extracted using SPME by direct immersion. Finally the extracted analytes on the SPME fiber were desorbed at 260°C and analyzed by gas chromatography-mass spectrometer (GC-MS) in electron ionization mode. Factors which affect the SPME efficiency were screened by Plackett-Burmann design; most significant factors were optimized with response surface methodology. The optimum conditions for SPME are as follows: pH of 1.7, ionic strength of 733 mg, extraction time of 30 min and fiber of divinyl benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS). The recovery of all the amino acids was found to be in the range of 89.17-100.98%. The limit of detection (LOD) of all derivatized amino acids in urine, hair and soybean was found to be in the range of 0.20-7.52 μg L(-1), 0.21-8.40 μg L(-1) and 0.18-5.62 μg L(-1), respectively. Finally, the proposed technique was successfully applied for the determination of amino acids in complex biological (hair, urine) and food samples (soybean). The method can find wide applications in the routine analysis of amino acids in any biological as well as food samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of biodegradation of poly(ethylene glycol)s and poly(propylene glycol)s.

PubMed

Zgoła-Grześkowiak, Agnieszka; Grześkowiak, Tomasz; Zembrzuska, Joanna; Łukaszewski, Zenon

2006-07-01

The biodegradation of poly(ethylene glycol)s (PEGs) and poly(propylene glycol)s (PPGs), both being major by-products of non-ionic surfactants biodegradation, was studied under the conditions of the River Water Die-Away Test. PEGs were isolated from a water matrix using solid-phase extraction with graphitized carbon black sorbent, then derivatized with phenyl isocyanate and determined by HPLC with UV detection. PPGs were isolated from a water matrix by liquid-liquid extraction with chloroform, then derivatized with naphthyl isocyanate and determined by HPLC with fluorescence detection. The primary biodegradation of both PEGs and PPGs reached approximately 99% during the test. The tests show different biodegradation pathways of PEG and PPG. During PEG biodegradation, their chains are shortened leading to the formation of ethylene glycol and diethylene glycol. During PPG biodegradation, no short-chained biodegradation products were found.

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids.

PubMed

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M; Qiao, Shanlei; Spencer, Melanie D; Zeisel, Steven H; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-08-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23-25 °C), or 7 days when stored at -20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research.

Phytohormone profiling of the sweet orange (Citrus sinensis (L.) Osbeck) leaves and roots using GC-MS-based method.

PubMed

Nehela, Yasser; Hijaz, Faraj; Elzaawely, Abdelnaser A; El-Zahaby, Hassan M; Killiny, Nabil

2016-07-20

Phytohormones mainly affect plant development and trigger varied responses to biotic and abiotic stresses. The sensitivity of methods used to profile phytohormones is a vital factor that affects the results. We used an improved GC-MS-based method in the selective ion-monitoring (SIM) mode to study the phytohormone profiling in citrus tissues. One extraction solvent mixture and two derivatization reagents were used, methyl chloroformate (MCF) and N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). The method showed a low limit of detection and low limit of quantification with high extraction recovery percentage and reproducibility. Overall, we detected 13 phytohormones belonging to six different groups. Auxins, SAs, tJA, and ABA were detected after derivatization with MCF while cytokinins and GAs were detected after derivatization with MSTFA. Cytokinins, SAs, and gibberellins were found in all tissues while auxins and tJA were observed only in the leaves. ABA was found in leaves and roots, but not in root tips. The method we used is efficient, precise, and appropriate to study citrus phytohormonal profiles to understand their crosstalk and responses to environmental and biological stresses. Copyright © 2016 Elsevier GmbH. All rights reserved.

Enantioselective separation of amino acids as biomarkers indicating life in extraterrestrial environments.

PubMed

Pietrogrande, Maria Chiara

2013-10-01

Traces of prebiotic amino acids, i.e., the building blocks of proteins, are excellent biomarkers that could provide evidence of extinct or extant life in extra-terrestrial environments. In particular, characterization of the enantiomeric excess of amino acids gives relevant information about the biotic or abiotic origin of molecules, because it is generally assumed that life elsewhere could be based on either L or D amino acids, but not both. The analytical procedures used in in-situ space missions for chiral discrimination of amino acids must meet severe requirements imposed by flight conditions: short analysis time, low energy consumption, robustness, storage for long periods under extreme conditions, high efficiency and sensitivity, automation, and remote-control operation. Such methods are based on gas chromatography, high-pressure liquid chromatography, and capillary electrophoresis, usually coupled with mass spectrometry; of these, gas chromatography-mass spectrometry (GC-MS) is the only such combination yet used in space missions. Preliminary in-situ sample derivatization is required before GC-MS analysis to convert amino acids into volatile and thermally stable compounds. The silylation reagent most commonly used, N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide, is unsuitable for detection of homochirality, and alternative derivatization techniques have been developed that preserve the stereochemical configuration of the original compounds and are compatible with spaceflight conditions. These include the reagent N,N-dimethylformamide dimethylacetal, which has already been used in the Rosetta mission, a mixture of alkyl chloroformate, ethanol, and pyridine, a mixture of perfluorinated anhydrides and perfluoro alcohols, and hexafluoroacetone, the first gaseous derivatizing agent. In all the space instruments, solvent extraction of organic matter and chemical derivatization have been combined in a single automatic and remote-controlled procedure in a chemical reactor. Liquid-based separation systems have been used in space missions. In particular, microchip capillary electrophoresis, based on microfluidic lab-on-a-chip systems, enables high-performance chemical analysis of amino acids with low mass and volume equipment and low power and reagent consumption. Coupling with laser-induced fluorescence detectors results in ultra-low limits of detection. This critical review describes applications of the on-board instruments used in the Rosetta mission to comets and in the more recent Mars exploration program, i.e., the Mars Science Laboratory and ExoMars missions.

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

PubMed

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

2006-01-01

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

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

PubMed Central

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M.; Qiao, Shanlei; Spencer, Melanie D.; Zeisel, Steven H.; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-01-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23–25 °C), or 7 days when stored at −20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research. PMID:23997757

Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection.

PubMed

Nakamoto, Akihiro; Nishida, Manami; Saito, Takeshi; Kishiyama, Izumi; Miyazaki, Shota; Murakami, Katsunori; Nagao, Masataka; Namura, Akira

2010-02-19

A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d(5) was used as an internal standard. The linear ranges were 0.01-5.0 microg mL(-1) for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 microg mL(-1) for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation > or = 0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 microg mL(-1) of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio > or = 3) in urine was 5 ng mL(-1) for MA and MDMA and 10 ng mL(-1) for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation. Copyright 2009 Elsevier B.V. All rights reserved.

Linker-assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate

USGS Publications Warehouse

Lee, E.A.; Zimmerman, L.R.; Bhullar, B.S.; Thurman, E.M.

2002-01-01

A novel, sensitive, linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was compared to on-line solidphase extraction (SPE) with high-performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of glyphosate in surface water and groundwater samples. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitotic attachment of glyphosate to horseradish peroxidase hapten. Thus, L'ELISA recognized the derivatized glyphosate more effectively (detection limit of 0.1 μg/L) and with increased sensitivity (10-100 times) over conventional ELISA and showed the potential for other applications. The precision and accuracy of L'ELISA then was compared with on-line SPE/HPLC/MS, which detected glyphosate and its degradate derivatized with 9-fluorenylmethyl chloroformate using negative-ion electrospray (detection limit 0.1 μg/L, relative standard deviation ±15%). Derivatization efficiency and matrix effects were minimized by adding an isotope-labeled glyphosate (2-13C15N). The accuracy of L'ELISA gave a false positive rate of 18% between 0.1 and 1.0 μg/L and a false positive rate of only 1% above 1.0 μg/L. The relative standard deviation was ±20%. The correlation of L'ELISA and HPLC/MS for 66 surface water and groundwater samples was 0.97 with a slope of 1.28, with many detections of glyphosate and its degradate in surface water but not in groundwater.

Gas chromatography-mass spectrometry of hexafluoroacetone derivatives: First time utilization of a gaseous phase derivatizing agent for analysis of extraterrestrial amino acids.

PubMed

Geffroy-Rodier, C; Buch, A; Sternberg, R; Papot, S

2012-07-06

Within the perspective of the current and next space missions to Mars (MSL 2011 and Exomars 2016-2018), the detection and enantioselective separation of building blocks such as the amino acids are important subjects which are becoming fundamental for the search for traces of life on the surface and subsurface of Mars. In this work, we have developed and optimized a method adapted to space experimentation to derivatize and analyze amino acids, using hexafluoroacetone as the derivatizing agent. The temperature, duration of the derivative transfer to the analyser, and chromatographic separation parameters have been optimized to meet the instrument design constraints imposed on devices for extraterrestrial experiments. The work presented in this rationale has established that hexafluoroacetone, in addition to its intrinsic qualities, such as the production of light-weight derivatives (no racemization) and great resistance to the drastic operating conditions, has indeed facilitated simple and fast derivatization that appears to be suitable for in situ analysis in space. By using hexafluoroacetone as the derivatizing agent, we successfully identified, 21 amino acids including 12 of the 20 proteinic amino acids without stirring or extraction steps. Ten of these derivatized amino acids were enantioselectively separated. The precision and accuracy measurements for the D/L ratio showed that the proposed method was also suitable for the determination of both enantioselective forms of most of the tested amino acids. The limits of detection obtained were lower than the ppb level of organic molecules detected in Martian meteorites. Copyright © 2012 Elsevier B.V. All rights reserved.

Organic Chemical Attribution Signatures for the Sourcing of a Mustard Agent and Its Starting Materials

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

Fraga, Carlos G.; Bronk, Krys; Dockendorff, Brian P.

Chemical attribution signatures (CAS) are being investigated for the sourcing of chemical warfare (CW) agents and their starting materials that may be implicated in chemical attacks or CW proliferation. The work reported here demonstrates for the first time trace impurities produced during the synthesis of tris(2-chloroethyl)amine (HN3) that point to specific reagent stocks used in the synthesis of this CW agent. Thirty batches of HN3 were synthesized using different combinations of commercial stocks of triethanolamine (TEA), thionyl chloride, chloroform, and acetone. The HN3 batches and reagent stocks were then analyzed for impurities by gas chromatography/mass spectrometry. Reaction-produced impurities indicative ofmore » specific TEA and chloroform stocks were exclusively discovered in HN3 batches made with those reagent stocks. In addition, some reagent impurities were found in the HN3 batches that were presumably not altered during synthesis and believed to be indicative of reagent type regardless of stock. Supervised classification using partial least squares discriminant analysis (PLSDA) on the impurity profiles of chloroform samples from seven stocks resulted in an average classification error by cross-validation of 2.4%. A classification error of zero was obtained using the seven-stock PLSDA model on a validation set of samples from an arbitrarily selected chloroform stock. In a separate analysis, all samples from two of seven chloroform stocks that were purposely not modeled had their samples matched to a chloroform stock rather than assigned a “no class” classification.« less

Pentafluorobenzyl bromide-A versatile derivatization agent in chromatography and mass spectrometry: I. Analysis of inorganic anions and organophosphates.

PubMed

Tsikas, Dimitrios

2017-02-01

Pentafluorobenzyl bromide (PFB-Br) is a versatile derivatization agent. It is widely used in chromatography and mass spectrometry since several decades. The bromide atom is largely the single leaving group of PFB-Br. It is substituted by wide a spectrum of nucleophiles in aqueous and non-aqueous systems to form electrically neutral, in most organic solvents soluble, generally thermally stable, volatile, strongly electron-capturing and ultraviolet light-absorbing derivatives. Because of these greatly favoured physicochemical properties, PFB-Br emerged an ideal derivatization agent for highly sensitive analysis of endogenous and exogenous substances including various inorganic and organic anions by electron capture detection or after electron-capture negative-ion chemical ionization in GC-MS. The present article attempts an appraisal of the utility of PFB-Br in analytical chemistry. It reviews and discusses papers dealing with the use of PFB-Br as the derivatization reagent in the qualitative and quantitative analysis of endogenous and exogenous inorganic anions in various biological samples, notably plasma, urine and saliva. These analytes include nitrite, nitrate, cyanide and dialkyl organophosphates. Special emphasis is given to mass spectrometry-based approaches and stable-isotope dilution techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimisation of resolution in micellar electrokinetic chromatography by multivariate evaluation of electrolytes.

PubMed

Mikaeli, S; Thorsén, G; Karlberg, B

2001-01-12

A novel approach to multivariate evaluation of separation electrolytes for micellar electrokinetic chromatography is presented. An initial screening of the experimental parameters is performed using a Plackett-Burman design. Significant parameters are further evaluated using full factorial designs. The total resolution of the separation is calculated and used as response. The proposed scheme has been applied to the optimisation of the separation of phenols and the chiral separation of (+)-1-(9-anthryl)-2-propyl chloroformate-derivatized amino acids. A total of eight experimental parameters were evaluated and optimal conditions found in less than 48 experiments.

Microwave-assisted synthesis of N-pyrazole ureas and the p38alpha inhibitor BIRB 796 for study into accelerated cell ageing.

PubMed

Bagley, Mark C; Davis, Terence; Dix, Matthew C; Widdowson, Caroline S; Kipling, David

2006-11-21

Microwave irradiation of substituted hydrazines and beta-ketoesters gives 5-aminopyrazoles in excellent yield, which can be transformed to the corresponding N-carbonyl derivatives by treatment with an isocyanate or chloroformate. Derivatization of 4-nitronaphth-1-ol using predominantly microwave heating methods and reaction with an N-pyrazole carbamate provides a rapid route to the N-pyrazole urea BIRB 796 in high purity, as a potent and selective inhibitor of p38alpha mitogen-activated protein kinase for the study of accelerated ageing in Werner syndrome cells.

On-matrix Derivatization for Dynamic Headspace Sampling of Nonvolatile Surface Residues

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

Harvey, Scott D.; Wahl, Jon H.

2012-09-01

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) purge-and-trap technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-µg level). It also was successful on the more difficult concrete (at the 500-µg level) and carpet (at the 20-µg level) substrates that cannot be successfully sampled using swipe techniques.more » Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-µg level), as well as carpet (at the 80-µg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes.« less

On-matrix derivatization for dynamic headspace sampling of nonvolatile surface residues.

PubMed

Harvey, Scott D; Wahl, Jon H

2012-09-21

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level). It also was successful on the more difficult concrete (at the 500-μg level) and carpet (at the 20-μg level), substrates that cannot be successfully sampled using swipe techniques. Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-μg level), as well as carpet (at the 80-μg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of amantadine in biological fluids using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection.

PubMed

Farajzadeh, Mir Ali; Nouri, Nina; Alizadeh Nabil, Ali Akbar

2013-12-01

A one-step derivatization and microextraction technique for the determination of amantadine in the human plasma and urine samples is presented. An appropriate mixture of methanol (disperser solvent), 1,2-dibromoethane (extraction solvent), and butylchloroformate (derivatization agent) is rapidly injected into samples. After centrifuging, the sedimented phase is analyzed by gas chromatography-flame ionization detection (GC-FID). The kind of extraction and disperser solvents and their volumes, amount of derivatization agent and reaction/extraction time which are effective in derivatization/dispersive liquid-liquid microextraction (DLLME) procedure are optimized. Under the optimal conditions, the enrichment factor (EF) of the target analyte was obtained to be 408 and 420, and limit of detection (LOD) 4.2 and 2.7ngmL(-1), in plasma and urine respectively. The linear range is 14-5000 and 8.7-5000ng/mL for plasma and urine, respectively (squared correlation coefficient≥0.990). The relative recoveries obtained for the spiked plasma and urine samples are between 72% and 93%. Moreover, the inter- and intra-day precisions are acceptable at all spiked concentrations (relative standard deviation <7%). Finally the method was successfully applied to determine amantadine in biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Dual element ((15)N/(14)N, (13)C/(12)C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS.

PubMed

Mogusu, Emmanuel O; Wolbert, J Benjamin; Kujawinski, Dorothea M; Jochmann, Maik A; Elsner, Martin

2015-07-01

To assess sources and degradation of the herbicide glyphosate [N-(phosphonomethyl) glycine] and its metabolite AMPA (aminomethylphosphonic acid), concentration measurements are often inconclusive and even (13)C/(12)C analysis alone may give limited information. To advance isotope ratio analysis of an additional element, we present compound-specific (15)N/(14)N analysis of glyphosate and AMPA by a two step derivatization in combination with gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The N-H group was derivatized with isopropyl chloroformate (iso-PCF), and remaining acidic groups were subsequently methylated with trimethylsilyldiazomethane (TMSD). Iso-PCF treatment at pH <10 gave too low (15)N/(14)N ratios indicating an incomplete derivatization; in contrast, too high (15)N/(14)N ratios at pH >10 indicated decomposition of the derivative. At pH 10, and with an excess of iso-PCF by 10-24, greatest yields and accurate (15)N/(14)N ratios were obtained (deviation from elemental analyzer-IRMS: -0.2 ± 0.9% for glyphosate; -0.4 ± 0.7% for AMPA). Limits for accurate δ(15)N analysis of glyphosate and AMPA were 150 and 250 ng injected, respectively. A combination of δ(15)N and δ(13)C analysis by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) (1) enabled an improved distinction of commercial glyphosate products and (2) showed that glyphosate isotope values during degradation by MnO2 clearly fell outside the commercial product range. This highlights the potential of combined carbon and nitrogen isotopes analysis to trace sources and degradation of glyphosate.

[The determination of the herbicide glyphosate and its chief metabolite aminomethylphosphonic acid (AMPA) in drinking water with the aid of HPLC].

PubMed

Gauch, R; Leuenberger, U; Müller, U

1989-01-01

A method for the determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) is described. With a detection limit of 0.02 microgram/l, the method suitably fulfills the requirements of the Swiss legislation (tolerance value of 0.1 micrograms/l water). The compounds are derivatized directly in the original water sample with 9-fluorenylmethyl chloroformate (FMOCC1) in order to obtain extractable and fluorescent derivatives. These are extracted with organic solvents and determined by HPLC using a fluorescence detector. Neither of the compounds could be detected in 151 tap water samples from the Canton of Berne.

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%.

Correlation of the rates of solvolysis of neopentyl chloroformate-a recommended protecting agent.

PubMed

D'Souza, Malcolm J; Carter, Shannon E; Kevill, Dennis N

2011-02-15

The specific rates of solvolysis of neopentyl chloroformate (1) have been determined in 21 pure and binary solvents at 45.0 °C. In most solvents the values are essentially identical to those for ethyl and n-propyl chloroformates. However, in aqueous-1,1,1,3,3,3-hexafluoro-2-propanol mixtures (HFIP) rich in fluoroalcohol, 1 solvolyses appreciably faster than the other two substrates. Linear free energy relationship (LFER) comparison of the specific rates of solvolysis of 1 with those for phenyl chloroformate and those for n-propyl chloroformate are helpful in the mechanistic considerations, as is also the treatment in terms of the Extended Grunwald-Winstein equation. It is proposed that the faster reaction for 1 in HFIP rich solvents is due to the influence of a 1,2-methyl shift, leading to a tertiary alkyl cation, outweighing the only weak nucleophilic solvation of the cation possible in these low nucleophilicity solvents.

Determination of hydrazine in drinking water: Development and multivariate optimization of a rapid and simple solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry protocol.

PubMed

Gionfriddo, Emanuela; Naccarato, Attilio; Sindona, Giovanni; Tagarelli, Antonio

2014-07-04

In this work, the capabilities of solid phase microextraction were exploited in a fully optimized SPME-GC-QqQ-MS analytical approach for hydrazine assay. A rapid and easy method was obtained by a simple derivatization reaction with propyl chloroformate and pyridine carried out directly in water samples, followed by automated SPME analysis in the same vial without further sample handling. The affinity of the different derivatized compounds obtained towards five commercially available SPME coatings was evaluated, in order to achieve the best extraction efficiency. GC analyses were carried out using a GC-QqQ-MS instrument in selected reaction monitoring (SRM) acquisition mode which has allowed the achievement of high specificity by selecting appropriate precursor-product ion couples improving the capability in analyte identification. The multivariate approach of experimental design was crucial in order to optimize derivatization reaction, SPME process and tandem mass spectrometry parameters. Accuracy of the proposed protocol, tested at 60, 200 and 800 ng L(-1), provided satisfactory values (114.2%, 83.6% and 98.6%, respectively), whereas precision (RSD%) at the same concentration levels were of 10.9%, 7.9% and 7.7% respectively. Limit of detection and quantification of 4.4 and 8.3 ng L(-1) were obtained. The reliable application of the proposed protocol to real drinking water samples confirmed its capability to be used as analytical tool for routine analyses. Copyright © 2014 Elsevier B.V. All rights reserved.

Vigabatrin in dried plasma spots: validation of a novel LC-MS/MS method and application to clinical practice.

PubMed

Kostić, Nađa; Dotsikas, Yannis; Jović, Nebojša; Stevanović, Galina; Malenović, Anđelija; Medenica, Mirjana

2014-07-01

This paper presents a LC-MS/MS method for the determination of antiepileptic drug vigabatrin in dried plasma spots (DPS). Due to its zwitterionic chemical structure, a pre-column derivatization procedure was performed, aiming to yield enhanced ionization efficiency and improved chromatographic behaviour. Propyl chloroformate, in the presence of propanol, was selected as the best derivatization reagent, providing a strong signal along with reasonable run time. A relatively novel sample collection technique, DPS, was utilized, offering easy sample handling and analysis, using a sample in micro amount (∼5μL). Derivatized vigabatrin and its internal standard, 4-aminocyclohexanecarboxylic acid, were extracted by liquid-liquid extraction (LLE) and determined in positive ion mode by applying two SRM transitions per analyte. A Zorbax Eclipse XDB-C8 column (150×4.6mm, 5μm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550μL/min and total run time 4.5min. The assay exhibited excellent linearity over the concentration range of 0.500-50.0μg/mL, which is suitable for the determination of vigabatrin level after per os administration in children and youths with epilepsy, who were on vigabatrin therapy, with or without co-medication. Specificity, accuracy, precision, recovery, matrix-effect and stability were also estimated and assessed within acceptance criteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Search for evidence of life in space: analysis of enantiomeric organic molecules by N,N-dimethylformamide dimethylacetal derivative dependant Gas Chromatography-Mass Spectrometry.

PubMed

Freissinet, C; Buch, A; Sternberg, R; Szopa, C; Geffroy-Rodier, C; Jelinek, C; Stambouli, M

2010-01-29

Within the context of the future space missions to Mars (MSL 2011 and Exomars 2016), which aim at searching for traces of life at the surface, the detection and quantitation of enantiomeric organic molecules is of major importance. In this work, we have developed and optimized a method to derivatize and analyze chiral organic molecules suitable for space experiments, using N,N-dimethylformamide dimethylacetal (DMF-DMA) as the derivatization agent. The temperature, duration of the derivatization reaction, and chromatographic separation parameters have been optimized to meet instrument design constraints imposed upon space experiment devices. This work demonstrates that, in addition to its intrinsic qualities, such as production of light-weight derivatives and a great resistance to drastic operating conditions, DMF-DMA facilitates simple and fast derivatization of organic compounds (three minutes at 140 degrees C in a single-step) that is suitable for an in situ analysis in space. By using DMF-DMA as the derivatization agent, we have successfully identified 19 of the 20 proteinic amino acids and been able to enantiomerically separate ten of the potential 19 (glycine being non-chiral). Additionally, we have minimized the percentage of racemized amino acid compounds produced by optimizing the conditions of the derivatization reaction itself. Quantitative linearity studies and the determination of the limit of detection show that the proposed method is also suitable for the quantitative determination of both enantiomeric forms of most of the tested amino acids, as limits of detection obtained are lower than the ppb level of organic molecules already detected in Martian meteorites. Copyright (c) 2009 Elsevier B.V. All rights reserved.

A novel high sensitivity HPLC assay for topiramate, using 4-chloro-7-nitrobenzofurazan as pre-column fluorescence derivatizing agent.

PubMed

Bahrami, Gholamreza; Mohammadi, Bahareh

2007-05-01

A new, sensitive and simple high-performance liquid chromatographic method for analysis of topiramate, an antiepileptic agent, using 4-chloro-7-nitrobenzofurazan as pre-column derivatization agent is described. Following liquid-liquid extraction of topiramate and an internal standard (amlodipine) from human serum, derivatization of the drugs was performed by the labeling agent in the presence of dichloromethane, methanol, acetonitrile and borate buffer (0.05 M; pH 10.6). A mixture of sodium phosphate buffer (0.05 M; pH 2.4): methanol (35:65 v/v) was eluted as mobile phase and chromatographic separation was achieved using a Shimpack CLC-C18 (150 x 4.6 mm) column. In this method the limit of quantification of 0.01 microg/mL was obtained and the procedure was validated over the concentration range of 0.01 to 12.8 microg/mL. No interferences were found from commonly co-administrated antiepileptic drugs including phenytoin, phenobarbital carbamazepine, lamotrigine, zonisamide, primidone, gabapentin, vigabatrin, and ethosuximide. The analysis performance was carried-out in terms of specificity, sensitivity, linearity, precision, accuracy and stability and the method was shown to be accurate, with intra-day and inter-day accuracy from -3.4 to 10% and precise, with intra-day and inter-day precision from 1.1 to 18%.

"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.

Chromatographic methods for determination of S-substituted cysteine derivatives--a comparative study.

PubMed

Kubec, Roman; Dadáková, Eva

2009-10-09

A novel HPLC method for determination of a wide variety of S-substituted cysteine derivatives in Allium species has been developed and validated. This method allows simultaneous separation and quantification of S-alk(en)ylcysteine S-oxides, gamma-glutamyl-S-alk(en)ylcysteines and gamma-glutamyl-S-alk(en)ylcysteine S-oxides in a single run. The procedure is based on extraction of these amino acids and dipeptides by methanol, their derivatization by dansyl chloride and subsequent separation by reversed phase HPLC. The main advantages of the new method are simplicity, excellent stability of derivatives, high sensitivity, specificity and the ability to simultaneously analyze the whole range of S-substituted cysteine derivatives. This method was critically compared with other chromatographic procedures used for quantification of S-substituted cysteine derivatives, namely with two other HPLC methods (derivatization by o-phthaldialdehyde/tert-butylthiol and fluorenylmethyl chloroformate), and with determination by gas chromatography or capillary electrophoresis. Major advantages and drawbacks of these analytical procedures are discussed. Employing these various chromatographic methods, the content and relative proportions of individual S-substituted cysteine derivatives were determined in four most frequently consumed alliaceous vegetables (garlic, onion, shallot, and leek).

Diastereoselective preparation of (R)- and (S)-2-methoxy-2-phenylpent-3-ynoic acids and their use as reliable chiral derivatizing agents.

PubMed

Pérez-Estrada, Salvador; Joseph-Nathan, Pedro; Jiménez-Vázquez, Hugo A; Medina-López, Manuel E; Ayala-Mata, Francisco; Zepeda, L Gerardo

2012-02-17

Benzoyl-S,O-acetals 1a and 1b were used as chiral auxiliaries to achieve the diastereoselective preparation of both enantiomers of 2-methoxy-2-phenylpent-3-ynoic acids (MPPAs). The latter were condensed with several chiral secondary alcohols and some primary amines to evaluate their potential as chiral derivatizing agents (CDAs). The (1)H NMR spectra of the corresponding esters and amides showed strong consistency with the absolute configuration of the carbinol and amine moieties, whose observed ΔδL(1) and ΔδL(2) values were in the ranges of 0.1-0.4 and 0.02-0.12 ppm, respectively.

Determination of free amino compounds in betalainic fruits and vegetables by gas chromatography with flame ionization and mass spectrometric detection.

PubMed

Kugler, Florian; Graneis, Stephan; Schreiter, Pat P-Y; Stintzing, Florian C; Carle, Reinhold

2006-06-14

Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

Analysis of chemical warfare agents by gas chromatography-mass spectrometry: methods for their direct detection and derivatization approaches for the analysis of their degradation products

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

Valdez, Carlos A.; Leif, Roald N.; Hok, Saphon

Abstract Chemical warfare agents (CWAs) are unarguably one of the most feared toxic substances produced by mankind. Their inception in conventional warfare can be traced as far back as the Middle Ages but their full breakthrough as central players in bellic conflicts was not realized until World War I. Since then, more modern CWAs along with efficient methods for their manufacture have emerged and violently shaped the way modern warfare and diplomatic relations are conducted. Owing to their mass destruction ability, counter methods to mitigate their impact appeared almost immediately on par with their development. These efforts have focused onmore » their efficient destruction, development of medical countermeasures and their detection by modern analytical chemistry methods. The following review seeks to provide the reader with a broad introduction on their direct detection by gas chromatography-mass spectrometry (GC-MS) and the various sample derivatization methods available for the analysis of their degradation products. The review concentrates on three of the main CWA classes and includes the nerve agents, the blistering agents and lastly, the incapacitating agents. Each section begins with a brief introduction of the CWA along with discussions of reports dealing with their detection in the intact form by GC-MS. Furthermore, as products arising from their degradation carry as much importance as the agents themselves in the field of forensic analysis, the available derivatization methods of these species are presented for each CWA highlighting some examples from our lab in the Forensic Science Center at the Lawrence Livermore National Laboratory.« less

Analysis of chemical warfare agents by gas chromatography-mass spectrometry: methods for their direct detection and derivatization approaches for the analysis of their degradation products

DOE PAGES

Valdez, Carlos A.; Leif, Roald N.; Hok, Saphon; ...

2017-07-25

Abstract Chemical warfare agents (CWAs) are unarguably one of the most feared toxic substances produced by mankind. Their inception in conventional warfare can be traced as far back as the Middle Ages but their full breakthrough as central players in bellic conflicts was not realized until World War I. Since then, more modern CWAs along with efficient methods for their manufacture have emerged and violently shaped the way modern warfare and diplomatic relations are conducted. Owing to their mass destruction ability, counter methods to mitigate their impact appeared almost immediately on par with their development. These efforts have focused onmore » their efficient destruction, development of medical countermeasures and their detection by modern analytical chemistry methods. The following review seeks to provide the reader with a broad introduction on their direct detection by gas chromatography-mass spectrometry (GC-MS) and the various sample derivatization methods available for the analysis of their degradation products. The review concentrates on three of the main CWA classes and includes the nerve agents, the blistering agents and lastly, the incapacitating agents. Each section begins with a brief introduction of the CWA along with discussions of reports dealing with their detection in the intact form by GC-MS. Furthermore, as products arising from their degradation carry as much importance as the agents themselves in the field of forensic analysis, the available derivatization methods of these species are presented for each CWA highlighting some examples from our lab in the Forensic Science Center at the Lawrence Livermore National Laboratory.« less

Skin penetration and kinetics of pristine fullerenes (C{sub 60}) topically exposed in industrial organic solvents

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

Xia, Xin R., E-mail: xia@ncsu.ed; Monteiro-Riviere, Nancy A.; Riviere, Jim E.

2010-01-01

Pristine fullerenes (C{sub 60}) in different solvents will be used in many industrial and pharmaceutical manufacturing and derivatizing processes. This report explores the impact of solvents on skin penetration of C{sub 60} from different types of industrial solvents (toluene, cyclohexane, chloroform and mineral oil). Yorkshire weanling pigs (n = 3) were topically dosed with 500 muL of 200 mug/mL C{sub 60} in a given solvent for 24 h and re-dosed daily for 4 days to simulate the worst scenario in occupational exposures. The dose sites were tape-stripped and skin biopsies were taken after 26 tape-strips for quantitative analysis. When dosedmore » in toluene, cyclohexane or chloroform, pristine fullerenes penetrated deeply into the stratum corneum, the primary barrier of skin. More C{sub 60} was detected in the stratum corneum when dosed in chloroform compared to toluene or cyclohexane. Fullerenes were not detected in the skin when dosed in mineral oil. This is the first direct evidence of solvent effects on the skin penetration of pristine fullerenes. The penetration of C{sub 60} into the stratum corneum was verified using isolated stratum corneum in vitro; the solvent effects on the stratum corneum absorption of C{sub 60} were consistent with those observed in vivo. In vitro flow-through diffusion cell experiments were conducted in pig skin and fullerenes were not detected in the receptor solutions by 24 h. The limit of detection was 0.001 mug/mL of fullerenes in 2 mL of the receptor solutions.« less

AAS and spectrophotometric methods for the determination metoprolol tartrate in tablets

NASA Astrophysics Data System (ADS)

Alpdoğan, Güzin; Sungur, Sidika

1999-11-01

Sensitive and specific atomic adsorption spectroscopy (AAS) and spectrophotometric methods have been developed for the determination of beta adrenergic blocking drug, metoprolol tartrate.The method is based on the formation of Cu(II) dithiocarbamate complex by derivatization of the secondary amino group of metoprolol with CS 2 and CuCl 2 in the presence of ammonia.The copper-bis(dithiocarbamate) complex was extracted into chloroform and the concentration of metoprolol tartrate was determined directly by spectrophotometric and indirectly by AAS measurement of copper.The two methods developed were applied to the assay of metoprolol tartrate in commercial tablet formulations.The methods were compared statistically with each other and with the high performance liquid chromatography (HPLC) method of USPXXII using t- and F-tests.

Stereoselective determination of amino acids in beta-amyloid peptides and senile plaques.

PubMed

Thorsén, G; Bergquist, J; Westlind-Danielsson, A; Josefsson, B

2001-06-01

A novel method for the determination of the enantiomeric composition of peptides is presented. In this paper, the focus has been on beta-amyloid peptides from deceased Alzheimer's disease patients. The peptides are hydrolyzed using mineral acid. The free amino acids are derivatized with the chiral reagent (+)- or (-)-1-(9-anthryl)-2-propyl chloroformate and subsequently separated using micellar electrokinetic chromatography (MEKC) and detected using laser-induced fluorescence (LIF) detection. The high separation efficiency of the MEKC-LIF system, yielding approximately 1 million theoretical plates/m for most amino acids, facilitates the simultaneous chiral determination of nine amino acids. The samples that have been analyzed were standard 1-40 beta-amyloid peptides, in vitro precipitated beta-amyloid fibrils, and human senile plaque samples.

Interconversion of ephedrine and pseudoephedrine during chemical derivatization.

PubMed

Wong, Colton H F; Ho, Emmie N M; Kwok, W H; Leung, David K K; Leung, Gary N W; Tang, Francis P W; Wong, April S Y; Wong, Jenny K Y; Yu, Nola H; Wan, Terence S M

2012-12-01

Gas chromatography-mass spectrometry (GC-MS) analysis after heptafluorobutyric anhydride (HFBA) derivatization was one of the published methods used for the quantification of ephedrine (EP) and pseudoephedrine (PE) in urine. This method allows the clear separation of the derivatized diastereoisomers on a methyl-silicone-based column. Recently the authors came across a human urine sample with apparently high levels (µg/ml) of EP and PE upon initial screening. However, duplicate analyses of this sample using the HFBA-GC-MS method revealed an unusual discrepancy in the estimated levels of EP and PE, with the area response ratios of EP/PE at around 29% on one occasion and around 57% on another. The same sample was re-analyzed for EP and PE using other techniques, including GC-MS after trimethylsilylation and ultra-high-performance liquid chromatography-tandem mass spectrometry. Surprisingly, the concentration of EP in the sample was determined to be at least two orders of magnitude less than what was observed with the HFBA-GC-MS method. A thorough investigation was then conducted, and the results showed that both substances could interconvert during HFBA derivatization. Similar diastereoisomeric conversion was also observed using other fluorinated acylating agents (e.g. pentafluoropropionic anhydride and trifluoroacetic anhydride). The extent of interconversion was correlated with the degree of fluorination of the acylating agents, with HFBA giving the highest conversion. This conversion has never been reported before. A mechanism for the interconversion was proposed. These findings indicated that fluorinated acylating agents should not be used for the unequivocal identification or quantification of EP and PE as the results obtained can be erroneous. Copyright © 2012 John Wiley & Sons, Ltd.

Hydrazine reagents as derivatizing agents in environmental analysis--a critical review.

PubMed

Vogel, M; Büldt, A; Karst, U

2000-04-01

Hydrazine reagents are a well-known group of derivatizing agents for the determination of aldehydes and ketones in liquid and gaseous samples. Within this article, the most important hydrazine reagents are critically summarized, and their major applications in different fields, including environmental analysis, food chemistry and industrial analysis are introduced. As 2,4-dinitrophenylhydrazine (DNPH) is the basic reagent for several international standard procedures, its properties are discussed in detail. Particular focus is directed on the chemistry of the hydrazine reagents, and chemical interferences are considered. Recent methods for the determination of various oxidants using hydrazine reagents are presented as well. Due to limited space, this review does not cover the related field of carbohydrate analysis, although many chemical aspects are similar.

Covalent Chemical Ligation Strategy for Mono- and Polyclonal Immunoglobulins at Their Nucleotide Binding Sites.

PubMed

Lac, Diana; Feng, Chun; Bhardwaj, Gaurav; Le, Huong; Tran, Jimmy; Xing, Li; Fung, Gabriel; Liu, Ruiwu; Cheng, Holland; Lam, Kit S

2016-01-20

Nonspecific ligation methods have been traditionally used to chemically modify immunoglobulins. Site-specific ligation of compounds (toxins or ligands) to antibodies has become increasingly important in the fields of therapeutic antibody-drug conjugates and bispecific antibodies. In this present study, we took advantage of the reported nucleotide-binding pocket (NBP) in the Fab arms of immunoglobulins by developing indole-based, 5-fluoro-2,4-dinitrobenzene-derivatized OBOC peptide libraries for the identification of affinity elements that can be used as site-specific derivatization agents against both mono- and polyclonal antibodies. Ligation can occur at any one of the few lysine residues located at the NBP. Immunoconjugates resulting from such affinity elements can be used as therapeutics against cancer or infectious agents.

Studies on a complex mechanism for the activation of plasminogen by kaolin and by chloroform: the participation of Hageman factor and additional cofactors

PubMed Central

Ogston, Derek; Ogston, C. Marie; Ratnoff, Oscar D.; Forbes, Charles D.

1969-01-01

As demonstrated by others, fibrinolytic activity was generated in diluted, acidified normal plasma exposed to kaolin, a process requiring Hageman factor (Factor XII). Generation was impaired by adsorbing plasma with glass or similar agents under conditions which did not deplete its content of Hageman factor or plasminogen. The defect could be repaired by addition of a noneuglobulin fraction of plasma or an agent or agents eluted from diatomaceous earth which had been exposed to normal plasma. The restorative agent, tentatively called Hageman factor-cofactor, was partially purified by chromatography and had an apparent molecular weight of approximately 165,000. It could be distinguished from plasma thromboplastin antecedent (Factor XI) and plasma kallikrein, other substrates of Hageman factor, and from the streptokinase-activated pro-activator of plasminogen. Evidence is presented that an additional component may be needed for the generation of fibrinolytic activity in mixtures containing Hageman factor, HF-cofactor, and plasminogen. The long-recognized generation of plasmin activity in chloroform-treated euglobulin fractions of plasma was found to be dependent upon the presence of Hageman factor. Whether chloroform activation of plasminogen requires Hageman factor-cofactor was not determined, but glass-adsorbed plasma, containing Hageman factor and plasminogen, did not generate appreciable fibrinolytic or caseinolytic activity. These studies emphasize the complex nature of the mechanisms which lead to the generation of plasmin in human plasma. PMID:4241814

[Early contributions from Erlangen to the theory and practice of ether and chloroform anesthesia. 1. Heyfelder's clinical trial with ether and chloroform].

PubMed

Hintzenstern, U v; Schwarz, W

1996-02-01

The era of modern anaesthesia in Germany began on January 24th, 1847. This day, professor in ordinary Johann Ferdinand Heyfelder anaesthetized a patient with sulphuric ether in the clinic of surgery and ophthalmology of the University of Erlangen. By March 17th, 1847, Heyfelder had performed 121 surgical procedures under ether. The operations in majority were teeth-extractions, and a few more complex operations such as the treatment of a harelip or of lip cancer or the resection of the shoulder joint. Heyfelder described in detail 108 of these inhalations in a little book entitled The experiments with sulphuric ether. This monograph published in March, 1847, represents one of the first complete dissertations on sulphuric ether in the German literature. In a special chapter he analyzed the development of various physiological and psychological parameters during etherization. Heyfelder also examined blood and urine of some etherized patients and reported that he did not find any important or specific alterations. In 1847, Heyfelder was probably the first to apply salt-ether in man. After 4 administrations he concluded that salt ether acted more quickly but shorter than sulphuric ether. Advantageous were its application without problems and ease of induction. Disadvantageous were its high volatility, its price and the difficulty of getting it in a pure form. From December, 1847, on Heyfelder started to use chloroform. He was now able to perform more major operations, for example, the total resection of the hip-joint. In his book The experiments with sulphuric ether, salt ether, and chloroform he describes a great number of anaesthetic administrations using these 3 agents. In his summary Heyfelder concluded, that chloroform was undoubtly superior to sulphuric ether mainly because it was a quicker acting and longer lasting agent and leads to deeper narcosis. Moreover its application was much easier for it needed no special apparatus. However, because of its great anaesthetic potency, Heyfelder particularly demanded great caution in the application of chloroform. Explicitely he expected an assistant for chloroformizations, whose only duty was to supervise the inhalations and the patient--a forerunner of the modern specialized anaesthesiologist.

Antibody-dendrimer conjugates: the number, not the size of the dendrimers, determines the immunoreactivity.

PubMed

Wängler, C; Moldenhauer, G; Eisenhut, M; Haberkorn, U; Mier, W

2008-04-01

Radioimmunotherapy using antibodies with favorable tumor targeting properties and high binding affinity is increasingly applied in cancer therapy. The potential of this valuable cancer treatment modality could be further improved by increasing the specific activity of the labeled proteins. This can be done either by coupling a large number of chelators which leads to a decreased immunoreactivity or by conjugating a small number of multimeric chelators. In order to systematically investigate the influence of conjugations on immunoreactivity with respect to size and number of the conjugates, the anti-EGFR antibody hMAb425 was reacted with PAMAM dendrimers of different size containing up to 128 chelating agents per conjugation site. An improved dendrimer synthesis protocol was established to obtain compounds of high homogeneity suitable for the formation of defined protein conjugates. The quantitative derivatization of the PAMAM dendrimers with DOTA moieties and the characterization of the products by isotopic dilution titration using (111)In/(nat)In are shown. The DOTA-containing dendrimers were conjugated with high efficiency to hMAb425 by applying Sulfo-SMCC as cross-linking agent and a 10- to 25-fold excess of the thiol-containing dendrimers. The determination of the immunoreactivities of the antibody-dendrimer conjugates by FACS analysis revealed a median retained immunoreactivity of 62.3% for 1.7 derivatization sites per antibody molecule, 55.4% for 2.8, 27.9% for 5.3, and 17.1% for 10.0 derivatization sites per antibody but no significant differences in immunoreactivity for different dendrimer sizes. These results show that the dendrimer size does not influence the immunoreactivity of the derivatized antibody significantly over a wide molecular weight range, whereas the number of derivatization sites has a crucial effect.

Determination of reduced homocysteine in human serum by elemental labelling and liquid chromatography with ICP-MS and ESI-MS detection.

PubMed

Espina, Juan Gómez; Montes-Bayón, Maria; Blanco-González, Elisa; Sanz-Medel, Alfredo

2015-10-01

Analytical methods allowing sensitive determination of reduced homocysteine (rHcy), one of the so-called biothiols, in human serum is a topic of growing interest due to its close relation to several human disorders, mainly cardiovascular diseases. Although most widely used analytical strategies to determine total Hcy involve derivatization by means of fluorescent labels, this work proposes the use of ebselen, a Se-containing labelling agent to derivatize the reactive sulfhydryl group of the Hcy molecule in its "free" reduced form, which is more likely to play different roles in disease pathogenesis. Optimization of the derivatization and separation conditions by high-performance liquid chromatography (HPLC) to isolate the excess of derivatizing reagent is carried out here using UV/VIS detection. Further, the study of the Se labelling reaction by electrospray ionization tandem mass spectrometry (ESI-MS/MS) provides a stoichiometry of the derivative of 1:1. The main advantage of using ebselen as a labelling agent is the presence of the Se atom in the molecule that allows the use of inductively coupled plasma mass spectrometry (ICP-MS) as a sensitive and selective Se detector. The coupling of HPLC with ICP-MS provided excellent features for the determination of Se-derivatized rHcy (detection limit of 9.6 nM) in real samples. Quantification was accomplished by using post-column isotope dilution (ID) of Se in serum samples, after precipitation of the main serum proteins. Quantitative results for "free" rHcy turned out to be around 0.18-0.22 μM in serum samples from healthy individuals that could be directly analyzed without sample preconcentration.

In Vitro Screening of Anti-lice Activity of Pongamia pinnata Leaves

PubMed Central

Radhamani, Suraj; Gopinath, Rejitha; Kalusalingam, Anandarajagopal; Vimala, Anita Gnana Kumari Anbumani; Husain, Hj Azman

2009-01-01

Growing patterns of pediculocidal drug resistance towards head louse laid the foundation for research in exploring novel anti-lice agents from medicinal plants. In the present study, various extracts of Pongamia pinnata leaves were tested against the head louse Pediculus humanus capitis. A filter paper diffusion method was conducted for determining the potential pediculocidal and ovicidal activity of chloroform, petroleum ether, methanol, and water extracts of P. pinnata leaves. The findings revealed that petroleum ether extracts possess excellent anti-lice activity with values ranging between 50.3% and 100% where as chloroform and methanol extracts showed moderate pediculocidal effects. The chloroform and methanol extracts were also successful in inhibiting nymph emergence and the petroleum ether extract was the most effective with a complete inhibition of emergence. Water extract was devoid of both pediculocidal and ovicidal activities. All the results were well comparable with benzoyl benzoate (25% w/v). These results showed the prospect of using P. pinnata leave extracts against P. humanus capitis in difficult situations of emergence of resistance to synthetic anti-lice agents. PMID:19967085

Measurement of oxidative DNA damage by gas chromatography-mass spectrometry: ethanethiol prevents artifactual generation of oxidized DNA bases.

PubMed Central

Jenner, A; England, T G; Aruoma, O I; Halliwell, B

1998-01-01

Analysis of oxidative damage to DNA bases by GC-MS enables identification of a range of base oxidation products, but requires a derivatization procedure. However, derivatization at high temperature in the presence of air can cause 'artifactual' oxidation of some undamaged bases, leading to an overestimation of their oxidation products, including 8-hydroxyguanine. Therefore derivatization conditions that could minimize this problem were investigated. Decreasing derivatization temperature to 23 degrees C lowered levels of 8-hydroxyguanine, 8-hydroxyadenine, 5-hydroxycytosine and 5-(hydroxymethyl)uracil measured by GC-MS in hydrolysed calf thymus DNA. Addition of the reducing agent ethanethiol (5%, v/v) to DNA samples during trimethylsilylation at 90 degrees C also decreased levels of these four oxidized DNA bases as well as 5-hydroxyuracil. Removal of guanine from hydrolysed DNA samples by treatment with guanase, prior to derivatization, resulted in 8-hydroxyguanine levels (54-59 pmol/mg of DNA) that were significantly lower than samples not pretreated with guanase, independent of the derivatization conditions used. Only hydrolysed DNA samples that were derivatized at 23 degrees C in the presence of ethanethiol produced 8-hydroxyguanine levels (56+/-8 pmol/mg of DNA) that were as low as those of guanase-pretreated samples. Levels of other oxidized bases were similar to samples derivatized at 23 degrees C without ethanethiol, except for 5-hydroxycytosine and 5-hydroxyuracil, which were further decreased by ethanethiol. Levels of 8-hydroxyguanine, 8-hydroxyadenine and 5-hydroxycytosine measured in hydrolysed calf thymus DNA by the improved procedures described here were comparable with those reported previously by HPLC with electrochemical detection and by GC-MS with prepurification to remove undamaged base. We conclude that artifactual oxidation of DNA bases during derivatization can be prevented by decreasing the temperature to 23 degrees C, removing air from the derivatization reaction and adding ethanethiol. PMID:9531471

Quantitation of total homocysteine in human plasma by derivatization to its N(O,S)-propoxycarbonyl propyl ester and gas chromatography-mass spectrometry analysis.

PubMed

Sass, J O; Endres, W

1997-08-01

Much evidence supports the hypothesis that mild or moderate hyperhomocysteinaemia represents an important and independent risk factor for occlusive vascular diseases. Therefore, the accurate and reliable determination of total plasma homocysteine has gained major importance for risk assessment. Furthermore, it can help in the detection of folate and vitamin B12 deficiency. This has prompted us to develop a sensitive gas chromatography-mass spectrometry (GC-MS) method in order to quantify total homocysteine in human plasma. Prior to chromatography, reduced homocysteine was released from disulfide bonds by incubation with excess dithiothreitol and converted into its N(O,S)-propoxycarbonyl propyl ester by derivatization with n-propyl chloroformate. Aminoethylcysteine served as internal standard. The method proved to be highly linear over the entire concentration range examined (corresponding to 0-266 microM homocysteine) and showed intra-assay and inter-assay variation (relative standard deviations) of approximately 5 and 5-10%, respectively. External quality control by comparison with duplicate analysis performed on a HPLC-based system revealed satisfactory correlation. The newly developed GC-MS based method provides simple, reliable and fast quantification of total homocysteine and requires only inexpensive chemicals, which are easy to obtain.

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.

One-Step Derivatization-Extraction Method for Rapid Analysis of Eleven Amphetamines and Cathinones in Oral Fluid by GC-MS.

PubMed

Mohamed, Khaled

2017-09-01

A simple analytical method was developed for in-matrix derivatization of 11 amphetamine-like molecules. Ethyl chloroformate as the derivatization reagent and ethyl acetate as the extraction solvent were added directly to oral fluid samples at alkaline pH. Samples were analyzed by gas chromatography-mass spectrometry. Ions monitored for quantification were m/z 44, 91 and 116 for amphetamine (AMP); m/z 58, 91 and 130 for methamphetamine (MA); m/z 44, 105 and 116 for 4-methylamphetamine; m/z 44, 116 and 251 for 3,4-methylenedioxyamphetamine; m/z 58, 130 and 265 for 3,4-methylenedioxymethamphetamine (MDMA); m/z 72, 116 and 144 for 3,4-methylenedioxyethylamphetamine; m/z 44, 105 and 116 for cathinone; m/z 58, 105 and 130 for methcathinone; m/z 58, 119 and 130 for mephedrone; m/z 58, 107 and 130 for ephedrine (EPH); m/z 207, 250 and 322 for fenethylline; m/z 48, 92 and 120 for AMP-D5; m/z 62, 92 and 134 for MA-D5; m/z 48, 120 and 256 for MDA-D5; and m/z 62, 134 and 270 for MDMA-D5. The underlined ions were used as quantifier ions. Calibration curves were linear in the concentration range of 2.5-1,000 ng/mL for all analytes except for EPH, which was linear within 5-1,000 ng/mL. Precision and accuracy were less than 12.9% (relative standard deviation) and ±12.8% (bias), respectively, for all analytes. The method was tested in the analysis of oral fluid specimens collected from users. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Developing a New Sampling And Analysis Method For Hydrazine And Monomethyl Hydrazine: Using a Derivatizing Agent With Solid Phase Microextraction

NASA Technical Reports Server (NTRS)

Allen, John

2001-01-01

Solid phase microextraction (SPME) will be used to develop a method for detecting monomethyl hydrazine (MMH) and hydrazine (Hz). A derivatizing agent, pentafluorobenzoyl chloride (PFBCI), is known to react readily with MMH and Hz. The SPME fiber can either be coated with PFBCl and introduced into a gaseous stream containing MMH, or PFBCl and MMH can react first in a syringe barrel and after a short equilibration period a SPME is used to sample the resulting solution. These methods were optimized and compared. Because Hz and MMH can degrade the SPME, letting the reaction occur first gave better results. Only MMH could be detected using either of these methods. Future research will concentrate on constructing calibration curves and determining the detection limit.

Comparison of MRI properties between derivatized DTPA and DOTA gadolinium-dendrimer conjugates.

PubMed

Nwe, K; Bernardo, M; Regino, C A S; Williams, M; Brechbiel, M W

2010-08-15

In this report we directly compare the in vivo and in vitro MRI properties of gadolinium-dendrimer conjugates of derivatized acyclic diethylenetriamine-N,N',N',N'',N''-pentaacetic acid (1B4M-DTPA) and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (C-DOTA). The metal-ligand chelates were pre-formed in alcohol prior to conjugation to the generation 4 PAMAM dendrimer (G4D), and the dendrimer-based agents were purified by Sephadex(R) G-25 column. The analysis and SE-HPLC data indicated chelate to dendrimer ratios of 30:1 and 28:1, respectively. Molar relaxivity measured at pH 7.4, 22 degrees C, and 3T are comparable (29.5 vs 26.9 mM(-1)s(-1)), and both conjugates are equally viable as MRI contrast agents based on the images obtained. The macrocyclic agent however exhibits a faster rate of clearance in vivo (t(1/2)=16 vs 29 min). Our conclusion is that the macrocyclic-based agent is the more suitable agent for in vivo use for these reasons combined with kinetic inertness associated with the Gd(III) DOTA complex stability properties. Published by Elsevier Ltd.

Comparison of MRI properties between derivatized DTPA and DOTA gadolinium-dendrimer conjugates

PubMed Central

Nwe, K.; Bernardo, M; Regino, C. A. S.; Williams, M; Brechbiel, M. W.

2010-01-01

In this report we directly compare the in vivo and in vitro MRI properties of gadolinium-dendrimer conjugates of derivatized acyclic diethylenetriamine-N,N’,N’,N’’, N’’-pentaacetic acid (1B4M-DTPA) and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N’,N’’,N’’’-tetraacetic acid (C-DOTA). The metal-ligand chelates were pre-formed in alcohol prior to conjugation to the generation 4 PAMAM dendrimer (G4D), and the dendrimer-based agents were purified by Sephadex® G-25 column. The analysis and SE-HPLC data indicated chelate to dendrimer ratios of 30:1 and 28:1 respectively. Molar relaxivity measured at pH 7.4, 22°C, and 3T are comparable (29.5 vs. 26.9 mM−1s−1), and both conjugates are equally viable as MRI contrast agents based on the images obtained. The macrocyclic agent however exhibits a faster rate of clearance in vivo (t1/2 = 16 vs. 29 min.). Our conclusion is that the macrocyclic-based agent is the more suitable agent for in vivo use for these reasons combined with kinetic inertness associated with the Gd(III) DOTA complex stability properties. PMID:20663676

Correlation of the Rates of Solvolysis of Neopentyl Chloroformate—A Recommended Protecting Agent

PubMed Central

D’Souza, Malcolm J.; Carter, Shannon E.; Kevill, Dennis N.

2011-01-01

The specific rates of solvolysis of neopentyl chloroformate (1) have been determined in 21 pure and binary solvents at 45.0 °C. In most solvents the values are essentially identical to those for ethyl and n-propyl chloroformates. However, in aqueous-1,1,1,3,3,3-hexafluoro-2-propanol mixtures (HFIP) rich in fluoroalcohol, 1 solvolyses appreciably faster than the other two substrates. Linear free energy relationship (LFER) comparison of the specific rates of solvolysis of 1 with those for phenyl chloroformate and those for n-propyl chloroformate are helpful in the mechanistic considerations, as is also the treatment in terms of the Extended Grunwald-Winstein equation. It is proposed that the faster reaction for 1 in HFIP rich solvents is due to the influence of a 1,2-methyl shift, leading to a tertiary alkyl cation, outweighing the only weak nucleophilic solvation of the cation possible in these low nucleophilicity solvents. PMID:21541050

Method for Derivatization and Detection of Chemical Weapons Convention Related Sulfur Chlorides via Electrophilic Addition with 3-Hexyne.

PubMed

Goud, D Raghavender; Pardasani, Deepak; Purohit, Ajay Kumar; Tak, Vijay; Dubey, Devendra Kumar

2015-07-07

Sulfur monochloride (S2Cl2) and sulfur dichloride (SCl2) are important precursors of the extremely toxic chemical warfare agent sulfur mustard and classified, respectively, into schedule 3.B.12 and 3.B.13 of the Chemical Weapons Convention (CWC). Hence, their detection and identification is of vital importance for verification of CWC. These chemicals are difficult to detect directly using chromatographic techniques as they decompose and do not elute. Until now, the use of gas chromatographic approaches to follow the derivatized sulfur chlorides is not reported in the literature. The electrophilic addition reaction of sulfur monochloride and sulfur dichloride toward 3-hexyne was explored for the development of a novel derivatization protocol, and the products were subjected to gas chromatography-mass spectrometric (GC-MS) analysis. Among various unsaturated reagents like alkenes and alkynes, symmetrical alkyne 3-hexyne was optimized to be the suitable derivatizing agent for these analytes. Acetonitrile was found to be the suitable solvent for the derivatization reaction. The sample preparation protocol for the identification of these analytes from hexane spiked with petrol matrix was also optimized. Liquid-liquid extraction followed by derivatization was employed for the identification of these analytes from petrol matrix. Under the established conditions, the detection and quantification limits are 2.6 μg/mL, 8.6 μg/mL for S2Cl2 and 2.3 μg/mL, 7.7 μg/mL for SCl2, respectively, in selected ion monitoring (SIM) mode. The calibration curve had a linear relationship with y = 0.022x - 0.331 and r(2) = 0.992 for the working range of 10 to 500 μg/mL for S2Cl2 and y = 0.007x - 0.064 and r(2) = 0.991 for the working range of 10 to 100 μg/mL for SCl2, respectively. The intraday RSDs were between 4.80 to 6.41%, 2.73 to 6.44% and interday RSDs were between 2.20 to 7.25% and 2.34 to 5.95% for S2Cl2 and SCl2, respectively.

Positional isomerization of trans-3-hexadecenoic acid employing 2-amino-2-methyl-propanol as a derivatizing agent for ethylenic bond location by gas chromatography/mass spectrometry.

PubMed

Lamberto, M; Ackman, R G

1995-09-20

The effect of derivatization with 2-amino-2-methyl-propanol on trans-3-hexadecenoic acid was investigated as part of the identification of the trans-3-hexadecenoic acid in two Nova Scotian seaweeds. After the extraction of the total fatty acids and their methylation, the monoenoic trans fraction was isolated by thin-layer chromatography on silica gels impregnated with silver nitrate. This fraction was first analyzed by gas chromatography and showed the presence of the trans-3-hexadecenoic acid; other fatty acids were not present. The isolated fraction was derivatized with 2-amino-2-methyl-propanol prior to analysis by gas chromatography/mass spectrometry. The chromatogram obtained showed the presence of a positional isomer formed during the derivatization of the trans-3-hexadecenoic acid. The mass spectrum showed a prominent [M+H] and diagnostic ions for the identification of the unknown isomer, corresponding to the 4,4-dimethyloxazoline (DMOX) derivative of a presumed 2-hexadecenoic acid. Definitive confirmation of the ethylenic bond position was obtained by oxidative ozonolysis of the DMOX derivatives of the fatty acids under investigation. Infrared spectroscopy showed that the artifact formed during the DMOX derivatization of trans-3-hexadecenoic acid was the DMOX derivative of cis-2-hexadecenoic acid.

Graphene oxide-based dispersive solid-phase extraction combined with in situ derivatization and gas chromatography-mass spectrometry for the determination of acidic pharmaceuticals in water.

PubMed

Naing, Nyi Nyi; Li, Sam Fong Yau; Lee, Hian Kee

2015-12-24

A fast and low-cost sample preparation method of graphene based dispersive solid-phase extraction combined with gas chromatography-mass spectrometric (GC-MS) analysis, was developed. The procedure involves an initial extraction with water-immiscible organic solvent, followed by a rapid clean-up using amine functionalized reduced graphene oxide as sorbent. Simple and fast one-step in situ derivatization using trimethylphenylammonium hydroxide was subsequently applied on acidic pharmaceuticals serving as model analytes, ibuprofen, gemfibrozil, naproxen, ketoprofen and diclofenac, before GC-MS analysis. Extraction parameters affecting the derivatization and extraction efficiency such as volume of derivatization agent, effect of desorption solvent, effect of pH and effect of ionic strength were investigated. Under the optimum conditions, the method demonstrated good limits of detection ranging from 1 to 16ngL(-1), linearity (from 0.01 to 50 and 0.05 to 50μgL(-1), depending on the analytes) and satisfactory repeatability of extractions (relative standard deviations, below 13%, n=3). Copyright © 2015 Elsevier B.V. All rights reserved.

High performance thin layer chromatography fingerprint analysis of guava (Psidium guajava) leaves

NASA Astrophysics Data System (ADS)

Astuti, M.; Darusman, L. K.; Rafi, M.

2017-05-01

High-performance thin layer chromatography (HPTLC) fingerprint analysis is commonly used for quality control of medicinal plants in term of identification and authentication. In this study, we have been developed HPTLC fingerprint analysis for identification of guava (Psidium guajava) leaves raw material. A mixture of chloroform, acetone, and formic acid in the ratio 10:2:1 was used as the optimum mobile phase in HPTLC silica plate and with 13 bands were detected. As reference marker we chose gallic acid (Rf = 0.21) and catechin (Rf = 0.11). The two compound were detected as pale black bands at 366 nm after derivatization with sulfuric acid 10% v/v (in methanol) reagent. Validation of the method was met within validation criteria, so the developed method could be used for quality control of guava leaves.

Development and validation of a general derivatization HPLC method for the trace analysis of acyl chlorides in lipophilic drug substances.

PubMed

Zheng, Xiangyuan; Luo, Lan; Zhou, Jie; Ruan, Xiaoling; Liu, Wenyuan; Zheng, Feng

2017-06-05

Acyl chlorides are important acylating agents in the synthesis of active pharmaceutical ingredients. Determining the residual acyl chlorides in drug substances is a challenge due to their high reactivity and the matrix interferences from drug substances and their related impurities. This paper describes a general derivatization HPLC method for the determination of aromatic and aliphatic acyl chlorides in lipophilic drug substances. Since most drug substances have weak absorptions in the visible range (above 380nm), the nitro-substituted anilines and nitro-substituted phenylhydrazines were selected as the derivatization reagents due to their weak basicity and red-shift of UV absorption spectra. The maximum wavelength and absorption intensity of nitro-substituted anilines decreased after derivatization with acyl chlorides, whereas the derivatization products of nitro-substituted phenylhydrazines showed the slight increases of maximum wavelength and absorbance intensity. Hence, 2-nitrophenylhydrazine was selected as the suitable derivatization reagent because the derivatives have the maximum UV wavelength absorbance at 395nm, which could largely minimize the matrix interferences. The optimization of the concentration of 2-nitrophenylhydrazine is important for the sensitivity and stability of derivatives. Other reaction conditions including reaction temperature, time and the influence of three competitive solvents (water, methanol and ethanol) on the reaction efficiency were also studied. After derivatization with 100μgmL -1 2-nitrophenylhydrazine at room temperature for 30min, the method was validated for high specificity and sensitivity with the detection limits in the range of 0.01-0.03μgmL -1 . The proposed method was applied as a generic method to determine the residual acyl chlorides in lipophilic drug substances. Copyright © 2017 Elsevier B.V. All rights reserved.

Multiresidue screening of endocrine-disrupting chemicals and pharmaceuticals in aqueous samples by multi-stir bar sorptive extraction-single desorption-capillary gas chromatography/mass spectrometry.

PubMed

Van Hoeck, Els; Canale, Francesca; Cordero, Chiara; Compernolle, Sien; Bicchi, Carlo; Sandra, Pat

2009-02-01

A multiresidue method for screening endocrine-disrupting chemicals (EDCs) and pharmaceuticals in aqueous samples is presented. Four 10-mL aliquots of water were taken for stir bar sorptive extraction (SBSE) and they were treated in the following way. In sample one, in situ derivatization was performed with acetic acid anhydride to improve the extraction efficiencies and chromatographic analysis of phenolic compounds. For the same reasons, aliquot two was treated with ethyl chloroformate to improve amine and acid extraction and analysis, and aliquot three with tetraethylborate to enhance organotin compound extraction and analysis. Methanol was added to sample four to stop adsorption of apolar solutes on the wall. After SBSE, the four stir bars, together with a plug of glass wool impregnated with bis(trimethylylsilyl)trifluoroacetamide (BSTFA) to derivatize hydroxyl functionalities, were introduced into the same thermal desorption tube, heat-desorbed, and analyzed simultaneously by capillary GC/MS. The figures of merit of the method were evaluated with an EDC model mixture. In scan-mode MS, the limits of detection (LODs) were in the range 1-500 ng/L, while the LODs dropped by a factor of 50-100 when ion monitoring MS was applied to the targets. The performance of the method was illustrated by analysing some real-world water samples.

Comprehensive analysis of the lipophilic reactive carbonyls present in biological specimens by LC/ESI-MS/MS.

PubMed

Tomono, Susumu; Miyoshi, Noriyuki; Ohshima, Hiroshi

2015-04-15

A new analytical method has been developed for profiling lipophilic reactive carbonyls (RCs) such as aldehydes and ketones in biological samples using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with selected reaction monitoring (SRM). The method consists of several phases, including (1) extraction of lipophilic RCs with a chloroform/methanol mixture; (2) derivatization of the extracted RCs with dansyl hydrazine (DH); and (3) SRM detection of the characteristic product ion of the 5-dimethylaminonaphthalene-1-sulfonyl moiety (m/z 236.1). The analytical results were expressed as RC maps, which allowed for the occurrence and levels of different lipophilic RCs to be visualized. We also developed a highly reproducible and accurate method to extract, purify and derivatize RCs in small volumes of biological specimens. This method was applied to the detection of free RCs in mice plasma samples, and resulted in the detection of more than 400 RCs in samples obtained from C57BL/6J mice. Thirty-four of these RCs were identified by comparison with authentic RCs. This method could be used to investigate the levels of RCs in biological and environmental samples, as well as studying the role of lipid peroxidation in oxidative stress related-disorders and discovering new biomarkers for the early diagnosis of these diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Capillary electrophoresis coupled with chloroform-acetonitrile extraction for rapid and highly selective determination of cysteine and homocysteine levels in human blood plasma and urine.

PubMed

Ivanov, Alexander Vladimirovich; Bulgakova, Polina Olegovna; Virus, Edward Danielevich; Kruglova, Maria Petrovna; Alexandrin, Valery Vasil'evich; Gadieva, Viktoriya Aleksandrovna; Luzyanin, Boris Petrovich; Kushlinskii, Nikolai Evgen'evich; Fedoseev, Anatolij Nikolaevich; Kubatiev, Aslan Amirkhanovich

2017-10-01

A rapid and selective method has been developed for highly sensitive determination of total cysteine and homocysteine levels in human blood plasma and urine by capillary electrophoresis (CE) coupled with liquid-liquid extraction. Analytes were first derivatized with 1,1'-thiocarbonyldiimidazole and then samples were purified by chloroform-ACN extraction. Electrophoretic separation was performed using 0.1 M phosphate with 30 mM triethanolamine, pH 2, containing 25 μM CTAB, 2.5 μM SDS, and 2.5% polyethylene glycol 600. Samples were injected into the capillary (with total length 32 cm and 50 μm id) at 2250 mbar*s and subsequent injection was performed for 30 s with 0.5 M KОН. The total analysis time was less than 9 min, accuracy was 98%, and precision was <2.6%. The LOD was 0.2 μM for homocysteine and 0.5 μM for cysteine. The use of liquid-liquid extraction allowed the precision and sensitivity of the CE method to be significantly increased. The validated method was applied to determine total cysteine and homocysteine content in human blood plasma and urine samples obtained from healthy volunteers and patients with kidney disorders. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monitoring dediazoniation product formation by high-performance liquid chromatography after derivatization.

PubMed

Bravo-Díaz, Carlos; González-Romero, Elisa

2003-03-14

A derivatization protocol that exploits the rapid reaction between arenediazonium ions and a suitable coupling agent followed by high-performance liquid chromatography analyses of the reaction mixture was employed to determine the product distribution, the rate constants for product formation and the association constant of 4-nitrobenzenediazonium, PNBD, ion with beta-cyclodextrin, beta-CD. The derivatization of PNBD with the coupling agent leads to the formation of a stable azo dye that prevents by-side reactions of PNBD with the solvents of the mobile phase, including water, or the metallic parts of the chromatographic system that would eventually lead to erroneous identification and quantification of dediazoniation products. The results show that in the presence of beta-CD, nitrobenzene is formed at the expense of 4-nitrophenol, which is the major product in its absence. The observed rate constants for the interaction between PNBD and beta-CD increase upon increasing [beta-CD] showing a saturation profile indicative of the formation of an inclusion complex between PNBD and beta-CD. By fitting the experimental data to a simplified Lineaweaver-Burk equation, the corresponding association constant and the maximum acceleration rate of beta-CD towards PNBD were estimated. The protocol is applicable under a variety of experimental conditions provided that the rate of the coupling reaction is much faster than that of dediazoniation.

Development of the 2007 Chemical Decontaminant Source Document

DTIC Science & Technology

2009-03-01

Chemical Agent Simulant Specific DEM diethyl malonate MeS methyl salicylate PEG200 Polyethylene glycol 200 TEP triethyl phosphate Group 6...simulants • H-agent simulants o Methyl salicylate (MeS) o Chloroethyl phenyl sulfide (CEPS) o Chloroethyl ethyl sulfide (CEES) • VX simulants... Methyl bromide Ethyl phosphonothioic dichloride Sulfur dioxide Methyl chloroformate Ethyl phosphonic dichloride Sulfuric acid Methyl chlorosilane

Determination of buoyant density and sensitivity to chloroform and freon for the etiological agent of infectious salmonid anaemia

USGS Publications Warehouse

Christie, K.E.; Hjeltnes, B.; Uglenes , I.; Winton, J.R.

1993-01-01

Plasma was collected from Atlantic salmon Salrno salar with acute infectious salmon anaemia (ISA) and used to challenge Atlantic salmon parr by intraperitoneal injection. Treatment of plasma with the lipid solvent, chloroform, showed that the etiological agent of ISA contained essential lipids, probably as a viral envelope. Some infectivity remained following treatment with freon. Injection challenges using fractions from equilibrium density gradient centrifugation of plasma from fish with acute ISA revealed a band of infectivity in the range 1.184 to 1.262 g cm-3. The band was believed to conta~n both complete ISA-virus particles and infectious particles lacking a complete envelope, nucleocapsid or genome. Density gradient centrifugation of infectious plasma for enrichment of the putative ISA virus appeared to offer a suitable method for obtaining virus-specific nucleic acid for use in the construction of cDNA libraries. 

Assay at low ppm level of dimethyl sulfate in starting materials for API synthesis using derivatization in ionic liquid media and LC-MS.

PubMed

Grinberg, Nelu; Albu, Florin; Fandrick, Keith; Iorgulescu, Elena; Medvedovici, Andrei

2013-03-05

Dimethyl sulfate (DMS) is frequently used in pharmaceutical manufacturing processes as an alkylating agent. Trace levels of DMS in drug substances should be carefully monitored since the compound can become an impurity which is genotoxic in nature. Derivatization of DMS with dibenzazepine leads to formation of the N-methyl derivative, which can be retained on a reversed phase column and subsequently separated from other potential impurities. Such derivatization occurs relatively slowly. However, it can be substantially speed up if ionic liquids are used as reaction media. In this paper we report the use of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (IL1) and 1-butyl-4-methylpyridinium tetrafluoroborate (IL2) as reaction media for the derivatization of DMS with dibenzazepine. It was determined that the stoichiometry between the substrate and DMS may be 1:1 or 2:1, in relation with the nature of the reaction media. An (+)ESI-MS/MS approach was used for quantitation of the derivatized product. Alternatively, DMS derivatization may be carried out with pyridine in acetonitrile (ACN). The N-methylpyridinium derivative was separated by hydrophilic interaction liquid chromatography (HILIC) and detected through (+)ESI-MS (in the SIM mode). In both cases, a limit of quantitation (LOQ) of 0.05 μg/ml DMS was achievable, with a linearity range up to 10 μg/ml. Both analytical alternatives were applied to assay DMS in 4-(2-methoxyethyl)phenol, which is used as a starting material in the synthesis of metoprolol. Copyright © 2012 Elsevier B.V. All rights reserved.

Utilization of a deuterated derivatization agent to synthesize internal standards for gas chromatography-tandem mass spectrometry quantification of silylated metabolites.

PubMed

Lien, Stina K; Kvitvang, Hans Fredrik Nyvold; Bruheim, Per

2012-07-20

GC-MS analysis of silylated metabolites is a sensitive method that covers important metabolite groups such as sugars, amino acids and non-amino organic acids, and it has become one of the most important analytical methods for exploring the metabolome. Absolute quantitative GC-MS analysis of silylated metabolites poses a challenge as different metabolites have different derivatization kinetics and as their silyl-derivates have varying stability. This report describes the development of a targeted GC-MS/MS method for quantification of metabolites. Internal standards for each individual metabolite were obtained by derivatization of a mixture of standards with deuterated N-methyl-N-trimethylsilyltrifluoroacetamide (d9-MSTFA), and spiking this solution into MSTFA derivatized samples prior to GC-MS/MS analysis. The derivatization and spiking protocol needed optimization to ensure that the behaviour of labelled compound responses in the spiked sample correctly reflected the behaviour of unlabelled compound responses. Using labelled and unlabelled MSTFA in this way enabled normalization of metabolite responses by the response of their deuterated counterpart (i.e. individual correction). Such individual correction of metabolite responses reproducibly resulted in significantly higher precision than traditional data correction strategies when tested on samples both with and without serum and urine matrices. The developed method is thus a valuable contribution to the field of absolute quantitative metabolomics. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of 14C/ 12C of acetaldehyde in indoor air by compound specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

Kato, Yoshimi; Shinohara, Naohide; Yoshinaga, Jun; Uchida, Masao; Matsuda, Ayuri; Yoneda, Minoru; Shibata, Yasuyuki

A method of compound-specific radiocarbon analysis (CSRA) for acetaldehyde in indoor air was established for the source apportionment purpose and the methodology was applied to indoor air samples. Acetaldehyde in indoor air samples was collected using the conventional 2,4-dinitrophenylhydrazine (DNPH) derivatization method. Typically 24-h air sampling at 5-10 L min -1 allowed collection of adequate amount of acetaldehyde for radiocarbon analysis by accelerator mass spectrometry (AMS). The 14C abundance of acetaldehyde in indoor air was measured by AMS after solvent extraction of derivatized acetaldehyde and sequential purification by a preparative liquid chromatography system and a preparative capillary gas chromatography system. The recovery and purity of the derivatized acetaldehyde was satisfactory for 14C analysis by AMS. 14C abundance of acetaldehyde was calculated by considering that of derivatizing agent DNPH. Our preliminary survey showed that percent modern carbon (pMC) values of acetaldehyde isolated from indoor air sampled in newly built, unoccupied housings ( n=5) in the suburb of Tokyo ranged from 49.4 to 67.0. This result indicated that contribution of anthropogenic source was greater than previously expected.

In situ continuous derivatization/pre-concentration of carbonyl compounds with 2,4-dinitrophenylhydrazine in aqueous samples by solid-phase extraction Application to liquid chromatography determination of aldehydes.

PubMed

Baños, Clara-Eugenia; Silva, Manuel

2009-03-15

A rapid and straightforward continuous solid-phase extraction system has been developed for in situ derivatization and pre-concentration of carbonyl compounds in aqueous samples. Initially 2,4-dinitrophenylhydrazine, the derivatizing agent, was adsorbed on a C(18) mini-column and then 15-ml of sample were continuously aspirated into the flow system, where the derivatization and pre-concentration of the analytes (low-molecular mass aldehydes) were performed simultaneously. Following elution, 20 microl of the extract were injected into a LC-DAD system, in which hydrazones were successfully separated in 12 min on a RP-C(18) column using a linear gradient mobile phase of acetonitrile-water of 60-100% acetonitrile for 8 min, flowing at 0.5 ml/min. The whole analytical process can be accomplished within ca. 35 min. Under optimum conditions, limits of detection were obtained between 0.3 and 1.0 microg/l and RSDs (inter-day precision) from 1.2 to 4.6%. Finally, some applications on water samples are presented with recoveries ranged from 95.8 to 99.4%.

Strategies for the capillary electrophoretic separation of indole alkaloids in Psilocybe semilanceata.

PubMed

Pedersen-Bjergaard, S; Rasmussen, K E; Sannes, E

1998-01-01

While the hallucinogenic mushrooms Psilocybe semilanceata have previously been analyzed for the indole alkaloids psilocybin and baeocystin by capillary zone electrophoresis (CZE) at pH 11.5, the present work focused on the development of an alternative and complementary capillary electrophoretic method for their identification. Owing to their structural similarity and zwitterionic nature, the compounds were difficult to resolve based on different interactions with cationic or anionic micelles. However, while the attempts with micellar electrokinetic chromatography (MEKC) were unsuccessful, rapid derivatization with propyl chloroformate and reanalysis by CZE at pH 11.5 was effective to support identification of the two indole alkaloids. Psilocin was difficult to analyze by CZE at pH 11.5 owing to comigration with the electroosmotic flow. For this compound, the pH of the running buffer was reduced to 7.2 to effectively enhance the electrophoretic mobility.

A novel LCMSMS method for quantitative measurement of short-chain fatty acids in human stool derivatized with 12C- and 13C-labelled aniline.

PubMed

Chan, James Chun Yip; Kioh, Dorinda Yan Qin; Yap, Gaik Chin; Lee, Bee Wah; Chan, Eric Chun Yong

2017-05-10

A novel liquid chromatography tandem mass spectrometry (LCMSMS) method for the quantitative measurement of gut microbial-derived short-chain fatty acids (SCFAs) in human infant stool has been developed and validated. Baseline chromatographic resolution was achieved for 12 SCFAs (acetic, butyric, caproic, 2,2-dimethylbutyric, 2-ethylbutyric, isobutyric, isovaleric, 2-methylbutyric, 4-methylvaleric, propionic, pivalic and valeric acids) within an analysis time of 15min. A novel sequential derivatization of endogenous and spiked SCFAs in stool via 12 C- and 13 C-aniline respectively, facilitated the accurate quantitation of 12 C-aniline derivatized endogenous SCFAs based on calibration of exogenously 13 C-derivatized SCFAs. Optimized quenching of derivatization agents prior to LCMSMS analysis further reduced to negligible levels the confounding chromatographic peak due to in-line derivatization of unquenched aniline with residual acetic acid present within the LCMS system. The effect of residual acetic acid, a common LCMS modifier, in analysis of SCFAs has not been addressed in previous SCFA assays. For the first time, a total of 9 SCFAs (acetic, butyric, caproic, isobutyric, isovaleric, 2-methylbutyric, 4-methylvaleric, propionic and valeric acids) were detected and quantitated in 107 healthy infant stool samples. The abundance and diversity of SCFAs in infant stool vary temporally from 3 weeks onwards and stabilize towards the end of 12 months. This in turn reflects the maturation of infant SCFA-producing gut microbiota community. In summary, this novel method is applicable to future studies that investigate the biological roles of SCFAs in paediatric health and diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Metabolite extraction from adherently growing mammalian cells for metabolomics studies: optimization of harvesting and extraction protocols.

PubMed

Dettmer, Katja; Nürnberger, Nadine; Kaspar, Hannelore; Gruber, Michael A; Almstetter, Martin F; Oefner, Peter J

2011-01-01

Trypsin/ethylenediaminetetraacetic acid (EDTA) treatment and cell scraping in a buffer solution were compared for harvesting adherently growing mammalian SW480 cells for metabolomics studies. In addition, direct scraping with a solvent was tested. Trypsinated and scraped cell pellets were extracted using seven different extraction protocols including pure methanol, methanol/water, pure acetone, acetone/water, methanol/chloroform/water, methanol/isopropanol/water, and acid-base methanol. The extracts were analyzed by GC-MS after methoximation/silylation and derivatization with propyl chloroformate, respectively. The metabolic fingerprints were compared and 25 selected metabolites including amino acids and intermediates of energy metabolism were quantitatively determined. Moreover, the influence of freeze/thaw cycles, ultrasonication and homogenization using ceramic beads on extraction yield was tested. Pure acetone yielded the lowest extraction efficiency while methanol, methanol/water, methanol/isopropanol/water, and acid-base methanol recovered similar metabolite amounts with good reproducibility. Based on overall performance, methanol/water was chosen as a suitable extraction solvent. Repeated freeze/thaw cycles, ultrasonication and homogenization did not improve overall metabolite yield of the methanol/water extraction. Trypsin/EDTA treatment caused substantial metabolite leakage proving it inadequate for metabolomics studies. Gentle scraping of the cells in a buffer solution and subsequent extraction with methanol/water resulted on average in a sevenfold lower recovery of quantified metabolites compared with direct scraping using methanol/water, making the latter one the method of choice to harvest and extract metabolites from adherently growing mammalian SW480 cells.

On-matrix derivatization extraction of chemical weapons convention relevant alcohols from soil.

PubMed

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Dubey, D K; Pardasani, Deepak

2013-10-11

Present study deals with the on-matrix derivatization-extraction of aminoalcohols and thiodiglycols, which are important precursors and/or degradation products of VX analogues and vesicants class of chemical warfare agents (CWAs). The method involved hexamethyldisilazane (HMDS) mediated in situ silylation of analytes on the soil. Subsequent extraction and gas chromatography-mass spectrometry analysis of derivatized analytes offered better recoveries in comparison to the procedure recommended by the Organization for the Prohibition of Chemical Weapons (OPCW). Various experimental conditions such as extraction solvent, reagent and catalyst amount, reaction time and temperature were optimized. Best recoveries of analytes ranging from 45% to 103% were obtained with DCM solvent containing 5%, v/v HMDS and 0.01%, w/v iodine as catalyst. The limits of detection (LOD) and limit of quantification (LOQ) with selected analytes ranged from 8 to 277 and 21 to 665ngmL(-1), respectively, in selected ion monitoring mode. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of alternative preservatives in cosmetic products by chromophoric derivatization followed by vortex-assisted liquid-liquid semimicroextraction and liquid chromatography.

PubMed

Miralles, Pablo; Vrouvaki, Ilianna; Chisvert, Alberto; Salvador, Amparo

2016-07-01

An analytical method for the simultaneous determination of phenethyl alcohol, methylpropanediol, phenylpropanol, caprylyl glycol, and ethylhexylglycerin, which are used as alternative preservatives in cosmetic products, has been developed. The method is based on liquid chromatography with UV spectrophotometric detection after chromophoric derivatization with benzoyl chloride and vortex-assisted liquid-liquid semimicroextraction. Different chromatographic parameters, derivatization conditions, and sample preparation variables were studied. Under optimized conditions, the limits of detection values for the analytes ranged from 0.02 to 0.06µgmL(-1). The method was validated with good recovery values (84-118%) and precision values (3.9-9.5%). It was successfully applied to 10 commercially available cosmetic samples. The good analytical features of the proposed method besides of its environmentally-friendly characteristics, make it useful to carry out the quality control of cosmetic products containing the target compounds as preservative agents. Copyright © 2016 Elsevier B.V. All rights reserved.

Cytotoxicity of different extracts of arial parts of Ziziphus spina-christi on Hela and MDA-MB-468 tumor cells

PubMed Central

Jafarian, Abbas; Zolfaghari, Behzad; Shirani, Kobra

2014-01-01

Background: It has been shown that plants from the family Rhamnaceae possess anticancer activity. In this study, we sought to determine if Ziziphus spina-christi, a species from this family, has cytotoxic effect on cancer cell lines. Materials and Methods: Using maceration method, different extracts of leaves of Z. spina-christi were prepared. Hexane, chloroform, chloroform-methanol (9:1), methanol-water (7:1) methanol, butanol and water were used for extraction, after preliminary phytochemical analyses were done. The cytotoxic activity of the extracts against Hela and MDA-MB-468 tumor cells was evaluated by MTT assay. Briefly, cells were seeded in microplates and different concentrations of extracts were added. After incubation of cells for 72 h, their viability was evaluated by addition of tetrazolium salt solution. After 3 h medium was aspirated, dimethyl sulfoxide was added and absorbance was determined at 540 nm with an ELISA plate reader. Extracts were considered cytotoxic when more than 50% reduction on cell survival was observed. Results: Hexane, chloroform, chloroform-methanol, butanol, methanol-water and aqueous extracts of Z. spina-christi significantly and concentration-dependently reduced viability of Hela and MAD-MB-468 cells. In the both cell lines, chloroform-methanol extract of Z. spina-christi was more potent than the other extracts. Results: From the finding of this study it can be concluded that Z. spina-christi is a good candidate for further study for new cytotoxic agents. PMID:24627846

On-Line Derivatization Gas Chromatography Ion Trap Mass Spectrometry for Determination of Endocrine Disruptors in Surface Water

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

Tzing, Shin-Hwa; Chang, Jia-Yaw; Ling, Yong-Chien

2004-03-31

A method has been developed for the determination of endocrine disruptors (EDs) (containing hydroxyl groups) in surface water from different sources. The surface water samples from different sites including school and local dormitory sewage effluents, lake water and river water were collected and analyzed. In this method, the pretreated sample is directly analyzed by GC-MS using on-line derivatization, where tetramethylammonium hydroxide (TMA-OH) was used as the derivatizing agent. Use of large-volume direct sample introduction (DSI) and co-injection of the sample and TMAOH avoids external contaminations as observed in conventional derivatization protocols. Additionally, the use of chemical ionization (CI) and CI-MS/MSmore » could enable detection of EDs at lower concentrations and reduce the matrices' interference thereby enhancing detection sensitivity of EDs for quantification. In this work, the use of dichloromethane as CI reagent for EDs is reported for the first time and could detect EDs to concentrations as low as 0.5 pg/mL. The recovery ranged from 74 to 112 % and the relative standard derivations for replicate analyses ranged from 5 to 17 %. We hope that this method will be applicable for routine analysis of EDs with hydroxyl functional groups.« less

Derivatizing assay for the determination of aldehydes using micellar electrokinetic chromatography.

PubMed

Donegatti, Tiago Augusto; Gonçalves, Luís Moreira; Pereira, Elisabete Alves

2017-04-01

In this work, the use of a novel derivatization agent for the determination of aldehydes (in this particular case: formaldehyde, acetaldehyde, propionaldehyde, and valeraldehyde) using micellar electrokinetic chromatography is reported. The derivatization reaction is based on the reaction of aldehydes with benzhydrazide to form the corresponding derivates with maximum absorbance at 250 nm. The experimental conditions of the derivatization reaction as well of the separation were optimized. The adducts were separated with a +22 kV voltage at a temperature of 29°C. The adducts' separation was performed in less than 14 min using as the running buffer a mixture containing 110 mmol/L of sodium dodecyl sulfate and 27 mmol/L of sodium tetraborate at pH 9.45. Samples were injected using hydrodynamic mode (50 mbar × 5 s). The calibration curves were linear up to 15.0 mg/L with r 2 above 0.99. Intra and inter-day precisions were in average 3 and 4%, respectively, and recoveries were in average of 95%. Limits of detection and quantification were around 0.5 and 1.5 mg/L, respectively. The developed method was successfully applied in the analysis of low molar weight aldehydes in yogurt and vinegar samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DEVELOPMENTS IN THE SUPERCRITICAL FLUID EXTRACTION OF CHLOROPHENOXY ACID HERBICIDES FROM SOIL SAMPLES

EPA Science Inventory

Extraction of chlorophenoxy acid herbicides from soil samples with supercritical carbon dioxide as extractant and tetrabutylammonium hydroxide and methyl iodide as derivatization agents was investigated. The extraction was carried out at 400 atm and 80 C for 15 min static, follow...

RAPID DECHLORINATION OF CARBON TETRACHLORIDE AND CHLOROFORM BY EXTRACELLULAR AGENTS IN CULTURES OF METHANOSARCINA THENNOPHILA. (R825549C044)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Hypolipidemic Activity of Chloroform Extract of Mimosa pudica Leaves

PubMed Central

Rajendran, Rekha; Krishnakumar, Ekambaram

2010-01-01

Mimosa pudica Lin., known as chue Mue, is a stout straggling prostrate shrubby plant, with spinous stipules and globose pinkish flower heads, and grows as weed in almost all parts of the country. It is traditionally used for its various properties and hence in the present study, chloroform extract of Mimosa pudica leaves has been screened for its hypolipidemic activity. Hypolipidemic activity is screened by inducing hyperlipidemia with the help of atherogenic diet in wistar albino rats and serum levels of various biochemical parameters such as total cholesterol, triglycerides, LDL, VLDL and HDL cholesterol were determined. Atherogenic index shows the measure of the athero-genic potential of the drugs. Chloroform extract showed significant (p < 0.05) hypolipidemic effect by lowering the serum levels of biochemical parameters such as significant reduction in the level of serum cholesterol, triglyceride, LDL, VLDL and increase in HDL level which was similar to the standard drug Atorvastatin. Chloroform extract exhibited significant atherogenic index and percentage protection against hyperlipidemia. These biochemical observations were in turn confirmed by histopathological examinations of aorta, liver and kidney sections and are comparable with the standard hypolipidemic drug Atorvastatin. Preliminary phytochemical analysis revealed the presence of phytoconstituents such as steroids, flavonoids, glycosides, alkaloids, phenolic compounds which is further confirmed by the thin layer chromatography, High Performance Thin Layer Chromatography (HPTLC). The overall experimental results suggests that the biologically active phytoconstituents such as flavonoids, glycosides alkaloids present in the chloroform extract of Mimosa pudica, may be responsible for the significant hypolipidemic activity and the results justify the use of Mimosa pudica as a significant hypolipidemic agent. PMID:23408779

Hypericum grandifolium Choisy: a species native to Macaronesian Region with antidepressant effect.

PubMed

Sánchez-Mateo, C C; Bonkanka, C X; Rabanal, R M

2009-01-21

Various species of Hypericum genus have been used in the Canary Islands as sedative, diuretic, vermifuge, wound healing, antihysteric and antidepressant agent. Studies have shown that methanol extract of Hypericum grandifolium Choisy is active in tetrabenazine-induced ptosis and forced swimming tests. In the current study, the aqueous, butanol and chloroform fractions obtained from the methanol extract as well as three sub-fractions derived from the chloroform fraction were evaluated for their central nervous effects in mice, particularly their antidepressant activity. The central nervous effect of different fractions and sub-fractions of Hypericum grandifolium was evaluated in mice using various behavioural models including locomotor and muscle relaxant activity, forced swimming test, effect on normal body temperature, barbiturate-induced sleep, tetrabenazine-induced syndrome and 5-hydroxytryptohan-induced head twitches and syndrome. We found that the butanol and chloroform fractions and all sub-fractions showed an antidepressant effect in the forced swimming test, the chloroform fraction being the most active. They produced no effects or only a slight depression of locomotor activity. Chloroform fraction significantly increased the pentobarbital-induced sleeping time, produced a slight but significant hypothermia and antagonized tetrabenazine-induced ptosis, whereas the butanol fraction produced a slight potentiation of 5-HTP-induced head twitches and syndrome. The present results, together with previous pharmacological and phytochemical data, indicated that Hypericum grandifolium possess antidepressant-like effects in mice and that different constituents, such as the flavonoids and the benzophenone derivatives, could be responsible at least in part for the antidepressant effects observed for this species.

Attenuation of Pseudomonas aeruginosa quorum sensing, virulence and biofilm formation by extracts of Andrographis paniculata.

PubMed

Banerjee, Malabika; Moulick, Soumitra; Bhattacharya, Kunal Kumar; Parai, Debaprasad; Chattopadhyay, Subrata; Mukherjee, Samir Kumar

2017-12-01

Quorum-sensing (QS) is known to play an essential role in regulation of virulence factors and toxins during Pseudomonas aeruginosa infection which may frequently cause antibiotic resistance and hostile outcomes of inflammatory injury. Therefore, it is an urgent need to search for a novel agent with low risk of resistance development that can target QS and inflammatory damage prevention as well. Andrographis paniculata, a herbaceous plant under the family Acanthaceae, native to Asian countries and also cultivated in Scandinavia and some parts of Europe, has a strong traditional usage with its known antibacterial, anti-inflammatory, antipyretic, antiviral and antioxidant properties. In this study, three different solvent extracts (viz., chloroform, methanol and aqueous) of A. paniculata were examined for their anti-QS and anti-inflammatory activities. Study was carried out to assess the effect on some selected QS-regulatory genes at transcriptional level using Real Time-PCR. In addition, ability to attenuate MAPK pathways upon P. aeruginosa infection was performed to check its potential anti-inflammatory activity. Chloroform and methanol extracts showed significant reduction (p < 0.05) of the QS-controlled extracellular virulence factors in P. aeruginosa including the expression of pyocyanin, elastase, total protease, rhamnolipid and hemolysin without affecting bacterial viability. They also significantly (p < 0.05) reduced swarming motility and biofilm formation of P. aeruginosa. The chloroform extract, which was found to be more effective, decreased expression of lasI, lasR, rhlI and rhlR by 61%, 75%, 41%, and 44%, respectively. Moreover, chloroform extract decreased activation of p-p38 and p-ERK1/2 expression levels in MAPK signal pathways in P. aeruginosa infected macrophage cells. As the present study demonstrates that A. paniculata extracts inhibit QS in P. aeruginosa and exhibit anti-inflammatory activities, therefore it represents itself as a prospective therapeutic agent against P. aeruginosa infection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitation of pregabalin in dried blood spots and dried plasma spots by validated LC-MS/MS methods.

PubMed

Kostić, Nađa; Dotsikas, Yannis; Jović, Nebojša; Stevanović, Galina; Malenović, Anđelija; Medenica, Mirjana

2015-05-10

In this paper, novel LC-MS/MS methods for the determination of antiepileptic drug pregabalin in dried matrix spots (DMS) are presented. This attractive technique of sample collection in micro amount was utilized in the form of dried blood spots (DBS) and dried plasma spots (DPS). Following a pre-column derivatization procedure, using n-propyl chloroformate in the presence of n-propanol, and consecutive liquid-liquid extraction, derivatized pregabalin and its internal standard, 4-aminocyclohexanecarboxylic acid, were detected in positive ion mode by applying two SRM transitions per analyte. A YMC-Pack Octyl column (50mm×4.0mm, 3μm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550μL/min and total run time 2min. Established methods were fully validated over the concentration range of 0.200-20.0μg/mL for DBS and 0.400-40.0μg/mL for DPS, respectively, while specificity, accuracy, precision, recovery, matrix-effect, stability, dilution integrity and spot homogeneity were found within acceptance criteria. Validated methods were applied for the determination of pregabalin levels in dried blood and plasma samples obtained from patients with epilepsy, after per os administration of commercial capsules. Comparison of drug level in blood and plasma, as well as correction steps undertaken in order to overcome hematocrit issue, when analyzing DBS, are also given. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

First Detection of Non-Chlorinated Organic Molecules Indigenous to a Martian Sample

NASA Technical Reports Server (NTRS)

Freissinet, C.; Glavin, D. P.; Buch, A.; Szopa, C.; Summons, R. E.; Eigenbrode, J. L.; Archer, P. D., Jr.; Brinckerhoff, W. B.; Brunner, A. E.; Cabane, M.;

Chiral separation of amino acids in biological fluids by micellar electrokinetic chromatography with laser-induced fluorescence detection.

PubMed

Thorsén, G; Bergquist, J

2000-08-18

A method is presented for the chiral analysis of amino acids in biological fluids using micellar electrokinetic chromatography (MEKC) and laser-induced fluorescence (LIF). The amino acids are derivatized with the chiral reagent (+/-)-1-(9-anthryl)-2-propyl chloroformate (APOC) and separated using a mixed micellar separation system. No tedious pre-purification of samples is required. The excellent separation efficiency and good detection capabilities of the MEKC-LIF system are exemplified in the analysis of urine and cerebrospinal fluid. This is the first time MEKC has been reported for chiral analysis of amino acids in biological fluids. The amino acids D-alanine, D-glutamine, and D-aspartic acid have been observed in cerebrospinal fluid, and D-alanine and D-glutamic acid in urine. To the best of our knowledge no measurements of either D-alanine in cerebrospinal fluid or D-glutamic acid in urine have been presented in the literature before.

An AAA-DDD triply hydrogen-bonded complex easily accessible for supramolecular polymers.

PubMed

Han, Yi-Fei; Chen, Wen-Qiang; Wang, Hong-Bo; Yuan, Ying-Xue; Wu, Na-Na; Song, Xiang-Zhi; Yang, Lan

2014-12-15

For a complementary hydrogen-bonded complex, when every hydrogen-bond acceptor is on one side and every hydrogen-bond donor is on the other, all secondary interactions are attractive and the complex is highly stable. AAA-DDD (A=acceptor, D=donor) is considered to be the most stable among triply hydrogen-bonded sequences. The easily synthesized and further derivatized AAA-DDD system is very desirable for hydrogen-bonded functional materials. In this case, AAA and DDD, starting from 4-methoxybenzaldehyde, were synthesized with the Hantzsch pyridine synthesis and Friedländer annulation reaction. The association constant determined by fluorescence titration in chloroform at room temperature is 2.09×10(7)  M(-1) . The AAA and DDD components are not coplanar, but form a V shape in the solid state. Supramolecular polymers based on AAA-DDD triply hydrogen bonded have also been developed. This work may make AAA-DDD triply hydrogen-bonded sequences easily accessible for stimuli-responsive materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Utilization of Ionic Liquids in Lignocellulose Biorefineries as Agents for Separation, Derivatization, Fractionation, or Pretreatment.

PubMed

Peleteiro, Susana; Rivas, Sandra; Alonso, José L; Santos, Valentín; Parajó, Juan C

2015-09-23

Ionic liquids (ILs) can play multiple roles in lignocellulose biorefineries, including utilization as agents for the separation of selected compounds or as reaction media for processing lignocellulosic materials (LCM). Imidazolium-based ILs have been proposed for separating target components from LCM biorefinery streams, for example, the dehydration of ethanol-water mixtures or the extractive separation of biofuels (ethanol, butanol) or lactic acid from the respective fermentation broths. As in other industries, ILs are potentially suitable for removing volatile organic compounds or carbon dioxide from gaseous biorefinery effluents. On the other hand, cellulose dissolution in ILs allows homogeneous derivatization reactions to be carried out, opening new ways for product design or for improving the quality of the products. Imidazolium-based ILs are also suitable for processing native LCM, allowing the integral benefit of the feedstocks via separation of polysaccharides and lignin. Even strongly lignified materials can yield cellulose-enriched substrates highly susceptible to enzymatic hydrolysis upon ILs processing. Recent developments in enzymatic hydrolysis include the identification of ILs causing limited enzyme inhibition and the utilization of enzymes with improved performance in the presence of ILs.

Microwave-assisted decomplexation and in-situ headspace in-syringe dynamic derivatization of dimethylamine borane with high performance liquid chromatography-fluorescence detection.

PubMed

Muniraj, Sarangapani; Lee, Hua-Kwang; Hsiech, Chunming; Jen, Jen-Fon

2018-02-16

A rapid, sensitive, selective, and simple method for monitoring dimethylamine borane (DMAB) in aqueous sample is proposed by combining microwave-assisted de-complexation, headspace liquid phase in-situ derivatization extraction, and high-performance liquid chromatography-fluorescence detection for the determination of DMAB in samples. The present procedure involves de-complexation of DMAB using microwave irradiation, evolution of dimethylamine (DMA) to the headspace from an alkalized sample solution, and dynamic headspace liquid-phase derivatization extraction (Dy-HS-LPDE) of DMA with 9-fluorenylmethyl chloroformate in a syringe barrel. In addition to the optimal Dy-HS-LPDE and chromatographic parameters described in our previous study, the de-complexation of DMAB by thermal and microwave-assisted procedures and evolution of DMA into the headspace from an alkalized solution and modification of the Dy-HS-LPDE method are thoroughly investigated. The results indicate that complete de-complexation was obtained at 70 °C for 5 min, 30 °C for 10 min, or using microwave irradiation for 30 s at any applied power. It indicates that the DMAB complex easily undergoes de-complexation under microwave irradiation. The linearity range was 0.01-0.5 mg L -1 for DMAB and 0.0077-0.38 mg L -1 for DMA, with a coefficient of determination of 0.9995, and limit of detection of 3 μg L -1 (limit of quantitation of 10 μg L -1 ) for DMAB. The recoveries of DMAB are 95.3% (3.0% RSD) for waste water when spiked 0.05 mg L -1 and 93.5% (5.4% RSD) for the samples spiked with copper and nickel salts (5 mM each in the spiked waste sample). The whole analytical procedure can be completed within 25 min. The results confirm that the present method is a rapid, sensitive, selective, automated, low-cost and eco-friendly procedure to identify DMAB in samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Gas chromatographic/mass spectrometric analysis of the essential oil of Houttuynia cordata Thunb by using on-column methylation with tetramethylammonium acetate.

PubMed

Ch, Muhammad Ishtiaq; Wen, Yang F; Cheng, YiYu

2007-01-01

This paper describes a simple and novel on-column derivatization procedure used with gas chromatography/mass spectrometry (GC/MS) for the analysis of essential oil of Houttuynia cordata Thunb (HCT), a traditional Chinese medicine. In the procedure, the essential oil was obtained by hydrodistillation, and the fatty acid components were derivatized with tetramethylammonium acetate (TMAA) at 250 degrees C and identified by GC/MS. Methylation improved the determination of both the fatty acids and the other components in the essential oil of HCT. To obtain optimum methylation conditions, several important factors were investigated with pentadecane as the internal standard and a GC inlet temperature of 250 degres C. Tetramethylammonium hydroxide (TMAH) and TMAA were compared as the derivatization agent, and a 2:1 ratio of TMAA to capric acid was evaluated. Fatty acid methyl esters produced good chromatographic peak shapes and did not interfere with the determination of dodecanal and caryophyllene. TMAA is a neutral methylation reagent, and it yielded no side reactions during derivatization. It was found that the fatty acid content of the essential oil was about 81%; among the methylated fatty acids found were capric acid, methyl (43.66%), methyl laurate (16.15%), methyl hexadecanoate (9.27%), undecanoic acid, methyl (5.62%), methyl oleate (1.98%), and methyl linoleate (1.40%). Other major constituents were (-)-beta-pinene (1.02%), beta-myrcene (1.62%), 1-terpinen-4-ol (1.59%), decanal (1.49%), and 2-undecanone (1.47%). The results obtained demonstrated good efficiency for the procedure. Pure chromatograms allowed quantitation, which was obtained by total volume integration. The on-column derivatization procedure was simple to perform, and it improved the sensitivity, the peak resolution, and the selectivity of the GC/MS determination.

Proline-coated column for the capillary electrochromatographic separation of amino acids by in-column derivatization.

PubMed

Lin, Chun-Chi; Liu, Chuen-Ying

2004-10-01

With 3-trimethoxysilylpropyl chloride as the spacer, a proline-coated capillary column was prepared for the capillary electrochromatographic (CEC) separation of amino acids by in-column derivatization. Nine standard mixtures, including aspartic acid, glutamic acid, valine, phenylalanine, alanine, isoleucine, leucine, tyrosine, and tryptophan, were injected. o-Phthalaldehyde (OPA), OPA/2-mercaptoethanol (2-ME) and OPA/N-acetylcysteine (NAC) in borate buffer were tested as the derivatizing agent. Among them, OPA (50 mM) in borate buffer (pH 9.5, 50 mM) gave the best performance. The formation of isoindole could be detected by UV detection. The sandwich-type injection was carried out in hydrostatic mode (10 cm) with the program R(10 s)S(10 s) R(10 s)W(10 min) with R, S, and W being the reagent, sample, and waiting times. Mesityl oxide, benzyl alcohol, and acetone showed some interaction with the column. A current monitoring method was used instead of the determination of the electroosmotic flow (EOF). The direction of EOF was from anode to cathode even under acidic condition lower than the pI value (6.31) of the bonded group due to some unreacted silanol groups. Some parameters including pH, nature, and concentration of the mobile phase and the effect of organic modifier with regard to the CEC separation were investigated. With the proline-coated column (75 (50) cm x 75 microm ID) the best separation was performed in phosphate buffer (pH 4.00, 100 mM) with an applied voltage of -15 kV. The established method was also compared with those precolumn derivatized prior to the separation with proline-coated column as well as with in-capillary derivatization and separation with a bare fused-silica column. Copyright 2004 WILEY-VCH Verlag GmbH & Co.

Analysis of some chlorophenoxy acids and carbamate herbicides in water and soil as amide derivatives using gas chromatography-mass spectrometry.

PubMed

Salem, A A

2007-03-01

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).

Water-soluble fullerene (C60) derivatives as nonviral gene-delivery vectors.

PubMed

Sitharaman, Balaji; Zakharian, Tatiana Y; Saraf, Anita; Misra, Preeti; Ashcroft, Jared; Pan, Su; Pham, Quynh P; Mikos, Antonios G; Wilson, Lon J; Engler, David A

2008-01-01

A new class of water-soluble C60 transfecting agents has been prepared using Hirsch-Bingel chemistry and assessed for their ability to act as gene-delivery vectors in vitro. In an effort to elucidate the relationship between the hydrophobicity of the fullerene core, the hydrophilicity of the water-solubilizing groups, and the overall charge state of the C60 vectors in gene delivery and expression, several different C60 derivatives were synthesized to yield either positively charged, negatively charged, or neutral chemical functionalities under physiological conditions. These fullerene derivatives were then tested for their ability to transfect cells grown in culture with DNA carrying the green fluorescent protein (GFP) reporter gene. Statistically significant expression of GFP was observed for all forms of the C60 derivatives when used as DNA vectors and compared to the ability of naked DNA alone to transfect cells. However, efficient in vitro transfection was only achieved with the two positively charged C60 derivatives, namely, an octa-amino derivatized C60 and a dodeca-amino derivatized C60 vector. All C60 vectors showed an increase in toxicity in a dose-dependent manner. Increased levels of cellular toxicity were observed for positively charged C60 vectors relative to the negatively charged and neutral vectors. Structural analyses using dynamic light scattering and optical microscopy offered further insights into possible correlations between the various derivatized C60 compounds, the C60 vector/DNA complexes, their physical attributes (aggregation, charge) and their transfection efficiencies. Recently, similar Gd@C60-based compounds have demonstrated potential as advanced contrast agents for magnetic resonance imaging (MRI). Thus, the successful demonstration of intracellular DNA uptake, intracellular transport, and gene expression from DNA using C60 vectors suggests the possibility of developing analogous Gd@C60-based vectors to serve simultaneously as both therapeutic and diagnostic agents.

In vitro biocompatibility and proliferative effects of polar and non-polar extracts of cucurbita ficifolia on human mesenchymal stem cells.

PubMed

Aristatile, Balakrishnan; Alshammari, Ghedeir M

2017-05-01

Cucurbita ficifolia (C. ficifolia) has been traditionally known for its medicinal properties as an antioxidant, anti-diabetic and anti-inflammatory agent. However, there has been an enduring attention towards the identification of unique method, to isolate the natural components for therapeutic applications. Our study focuses on different polar and non-polar solvents (methanol, hexane and chloroform) to extract the bioactive components from C. ficifolia (pumpkin) and to study the biocompatibility and cytotoxicity effects on human bone marrow-mesenchymal stem cells (hBM-MSCs). The extracts were screened for their effects on cytotoxicity, cell proliferation and cell cycle on the hBM-MSCs cell line. The assays demonstrated that the chloroform extract was highly biocompatible, with less cytotoxic effect, and enhanced the cell proliferation. The methanol extract did not exhibit significant cytotoxicity when compare to the control. Concordantly, the cell cycle analysis confirmed that chloroform extract enhances the proliferation at lower concentrations. On the other hand, hexane extract showed high level of cytotoxicity with apoptotic and necrotic changes in hBM-MSCs. Collectively, our data revealed that chloroform is a good candidate to extract the bioactive components from C. ficifolia. Furthermore, our results suggest that specific gravity and density of the solvent might play a crucial role in the extraction process, which warrants further investigations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Allelopathic agents from Cyrtocymura cincta.

PubMed

Alvarez Valdés, D; Elías, A; Bardón, A

2001-01-01

The sesquiterpenoid fractions from the chloroform extracts of roots and aerial parts of the weed Cyrtocymura cincta (Griseb.) H. Robinson (Compositae) were tested to observe the effects on seed germination and growth of three dicot and four monocot species. Promotion and inhibition effects were observed according to the examined compound, specific seed or cultivar, and concentration.

HPLC method for determination of biologically active epoxy-transformers of treosulfan in human plasma: pharmacokinetic application.

PubMed

Główka, Franciszek K; Romański, Michał; Teżyk, Artur; Zaba, Czesław; Wróbel, Tomasz

2012-03-25

Clinical trials demonstrated treosulfan (TREO) as a promising myeloablative agent prior to hematopoietic stem cell transplantation (HSCT). TREO is a specific pro-drug from which biologically active mono- (S,S-EBDM) and diepoxybutane (S,S-DEB) derivatives are formed in vitro or in vivo by a non-enzymatic pH and temperature-dependent intramolecular nucleophilic substitution. Following extraction of the plasma samples with a mixture of dichloromethane and acetonitrile, S,S-EBDM and S,S-DEB were derivatized with 3-nitrobenzenesulfonic acid (3-NBS) to UV-absorbing esters. Optimal temperature and time of derivatization as well as extraction method and also the effect of pH on TREO stability in plasma were established. Identity of the synthesized derivatives was confirmed by mass spectrometry. The post-derivatization mixture was purified from the excess of unreacted 3-NBS by extraction with water. The derivatization products and 2,2'-dinitrobiphenyl (internal standard) were separated on Nucleosil 100 C18 column using a mobile phase consisted of acetonitrile and water. The developed method was validated and demonstrated adequate accuracy and precision. Limit of quantification for both S,S-EBDM and S,S-DEB amounted to 2.5 μM. The method was applied in clinical conditions to quantify the levels of TREO activation products in plasma of children undergoing HSCT. The methodology for simultaneous determination of TREO epoxy-transformers in human plasma is described for the first time. Copyright © 2011 Elsevier B.V. All rights reserved.

Simultaneously determination of bisphenol A and its alternatives in sediment by ultrasound-assisted and solid phase extractions followed by derivatization using GC-MS.

PubMed

Wang, Qiang; Zhu, Lingyan; Chen, Meng; Ma, Xinxin; Wang, Xiaolei; Xia, Junchao

2017-02-01

Bisphenol analogues are a group of chemicals which are being widely applied in industrial and household products owing to regulations on bisphenol A (BPA) in many countries. In this study, an analytical method, including extraction from complex environmental matrices, clean-up using solid phase extraction (SPE) and following-up derivatization prior to gas chromatography coupled with mass spectrometry (GC-MS), was developed to analyze seven commonly used bisphenols in sediment. Five kinds of extraction solvents, four kinds of SPE cartridges, and four kinds of SPE eluting solvents were individually tested for their performances; and the conditions for derivatizing were also optimized. Finally, C 18 cartridge was determined as the SPE cartridge and methanol was selected as extracting and eluting solvent. Acetic anhydride (AA) was used as derivatizing agent and reaction took 20 min at room temperature. The method was used successfully to measure the seven bisphenol compounds in sediment samples from Taihu Lake, China. BPA, bisphenol F and bisphenol S were detected in all sediment samples, with concentrations in the range of 3.94-33.2; 0.503-3.28 and 0.323-27.3 ng g -1 dw. Other compounds were detected at low frequencies or not detected. We provided a convenient, reliable, and sensitive method to analyze bisphenol compounds in complex environmental samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integrated on-chip derivatization and electrophoresis for the rapid analysis of biogenic amines.

PubMed

Beard, Nigel P; Edel, Joshua B; deMello, Andrew J

2004-07-01

We demonstrate the monolithic integration of a chemical reactor with a capillary electrophoresis device for the rapid and sensitive analysis of biogenic amines. Fluorescein isothiocyanate (FITC) is widely employed for the analysis of amino-group containing analytes. However, the slow reaction kinetics hinders the use of this dye for on-chip labeling applications. Other alternatives are available such as o-phthaldehyde (OPA), however, the inferior photophysical properties and the UV lambdamax present difficulties when using common excitation sources leading to a disparity in sensitivity. Consequently, we present for the first time the use of dichlorotriazine fluorescein (DTAF) as a superior in situ derivatizing agent for biogenic amines in microfluidic devices. The developed microdevice employs both hydrodynamic and electroosmotic flow, facilitating the creation of a polymeric microchip to perform both precolumn derivatization and electrophoretic analysis. The favorable photophysical properties of the DTAF and its fast reaction kinetics provide detection limits down to 1 nM and total analysis times (including on-chip mixing and reaction) of <60 s. The detection limits are two orders of magnitude lower than current limits obtained with both FITC and OPA. The optimized microdevice is also employed to probe biogenic amines in real samples.

[Determination of three phenoxyalkanoic acid herbicides in blood using gas chromatography coupled with solid-phase extraction and derivatization].

PubMed

Xin, Guobin; Tan, Jiayi; Yao, Lijuan; Zhu, Yu; Jiang, Zhaolin; Song, Hui

2008-01-01

A method for the determination of three phenoxyalkanoic acid herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2,4-dichlorophenoxy)-propanoic acid (2,4-DP), and 4-chloro-2-methylphenoxy-acetic acid (MCPA), in blood was developed. The blood sample was diluted with 0.1 mol/L hydrochloric acid, and extracted by solid-phase extraction using porous resin GDX401 as adsorbent and ethyl ether as eluent. The extract was esterified with dichloropropanol in the presence of sulfuric acid as catalyst. The derivatives were analysed by gas chromatography with electron-capture detection. The detection limits of 2,4-D, 2,4-DP and MCPA were 20, 8 and 40 ng/mL, respectively. In quantitative analysis, 2,4-dichlorophenylacetic acid was used as an internal standard. The linear relationships and recoveries were satisfactory. The derivatization of the three herbicides with methanol, ethanol, n-propanol, n-butanol, and trifluoroethanol were also studied, and the analytical methods of these derivatization were compared with that of dichloropropanol as esterifying agent. The method is sensitive enough for the examination of the poison samples in actual.

Analysis of 26 amino acids in human plasma by HPLC using AQC as derivatizing agent and its application in metabolic laboratory.

PubMed

Sharma, Gaurav; Attri, Savita Verma; Behra, Bijaylaxmi; Bhisikar, Swapnil; Kumar, Praveen; Tageja, Minni; Sharda, Sheetal; Singhi, Pratibha; Singhi, Sunit

2014-05-01

The present study reports the simultaneous analysis of 26 physiological amino acids in plasma along with total cysteine and homocysteine by high-performance liquid chromatography (HPLC) employing 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) as precolumn derivatizing reagent. Separations were carried out using Lichrospher 100 RP-18e (5 μm) 250 × 4.0 mm column connected to 100 CN 4.0 × 4.0 mm guard column on a quaternary HPLC system and run time was 53 min. Linearity of the peak areas for different concentrations ranging from 2.5 to 100 pmol/μL of individual amino acids was determined. A good linearity (R (2) > 0.998) was achieved in the standard mixture for each amino acid. Recovery of amino acids incorporated at the time of derivatization ranged from 95 to 106 %. Using this method we have established the normative data of amino acids in plasma, the profile being comparable to the range reported in literature and identified cases of classical homocystinuria, cobalamin defect/deficiency, non-ketotic hyperglycinemia, hyperprolinemia, ketotic hyperglycinemia, urea cycle defect and maple syrup urine disease.

Terahertz wave techniques using a metal mesh for evaluating the components of the stratum corneum.

PubMed

Mizukoshi, Koji; Yonekura, Kazuki; Ogura, Hidehiro; Guan, Yu; Kawase, Kodo

2013-02-01

Terahertz waves are located in the region of the spectrum between milliwaves and infrared. We analyzed the feasibility of terahertz spectroscopy to inspect the compositional variations of the stratum corneum (SC). We used a terahertz time-domain spectroscopy system with the metal mesh technique. To investigate whether terahertz can inspect compositional variation of SC, we measured the terahertz frequency spectra of the SC sheet that was treated with chloroform-methanol, lipid mixture, a denaturation agent, and heating with hot air. The chloroform-methanol treatment of the SC shifted the dip position, which represents a convex downward shape of the spectra, to a higher frequency. This dip shift was reversed to an untreated position by the dose-dependent application of a lipid mixture. The heating treatment of the SC shifted the dip position to a higher frequency. The same dip shift was also induced by the application of a denaturation agent to the SC. The technique using terahertz waves with a metal mesh is effective because of its simplicity and its high degree of accuracy in detecting the amount of lipid and the protein conformation state. © 2012 John Wiley & Sons A/S.

In-vitro antiviral activity of Solanum nigrum against Hepatitis C Virus

PubMed Central

2011-01-01

Background Hepatitis C is a major health problem causes liver cirrhosis, hepatocellular carcinoma and death. The current treatment of standard interferon in combination with ribavirin, has limited benefits due to emergence of resistant mutations during long-term treatment, adverse side effects and high cost. Hence, there is a need for the development of more effective, less toxic antiviral agents. Results The present study was designed to search anti-HCV plants from different areas of Pakistan. Ten medicinal plants were collected and tested for anti-HCV activity by infecting the liver cells with HCV 3a innoculum. Methanol and chloroform extracts of Solanum nigrum (SN) seeds exhibited 37% and more than 50% inhibition of HCV respectively at non toxic concentration. Moreover, antiviral effect of SN seeds extract was also analyzed against HCV NS3 protease by transfecting HCV NS3 protease plasmid into liver cells. The results demonstrated that chloroform extract of SN decreased the expression or function of HCV NS3 protease in a dose- dependent manner and GAPDH remained constant. Conclusion These results suggest that SN extract contains potential antiviral agents against HCV and combination of SN extract with interferon will be better option to treat chronic HCV. PMID:21247464

A sensitive and rapid ultra HPLC-MS/MS method for the simultaneous detection of clopidogrel and its derivatized active thiol metabolite in human plasma.

PubMed

Peer, Cody J; Spencer, Shawn D; VanDenBerg, Dustin A H; Pacanowski, Michael A; Horenstein, Richard B; Figg, William D

2012-01-01

A sensitive, selective, and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (uHPLC-MS/MS) was developed for the simultaneous quantification of clopidogrel (Plavix(®)) and its derivatized active metabolite (CAMD) in human plasma. Derivatization of the active metabolite in blood with 2-bromo-3'-methoxy acetophenone (MPB) immediately after collection ensured metabolite stability during sample handling and storage. Following addition of ticlopidine as an internal standard and simple protein precipitation, the analytes were separated on a Waters Acquity UPLC™ sub-2 μm-C(18) column via gradient elution before detection on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. The method was validated across the clinically relevant concentration range of 0.01-50 ng/mL for parent clopidogrel and 0.1-150 ng/mL (r(2)=0.99) for CAMD, with a fast run time of 1.5 min to support pharmacokinetic studies using 75, 150, or 300 mg oral doses of clopidogrel. The analytical method measured concentrations of clopidogrel and CAMD with accuracy (%DEV) <±12% and precision (%CV) of <±6%. The method was successfully applied to measure the plasma concentrations of clopidogrel and CAMD in three subjects administered single oral doses of 75, 150, and 300 mg clopidogrel. It was further demonstrated that the derivatizing agent (MPB) does not affect clopidogrel levels, thus from one aliquot of blood drawn clinically, this method can simultaneously quantify both clopidogrel and CAMD with sensitivity in the picogram per mL range. Published by Elsevier B.V.

A Sensitive and Rapid Ultra HPLC-MS/MS Method for the Simultaneous Detection of Clopidogrel and its Derivatized Active Thiol Metabolite in Human Plasma

PubMed Central

Peer, Cody J.; Spencer, Shawn D.; VanDenBerg, Dustin A. H.; Pacanowski, Michael A.; Horenstein, Richard B.; Figg, William D.

2011-01-01

A sensitive, selective, and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (uHPLC-MS/MS) was developed for the simultaneous quantification of clopidogrel (Plavix®) and its derivatized active metabolite (CAMD) in human plasma. Derivatization of the active metabolite in blood with 2-bromo-3’-methoxy acetophenone (MPB) immediately after collection ensured metabolite stability during sample handling and storage. Following addition of ticlopidine as an internal standard and simple protein precipitation, the analytes were separated on a Waters Acquity UPLC™ sub-2µm-C18 column via gradient elution before detection on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. The method was validated across the clinically-relevant concentration range of 0.01–50 ng/mL for parent clopidogrel and 0.1–150 ng/mL (r2= 0.99) for CAMD, with a fast run time of 1.5 min to support pharmacokinetic studies using 75, 150, or 300 mg oral doses of clopidogrel. The analytical method measured concentrations of clopidogrel and CAMD with accuracy (%DEV) < ±12% and precision (%CV) of < ±6%. The method was successfully applied to measure the plasma concentrations of clopidogrel and CAMD in three subjects administered single oral doses of 75, 150, and 300 mg clopidogrel. It was further demonstrated that the derivatizing agent (MPB) does not affect clopidogrel levels, thus from one aliquot of blood drawn clinically, this method can simultaneously quantify both clopidogrel and CAMD with sensitivity in the picogram per mL range. PMID:22169056

Saccharin Derivative Synthesis via [1,3] Thermal Sigmatropic Rearrangement: A Multistep Organic Chemistry Experiment for Undergraduate Students

ERIC Educational Resources Information Center

Fonseca, Custódia S. C.

2016-01-01

Saccharin (1,2-benzisothiazole-3-one 1,1-dioxide) is an artificial sweetener used in the food industry. It is a cheap and easily available organic compound that may be used in organic chemistry laboratory classes for the synthesis of related heterocyclic compounds and as a derivatizing agent. In this work, saccharin is used as a starting material…

HPLC purification and re-evaluation of chemical identity of two circular bacteriocins, gassericin A and reutericin 6.

PubMed

Arakawa, K; Kawai, Y; Ito, Y; Nakamura, K; Chujo, T; Nishimura, J; Kitazawa, H; Saito, T

2010-04-01

The study aimed for the complete purification and recharacterization of the highly hydrophobic circular bacteriocins, gassericin A and reutericin 6. Gassericin A and reutericin 6 were purified to homogeneity using previously described method and reverse-phase HPLC with an octyl column and eluents of aqueous acetonitrile and 2-propanol. Mass analysis, N-terminal sequencing and bacteriocin assay of the HPLC-purified bacteriocins showed the two bacteriocins had identical seamless circular structures with the same m/z value (5651) of [M + H](+) and both had the same specific activity. D/L-amino acid composition analysis using two distinct methods with the chiral fluorescent derivatization reagents (+)-1-(9-fluorenyl)ethyl chloroformate and O-phthalaldehyde/N-acetyl-L-cystein revealed neither gassericin A nor reutericin 6 contained D-alanine residues contrary to our previous results. Purified gassericin A and reutericin 6 are chemically identical circular molecules containing no D-alanine residues. The HPLC conditions developed in this study will facilitate advanced purification and correct characterization of other highly hydrophobic bacteriocins.

Cytotoxic effects of chloroform and hydroalcoholic extracts of aerial parts of Cuscuta chinensis and Cuscuta epithymum on Hela, HT29 and MDA-MB-468 tumor cells

PubMed Central

Jafarian, A.; Ghannadi, A.; Mohebi, B.

2014-01-01

Previous studies have indicated that some species of Cuscuta possess anticancer activity on various cell lines. Due to the lack of detailed researches on the cytotoxic effects of Cuscuta chinensis and Cuscuta epithymum, the aim of the present study was to evaluate cytotoxic effects of chloroform and hydroalcoholic extracts of these plants on the human breast carcinoma cell line (MDA-MB-468), human colorectal adenocarcinoma cell line (HT29) and human uterine cervical carcinoma (Hela). Using maceration method, different extracts of aerial parts of C. chinensis and C. epithymum were prepared. Extraction was performed using chloroform and ethanol/water (70/30). Total phenolic contents of the extracts were determined according to the Folin-Ciocalteu method. Using MTT assay, the cytotoxic activity of the extracts against HT29, Hela and MDA-MB-468 tumor cells was evaluated. Extracts were considered cytotoxic when more than 50% reduction on cell survival was observed. The poly-phenolic content of the hydroalcoholic and chloroform extracts of C. chinensis and C. epithymum were 56.08 ± 4.11, 21.49 ± 2.00, 10.64 ± 0.86 and 4.81 ± 0.38, respectively. Our findings showed that the chloroform extracts of C. chinensis and C. epithyum significantly reduced the viability of Hela, HT-29 and MDA-MB-468 cells. Also, hydroalcoholic extracts of C. chinensis significantly decreased the viability of HT29, Hela and MDA-MB-468 cells. However, in the case of hydroalcoholic extracts of C. epithymum only significant decrease in the viability of MDA-MB-468 cells was observed (IC50 = 340 μg/ml). From these findings it can be concluded that C. chinensis and C. epithymum are good candidates for further study to find new possible cytotoxic agents. PMID:25657780

Cytotoxic effects of chloroform and hydroalcoholic extracts of aerial parts of Cuscuta chinensis and Cuscuta epithymum on Hela, HT29 and MDA-MB-468 tumor cells.

PubMed

Jafarian, A; Ghannadi, A; Mohebi, B

2014-01-01

Previous studies have indicated that some species of Cuscuta possess anticancer activity on various cell lines. Due to the lack of detailed researches on the cytotoxic effects of Cuscuta chinensis and Cuscuta epithymum, the aim of the present study was to evaluate cytotoxic effects of chloroform and hydroalcoholic extracts of these plants on the human breast carcinoma cell line (MDA-MB-468), human colorectal adenocarcinoma cell line (HT29) and human uterine cervical carcinoma (Hela). Using maceration method, different extracts of aerial parts of C. chinensis and C. epithymum were prepared. Extraction was performed using chloroform and ethanol/water (70/30). Total phenolic contents of the extracts were determined according to the Folin-Ciocalteu method. Using MTT assay, the cytotoxic activity of the extracts against HT29, Hela and MDA-MB-468 tumor cells was evaluated. Extracts were considered cytotoxic when more than 50% reduction on cell survival was observed. The poly-phenolic content of the hydroalcoholic and chloroform extracts of C. chinensis and C. epithymum were 56.08 ± 4.11, 21.49 ± 2.00, 10.64 ± 0.86 and 4.81 ± 0.38, respectively. Our findings showed that the chloroform extracts of C. chinensis and C. epithyum significantly reduced the viability of Hela, HT-29 and MDA-MB-468 cells. Also, hydroalcoholic extracts of C. chinensis significantly decreased the viability of HT29, Hela and MDA-MB-468 cells. However, in the case of hydroalcoholic extracts of C. epithymum only significant decrease in the viability of MDA-MB-468 cells was observed (IC50 = 340 μg/ml). From these findings it can be concluded that C. chinensis and C. epithymum are good candidates for further study to find new possible cytotoxic agents.

Antileukemia activity in the Osillatoriaceae: isolation of Debromoaplysiatoxin from Lyngbya.

PubMed

Mynderse, J S; Moore, R E; Kashiwagi, M; Norton, T R

1977-04-29

Chloroform extracts of several seaweeds, of the family Oscillatoriaceae, from Enewetak Atoll, Marshall Islands, display activity against P-388 lymphocytic mouse leukemia. A P-388 active compound, debromoaplysiatoxin, has been isolated from Lyngbya gracilis and characterized. This compound also has dermonecrotic activity and may be the dermatitis-producing substance in L. majuscula, the causative agent of "swimmers' itch" outbreaks in Hawaiian waters.

Analysis of malondialdehyde in human plasma samples through derivatization with 2,4-dinitrophenylhydrazine by ultrasound-assisted dispersive liquid-liquid microextraction-GC-FID approach.

PubMed

Malaei, Reyhane; Ramezani, Amir M; Absalan, Ghodratollah

2018-05-04

A sensitive and reliable ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) procedure was developed and validated for extraction and analysis of malondialdehyde (MDA) as an important lipids-peroxidation biomarker in human plasma. In this methodology, to achieve an applicable extraction procedure, the whole optimization processes were performed in human plasma. To convert MDA into readily extractable species, it was derivatized to hydrazone structure-base by 2,4-dinitrophenylhydrazine (DNPH) at 40 °C within 60 min. Influences of experimental variables on the extraction process including type and volume of extraction and disperser solvents, amount of derivatization agent, temperature, pH, ionic strength, sonication and centrifugation times were evaluated. Under the optimal experimental conditions, the enhancement factor and extraction recovery were 79.8 and 95.8%, respectively. The analytical signal linearly (R 2  = 0.9988) responded over a concentration range of 5.00-4000 ng mL -1 with a limit of detection of 0.75 ng mL -1 (S/N = 3) in the plasma sample. To validate the developed procedure, the recommend guidelines of Food and Drug Administration for bioanalytical analysis have been employed. Copyright © 2018. Published by Elsevier B.V.

The indirect detection of bleach (sodium hypochlorite) in beverages as evidence of product tampering.

PubMed

Jackson, David S; Crockett, David F; Wolnik, Karen A

2006-07-01

Bleach (sodium hypochlorite) has been identified as the adulterant in a relatively large number of product tamperings that have been investigated by the Forensic Chemistry Center (FCC) of the U.S. Food and Drug Administration. In this work, household bleach was added to 23 different beverages at each of three levels. The impact of sodium hypochlorite on these beverages over a 13-day study period was evaluated using the following techniques: diphenylamine spot test for oxidizing agents, potassium iodide-starch test paper for oxidizing agents, pH, iodometric titration for quantitating hypochlorite, ion chromatography for chloride and chlorate quantitation, automated headspace sampling with gas chromatography-flame ionization detection (GC-FID) for determination of chloroform, and visual and organoleptic observations. This study has shown that hypochlorite is fragile when added to most common beverages and typically breaks down either partially or completely over time. In cases where a beverage is suspected of being adulterated with bleach but tests for hypochlorite are negative, it is still possible to characterize the product to demonstrate that the results are consistent with the addition of bleach. An adulterated product will give a positive test for oxidizing agents using the diphenylamine spot test. It is likely that the pH of the adulterated product will be higher than a control of that product. Ion chromatographic analysis shows elevated chloride and chlorate as compared with a control. And, chloroform may also be detected by GC-FID especially if the beverage that was adulterated contains citric acid.

Antibacterial screening of traditional herbal plants and standard antibiotics against some human bacterial pathogens.

PubMed

Awan, Uzma Azeem; Andleeb, Saiqa; Kiyani, Ayesha; Zafar, Atiya; Shafique, Irsa; Riaz, Nazia; Azhar, Muhammad Tehseen; Uddin, Hafeez

2013-11-01

Chloroformic and isoamyl alcohol extracts of Cinnnamomum zylanicum, Cuminum cyminum, Curcuma long Linn, Trachyspermum ammi and selected standard antibiotics were investigated for their in vitro antibacterial activity against six human bacterial pathogens. The antibacterial activity was evaluated and based on the zone of inhibition using agar disc diffusion method. The tested bacterial strains were Streptococcus pyogenes, Staphylococcus epidermidis, Klebsiella pneumonia, Staphylococcus aurues, Serratia marcesnces, and Pseudomonas aeruginosa. Ciprofloxacin showed highly significant action against K. pneumonia and S. epidermidis while Ampicillin and Amoxicillin indicated lowest antibacterial activity against tested pathogens. Among the plants chloroform and isoamyl alcohol extracts of C. cyminum, S. aromaticum and C. long Linn had significant effect against P. aeruginosa, S. marcesnces and S. pyogenes. Comparison of antibacterial activity of medicinal herbs and standard antibiotics was also recorded via activity index. Used medicinal plants have various phytochemicals which reasonably justify their use as antibacterial agent.

Advanced Materials Deposition for Semiconductor Nanostructures Using Supercritical Fluids

DTIC Science & Technology

2007-04-01

thickness. Various shapes can be devel- obtained from water-in-hexanes microemulsionr:* usl rig a. end:t• ; im in tickness V molar ratio of the reducing...carbon dioxide and supported on multi- detection for aminoaromatics in soil has been reported.’ This walled carbon nanotubes. These aminoaromatics are...explosive vapors rather derivatizing agents such as fluorescamine. Corrected spectra for these than soil or ground water samples, most matrix and

In Vitro Screening of Three Indian Medicinal Plants for Their Phytochemicals, Anticholinesterase, Antiglucosidase, Antioxidant, and Neuroprotective Effects.

PubMed

Penumala, Mohan; Zinka, Raveendra Babu; Shaik, Jeelan Basha; Amooru Gangaiah, Damu

2017-01-01

Cooccurrence of Diabetes Mellitus and Alzheimer's disease in elder people prompts scientists to develop multitarget agents that combat causes and symptoms of both diseases simultaneously. In line with this modern paradigm and as a follow-up to our previous studies, the present study is designed to investigate the crude methanolic extracts and subsequent CHCl 3 , n -BuOH, and H 2 O fractions of Acalypha alnifolia , Pavetta indica, and Ochna obtusata for their inhibitory activities towards specific targets involved in AD and DM, namely, acetylcholinesterase, butyrylcholinesterase, and α -glucosidase ( α -Glc). The methanolic extract and its derived chloroform fractions exhibited remarkable inhibitory capacities with IC 50 values being found at the μ g/mL level. Further studies on most active chloroform fractions presented a prominent ability to scavenge DPPH and ABTS reactive species and highest neuroprotective effect against H 2 O 2 induced cell injury. Phytochemical analysis showed a large amount of phenolics, flavonoids, and terpenoids in active fractions. In conclusion, A. alnifolia , P. indica, and O. obtusata could be promising sources for the treatment of AD and DM since these fractions induced significant anticholinesterase, antidiabetic, antioxidant, and neuroprotection effects attributable to phenolic, flavonoid, and terpenoid contents and encourage further studies for development of multifunctional therapeutic agent for AD and DM dual therapy.

In vitro Antioxidant and Antiproliferative Activities of Various Solvent Fractions from Clerodendrum viscosum Leaves.

PubMed

Shendge, Anil Khushalrao; Basu, Tapasree; Chaudhuri, Dipankar; Panja, Sourav; Mandal, Nripendranath

2017-07-01

Free radicals such as reactive oxygen and nitrogen species, generated in the body, play an important role in the fulfillment of various physiological functions but their imbalance in the body lead to cellular injury and various clinical disorders such as cancer, neurodegenaration, and inflammation. The objective of this study is to fight this problem, natural antioxidant from plants can be considered as possible protective agents against various diseases such as cancer which might also modify the redox microenvironment to reduce the genetic instability. This study was designed to evaluate the antioxidant and antiproliferative potential of Clerodendrum viscosum fractions against various carcinomas. In this present study, 70% methanolic extract of C. viscosum leaves have been fractionated to obtain hexane, chloroform, ethyl acetate, butanol, and water fractions, which were tested for their antioxidant and anticancer properties. It was observed that chloroform and ethyl acetate fractions showed good free radical scavenging properties as well as inhibited the proliferation of human lung cancer (A459), breast (MCF-7), and brain (U87) cells. Moreover, they arrested the cell cycle at G2/M phase of breast and brain cancer. These inhibitory effects were further confirmed by bromodeoxyuridine uptake imaging. Phytochemical investigations further indicate the presence of tannic acid, quercetin, ellagic caid, gallic acid, reserpine, and methyl gallate which might be the reason for these fractions' antioxidant and antiproliferative activities. Clerodendrum viscosum leaf chloroform and Clerodendrum viscosum leaf ethyl acetate fractions from C. viscosum showed good reactive oxygen species and reactive nitrogen species scavenging potential. Both the fractions arrested cell cycle at G2/M phase in MCF-7 and U87 cells which lead to induce apoptosis. Crude extract of Clerodendrum viscosum leaves was fractionated using different solventsAmong them, chloroform and ethyl acetate fractions exhibited excellent free radical scavenging propertiesThe same fractions inhibited the proliferation of human lung cancer (A459), breast (MCF-7), and brain (U87) cellsChloroform and ethyl acetate fractions arrested the cell cycle at G2/M phase of breast and brain cancerPhytochemical investigations further indicate the presence of several bioactive principles present in them. Abbreviations used: CVLME: Clerodendrum viscosum leaf methanolic extract; CVLH: Clerodendrum viscosum leaf hexane; CVLC: Clerodendrum viscosum leaf chloroform; CVLE: Clerodendrum viscosum leaf ethyl acetate; CVLB: Clerodendrum viscosum leaf butanol; CVLW: Clerodendrum viscosum leaf water; BrdU: Bromodeoxyuridine; WST-1: Water soluble tetrazolium salt.

Anticancer Activity of Chloroform Extract and Sub-fractions of Nepeta deflersiana on Human Breast and Lung Cancer Cells: An In vitro Cytotoxicity Assessment.

PubMed

Al-Oqail, Mai M; Al-Sheddi, Ebtesam S; Siddiqui, Maqsood A; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; Farshori, Nida N

2015-10-01

Cancer is one of the major causes of death worldwide. The plant-derived natural products have received considerable attention in recent years due to their diverse pharmacological properties including anticancer effects. Nepeta deflersiana (ND) is used in the folk medicine as antiseptic, carminative, antimicrobial, antioxidant, and for treating rheumatic disorders. However, the anticancer activity of ND chloroform extract has not been explored so far. The present study was aimed to investigate the anticancer activities of chloroform Nepeta deflersiana extract and various sub-fractions (ND-1-ND-15) of ND against human breast cancer cells (MCF-7) and human lung cancer cells (A-549). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and neutral red uptake assays, and cellular morphological alterations using phase contrast light microscope were studied. Cells were exposed with 10-1000 μg/ml of sub-fractions of ND for 24 h. Results showed that selected sub-fractions of the chloroform extract significantly reduced the cell viability of MCF-7 and A-549 cells, and altered the cellular morphology in a concentration-dependent manner. Among the sub-fractions, ND-10 fraction showed relatively higher cytotoxicity compared to other fractions whereas, ND-1 did not cause any cytotoxicity even at higher concentrations. The A-549 cells were found to be more sensitive to growth inhibition by all the extracts as compared to the MCF-7 cells. The present study provides preliminary screening of anticancer activities of chloroform extract and sub-fractions of ND, which can be further used for the development of a potential therapeutic anticancer agent. Nepeta deflersiana extract exhibit cytotoxicity and altered the cellular morphology. Sub-fractions of the chloroform extract of Nepeta deflersiana reduced the cell viability of MCF-7 and A-549 cells. Among the sub-fractions, ND-10 fraction showed relatively higher cytotoxicity. The A-549 cells were found to be more sensitive as compared to the MCF-7 cells. Abbreviations used: MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; NRU: Neutral red uptake; DMEM: Dulbecco's modified eagle medium; FBS: Fetal bovine serum; PBS: Phosphate buffer saline; DMSO: Dimethyl sulfoxide.

Thioimidazolium Ionic Liquids as Tunable Alkylating Agents.

PubMed

Guterman, Ryan; Miao, Han; Antonietti, Markus

2018-01-19

Alkylating ionic liquids based on the thioimidazolium structure combine the conventional properties of ionic liquids, including low melting point and nonvolatility, with the alkylating function. Alkyl transfer occurs exclusively from the S-alkyl position, thus allowing for easy derivatization of the structure without compromising specificity. We apply this feature to tune the electrophilicty of the cation to profoundly affect the reactivity of these alkylating ionic liquids, with a caffeine-derived compound possessing the highest reactivity. Anion choice was found to affect reaction rates, with iodide anions assisting in the alkylation reaction through a "shuttling" process. The ability to tune the properties of the alkylating agent using the toolbox of ionic liquid chemistry highlights the modular nature of these compounds as a platform for alkylating agent design and integration in to future systems.

Selenium Derivatization of Nucleic Acids for Crystallography

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

Jiang,J.; Sheng, J.; Carrasco, N.

2007-01-01

The high-resolution structure of the DNA (5'-GTGTACA-C-3') with the selenium derivatization at the 2'-position of T2 was determined via MAD and SAD phasing. The selenium-derivatized structure (1.28 {angstrom} resolution) with the 2'-Se modification in the minor groove is isomorphorous to the native structure (2.0 {angstrom}). To directly compare with the conventional bromine derivatization, we incorporated bromine into the 5-postion of T4, determined the bromine-derivatized DNA structure at 1.5 {angstrom} resolution, and found that the local backbone torsion angles and solvent hydration patterns were altered in the structure with the Br incorporation in the major groove. Furthermore, while the native andmore » Br-derivatized DNAs needed over a week to form reasonable-size crystals, we observed that the Se-derivatized DNAs grew crystals overnight with high-diffraction quality, suggesting that the Se derivatization facilitated the crystal formation. In addition, the Se-derivatized DNA sequences crystallized under a broader range of buffer conditions, and generally had a faster crystal growth rate. Our experimental results indicate that the selenium derivatization of DNAs may facilitate the determination of nucleic acid X-ray crystal structures in phasing and high-quality crystal growth. In addition, our results suggest that the Se derivatization can be an alternative to the conventional Br derivatization.« less

Characterization of dicarboxylic naphthenic acid fraction compounds utilizing amide derivatization: Proof of concept.

PubMed

Kovalchik, Kevin A; MacLennan, Matthew S; Peru, Kerry M; Ajaero, Chukwuemeka; McMartin, Dena W; Headley, John V; Chen, David D Y

2017-12-30

The characterization of naphthenic acid fraction compounds (NAFCs) in oil sands process affected water (OSPW) is of interest for both toxicology studies and regulatory reasons. Previous studies utilizing authentic standards have identified dicarboxylic naphthenic acids using two-dimensional gas chromatography hyphenated to time-of-flight mass spectrometry (GC × GC/TOFMS). The selective derivatization of hydroxyl groups has also recently aided in the characterization of oxy-NAFCs, and indirectly the characterization of dicarboxylic NAFCs. However, there has been no previous report of derivatization being used to directly aid in the standard-free characterization of NAFCs with multiple carboxylic acid functional groups. Herein we present proof-of-concept for the characterization of dicarboxylic NAFCs utilizing amide derivatization. Carboxylic acid groups in OSPW extract and in a dicarboxylic acidstandard were derivatized to amides using a previously described method. The derivatized extract and derivatized standard were analyzed by direct-injection positive-mode electrospray ionization ((+)ESI) high-resolution mass spectrometry (HRMS), and the underivatized extract was analyzed by (-)ESI MS. Tandem mass spectrometry (MS/MS) was carried out on selected ions of the derivatized standard and derivatized OSPW. Data analysis was carried out using the Python programming language. The distribution of monocarboxylic NAFCs observed in the amide-derivatized OSPW sample by (+)ESI-MS was generally similar to that seen in underivatized OSPW by (-)ESI-MS. The dicarboxylic acid standard shows evidence of being doubly derivatized, although the second derivatization appears to be inefficient. Furthermore, a spectrum of potential diacid NAFCs is presented, identified by both charge state and derivatization mass. Interference due to the presence of multiple derivatization products is noted, but can be eliminated using on-line separation or an isotopically labelled derivatization reagent. Proof of concept for the characterization of dicarboxylic NAFCs utilizing amide derivatization is demonstrated. Furthermore, (+)ESI-HRMS of the derivatized monocarboxylic NAFCS yields similar information to (-)ESI-MS analysis of underivatized NAFCs, with the benefit of added selectivity for carboxylic acid species and the characterization of diacids. Copyright © 2017 John Wiley & Sons, Ltd.

Screening of plant extracts for anthelmintic activity against Dactylogyrus intermedius (Monogenea) in goldfish (Carassius auratus).

PubMed

Huang, Ai-Guo; Yi, Yang-Lei; Ling, Fei; Lu, Lin; Zhang, Qi-Zhong; Wang, Gao-Xue

2013-12-01

With the aim of finding natural anthelmintic agents against Dactylogyrus intermedius (Monogenea) in goldfish (Carassius auratus), 26 plants were screened for antiparasitic properties using in vivo anthelmintic efficacy assay. The results showed that Caesalpinia sappan, Lysima chiachristinae, Cuscuta chinensis, Artemisia argyi, and Eupatorium fortunei were found to have 100% anthelmintic efficacy at 125, 150, 225, 300, and 500 mg L(-1) after 48 h of exposure. Crude extract of the five plants were further partitioned with petroleum ether, chloroform, ethyl acetate, methanol, and water to obtain anthelmintically active fractions with various polarity. Among these fractions tested, the ethyl acetate extract of L. chiachristinae was found to be the most effective with a 50% effective concentration (EC50) value of 5.1 mg/L after 48 h of exposure. This was followed by ethyl acetate extract of C. chinensis (48 h-EC50 = 8.5 mg L(-1)), chloroform extracts of C. sappan (48 h-EC50 = 15.6 mg L(-1)), methanol extract of C. chinensis (48 h-EC50 = 15.9 mg L(-1)), and chloroform and petroleum ether extract of L. chiachristinae (EC50 values of 17.2 and 21.1 mg/L, respectively), suggesting that these plants, as well as the active fractions, provide potential sources of botanic drugs for the control of D. intermedius in aquaculture.

Low-level (PPB) determination of cisplatin in cleaning validation (rinse water) samples. II. A high-performance liquid chromatographic method.

PubMed

Raghavan, R; Burchett, M; Loffredo, D; Mulligan, J A

2000-04-01

A high-performance liquid chromatographic (HPLC) method is described for the determination of residual levels of cisplatin from extracts of surfaces with very low surface area; from extracts of surfaces of coupons made of Teflon (polytetrafluoroethylene, PTFE), stainless steel, and glass; and in aqueous solution collected after rinsing equipment and parts. Initially, the method was developed to determine cisplatin at concentrations ranging from 20 to 200 ng/ml by direct injection. Retaining the same method conditions, the scope of the method was expanded by the addition of a sample preconcentration step, allowing analyses at levels ranging from 0.5 ng to 20 ng/ml. Preconcentration is necessary for the determination of cisplatin in rinse waters at a quantifiable concentration of about 2 PPB. Under these conditions, the detection limit is about 0.2 to 0.3 ng/ml. Residual cisplatin on different types of surfaces, including surfaces with very low surface area, can be determined by swabbing each test surface with a derivatizing solution. The cisplatin recovered in the swabbing solution can be analyzed by HPLC using direct injection or preconcentration, depending on the expected level of cisplatin in the sample. Initial methods were developed to quantitate at a cisplatin concentration of about 100 PPB or higher in solution extracted from surfaces. However, when surface areas are limited because of the size of the parts, solution concentration becomes very low as a result of the minimum volume required for extraction. To support the application of swabbing techniques to surface analysis, stainless steel, Teflon, and glass surfaces were spiked with cisplatin at 2.5 to 20 ng/cm2. Satisfactory overall recoveries of 90% +/- 10% were obtained from all surfaces. Cisplatin has no ultraviolet/visible (UV/Vis) spectral-active functional group that can be used to detect low levels of cisplatin. Hence, diethyldithiocarbamate (DDTC) was used as a derivatizing agent to increase sensitivity to UV absorption at 340 nm. Diethyldithiocarbamate forms complexes with the platinum in cisplatin to yield a platinum-DDTC (Pt-DDTC) complex with a high molar-extinction coefficient. The Pt(DDTC)2 complex thus formed was chromatographically separated and the quantitated by comparison of its detector response to that of a similarly derivatized standard preparation. DDTC also has application as a cleaning agent for cisplatin (e.g., for production equipment cleaning, spill cleanup). Destruction of cisplatin can be affected by the reaction of cisplatin with this cleaning agent. Derivatization of cisplatin will convert active cisplatin to platinum-DDTC on surfaces or in solution. Final cleaning can be accomplished using a water-for-injection rinse. After such a cleaning process, the rinse water, when collected and analyzed, showed levels of free cisplatin less than the detection concentration of 0.2 PPB and a total platinum concentration less than 10 PPB as Pt-DDTC complex.

Gas and Particle Oxidation Products from Ozone Aging of Airborne Diesel Particles

NASA Astrophysics Data System (ADS)

Holmen, B. A.; Chen, Z.

2005-12-01

Diesel exhaust emissions contain fine particulate matter (PM2.5) composed of carbon-based particles with adsorbed compounds, including water soluble and insoluble substances. Many nonpolar organic compounds associated with diesel particulate matter (DPM) are known to be mutagenic and carcinogenic. In the presence of ozone, these DPM compounds can be transformed into polar species that are more toxic and poorly characterized. Understanding the gas and particle reaction products from DPM aging in the presence of tropospheric ozone is important for air quality, climate change and aerosol health effects. Aging experiments were conducted in a flow reactor to identify gas and particle-phase reaction products of DPM exposed to ambient levels of ozone. Diesel bus exhaust particles were collected on filters and then exposed to 0.1 - 0.5 ppm O3 for 0 to 72 h. Gaseous polar organic products formed during the aging experiments were collected on Tenax TA adsorbent coated with PFBHA derivatization agent. A thermal desorption gas chromatography mass spectrometry (TD/GC/MS) method was developed to determine gas-phase and particle-phase organic compounds. PFBHA and BSTFA derivatization agents converted polar species into less polar analogues prior to analysis. Preliminary results indicate that DPM hydrocarbons react with O3 to form many gas-phase polar products containing C=O (carbonyl) and COOH (carboxy) functional groups. Particle-phase PAH and alkane concentrations decreased significantly depending on time of exposure.

Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent.

PubMed

Liu, Yong-Qiang; Yu, Hong

2016-08-01

Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Therapeutic drug monitoring of topiramate with a new HPLC method, SPE extraction and high sensitivity pre-column fluorescent derivatization.

PubMed

Bolner, Andreas; De Riva, Valentina; Galloni, Elisabetta; Perini, Francesco

2014-01-01

Topiramate is a 2nd generation antiepileptic drug (AED) recently approved by the FDA for migraine prophylaxis. Its pharmacological activity already appears significant at low doses. Unfortunately, the difficulty in determining the drug in serum at low concentrations hampers the completion of accurate pharmacokinetic studies in humans. Only chromatographic methods allow reaching the necessary sensitivities. Almost all of the HPLC methods proposed were based on the preliminary extraction of topiramate from the sample using organic solvents. In our study, the conditions for purifying topiramate through solid-liquid technique in disposable cartridges (SPE) packed with C18 reversed phase were examinated and optimised. After a pre-column derivatization step with 9-fluorenylmethyl chloroformate (FMOC-Cl) and internal standard addition, topiramate was analysed on a CN column with sodium phosphate buffer 50 mmol/L (pH 2.5) containing acetonitrile (60:40, v/v) as the mobile phase. The column effluent was monitored with a fluorescence detector (excitation and emission 1 260 and 315 nm, respectively). 122 samples from our routine laboratory work were analysed in order to confirm the existence of a relationship between topiramate dose and serum concentration and to evaluate the effect of concomitant therapies with enzyme-inducing AEDs. Sensitivity (2 ng/mL), precision (CV within assay of 3.8% and between assays of 6.6%), linearity and accuracy of the method were better than other analytical procedures previously reported. Serum topiramate levels in the group with enzyme-inducing AEDs showed a reduction with respect to the group with non-enzyme-inducing AEDs and the correlation between doses and mean serum concentration gives a linear trend (r2 = 0.916). The efficacy of SPE extraction together with the method's reliability proved very advantageous for pharmacokinetics studies and, in principle, for therapeutic drug monitoring and toxicological investigations.

Calibrating compound-specific stable nitrogen isotope analysis in avian eggs as bioarchives for paleoreconstruction

NASA Astrophysics Data System (ADS)

Preciado, C., Jr.

2016-12-01

Compound-specific stable isotope analysis (CSIA) has become a powerful tool for reconstructing consumer-resource relationships in modern and ancient systems. Stable nitrogen isotope analysis (δ15N) of "trophic" and "source" amino acids provides independent proxies of trophic position and the δ15N value at the base of the food web, respectively. When applied to avian egg tissues (e.g., shell protein, membrane), which can be preserved in the archaeological record, this approach can be used to address complex questions in food web architecture and biogeochemical cycling. In this study, we examined how sample-processing protocols affected the chromatography and reliability of δ15N values of individual amino acids in avian (chicken and penguin) egg components (shell protein, membrane, yolk, and albumen) via gas chromatography-combustion-isotope ratio mass spectrometry. "Unprocessed" egg tissues underwent standard acid hydrolysis protocols prior to derivatization, and resulted in poor chromatography with highly variable δ15N values across replicates. "Processed" samples were eluted through cation exchange columns (Dowex 50WX*400) prior to derivatization, followed by a P-buffer (KH2PO4 + Na2HPO4)-chloroform centrifugation extraction to remove confounding peaks and matrix impurities. These additional procedures greatly improved the chromatography of the "processed" samples, revealing better peak separation and baseline integration as well as lower δ15N variability. Additionally, a standard lipid extraction was necessary for yolk but not membrane, albumen, and shell. While the additional procedures applied to the "columned" samples did result in a significant reduction in sample yield ( 20%), it was non-fractionating and thus only affected the total sample sizes necessary for δ15N CSIA (shell protein 50mg and membrane, yolk, and albumen 0.5mg). The protocols developed here will streamline CSIA of egg tissues for future work in avian ecology.

Condensation of the isoprenoid and amino precursors in the biosynthesis of domoic acid.

PubMed

Savage, Thomas J; Smith, G Jason; Clark, Amy T; Saucedo, Portia N

2012-01-01

Understanding how environmental signals regulate production of domoic acid in blooms of Pseudo-nitzschia spp. at a molecular level requires description of the biochemical pathway to this kainoid neurotoxin. Precursor feeding studies have suggested domoic acid arises from the condensation of the C(10) isoprenoid geranyl diphosphate with glutamate, but the specific reactions leading to domoic acid from these precursors remain undescribed. Here, we develop a method to derivatize domoic acid with propyl chloroformate that enables gas chromatography-mass spectrometry (GC-MS) analysis to measure incorporation of stable isotopes into domoic acid generated in cultures incubated with isotopically-labeled substrates. We apply this method to demonstrate that both (2)H from [1-(2)H(2)]geraniol are incorporated into domoic acid, suggesting that the condensation of geranyl diphosphate with an amino group occurs by nucleophilic substitution of the diphosphate rather than by oxidation of geraniol to the aldehyde before reaction with an amino group to form an imine. Ultimately, these and similar studies will facilitate the identification of DA biosynthetic enzymes and genes which will enable the study of how environmental factors regulate DA biosynthesis at the molecular level. Copyright © 2011 Elsevier Ltd. All rights reserved.

A fast and simple solid phase microextraction coupled with gas chromatography-triple quadrupole mass spectrometry method for the assay of urinary markers of glutaric acidemias.

PubMed

Naccarato, Attilio; Gionfriddo, Emanuela; Elliani, Rosangela; Sindona, Giovanni; Tagarelli, Antonio

2014-10-30

The analysis of characteristic urinary acidic markers such as glutaric, 3-hydroxyglutaric, 2-hydroxyglutaric, adipic, suberic, sebacic, ethylmalonic, 3-hydroxyisovaleric and isobutyric acid constitutes the recommended follow-up testing procedure for glutaric acidemia type 1 (GA-1) and type 2 (GA-2). The goal of the work herein presented is the development of a fast and simple method for the quantification of these biomarkers in human urine. The proposed analytical approach is based on the use of solid phase microextraction (SPME) combined with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) afterward a rapid derivatization of acidic moieties by propyl chloroformate, propanol and pyridine. Trueness and precision of the proposed protocol, tested at 5, 30 and 80mgl -1 , provided satisfactory values: recoveries were in the range between 72% and 116% and the relative standard deviations (RSD%) were between 0.9% and 18% (except for isobutyric acid at 5mgl -1 ). The LOD values achieved by the proposed method ranged between 1.0 and 473μgl -1 . Copyright © 2014 Elsevier B.V. All rights reserved.

[Simultaneous determination of cocaine and its metabolite ecgonine methyl ester in human blood using microwave extraction-gas chromatography].

PubMed

Wang, Xiaobo; Ye, Nengsheng; Wang, Jifen; Gu, Xuexin

2010-07-01

A method was developed for the simultaneous determination of cocaine (COC) and its metabolite ecgonine methyl ester (EME) in human blood using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The blood sample was prepared by microwave extraction (MWE). The optimal parameters of MWE were as follows: 6 mL of chloroform-isopropanol (9: 1, v/v) mixture as extraction solvent, the pH value of the sample was adjusted at 10.0 with 0.05 mol/L Na2CO3-NaHCO3 buffer, the extraction was performed at 40 degrees C for 6 min. The COC and EME in the extract were qualified using GC-MS and quantitated using GC-FID. The average recoveries of COC and EME were from 79.91% to 99.85%, the relative standard deviations were less than 3.10%, and the limits of detection (LOD) were 60 and 40 mg/L, respectively. In the method COC and EME were detected without derivatization. The method is rapid, accurate and sensitive, and can be used for the simultaneous determination of COC and EME in blood samples.

Generation of a natural glycan microarray using 9-fluorenylmethyl chloroformate (FmocCl) as a cleavable fluorescent tag.

PubMed

Song, Xuezheng; Lasanajak, Yi; Rivera-Marrero, Carlos; Luyai, Anthony; Willard, Margaret; Smith, David F; Cummings, Richard D

2009-12-15

Glycan microarray technology has become a successful tool for studying protein-carbohydrate interactions, but a limitation has been the laborious synthesis of glycan structures by enzymatic and chemical methods. Here we describe a new method to generate quantifiable glycan libraries from natural sources by combining widely used protease digestion of glycoproteins and Fmoc chemistry. Glycoproteins including chicken ovalbumin, bovine fetuin, and horseradish peroxidase (HRP) were digested by Pronase, protected by FmocCl, and efficiently separated by 2D-HPLC. We show that glycans from HRP glycopeptides separated by HPLC and fluorescence monitoring retained their natural reducing end structures, mostly core alpha1,3-fucose and core alpha1,2-xylose. After simple Fmoc deprotection, the glycans were printed on NHS-activated glass slides. The glycans were interrogated using plant lectins and antibodies in sera from mice infected with Schistosoma mansoni, which revealed the presence of both IgM and IgG antibody responses to HRP glycopeptides. This simple approach to glycopeptide purification and conjugation allows for the development of natural glycopeptide microarrays without the need to remove and derivatize glycans and potentially compromise their reducing end determinants.

Sensitive Determination of Volatile Organic Compounds and Aldehydes in Tattoo Inks.

PubMed

Lim, Hyun-Hee; Shin, Ho-Sang

2017-02-01

As the popularity of body art including tattoo ink has increased, the safety associated with it has become an important interest. In this study, twenty volatile organic compounds (VOCs) and two aldehydes in tattoo inks were identified and quantified. Headspace and gas chromatography-mass spectrometry (HS GC-MS) for the VOCs and HS GC-MS based on derivatization with 2,2,2-trifluoroethylhydrazine (TFEH) for aldehydes was developed. Benzene, chloroform, toluene, ethylbenzene, m-xylene, p-xylene, o-xylene, propylbenzene, chlorobenzene, tert-butylbenzene, 1,3,5-trimethylbenzene, styrene, 1,2,4-trimethylbenzene, 2-chlorotoluene, 4-chlorotoluene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene and isopropyl alcohol were detected with the concentration range of 0.02-207,000 mg/kg in 16 different tattoo inks. Formaldehyde and acetaldehyde were detected with the concentration range of 0.4-308 mg/kg in the same samples. Our analytical results represent solvents used intentionally or non-intentionally in tattoo inks, and thus they may provide important information for national regulation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of a fast and simple gas chromatographic protocol based on the combined use of alkyl chloroformate and solid phase microextraction for the assay of polyamines in human urine.

PubMed

Naccarato, Attilio; Elliani, Rosangela; Cavaliere, Brunella; Sindona, Giovanni; Tagarelli, Antonio

2018-05-11

Polyamines are aliphatic amines with low molecular weight that are widely recognized as one of the most important cancer biomarkers for early diagnosis and treatment. The goal of the work herein presented is the development of a rapid and simple method for the quantification of free polyamines (i.e., putrescine, cadaverine, spermidine, spermine) and N-monoacetylated polyamines (i.e., N 1 -Acetylspermidine, N 8 -Acetylspermidine, and N 1 -Acetylspermine) in human urine. A preliminary derivatization with propyl chloroformate combined with the use of solid phase microextraction (SPME) allowed for an easy and automatable protocol involving minimal sample handling and no consumption of organic solvents. The affinity of the analytes toward five commercial SPME coatings was evaluated in univariate mode, and the best result in terms of analyte extraction was achieved using the divinylbenzene/carboxen/polydimethylsiloxane fiber. The variables affecting the performance of SPME analysis were optimized by the multivariate approach of experimental design and, in particular, using a central composite design (CCD). The optimal working conditions in terms of response values are the following: extraction temperature 40 °C, extraction time of 15 min and no addition of NaCl. Analyses were carried out by gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) in selected reaction monitoring (SRM) acquisition mode. The developed method was validated according to the guidelines issued by the Food and Drug Administration (FDA). The satisfactory performances reached in terms of linearity, sensitivity (LOQs between 0.01 and 0.1 μg/mL), matrix effect (68-121%), accuracy, and precision (inter-day values between -24% and +16% and in the range 3.3-28.4%, respectively) make the proposed protocol suitable to be adopted for quantification of these important biomarkers in urine samples. Copyright © 2018 Elsevier B.V. All rights reserved.

[The development of vaporizers. A question of precise dose].

PubMed

Petermann, Heike

2009-05-01

Since the beginning of anaesthesia it was well known that anaesthetic agents administered by inhalation must be capable of existing in gaseous form. For vaporization various types tried to work accurately. Since oxygen was available there could be realized new concepts like the principles of injection or bubble through. With Copper Kettle (1948) for ether and chloroform and Draeger Vapor (1958) for Halothane accurate administration of volatile anaesthetics was available. Today vaporizers are part of anaesthetic machines.

In Vitro Screening of Three Indian Medicinal Plants for Their Phytochemicals, Anticholinesterase, Antiglucosidase, Antioxidant, and Neuroprotective Effects

PubMed Central

Penumala, Mohan; Zinka, Raveendra Babu; Shaik, Jeelan Basha

2017-01-01

Cooccurrence of Diabetes Mellitus and Alzheimer's disease in elder people prompts scientists to develop multitarget agents that combat causes and symptoms of both diseases simultaneously. In line with this modern paradigm and as a follow-up to our previous studies, the present study is designed to investigate the crude methanolic extracts and subsequent CHCl3, n-BuOH, and H2O fractions of Acalypha alnifolia, Pavetta indica, and Ochna obtusata for their inhibitory activities towards specific targets involved in AD and DM, namely, acetylcholinesterase, butyrylcholinesterase, and α-glucosidase (α-Glc). The methanolic extract and its derived chloroform fractions exhibited remarkable inhibitory capacities with IC50 values being found at the μg/mL level. Further studies on most active chloroform fractions presented a prominent ability to scavenge DPPH and ABTS reactive species and highest neuroprotective effect against H2O2 induced cell injury. Phytochemical analysis showed a large amount of phenolics, flavonoids, and terpenoids in active fractions. In conclusion, A. alnifolia, P. indica, and O. obtusata could be promising sources for the treatment of AD and DM since these fractions induced significant anticholinesterase, antidiabetic, antioxidant, and neuroprotection effects attributable to phenolic, flavonoid, and terpenoid contents and encourage further studies for development of multifunctional therapeutic agent for AD and DM dual therapy. PMID:29204442

Beyond Ether and Chloroform-A Major Breakthrough With Halothane.

PubMed

Huang, Lisa; Sang, Christine N; Desai, Manisha S

2017-07-01

The use of equipment powered by electricity in the operating room increased the risk of fires in the presence of flammable agents such as ether and cyclopropane. Chloroform was associated with cardiac arrhythmias and liver damage. The introduction of halothane in the late 1950s was heralded as a solution to many problems facing the specialty of anesthesia. We explore whether the manufacturer promptly reported halothane's adverse effects to regulatory agencies and practitioners. We consulted documents submitted by Ayerst Laboratories to federal authorities through the Freedom of Information Act, promotional advertisements, package inserts, published articles, and textbooks. Two major complications associated with the use of halothane, cardiac arrhythmias and the risk of hepatotoxicity, were disclosed by the manufacturer when the drug was first introduced to the US market. Reports appeared timely and complete; there was no apparent attempt to conceal or otherwise downplay these risks. The process of drug discovery and approval for clinical use has always been a lengthy, complex, and extremely expensive undertaking, with only a small minority of compounds receiving approval. The risk of adverse effects or drug interaction directly impacts commercial viability. In the case of halothane, the manufacturer disclosed major adverse effects, and the drug enjoyed decades of popularity until it was replaced by agents with a better drug profile. Copyright © 2017 Elsevier Inc. All rights reserved.

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

McDonald, M.N.; Vire, D.E.

This article reviews the role chloroform has played in dentistry and describes an occupational health clinical investigation into the possible hazards of chloroform use in the operatory. Due to a Food and Drug Administration ban on drugs and cosmetics containing chloroform, there has been some confusion as to whether the use of chloroform in the practice of dentistry is considered unsafe or has been prohibited. Utilizing common endodontic treatment methods employing chloroform, this study reports no negative health effects to the dentist or assistant and air vapor levels well below Occupational Health and Safety Administration mandated maximum levels. The reportmore » concludes that, with careful and controlled use, chloroform can be a useful adjunct in the practice of dentistry. The Food and Drug Administration has no jurisdiction over a dentist's use of chloroform in clinical practice and has not proven that chloroform is a human carcinogen.« less

In vitro Antioxidant and Antiproliferative Activities of Various Solvent Fractions from Clerodendrum viscosum Leaves

PubMed Central

Shendge, Anil Khushalrao; Basu, Tapasree; Chaudhuri, Dipankar; Panja, Sourav; Mandal, Nripendranath

2017-01-01

Background: Free radicals such as reactive oxygen and nitrogen species, generated in the body, play an important role in the fulfillment of various physiological functions but their imbalance in the body lead to cellular injury and various clinical disorders such as cancer, neurodegenaration, and inflammation. Objective: The objective of this study is to fight this problem, natural antioxidant from plants can be considered as possible protective agents against various diseases such as cancer which might also modify the redox microenvironment to reduce the genetic instability. This study was designed to evaluate the antioxidant and antiproliferative potential of Clerodendrum viscosum fractions against various carcinomas. Materials and Methods: In this present study, 70% methanolic extract of C. viscosum leaves have been fractionated to obtain hexane, chloroform, ethyl acetate, butanol, and water fractions, which were tested for their antioxidant and anticancer properties. Results: It was observed that chloroform and ethyl acetate fractions showed good free radical scavenging properties as well as inhibited the proliferation of human lung cancer (A459), breast (MCF-7), and brain (U87) cells. Moreover, they arrested the cell cycle at G2/M phase of breast and brain cancer. These inhibitory effects were further confirmed by bromodeoxyuridine uptake imaging. Phytochemical investigations further indicate the presence of tannic acid, quercetin, ellagic caid, gallic acid, reserpine, and methyl gallate which might be the reason for these fractions’ antioxidant and antiproliferative activities. Conclusion: Clerodendrum viscosum leaf chloroform and Clerodendrum viscosum leaf ethyl acetate fractions from C. viscosum showed good reactive oxygen species and reactive nitrogen species scavenging potential. Both the fractions arrested cell cycle at G2/M phase in MCF-7 and U87 cells which lead to induce apoptosis. SUMMARY Crude extract of Clerodendrum viscosum leaves was fractionated using different solventsAmong them, chloroform and ethyl acetate fractions exhibited excellent free radical scavenging propertiesThe same fractions inhibited the proliferation of human lung cancer (A459), breast (MCF-7), and brain (U87) cellsChloroform and ethyl acetate fractions arrested the cell cycle at G2/M phase of breast and brain cancerPhytochemical investigations further indicate the presence of several bioactive principles present in them. Abbreviations used: CVLME: Clerodendrum viscosum leaf methanolic extract; CVLH: Clerodendrum viscosum leaf hexane; CVLC: Clerodendrum viscosum leaf chloroform; CVLE: Clerodendrum viscosum leaf ethyl acetate; CVLB: Clerodendrum viscosum leaf butanol; CVLW: Clerodendrum viscosum leaf water; BrdU: Bromodeoxyuridine; WST-1: Water soluble tetrazolium salt. PMID:28808404

Mechanism of chloroform-induced renal toxicity: Non-involvement of hepatic cytochrome P450-dependent metabolism

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

Fang Cheng; Behr, Melissa; Xie Fang

2008-02-15

Chloroform causes hepatic and renal toxicity in a number of species. In vitro studies have indicated that chloroform can be metabolized by P450 enzymes in the kidney to nephrotoxic intermediate, although direct in vivo evidence for the role of renal P450 in the nephrotoxicity has not been reported. This study was to determine whether chloroform renal toxicity persists in a mouse model with a liver-specific deletion of the P450 reductase (Cpr) gene (liver-Cpr-null). Chloroform-induced renal toxicity and chloroform tissue levels were compared between the liver-Cpr-null and wild-type mice at 24 h following differing doses of chloroform. At a chloroform dosemore » of 150 mg/kg, the levels of blood urea nitrogen (BUN) were five times higher in the exposed group than in the vehicle-treated one for the liver-Cpr-null mice, but they were only slightly higher in the exposed group than in the vehicle-treated group for the wild-type mice. Severe lesions were found in the kidney of the liver-Cpr-null mice, while only mild lesions were found in the wild-type mice. At a chloroform dose of 300 mg/kg, severe kidney lesions were observed in both strains, yet the BUN levels were still higher in the liver-Cpr-null than in the wild-type mice. Higher chloroform levels were found in the tissues of the liver-Cpr-null mice. These findings indicated that loss of hepatic P450-dependent chloroform metabolism does not protect against chloroform-induced renal toxicity, suggesting that renal P450 enzymes play an essential role in chloroform renal toxicity.« less

2-Aminoquinazolin-4(3H)-one as an Organocatalyst for the Synthesis of Tertiary Amines.

PubMed

Thakur, Maheshwar S; Nayal, Onkar S; Upadhyay, Rahul; Kumar, Neeraj; Maurya, Sushil K

2018-03-02

The potential of 2-aminoquinazolin-4(3H)-one as an organocatalyst for the activation of aldehydes via noncovalent interaction for the synthesis of tertiary amines using formic acid as a reducing agent is reported for the first time. The developed protocol demonstrated a dilated substrate scope for aromatic and aliphatic amines with aromatic and aliphatic aldehydes. Furthermore, the current method was also fruitful for the derivatization of ciprofloxacin and its derivative in good to excellent yields.

Method for the synthesis of chiral allylic alcohols utilizing selone based chiral derivatizing agents

DOEpatents

Silks, III, Louis A.

2002-01-01

Molecules containing a chiral 1,2-diol unit are synthesized from reactions between aldehydes and N-acyl selones. A chilled N-acyl selone is reacted with a Lewis acid such as TiCl.sub.4 and mixed with a tertiary amine such as diisopropylethylamine to generate an enolate solution. Upon further chilling of the enolate solution a desired aldehyde is added and after an acceptable reaction period a quencher is introduced and the product isolated.

Rapid evaluation and comparison of natural products and antioxidant activity in calendula, feverfew, and German chamomile extracts.

PubMed

Agatonovic-Kustrin, Snezana; Babazadeh Ortakand, Davoud; Morton, David W; Yusof, Ahmad P

2015-03-13

The present study describes a simple high performance thin layer chromatographic (HPTLC) method for the simultaneous quantification of apigenin, chamazulene, bisabolol and the use of DPPH free radical as a post-chromatographic derivatization agent to compare the free radical scavenging activities of these components in leaf and flower head extracts from feverfew, German chamomile and marigold from the Asteraceae family. Feverfew (Tanacetum parthenium) leaves have been traditionally used in the treatment of migraine with parthenolide being the main bioactive compound. However, due to similar flowers, feverfew is sometimes mistaken for the German chamomile (Matricaria recutita). Bisabolol and chamazulene are the main components in chamomile essential oil. Marigold (Calendula officinalis) was included in the study for comparison, as it belongs to the same family. Parthenolide was found to be present in all leaf extracts but was not detected in calendula flower extract. Chamazulene and bisabolol were found to be present in higher concentrations in chamomile and Calendula flowers. Apigenin was detected and quantified only in chamomile extracts (highest concentration in flower head extracts). Antioxidant activity in sample extracts was compared by superimposing the chromatograms obtained after post-chromatographic derivatization with DPPH and post-chromatographic derivatization with anisaldehyde. It was found that extracts from chamomile flower heads and leaves have the most prominent antioxidant activity, with bisabolol and chamazulene being the most effective antioxidants. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Synthesis and biological activity of imidazopyridine anticoccidial agents: Part II.

PubMed

Scribner, Andrew; Dennis, Richard; Lee, Shuliang; Ouvry, Gilles; Perrey, David; Fisher, Michael; Wyvratt, Matthew; Leavitt, Penny; Liberator, Paul; Gurnett, Anne; Brown, Chris; Mathew, John; Thompson, Donald; Schmatz, Dennis; Biftu, Tesfaye

2008-06-01

Coccidiosis is the major cause of morbidity and mortality in the poultry industry. Protozoan parasites of the genus Eimeria invade the intestinal lining of the avian host causing tissue pathology, poor weight gain, and in some cases mortality. Resistance to current anticoccidials has prompted the search for new therapeutic agents with potent in vitro and in vivo activity against Eimeria. Recently, we reported the synthesis and biological activity of potent imidazo[1,2-a]pyridine anticoccidial agents. Antiparasitic activity is due to inhibition of a parasite specific cGMP-dependent protein kinase (PKG). In this study, we report the synthesis and anticoccidial activity of a second set of such compounds, focusing on derivatization of the amine side chain at the imidazopyridine 7-position. From this series, several compounds showed subnanomolar in vitro activity and commercial levels of in vivo activity. However, the potential genotoxicity of these compounds precludes them from further development.

Surface Analysis of Nerve Agent Degradation Products by ...

EPA Pesticide Factsheets

Report This sampling and analytical procedure was developed and applied by a single laboratory to investigate nerve agent degradation products, which may persist at a contaminated site, via surface wiping followed by analytical characterization. The performance data presented demonstrate the fitness-for-purpose regarding surface analysis in that single laboratory. Surfaces (laminate, glass, galvanized steel, vinyl tile, painted drywall and treated wood) were wiped with cotton gauze wipes, sonicated, extracted with distilled water, and filtered. Samples were analyzed with direct injection electrospray ionization liquid chromatography tandem mass spectrometry (ESI-LC/MS/MS) without derivatization. Detection limit data were generated for all analytes of interest on a laminate surface. Accuracy and precision data were generated from each surface fortified with these analytes.

Synthesis and Biological Evaluation of Brain-Specific Anti-RNA Viral Agents

DTIC Science & Technology

1990-03-31

water (200 iL). It was dried over sodium sulfate and the solvent was removed under reduced pressure. The resulting oil was dissolved in a minimum...The organic extracts were washed with NaHCO3 (2 x 200 mL), water (200 mL) and dried over sodium sulfate . The solvent was removed in vacuo and the...chloroform. The combined organic extracts were washed with 2 x 250 mL cold deionised water, dried ( sodium sulfate ) and removed under reduced pressure to

ISOTOPE FRACTIONATION PROCESS

DOEpatents

Clewett, G.H.; Lee, DeW.A.

1958-05-20

A new method is described for isotopic enrichment of uranium. It has been found that when an aqueous acidic solution of ionic tetravalent uraniunn is contacted with chelate complexed tetravalent uranium, the U/sup 238/ preferentially concentrates in the complexed phase while U/sup 235/ concentrates in the ionic phase. The effect is enhanced when the chelate compound is water insoluble and is dissolved in a water-immiscible organic solvent. Cupferron is one of a number of sultable complexing agents, and chloroform is a suitable organic solvent.

Riot Control Agent Decontamination: Evaluation of Commercial Products

DTIC Science & Technology

1983-06-01

yellow crystals, m.p. 72 to 73 0 C. CN (phenacyl chloride ) was obtained from commercial sources and used without further purification. To evaluate the...vial. After waiting a suitable length of time, 1.00 ml of chloroform and ca. 100 mg of sodiur-i chloride were added to the vial and the mixture shaken...been employed in the quantitation of the same. It was initially thought that dithionite was promoting the reduction of the cyano gros in CS to amines

Solute-solvent complex switching dynamics of chloroform between acetone and dimethylsulfoxide-two-dimensional IR chemical exchange spectroscopy.

PubMed

Kwak, Kyungwon; Rosenfeld, Daniel E; Chung, Jean K; Fayer, Michael D

2008-11-06

Hydrogen bonds formed between C-H and various hydrogen bond acceptors play important roles in the structure of proteins and organic crystals, and the mechanisms of C-H bond cleavage reactions. Chloroform, a C-H hydrogen bond donor, can form weak hydrogen-bonded complexes with acetone and with dimethylsulfoxide (DMSO). When chloroform is dissolved in a mixed solvent consisting of acetone and DMSO, both types of hydrogen-bonded complexes exist. The two complexes, chloroform-acetone and chloroform-DMSO, are in equilibrium, and they rapidly interconvert by chloroform exchanging hydrogen bond acceptors. This fast hydrogen bond acceptor substitution reaction is probed using ultrafast two-dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy. Deuterated chloroform is used in the experiments, and the 2D-IR spectrum of the C-D stretching mode is measured. The chemical exchange of the chloroform hydrogen bonding partners is tracked by observing the time-dependent growth of off-diagonal peaks in the 2D-IR spectra. The measured substitution rate is 1/30 ps for an acetone molecule to replace a DMSO molecule in a chloroform-DMSO complex and 1/45 ps for a DMSO molecule to replace an acetone molecule in a chloroform-acetone complex. Free chloroform exists in the mixed solvent, and it acts as a reactive intermediate in the substitution reaction, analogous to a SN1 type reaction. From the measured rates and the equilibrium concentrations of acetone and DMSO, the dissociation rates for the chloroform-DMSO and chloroform-acetone complexes are found to be 1/24 ps and 1/5.5 ps, respectively. The difference between the measured rate for the complete substitution reaction and the rate for complex dissociation corresponds to the diffusion limited rate. The estimated diffusion limited rate agrees well with the result from a Smoluchowski treatment of diffusive reactions.

Inhibition of aflatoxin biosynthesis in Aspergillus flavus by phenolic compounds extracted of Piper betle L.

PubMed

Yazdani, Darab; Mior Ahmad, Zainal Abidin; Yee How, Tan; Jaganath, Indu Bala; Shahnazi, Sahar

2013-12-01

Food contamination by aflatoxins is an important food safety concern for agricultural products. In order to identify and develop novel antifungal agents, several plant extracts and isolated compounds have been evaluated for their bioactivities. Anti-infectious activity of Piper betle used in traditional medicine of Malaysia has been reported previously. Crude methanol extract from P. betel powdered leaves was partitioned between chloroform and water. The fractions were tested against A. flavus UPMC 89, a strong aflatoxin producing strain. Inhibition of mycelial growth and aflatoxin biosynthesis were tested by disk diffusion and macrodillution techniques, respectively. The presence of aflatoxin was determined by thin-layer chromatography (TLC) and fluorescence spectroscopy techniques using AFB1 standard. The chloroform soluble compounds were identified using HPLC-Tandem mass spectrometry technique. The results, evaluated by measuring the mycelial growth and quantification of aflatoxin B1(AFLB1) production in broth medium revealed that chloroform soluble compounds extract from P. betle dried leaves was able to block the aflatoxin biosynthesis pathway at concentration of 500μg/ml without a significant effect on mycelium growth. In analyzing of this effective fractions using HPLC-MS(2) with ESI ionization technique, 11 phenolic compounds were identified. The results showed that the certain phenolic compounds are able to decline the aflatoxin production in A. flavus with no significant effect on the fungus mycelia growth. The result also suggested P. betle could be used as potential antitoxin product.

Xanthatin and xanthinosin from the burs of Xanthium strumarium L. as potential anticancer agents.

PubMed

Ramírez-Erosa, Irving; Huang, Yaoge; Hickie, Robert A; Sutherland, Ronald G; Barl, Branka

2007-11-01

Xanthatin and xanthinosin, 2 sesquiterpene lactones isolated from the burs of Xanthiun strumarium L. (cocklebur), showed moderate to high in vitro cytotoxic activity in the human cancer cell lines WiDr ATCC (colon), MDA-MB-231 ATCC (breast), and NCI-417 (lung). Xanthatin and xanthinosin were purified as the result of a multi-screening bioassay-guided study of wild plant species of the family Asteraceae, collected from various sites in Saskatchewan, Canada. Seventy-five extracts at a single concentration of 100 microg/mL were evaluated for in vitro cytotoxicity to the human cancer cell lines used. The chloroform extract of Carduus nutans L. (nodding thistle) aerial parts (IC50, 9.3 microg/mL) and the hexane extract of Echinacea angustifolia DC. (narrow-leaved purple coneflower) root (IC50, 4.0 microg/mL) were moderately to highly cytotoxic to the lung cancer cell line. The chloroform extracts of X. strumarium L. burs and Tanacetum vulgare L. (tansy) aerial parts exhibited the highest cytotoxicity for all cell lines tested; their IC50 values, obtained from multidose testing, ranged from 0.1 to 6.2 microg/mL (X. strumarium) and from 2.4 to 9.1 microg/mL (T. vulgare). Further purification of the chloroform fraction of X. strumarium yielded xanthatin and xanthinosin in high yields. This is the first time that these compounds have been reported in the burs of X. strumarium. Their IC50 values are also reported herein.

Hydrolysis of Nerve Agents by Model Nucleophiles: A Computational Study

PubMed Central

Beck, Jeremy M.

2008-01-01

Density functional theory calculations were employed to study the reaction of five nerve agents with model nucleophiles, including EtX− and EtXH (X = O, S, Se) for serine, cysteine and selenocysteine, respectively. Calculations at the B3LYP/6-311++G(2d,p) level of theory predict an exothermic reaction between ethoxide and all of the nerve agents studied. As compared to EtO− as a nucleophile, these reactions become ~30 kcal/mol more endothermic for EtS−, and by ~40 kcal/mol for EtSe−. The equivalent reactions with the neutral nucleophiles (EtXH) were more endothermic. The effect of solvation on the reaction thermochemistry was determined using a polarizable continuum model simulating the dielectric constant of chloroform. While there was a large exothermic shift for reactions involving charged nucleophiles with solvation modeling, the corresponding shift was minimal for the reaction with neutral nucleophiles. PMID:18538754

Proposals for chemical weapons during the American Civil War.

PubMed

Hasegawa, Guy R

2008-05-01

Proposals for chemical weapons that arose during the American Civil War are described. Most incendiary and all biological agents are excluded. The described proposals appeared primarily in periodicals or letters to government officials on both sides. The weapons were usually meant to temporarily disable enemy combatants, but some might have been lethal, and Civil War caregivers were ill-prepared to deal with the weapons' effects. Evidently, none of the proposed weapons were used. In only one instance was use against civilians mentioned. Among the agents most commonly proposed were cayenne pepper or other plant-based irritants such as black pepper, snuff, mustard, and veratria. Other suggested agents included chloroform, chlorine, hydrogen cyanide, arsenic compounds, sulfur, and acids. Proponents usually suggested that the chemicals be included in explosive artillery projectiles. Less commonly proposed vehicles of delivery included fire engines, kites, and manned balloons. Some of the proposed weapons have modern counterparts.

1-(3-aminopropyl)-3-butylimidazolium bromide for carboxyl group derivatization: potential applications in high sensitivity peptide identification by mass spectrometry.

PubMed

Qiao, Xiaoqiang; Zhou, Yuan; Hou, Chunyan; Zhang, Xiaodan; Yang, Kaiguang; Zhang, Lihua; Zhang, Yukui

2013-03-01

The cationic reagent 1-(3-aminopropyl)-3-butylimidazolium bromide (BAPI) was exploited for the derivatization of carboxyl groups on peptides. Nearly 100% derivatization efficiency was achieved with the synthetic peptide RVYVHPI (RI-7). Furthermore, the peptide derivative was stable in a 0.1% TFA/water solution or a 0.1% (v/v) TFA/acetonitrile/water solution for at least one week. The effect of BAPI derivatization on the ionization of the peptide RI-7 was further investigated, and the detection sensitivity was improved >42-fold via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), thus outperforming the commercial piperazine derivatization approach. Moreover, the charge states of the peptide were largely increased via BAPI derivatization by electrospray ionization (ESI) MS. The results indicate the potential merits of BAPI derivatization for high sensitivity peptide analysis by MS.

Apparent pollution of groundwater caused by natural formation of chloroform in forest soils

NASA Astrophysics Data System (ADS)

Jacobsen, O.; Laier, T.; Albers, C. N.; Hunkeler, D.

2011-12-01

Halogenated compounds are known to be formed in natural environments. Many of these compounds are similar to industrially produced compounds and are toxic or carcinogenic. High concentration of chloroform in groundwater is usually attributed to anthropogenic input, but we have found that the groundwater beneath some pristine areas contained chloroform exceeding 1 μg/L. We investigated four coniferous forests over a period of several years in order to measure the net-formation of chloroform. Field measurements of atmospheric and soil air concentrations of chloroform were monitored. Analyses of soil air at 40 cm depth in different parts of the forests and adjacent areas revealed an extremely large variation in chloroform concentration exceeding two orders of magnitude. Up to 100 ppbv was found in soil air under the spruce forest, to be compared to an ambient atmospheric concentration of 0.02 ppbv. The concentration of chloroform in soil air showed seasonal variation similar to that of CO2. Chloroform formation during incubation of undisturbed top-soil samples was found to be largest in soils from dense conifers stands with well-developed humus layers, while low chloroform formation occurred in soils from beech forest and agricultural grassland. We suggest that the mechanism behind the formation of chloroform is an unspecific chlorination of organic matter, caused by microbial activity in the soil. The aquifers are in fluvio-glacial sands with few layers of silt and a groundwater table from 4 to 7 m below the surface. In the shallowest parts of the aquifer, the groundwater has chloroform concentrations of 0.1 to 5 μg/L, and the groundwater is oxic with an age from 5 to 45 years using CFC-dating. Analyses of oxic groundwater > 40 years showed that it still contained chloroform at concentrations of 1 μg/L. Stable carbon isotopic analyses of chloroform from the uppermost groundwater in different parts of the forests and from soil water showed values from δ13C = -13 % to -27 %, corresponding to the ratio in natural organic materials and quite different from those of industrial products and from contaminated groundwater (δ13C = -46 % to -63 %). The isotopic ratio showed a minor decrease with depth due to a decomposition of chloroform. Measurements in a groundwater transect in one of the forest areas indicated that anoxic conditions in the groundwater depleted chloroform totally.

Development and validation of a sensitive thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method for the determination of phosgene in air samples.

PubMed

Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bossée, A

2014-08-01

A new rapid, sensitive and reliable method was developed for the determination of phosgene in air samples using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of air onto a Tenax® GR tube doped with 0.5 mL of derivatizing mixture containing dimercaptotoluene and triethylamine in hexane solution. Validation of the TD-GC-MS method showed a low limit of detection (40 ppbv), acceptable repeatability, intermediate fidelity (relative standard deviation within 12 %) and excellent accuracy (>95%). Linearity was demonstrated for two concentration ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high concentration levels. Due to its simple on-site implementation and its close similarity with recommended operating procedure (ROP) for chemical warfare agents vapour sampling, the method is particularly useful in the process of verification of the Chemical Weapons Convention.

Crystallization of a pentapeptide-repeat protein by reductive cyclic pentylation of free amines with glutaraldehyde

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

Vetting, Matthew W., E-mail: vetting@aecom.yu.edu; Hegde, Subray S.; Blanchard, John S.

2009-05-01

A method to modify proteins with glutaraldehyde under reducing conditions is presented. Treatment with glutaraldehyde and dimethylaminoborane was found to result in cyclic pentylation of free amines and facilitated the structural determination of a protein previously recalcitrant to the formation of diffraction quality crystals. The pentapeptide-repeat protein EfsQnr from Enterococcus faecalis protects DNA gyrase from inhibition by fluoroquinolones. EfsQnr was cloned and purified to homogeneity, but failed to produce diffraction-quality crystals in initial crystallization screens. Treatment of EfsQnr with glutaraldehyde and the strong reducing agent borane–dimethylamine resulted in a derivatized protein which produced crystals that diffracted to 1.6 Å resolution;more » their structure was subsequently determined by single-wavelength anomalous dispersion. Analysis of the derivatized protein using Fourier transform ion cyclotron resonance mass spectrometry indicated a mass increase of 68 Da per free amino group. Electron-density maps about a limited number of structurally ordered lysines indicated that the modification was a cyclic pentylation of free amines, producing piperidine groups.« less

Synthesis and evaluation of thermo-rheological behaviour and ionotropic crosslinking of new gellan gum-alkyl derivatives.

PubMed

Agnello, Stefano; Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Giammona, Gaetano

2018-04-01

This paper reports the synthesis and the physicochemical characterization of two series of gellan gum (GG) derivatives functionalized with alkyl chains with different number of carbon, from 8 to 18. In particular, low molecular weight gellan gum samples with 52.6 or 96.7 kDa, respectively, were functionalized with octylamine (C 8 ), dodecylamine (C 12 ) and octadecylamine (C 18 ) by using bis(4-nitrophenyl) carbonate (4-NPBC) as a coupling agent. Thermo-rheological and ionotropic crosslinking properties of these gellan gum-alkyl derivatives were evaluated and related to the degree of derivatization in alkyl chains. Results suggested as length and degree of derivatization differently influenced coil-to-helix gelation mechanism of GG derivatives, ionotropic crosslinking, and strength of crosslinked hydrogels obtained in CaCl 2 0.102 M and NaCl 0.15 M. Statement of hypothesis: The insertion of alkyl chains on the gellan gum backbone interferes with coil-to-helix transition mechanism and allows the production of hydrophobically assembled hydrogels. Copyright © 2018 Elsevier Ltd. All rights reserved.

The application of hyaluronic acid-derivatized carbon nanotubes in hematoporphyrin monomethyl ether-based photodynamic therapy for in vivo and in vitro cancer treatment

PubMed Central

Shi, Jinjin; Ma, Rourou; Wang, Lei; Zhang, Jing; Liu, Ruiyuan; Li, Lulu; Liu, Yan; Hou, Lin; Yu, Xiaoyuan; Gao, Jun; Zhang, Zhenzhong

2013-01-01

Carbon nanotubes (CNTs) have shown great potential in both photothermal therapy and drug delivery. In this study, a CNT derivative, hyaluronic acid-derivatized CNTs (HA-CNTs) with high aqueous solubility, neutral pH, and tumor-targeting activity, were synthesized and characterized, and then a new photodynamic therapy agent, hematoporphyrin monomethyl ether (HMME), was adsorbed onto the functionalized CNTs to develop HMME-HA-CNTs. Tumor growth inhibition was investigated both in vivo and in vitro by a combination of photothermal therapy and photodynamic therapy using HMME-HA-CNTs. The ability of HMME-HA-CNT nanoparticles to combine local specific photodynamic therapy with external near-infrared photothermal therapy significantly improved the therapeutic efficacy of cancer treatment. Compared with photodynamic therapy or photothermal therapy alone, the combined treatment demonstrated a synergistic effect, resulting in higher therapeutic efficacy without obvious toxic effects to normal organs. Overall, it was demonstrated that HMME-HA-CNTs could be successfully applied to photodynamic therapy and photothermal therapy simultaneously in future tumor therapy. PMID:23843694

Migration of formaldehyde from melamine-ware: UK 2008 survey results.

PubMed

Potter, E L J; Bradley, E L; Davies, C R; Barnes, K A; Castle, L

2010-06-01

Fifty melamine-ware articles were tested for the migration of formaldehyde - with hexamethylenetetramine (HMTA) expressed as formaldehyde - to see whether the total specific migration limit (SML(T)) was being observed. The SML(T), given in European Commission Directive 2002/72/EC as amended, is 15 mg kg(-1). Fourier transform-infrared (FT-IR) spectroscopy was carried out on the articles to confirm the plastic type. Articles were exposed to the food simulant 3% (w/v) aqueous acetic acid under conditions representing their worst foreseeable use. Formaldehyde and HMTA in food simulants were determined by a spectrophotometric derivatization procedure. Positive samples were confirmed by a second spectrophotometric procedure using an alternative derivatization agent. As all products purchased were intended for repeat use, three sequential exposures to the simulant were carried out. Formaldehyde was detected in the simulant exposed to 43 samples. Most of the levels found were well below the limits set in law such that 84% of the samples tested were compliant. However, eight samples had formaldehyde levels that were clearly above the legal maximum at six to 65 times the SML(T).

Morphing structures and signal transduction in Mimosa pudica L. induced by localized thermal stress.

PubMed

Volkov, Alexander G; O'Neal, Lawrence; Volkova, Maia I; Markin, Vladislav S

2013-10-15

Leaf movements in Mimosa pudica, are in response to thermal stress, touch, and light or darkness, appear to be regulated by electrical, hydrodynamical, and chemical signal transduction. The pulvinus of the M. pudica shows elastic properties. We have found that the movements of the petiole, or pinnules, are accompanied by a change of the pulvinus morphing structures. After brief flaming of a pinna, the volume of the lower part of the pulvinus decreases and the volume of the upper part increases due to the redistribution of electrolytes between these parts of the pulvinus; as a result of these changes the petiole falls. During the relaxation of the petiole, the process goes in the opposite direction. Ion and water channel blockers, uncouplers as well as anesthetic agents diethyl ether or chloroform decrease the speed of alert wave propagation along the plant. Brief flaming of a pinna induces bidirectional propagation of electrical signal in pulvini. Transduction of electrical signals along a pulvinus induces generation of an action potential in perpendicular direction between extensor and flexor sides of a pulvinus. Inhibition of signal transduction and mechanical responses in M. pudica by volatile anesthetic agents chloroform or by blockers of voltage gated ion channels shows that the generation and propagation of electrical signals is a primary effect responsible for turgor change and propagation of an excitation. There is an electrical coupling in a pulvinus similar to the electrical synapse in the animal nerves. Copyright © 2013 Elsevier GmbH. All rights reserved.

Tricaproin Isolated From Simarouba glauca Inhibits the Growth of Human Colorectal Carcinoma Cell Lines by Targeting Class-1 Histone Deacetylases

PubMed Central

Jose, Asha; Chaitanya, Motamari V. N. L.; Kannan, Elango; Madhunapantula, SubbaRao V.

2018-01-01

While anticancer properties of Simarouba glauca (SG, commonly known as Paradise tree) are well documented in ancient literature, the underlying mechanisms leading to cancer cell death begin to emerge very recently. The leaves of SG have been used as potential source of anticancer agents in traditional medicine. Recently attempts have been made to isolate anticancer agents from the leaves of SG using solvent extraction, which identified quassinoids as the molecules with tumoricidal activity. However, it is not known whether the anti-cancer potential of SG leaves is just because of quassinoids alone or any other phytochemicals also contribute for the potency of SG leaf extracts. Therefore, SG leaves were first extracted with hexane, chloroform, ethyl acetate, 70% ethanol, water and anti-cancer potential (for inhibiting colorectal cancer (CRC) cells HCT-116 and HCT-15 proliferation) determined using Sulforhodamine-B (SRB) assay. The chloroform fraction with maximal anticancer activity was further fractionated by activity-guided isolation procedure and structure of the most potent compound determined using spectral analysis. Analysis of the structural characterization data showed the presence of tricaproin (TCN). TCN inhibited CRC cells growth in a time- and dose dependent manner but not the normal cell line BEAS-2B. Mechanistically, TCN reduced oncogenic Class-I Histone deacetylases (HDACs) activity, followed by inducing apoptosis in cells. In conclusion, the anti-cancer potential of SG is in part due to the presence of TCN in the leaves. PMID:29593526

Comparison of two derivatization methods for the analysis of short chain fatty acids in the ambient aerosol using GC-MS

NASA Astrophysics Data System (ADS)

Kim, G.; Jeon, S.

2016-12-01

Fatty acids are one of the important compound classes in the polar organic fraction of ambient aerosols. Among them, short chain fatty acids play a significant role in the atmospheric transformation processes. For short-chain acids, the bottleneck of analysis has been the difficulty of sample preparation due to the high solubility and volatility. To overcome this problem, derivatization of polar organic fraction is widely used with silylation reagents to increase the resolution and sensitivity. Two different derivatization procedures; (1) using the tertbutyldimethylsilyl (TBDMS) derivatization and (2) the headspace-solid phase microextraction (HS-SPME) with in-fiber derivatization are compared using gas chromatography-mass spectrometry (GC-MS). At the second method, simultaneous derivatization and extraction were performed by a poly acrylate (PA) coated fiber doped with pyrenyldiazomethane (PDAM). We investigated the chromatographic property and relative sensitivities of each individual short chain acids according to two different derivatization procedures. For the method validation, the linearity, recovery and method detection limit (MDL) were compared. Also, two derivatization methods were applied to the ambient aerosol samples and evaluated with respect to the effectiveness.

Subchronic chloroform priming protects mice from a subsequently administered lethal dose of chloroform

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

Philip, Binu K.; Anand, Sathanandam S.; Palkar, Prajakta S.

2006-10-01

Protection offered by pre-exposure priming with a small dose of a toxicant against the toxic and lethal effects of a subsequently administered high dose of the same toxicant is autoprotection. Although autoprotection has been extensively studied with diverse toxicants in acute exposure regimen, not much is known about autoprotection after priming with repeated exposure. The objective of this study was to investigate this concept following repeated exposure to a common water contaminant, chloroform. Swiss Webster (SW) mice, exposed continuously to either vehicle (5% Emulphor, unprimed) or chloroform (150 mg/kg/day po, primed) for 30 days, were challenged with a normally lethalmore » dose of chloroform (750 mg chloroform/kg po) 24 h after the last exposure. As expected, 90% of the unprimed mice died between 48 and 96 h after administration of the lethal dose in contrast to 100% survival of mice primed with chloroform. Time course studies indicated lower hepato- and nephrotoxicity in primed mice as compared to unprimed mice. Hepatic CYP2E1, glutathione levels (GSH), and covalent binding of {sup 14}C-chloroform-derived radiolabel did not differ between livers of unprimed and primed mice after lethal dose exposure, indicating that protection in liver is neither due to decreased bioactivation nor increased detoxification. Kidney GSH and glutathione reductase activity were upregulated, with a concomitant reduction in oxidized glutathione in the primed mice following lethal dose challenge, leading to decreased renal covalent binding of {sup 14}C-chloroform-derived radiolabel, in the absence of any change in CYP2E1 levels. Buthionine sulfoximine (BSO) intervention led to 70% mortality in primed mice challenged with lethal dose. These data suggest that higher detoxification may play a role in the lower initiation of kidney injury observed in primed mice. Exposure of primed mice to a lethal dose of chloroform led to 40% lower chloroform levels (AUC{sub 15-360min}) in the systemic circulation. Exhalation of {sup 14}C-chloroform was unchanged in primed as compared to unprimed mice (AUC{sub 1-6h}). Urinary excretion of {sup 14}C-chloroform was higher in primed mice after administration of the lethal dose. However, neither slightly higher urinary elimination nor unchanged expiration can account for the difference in systemic levels of chloroform. Liver and kidney regeneration was inhibited by the lethal dose in unprimed mice leading to progressive injury, organ failure, and 90% mortality. In contrast, sustained and highly stimulated compensatory hepato- and nephrogenic repair prevented the progression of injury resulting in 100% survival of primed mice challenged with the lethal dose. These findings affirm the critical role of tissue regeneration and favorable detoxification (only in kidney) of the lethal dose of chloroform in subchronic chloroform priming-induced autoprotection.« less

Metabolomics relative quantitation with mass spectrometry using chemical derivatization and isotope labeling

DOE PAGES

O'Maille, Grace; Go, Eden P.; Hoang, Linh; ...

2008-01-01

Comprehensive detection and quantitation of metabolites from a biological source constitute the major challenges of current metabolomics research. Two chemical derivatization methodologies, butylation and amination, were applied to human serum for ionization enhancement of a broad spectrum of metabolite classes, including steroids and amino acids. LC-ESI-MS analysis of the derivatized serum samples provided a significant signal elevation across the total ion chromatogram to over a 100-fold increase in ionization efficiency. It was also demonstrated that derivatization combined with isotopically labeled reagents facilitated the relative quantitation of derivatized metabolites from individual as well as pooled samples.

Effects of organic solvents on drug incorporation into polymeric carriers and morphological analyses of drug-incorporated polymeric micelles.

PubMed

Harada, Yoshiko; Yamamoto, Tatsuhiro; Sakai, Masaru; Saiki, Toshiharu; Kawano, Kumi; Maitani, Yoshie; Yokoyama, Masayuki

2011-02-14

We incorporated an anticancer agent, camptothecin (CPT), into polymeric micelle carriers by using two different solvents (TFE and chloroform) in the solvent-evaporation drug incorporation process. We observed significant differences in the drug-incorporation behaviors, in the morphologies of the incorporated drug and the polymeric micelles, and in the pharmacokinetic behaviors between the two solvents' cases. In particular, the CPT-incorporated polymeric micelles prepared with TFE as the incorporation solvent exhibited more stable circulation in blood than those prepared with chloroform. This contrast indicates a novel technological perspective regarding the drug incorporation into polymeric micelle carriers. Morphological analyses of the inner core have revealed the presence of the directed alignment of the CPT molecules and CPT crystals in the micelle inner core. This is the first report of the morphologies of the drug incorporated into the polymeric micelle inner cores. We believe these analyses are very important for further pharmaceutical developments of polymeric micelle drug-carrier systems. Copyright © 2010 Elsevier B.V. All rights reserved.

In vitro antimicrobial activity of extracts and isolated compound from Dalbergia stipulacea Roxb. leaves

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Bhat, Tahir Ahmad; Singh, Rattan Deep

2017-07-01

The study was designed to examine the in vitro antimicrobial efficacy of extracts and isolated compound of Dalbergia stipulacea. Combined extracts (chloroform and methanol) of plant leaves fractionated with n-butanol loaded with column afforded a flavonoid glycoside compound identified as luteolin 4'-rutinoside. Different extracts and isolated compound exhibited pronounced antibacterial and antifungal varied activities against four bacteria (Clostridium acetobutylinium, Bacillus subtilis, Streptococcus mutans, and Pseudomonas sp.) and one fungus (Candida albicans) susceptibility were determined using disc diffusion method. The minimum inhibitory concentration (MIC) of extracts and isolated compounds was determined by broth dilution method. The maximum activity was shown by chloroform extract against C. albicans with a zone of inhibition of 17 mm and minimum activity was displayed by methanolic extract against Pseudomonas sp. with 5 mm. However, isolated compound has shown maximum activity against Pseudomonas sp. with 15 mm. The MIC values higher in methanol extract against Pseudomonas sp. and isolated compound shows good against Pseudomonas sp. and B. subtilis. Our findings indicate that plant could be used as a good antimicrobial agent in food, pharmaceutical and bio-pesticide industries.

A new biological recovery approach for PHA using mealworm, Tenebrio molitor.

PubMed

Murugan, Paramasivam; Han, Lizhu; Gan, Chee-Yuen; Maurer, Frans H J; Sudesh, Kumar

2016-12-10

Bacterial polyhydroxyalkanoates (PHA) are expensive partly due to the recovery and purification processes. Thus, many studies have been carried out in order to minimize the cost. Here we report on the use of mealworm, which is the larva of mealworm beetle (Tenebrio molitor) to recover PHA granules from Cupriavidus necator. Mealworms were shown to readily consume the freeze-dried C. necator cells and excrete the PHA granules in the form of whitish feces. Further purification using water, detergent and heat resulted in almost 100% pure PHA granules. Comparison with chloroform extraction showed no signs of reduction in the molecular weight and dispersion of the PHA molecules. Scanning electron microscopy and dynamic light scattering measurements revealed that the biologically recovered PHA granules retained their native spherical morphology. The PHA granules were subjected to a battery of tests to determine their purity and properties in comparison to the chloroform extracted PHA. This study has demonstrated the possibility of using mealworms as a biological agent to partially purify the PHA granules. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradable Organically-Derivatized Polyoxometalate with Enhanced Activity against Glioblastoma Cell Line

NASA Astrophysics Data System (ADS)

She, Shan; Bian, Shengtai; Huo, Ruichao; Chen, Kun; Huang, Zehuan; Zhang, Jiangwei; Hao, Jian; Wei, Yongge

2016-09-01

High efficacy and low toxicity are critical for cancer treatment. Polyoxometalates (POMs) have been reported as potential candidates for cancer therapy. On accounts of the slow clearance of POMs, leading to long-term toxicity, the clinical application of POMs in cancer treatment is restricted. To address this problem, a degradable organoimido derivative of hexamolybdate is developed by modifying it with a cleavable organic group, leading to its degradation. Of note, this derivative exhibits favourable pharmacodynamics towards human malignant glioma cell (U251), the ability to penetrate across blood brain barrier and low toxicity towards rat pheochromocytoma cell (PC12). This line of research develops an effective POM-based agent for glioblastoma inhibition and will pave a new way to construct degradable anticancer agents for clinical cancer therapy.

Simultaneous derivatization and lighter-than-water air-assisted liquid-liquid microextraction using a homemade device for the extraction and preconcentration of some parabens in different samples.

PubMed

Farajzadeh, Mir Ali; Aghdam, Mehri Bakhshizadeh; Mogaddam, Mohammad Reza Afshar; Nabil, Ali Akbar Alizadeh

2018-06-06

Simultaneous derivatization and air-assisted liquid-liquid microextraction using an organic solvent lighter than water has been developed for the extraction of some parabens in different samples with the aid of a newly designed device for collecting the extractant. For this purpose, the sample solution is transferred into a glass test tube and a few microliters of acetic anhydride (as a derivatization agent) and p-xylene (as an extraction solvent) are added to the solution. After performing the procedure, the homemade device consists of an inverse funnel with a capillary tube placed into the tube. In this step, the collected extraction solvent and a part of the aqueous solution are transferred into the device and the organic phase indwells in the capillary tube of the device. Under the optimal conditions, limits of detection and quantification for the analytes were obtained in the ranges of 0.90-2.7 and 3.0-6.1 ng mL -1 , respectively. The enrichment and enhancement factors were in the ranges of 370-430 and 489-660, respectively. The method precision, expressed as the relative standard deviation, was within the ranges of 4-6% (n = 6) and 4-9% (n = 4) for intra- and inter-day precisions, respectively. The proposed method was successfully used for the determination of methyl-, ethyl-, and propyl parabens in cosmetic, hygiene, and food samples, and personal care products. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Quantitation of polyamines in cultured cells and tissue homogenates by reversed-phase high-performance liquid chromatography of their benzoyl derivatives.

PubMed

Verkoelen, C F; Romijn, J C; Schroeder, F H; van Schalkwijk, W P; Splinter, T A

1988-04-08

A rapid and simple method, originally described by Redmond and Tseng [J. Chromatogr., 170 (1979) 479] was applied to the analysis of di- and polyamines in cultured human tumour cells and human tumour xenografts. Optimization of the procedures and evaluation of the characteristic features of the assay are described. The (modified) procedure employs precolumn derivatization with benzoyl chloride, extraction of the derivatives by chloroform, separation by reversed-phase high-performance liquid chromatography under isocratic conditions and detection by ultraviolet absorbance measurement at 229 nm. The complete analysis was accomplished within 10 min per sample. The detection limit was ca. 1 pmol. The intra- and inter-assay coefficients of variation were 2.5-4.4% and 3.4-13.1%, respectively. The presence of well known inhibitors of polyamine biosynthesis, such as DL-alpha-difluoromethylornithine and methylglyoxal bis(guanylhydrazone), did not interfere with the assay, and disturbance by cyclohexylamine could be avoided by changing the polarity of the mobile phase. The method proved to be very suitable because it is rapid, simple, requires a minimum of sample pretreatment, and still provides sufficient sensitivity to quantitate polyamines in relatively small amounts of cells (10(5) cells) or tumour tissues (less than 1 mg), even after treatment with inhibitors of polyamine biosynthesis.

Physicochemical and biological characteristics of DEAE-derivatized PS7 biopolymer of Beijerinckia indica.

PubMed

Lee, Kyung Hee; Yoo, Sang-Ho; Baek, Seung Hee; Lee, Hyeon Gyu

2007-07-01

Physicochemical and biological characteristics of the exopolysaccharide, PS7, produced from Beijerinckia indica were investigated. The PS7 weight fractions of Glc and GlcUA were 0.45 and 0.25, respectively, and the molar ratio of Glc:Rha:GalUA was approximately 5:1:1.3. The PS7 was chemically derivatized with diethylaminoethyl chloride-HCl (DEAE-HCl), and the resulting modified PS7 contained both positive and negative charges. The elemental and IR analyses were conducted to confirm the successful incorporation of DEAE groups into PS7. Large increase in nitrogen fraction was observed from the derivatized PS7 by elemental analysis. The characteristic CH(3) and CH(2) peaks originated from DEAE group were detected in (1)H NMR spectrum of the derivatized PS7 as well. Solubility of native PS7 was improved almost twice from 40 to 75% after DEAE-derivatization, while water holding capacity (WHC) drastically decreased from 10,026 to 245%. Oil binding capacity (OBC) of PS7 also significantly dropped from 1528 to 331% after the derivatization. The [eta] values of native and derivatized PS7 were 27.6 and 0.31 dL/g at 25 degrees C, respectively, which means that the DEAE-derivatization significantly decreased the [eta] of PS7. The bile acid binding capacity of PS7 was indirectly determined by measuring the holding capability of cholic acid inside the dialysis membrane. When PS7 was DEAE-derivatized, there was substantial decrease in the cholic acid retardation index (CRI). Up to 8-9h of dialysis, the derivatized PS7 hold 8.6% less of cholic acid compared to native one.

Bacterial Cellular Materials as Precursors of Chloroform

NASA Astrophysics Data System (ADS)

Wang, J.; Ng, T.; Zhang, Q.; Chow, A. T.; Wong, P.

2011-12-01

The environmental sources of chloroform and other halocarbons have been intensively investigated because their effects of stratospheric ozone destruction and environmental toxicity. It has been demonstrated that microorganisms could facilitate the biotic generation of chloroform from natural organic matters in soil, but whether the cellular materials itself also serves as an important precursor due to photo-disinfection is poorly known. Herein, seven common pure bacterial cultures (Acinetobacter junii, Aeromonas hydrophila, Bacillus cereus, Bacillus substilis, Escherichia coli, Shigella sonnei, Staphylococcus sciuri) were chlorinated to evaluate the yields of chloroform, dibromochloromethane, dichlorobromomethane, and bromoform. The effects of bromide on these chemical productions and speciations were also investigated. Results showed that, on average, 5.64-36.42 μg-chloroform /mg-C were generated during the bacterial chlorination, in similar order of magnitude to that generated by humic acid (previously reported as 78 μg-chloroform/mg-C). However, unlike humic acid in water chlorination, chloroform concentration did not simply increase with the total organic carbon in water mixture. In the presence of bromide, the yield of brominated species responded linearly to the bromide concentration. This study provides useful information to understand the contributions of chloroform from photodisinfection processes in coastal environments.

A comparison of the effectiveness of chloroform and eucalyptus oil in dissolving root canal sealers.

PubMed

Schäfer, Edgar; Zandbiglari, Tannaz

2002-05-01

The solubility of 8 different root canal sealers in chloroform and in eucalyptus oil was compared. For standardized samples (n=12), ring molds were filled with mixed sealers based on epoxy resin, silicone, calcium hydroxide, zinc oxide-eugenol, glass ionomer, and polyketone. These samples were immersed in chloroform or eucalyptus oil for 30 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, and 20 minutes. Then, the mean weight loss was determined and statistically analyzed. With the exception of the silicone, all the sealers showed significantly higher solubilities (P <.05) in chloroform than in eucalyptus oil. Epoxy resin was the most soluble sealer in chloroform. In eucalyptus oil, calcium hydroxide, and zinc oxide-eugenol showed the highest solubility. Under the conditions of this study, chloroform was a far more effective solvent of root canal sealers than eucalyptus oil. Because of the potential hazards of chloroform, further studies on the dissolution of root canal sealers in different solvents seem to be necessary.

Mechanism of Action of Ribavirin: An Antiviral Drug of Military Importance,

DTIC Science & Technology

1980-06-01

was suspended in 120 mM Tris, 60 mM sodium ace- tate, 3 mM EDTA (pH 7.4) plus 10% glycerol and 0.1% bromophenol blue. Following electrophoresis, gels ... polyacryl - amide gels . J. Mol. Biol. 26:373-387. 2. Browne, M. J. 1979. Mechanism and specificity of action of ri- bavirin. Antimicrob. Agents...of 10 mM EDTA, 1% sodi- um dodecylsulfate (SDS) and 0.4 N sodium acetate (pH 5.2) then ex- tracted twice with a mixture of 50% phenol, 49% chloroform

CASTING SLIPS FOR FABRICATION OF REFRACTORY METAL WARE

DOEpatents

Stoddard, S.D.; Nuckolls, D.E.; Cowan, R.E.

1962-09-01

A composition is given for slip casting tungsten metal. The composition consists essentially of tungsten metal with an average particle size of 0.9 micron, an organic vehicle such as methyl chloroform, o-xylene, n-butyl acetate, isobutyl acetate, and 1, 1, 2, 2-tetrachlorethane, and a suspending agent such as ethyl cellulose, with the approximate ratio of said vehicle to the tungsten metal being 12 cc of a solution containing from 5 to about 20 grams of said ethyl cellulose in 400 cc of said organic vehicle per 100 grams of metal. (AEC)

Acute chloroform ingestion successfully treated with intravenously administered N-acetylcysteine.

PubMed

Dell'Aglio, Damon M; Sutter, Mark E; Schwartz, Michael D; Koch, David D; Algren, D A; Morgan, Brent W

2010-06-01

Chloroform, a halogenated hydrocarbon, causes central nervous system depression, cardiac arrhythmias, and hepatotoxicity. We describe a case of chloroform ingestion with a confirmatory serum level and resultant hepatotoxicity successfully treated with intravenously administered N-acetylcysteine (NAC). A 19-year-old man attempting suicide ingested approximately 75 mL of chloroform. He was unresponsive and intubated upon arrival. Intravenously administered NAC was started after initial stabilization was complete. His vital signs were normal. Admission laboratory values revealed normal serum electrolytes, AST, ALT, PT, BUN, creatinine, and bilirubin. Serum ethanol level was 15 mg/dL, and aspirin and acetaminophen were undetectable. The patient was extubated but developed liver function abnormalities with a peak AST of 224 IU/L, ALT of 583 IU/L, and bilirubin level reaching 16.3 mg/dL. NAC was continued through hospital day 6. Serum chloroform level obtained on admission was 91 μg/mL. The patient was discharged to psychiatry without known sequelae and normal liver function tests. The average serum chloroform level in fatal cases of inhalational chloroform poisoning was 64 μg/mL, significantly lower than our patient. The toxicity is believed to be similar in both inhalation and ingestion routes of exposure, with mortality predominantly resulting from anoxia secondary to central nervous system depression. Hepatocellular toxicity is thought to result from free radical-induced oxidative damage. Previous reports describe survival after treatment with orally administered NAC, we report the first use of intravenously administered NAC for chloroform ingestion. Acute oral ingestion of chloroform is extremely rare. Our case illustrates that with appropriate supportive care, patients can recover from chloroform ingestion, and intravenously administered NAC may be of benefit in such cases.

LFER Studies Evaluating Solvent Effects on an α-Chloro-and two β,β,β-Trichloro-Ethyl Chloroformate Esters

PubMed Central

D’Souza, Malcolm J.; Sandosky, Brandon; Fernandez-Bueno, Gabriel A.; McAneny, Matthew J.; Kevill, Dennis N.

2014-01-01

To provide insight and to identify the occurrence of mechanistic changes in relation to variance in solvent-type, the solvent effects on the rates of solvolysis of three substrates, 2,2,2-trichloro-1,1-dimethylethyl chloroformate, 2,2,2-trichloroethyl chloroformate, and 1-chloroethyl chloroformate, are analyzed using linear free energy relationships (LFERs) such as the extended Grunwald-Winstein equation, and a similarity-based LFER model approach that is based on the solvolysis of phenyl chloroformate. At 25.0 °C, in four common solvents, the α-chloroethyl chloroformate was found to react considerably faster than the two β,β,β-trichloro-substituted analogs. This immense rate enhancement can be directly related to the proximity of the electron-withdrawing α-chlorine atom to the carbonyl carbon reaction center. In the thirteen solvents studied, 1-chloroethyl chloroformate was found to strictly follow a carbonyl addition process, with the addition-step being rate-determining. For the two β,β,β-trichloro-substrates, in aqueous mixtures that are very rich in a fluoroalcohol component, there is compelling evidence for the occurrence of side-by-side addition-elimination and ionization mechanisms, with the ionization pathway being predominant. The presence of the two methyl groups on the α-carbon of 2,2,2-trichloro-1,1-dimethylethyl chloroformate has additive steric and stereoelectronic implications, causing its rate of reaction to be significantly slower than that of 2,2,2-trichloroethyl chloroformate. PMID:24812595

Microbial reductive dehalogenation of trihalomethanes by a Dehalobacter-containing co-culture.

PubMed

Zhao, Siyan; Rogers, Matthew J; He, Jianzhong

2017-07-01

Trihalomethanes such as chloroform and bromoform, although well-known as a prominent class of disinfection by-products, are ubiquitously distributed in the environment due to widespread industrial usage in the past decades. Chloroform and bromoform are particularly concerning, of high concentrations detected and with long half-lives up to several hundred days in soils and groundwater. In this study, we report a Dehalobacter- and Desulfovibrio-containing co-culture that exhibits dehalogenation of chloroform (~0.61 mM) to dichloromethane and bromoform (~0.67 mM) to dibromomethane within 10-15 days. This co-culture was further found to dechlorinate 1,1,1-trichloroethane (1,1,1-TCA) (~0.65 mM) to 1,1-dichloroethane within 12 days. The Dehalobacter species present in this co-culture, designated Dehalobacter sp. THM1, was found to couple growth with dehalogenation of chloroform, bromoform, and 1,1,1-TCA. Strain THM1 harbors a newly identified reductive dehalogenase (RDase), ThmA, which catalyzes chloroform, bromoform, and 1,1,1-TCA dehalogenation. Additionally, based on the sequences of thmA and other identified chloroform RDase genes, ctrA, cfrA, and tmrA, a pair of chloroform RDase gene-specific primers were designed and successfully applied to investigate the chloroform dechlorinating potential of microbial communities. The comparative analysis of chloroform RDases with tetrachloroethene RDases suggests a possible approach in predicting the substrate specificity of uncharacterized RDases in the future.

Cobra venom factor immunoconjugates: effects of carbohydrate-directed versus amino group-directed conjugation.

PubMed

Zara, J; Pomato, N; McCabe, R P; Bredehorst, R; Vogel, C W

1995-01-01

Human IgM monoclonal antibody 16-88, derived from patients immunized with autologous colon carcinoma cells, was derivatized with two different cross-linkers, S-(2-thiopyridyl)-L-cysteine hydrazide (TPCH), which is carbohydrate-directed, and N-succinimidyl-3-(2- pyridyldithio)propionate (SPDP), which is amino group-directed. Two antibody functions, antigen binding and complement activation, were assayed upon derivatization with TPCH and SPDP. TPCH allowed for extensive modification (up to 17 TPCH molecules per antibody) without impairment of antigen binding activity, while this function was significantly compromised upon derivatization with SPDP. Antibody molecules derivatized with 16 SPDP residues showed almost complete loss of their antigen binding function. The complement activating ability of antibody 16-88 was significantly decreased after derivatization with TPCH or SPDP. In the case of SPDP derivatization, this decrease of the complement activating ability is predominantly a consequence of the impaired binding function. Upon conjugation of cobra venom factor (CVF), a nontoxic 137-kDa glycoprotein which is capable of activating the alternative pathway of complement, the antigen binding activity of SPDP-derivatized antibody was further compromised, whereas that of TPCH-derivatized antibody remained unaffected even after attachment of three or four CVF molecules per antibody. In both conjugates CVF retained good functional activity. CVF was slightly more active when attached to SPDP-derivatized antibody, suggesting a better accessibility of amino group-coupled CVF for its interaction with other complement proteins. These results indicate that carbohydrate-directed conjugation compromises the antibody function of complement activation, but allows for the generation of immunoconjugates with unimpaired antigen binding capability.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of solvent/derivatization agent systems for determination of extractable toluene diisocyanate from flexible polyurethane foam.

PubMed

Vangronsveld, Erik; Berckmans, Steven; Spence, Mark

2013-06-01

Flexible polyurethane foam (FPF) is produced from the reaction of toluene diisocyanate (TDI) and polyols. Limited and conflicting results exist in the literature concerning the presence of unreacted TDI remaining in FPF as determined by various solvent extraction and analysis techniques. This study reports investigations into the effect of several solvent/derivatization agent combinations on extractable TDI results and suggests a preferred method. The suggested preferred method employs a syringe-based multiple extraction of foam samples with a toluene solution of 1-(2-methoxyphenyl)-piperazine. Extracts are analyzed by liquid chromatography using an ion trap mass spectrometry detection technique. Detection limits of the method are ~10ng TDI g(-1) foam (10 ppb, w/w) for each TDI isomer (i.e. 2,4-TDI and 2,6-TDI). The method was evaluated by a three-laboratory interlaboratory comparison using two representative foam samples. The total extractable TDI results found by the three labs for the two foams were in good agreement (relative standard deviation of the mean of 30-40%). The method has utility as a basis for comparing FPFs, but the interpretation of extractable TDI results using any solvent as the true value for 'free' or 'unreacted' TDI in the foam is problematic, as demonstrated by the difference in the extracted TDI results from the different extraction systems studied. Further, a consideration of polyurethane foam chemistry raises the possibility that extractable TDI may result from decomposition of parts of the foam structure (e.g. dimers, biurets, and allophanates) by the extraction system.

Chloroform-induced insanity defence confounds lawyer Lincoln.

PubMed

Spiegel, A D; Suskind, P B

1997-12-01

During an 1857 trial, the defence claimed that the accused should be absolved of wilful murder because an overdose of chloroform during surgery induced insanity. In a rare appearance as a prosecutor, Abraham Lincoln tried the case for the State of Illinois. Expert medical witnesses testified about the side effects of chloroform and chloroform-induced insanity. Significantly, Lincoln was not knowledgeable about medical jurisprudence and overlooked potential sources of evidence and expert witnesses. Defence lawyers presented an impressive array of physicians to testify about insanity, about chloroform and about the results of an overdosage during anaesthesia. Considering the state of scientific knowledge at the time, the trial was notable.

Derivatization of phytochelatins from Silene vulgaris, induced upon exposure to arsenate and cadmium: comparison of derivatization with Ellman's reagent and monobromobimane.

PubMed

Sneller, F E; van Heerwaarden, L M; Koevoets, P L; Vooijs, R; Schat, H; Verkleij, J A

2000-09-01

Phytochelatins (PCs) are a family of thiol-rich peptides, with the general structure (gamma-Glu-Cys)(n)()-Gly, with n = 2-11, induced in plants upon exposure to excessive amounts of heavy metals and some metalloids, such as arsenic. Two types of PC analyses are currently used, i.e., acid extraction and separation on HPLC with either precolumn derivatization (pH 8.2) with monobromobimane (mBBr) or postcolumn derivatization (pH 7.8) with Ellman's reagent [5, 5'-dithiobis(2-nitrobenzoic acid), DTNB]. Although both methods were satisfactory for analysis of Cd-induced PCs, formation of (RS)(3)-As complexes during extraction of As-induced PCs rendered the DTNB method useless. This paper shows that precolumn derivatization with mBBr, during which the (RS)(3)-As complexes are disrupted, provides a qualitative and quantitative analysis of both Cd- and As-induced PCs. In addition, derivatization efficiencies of both methods for the oligomers with n = 2-4 (PC(2)(-)(4)) are compared. Derivatization efficiency decreased from 71.8% and 81.4% for mBBr and DTNB derivatization, respectively, for PC(2) to 27.4% and 50.2% for PC(4). This decrease is most likely due to steric hindrance. Correction of measured thiol concentration is therefore advised for better quantification of PC concentrations in plant material.

Derivatization of Dextran for Multiply Charged Ion Formation and Electrospray Ionization Time-of-Flight Mass Spectrometric Analysis

NASA Astrophysics Data System (ADS)

Tapia, Jesus B.; Hibbard, Hailey A. J.; Reynolds, Melissa M.

2017-10-01

We present the use of a simple, one-pot derivatization to allow the polysaccharide dextran to carry multiple positive charges, shifting its molecular weight distribution to a lower m/ z range. We performed this derivatization because molecular weight measurements of polysaccharides by mass spectrometry are challenging because of their lack of readily ionizable groups. The absence of ionizable groups limits proton abstraction and suppresses proton adduction during the ionization process, producing mass spectra with predominantly singly charged metal adduct ions, thereby limiting the detection of large polysaccharides. To address this challenge, we derivatized dextran T1 (approximately 1 kDa) by attaching ethylenediamine, giving dextran readily ionizable, terminal amine functional groups. The attached ethylenediamine groups facilitated proton adduction during the ionization process in positive ion mode. Using the low molecular weight dextran T1, we tracked the number of ethylenediamine attachments by measuring the mass shift from underivatized to derivatized dextran T1. Using electrospray ionization time-of-flight mass spectrometry, we observed derivatized dextran chains ranging from two to nine glucose residues with between one and four attachments/charges. Our success in shifting derivatized dextran T1 toward the low m/ z range suggests potential for this derivatization as a viable route for analysis of high molecular weight polysaccharides using electrospray ionization time-of-flight mass spectrometry. [Figure not available: see fulltext.

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 to false negatives due to the detection limit.

Use of Linear Free Energy Relationships (LFERs) to Elucidate the Mechanisms of Reaction of a γ-Methyl-β-alkynyl and an ortho-Substituted Aryl Chloroformate Ester

PubMed Central

D’Souza, Malcolm J.; Knapp, Jaci A.; Fernandez-Bueno, Gabriel A.; Kevill, Dennis N.

2012-01-01

The specific rates of solvolysis of 2-butyn-1-yl-chloroformate (1) and 2-methoxyphenyl chloroformate (2) are studied at 25.0 °C in a series of binary aqueousorganic mixtures. The rates of reaction obtained are then analyzed using the extended Grunwald-Winstein (G-W) equation and the results are compared to previously published G-W analyses for phenyl chloroformate (3), propargyl chloroformate (4), p-methoxyphenyl choroformate (5), and p-nitrophenyl chloroformate (6). For 1, the results indicate that dual side-by-side addition-elimination and ionization pathways are occurring in some highly ionizing solvents due to the presence of the electron-donating γ-methyl group. For 2, the analyses indicate that the dominant mechanism is a bimolecular one where the formation of a tetrahedral intermediate is rate-determining. PMID:22312278

Extended Grunwald-Winstein Analysis - LFER Used to Gauge Solvent Effects in p-Nitrophenyl Chloroformate Solvolysis

PubMed Central

D’Souza, Malcolm J.; Shuman, Kevin E.; Carter, Shannon E.; Kevill, Dennis N.

2008-01-01

Specific rates of solvolysis at 25 °C for p-nitrophenyl chloroformate (1) are analyzed using the extended (two-term) Grunwald-Winstein equation. For 39 solvents, the sensitivities (l = 1.68±0.06 and m = 0.46±0.04) towards changes in solvent nucleophilicity (l) and solvent ionizing power (m) obtained, are similar to those previously observed for phenyl chloroformate (2) and p-methoxyphenyl chloroformate (3). The observations incorporating new kinetic data in several fluoroalcohol-containing mixtures, are rationalized in terms of the reaction being sensitive to substituent effects and the mechanism of reaction involving the addition (association) step of an addition-elimination (association-dissociation) pathway being rate-determining. The l/m ratios obtained for 1, 2, and 3, are also compared to the previously published l/m ratios for benzyl chloroformate (4) and p-nitrobenzyl chloroformate (5). PMID:19330071

Characterization of hot spots for natural chloroform formation: Relevance for groundwater quality

NASA Astrophysics Data System (ADS)

Jacobsen, Ole S.; Albers, Christian N.; Laier, Troels

2015-04-01

Chloroform soil hot spot may deteriorate groundwater quality and may even result in chloroform concentration exceeding the Danish maximum limit of 1 µg/L in groundwater for potable use. In order to characterize the soil properties important for the chloroform production, various ecosystems were examined with respect to soil air chloroform and soil organic matter type and content. Coniferous forest areas, responsible for highest chloroform concentrations, were examined on widely different scales from km to cm scale. Furthermore, regular soil gas measurements including chloroform were performed during 4 seasons at various depths, together with various meteorological measurements and soil temperature recordings. Laboratory incubation experiments were also performed on undisturbed soil samples in order to examine the role of various microbiota, fungi and bacteria. To identify hot spots responsible for the natural contamination we have measured the production of chloroform in the upper soil from different terrestrial systems. Field measurements of chloroform in top soil air were used as production indicators. The production was however not evenly distributed at any scale. The ecosystems seem to have quite different net-productions of chloroform from very low in grassland to very high in some coniferous forests. Within the forest ecosystem we found large variation in chloroform concentrations depending on vegetation. In beech forest we found the lowest values, somewhat higher in an open pine forest, but the highest concentrations were detected in spruce forest without any vegetation beneath. Within this ecotype, it appeared that the variation was also large; hot spots with 2-4 decades higher production than the surrounding area. These hot spots were not in any way visually different from the surroundings and were of variable size from 3 to 20 meters in diameter. Besides this, measurements within a seemingly homogenous hot spot showed that there was still high variability at 10 cm level. We suggest that the mechanism behind the formation of chloroform is an unspecific chlorination of organic matter, caused by microbial activity in the soil forming trichloroacetyl compounds. Laboratory measurements on intact soil cores have identified that the F and H horizons in the forest soil are the main producers of chloroform. Despite various attempts to identify the mechanisms responsible for the variability within a visually and chemically homogeneous area we have not yet succeeded. Parameters like soil respiration, inorganic and total organic chlorine, organic matter and soil structure were studied without any significant difference in favour of hot spots. By the use of 13C-isotopes we could identify the natural origin of the chloroform, and over a three years period we could conclude that the hot spots were permanent on the sites. At the same time a significant seasonal variation were measured depending on temperature and soil moisture.

Efficient encapsulation of chloroform with cryptophane-M and the formation of exciplex studied by fluorescence spectroscopy.

PubMed

Shi, Yanqi; Li, Xueming; Yang, Jianchun; Gao, Fang; Tao, Chuanyi

2011-03-01

Efficient encapsulation of small molecules with supermolecules is one of significantly important subjects due to strong application potentials. This article presents the interaction between cryptophane-M and chloroform by fluorescence spectroscopy. The sonicated cryptophane-M solution exhibits light green color in chloroform, and the solid obtained from the evaporation of chloroform also has different color from that of cryptophane-M. In contrast, the sonicated cryptophane-M solutions in other solvents are colorless, and the solid obtained from the evaporation of these solvents has the same color as that of cryptophane-M. Furthermore, the freshly prepared cryptophane-M solution in different solvents is almost colorless, and the solid obtained from the evaporation of these solvents displays the same color as that of cryptophane-M. Although the sonicated cryptophane-M solutions in different solvents have very similar absorption spectra, they exhibit quite different emission spectra in chloroform. In contrast, the freshly-prepared cryptophane-M solutions show similar absorption and emission spectroscopy in various solvents. The variation of the fluorescence spectroscopy in binary solvents with the increasing chloroform ratio suggests that cryptophane-M and chloroform form a 1:1 exciplex, and the binding constant is estimated to be 292.95 M(-1). Although all solvents are able to enter into the cavity of cryptophane-M, only chloroform can stay in the cavity of cryptophane-M for a while, which is mostly due to the strong intermolecular interaction between cryptophane-M and chloroform, and this results in the formation of the exciplex between them. © Springer Science+Business Media, LLC 2010

Retreatability of two endodontic sealers, EndoSequence BC Sealer and AH Plus: a micro-computed tomographic comparison.

PubMed

Oltra, Enrique; Cox, Timothy C; LaCourse, Matthew R; Johnson, James D; Paranjpe, Avina

2017-02-01

Recently, bioceramic sealers like EndoSequence BC Sealer (BC Sealer) have been introduced and are being used in endodontic practice. However, this sealer has limited research related to its retreatability. Hence, the aim of this study was to evaluate the retreatability of two sealers, BC Sealer as compared with AH Plus using micro-computed tomographic (micro-CT) analysis. Fifty-six extracted human maxillary incisors were instrumented and randomly divided into 4 groups of 14 teeth: 1A, gutta-percha, AH Plus retreated with chloroform; 1B, gutta-percha, AH Plus retreated without chloroform; 2A, gutta-percha, EndoSequence BC Sealer retreated with chloroform; 2B, gutta-percha, EndoSequence BC Sealer retreated without chloroform. Micro-CT scans were taken before and after obturation and retreatment and analyzed for the volume of residual material. The specimens were longitudinally sectioned and digitized images were taken with the dental operating microscope. Data was analyzed using an ANOVA and a post-hoc Tukey test. Fisher exact tests were performed to analyze the ability to regain patency. There was significantly less residual root canal filling material in the AH Plus groups retreated with chloroform as compared to the others. The BC Sealer samples retreated with chloroform had better results than those retreated without chloroform. Furthermore, patency could be re-established in only 14% of teeth in the BC Sealer without chloroform group. The results of this study demonstrate that the BC Sealer group had significantly more residual filling material than the AH Plus group regardless of whether or not both sealers were retreated with chloroform.

IRIS Toxicological Review of Chloroform (Final Report)

EPA Science Inventory

EPA is announcing the release of the final report, Toxicological Review of Chloroform: in support of the Integrated Risk Information System (IRIS). The updated Summary for Chloroform and accompanying Quickview have also been added to the IRIS Database.

Antifungal and antimycotoxigenic potency of Solanum torvum Swartz. leaf extract: isolation and identification of compound active against mycotoxigenic strains of Aspergillus flavus and Fusarium verticillioides.

PubMed

Abhishek, R U; Thippeswamy, S; Manjunath, K; Mohana, D C

2015-12-01

The main objective of this study was to investigate the antifungal effect of Solanum torvum leaves against different field and storage fungi, and to identify its active compound. In addition, to evaluate in vitro and in vivo inhibitory efficacy on toxigenic strains of Aspergillus flavus and Fusarium verticillioides. Leaves of S. torvum were sequentially extracted with petroleum ether, toluene, chloroform, methanol and ethanol. The antifungal compound isolated from chloroform extract was identified as torvoside K based on spectral analysis. The antifungal activity of chloroform extract and torvoside K was determined by broth microdilution and poisoned food techniques. The minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC) and zone of inhibition (ZOI) were recorded. Further, inhibitory effects of chloroform extract and torvoside K on growth of A. flavus and F. verticillioides, and their toxin productions were evaluated using in vitro and in vivo assays. Torvoside K showed the significant activity against tested fungi with ZOIs and MICs ranging from 33·4 to 87·4% and 31·25-250 μg ml(-1) , respectively. Further, torvoside K showed concentration-dependent antimycotoxigenic activity against aflatoxin B1 and fumonisin B1 production by A. flavus and F. verticillioides, respectively. It was observed that the compound torvoside K significantly inhibited the growth of all fungi tested. Growth of A. flavus and F. verticillioides, and aflatoxin B1 and fumonisin B1 productions were completely inhibited in vitro and in vivo by torvoside K with increasing concentration. Control of mycotoxigenic fungi requires compounds that able to inhibit both fungal growth and mycotoxin production. The antimycotoxigenic potential of torvoside K of S. torvum is described in this study for the first time. The results indicate the possible use of S. torvum as source of antifungal agents against postharvest fungal infestation of food commodities and mycotoxin contaminations. © 2015 The Society for Applied Microbiology.

Dynamic real-time monitoring of chloroform in an indoor swimming pool air using open-path Fourier transform infrared spectroscopy.

PubMed

Chen, M-J; Duh, J-M; Shie, R-H; Weng, J-H; Hsu, H-T

2016-06-01

This study used open-path Fourier transform infrared (OP-FTIR) spectroscopy to continuously assess the variation in chloroform concentrations in the air of an indoor swimming pool. Variables affecting the concentrations of chloroform in air were also monitored. The results showed that chloroform concentrations in air varied significantly during the time of operation of the swimming pool and that there were two peaks in chloroform concentration during the time of operation of the pool. The highest concentration was at 17:30, which is coincident with the time with the highest number of swimmers in the pool in a day. The swimmer load was one of the most important factors influencing the chloroform concentration in the air. When the number of swimmers surpassed 40, the concentrations of chloroform were on average 4.4 times higher than the concentration measured without swimmers in the pool. According to the results of this study, we suggest that those who swim regularly should avoid times with highest number of swimmers, in order to decrease the risk of exposure to high concentrations of chloroform. It is also recommended that an automatic mechanical ventilation system is installed to increase the ventilation rate during times of high swimmer load. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Piperazines for peptide carboxyl group derivatization: effect of derivatization reagents and properties of peptides on signal enhancement in matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Qiao, Xiaoqiang; Sun, Liangliang; Chen, Lingfan; Zhou, Yuan; Yang, Kaiguang; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2011-03-15

Piperazine-based derivatives, including 1-(2-pyridyl)piperazine (2-PP), 1-(2-pyrimidyl)piperazine (2-PMP), 1-(4-pyridyl)piperazine (4-PP), and 1-(1-methyl-4-piperidinyl)piperazine (M-PP), were used for the derivatization of carboxyl groups on peptides with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxy-7-azabenzotriazole (HOAt) as coupling reagents, and trifluoroacetic acid (TFA) as activator. Taking synthetic peptides RVYVHPI (RI-7) and APGDRIYVHPF (AF-11) as samples, the yields of derivatized peptides by 2-PP, 2-PMP and 4-PP were higher than 94%. The effect of piperazine derivatives on the signals of tryptic digests of α-transferrin and bovine serum albumin (BSA) was investigated, and it was found that peptides derivatized by 2-PP and 2-PMP exhibited obviously improved ionization efficiency. Furthermore, comparison of identified peptides before and after derivatization showed that peptides with low molecular weight (MW) and high pI value were preferably detected after derivatization. In addition, after derivatization with 2-PP and 2-PMP, protein myelin basic protein S, 20 kDa protein, and histone H were confidently identified from the tryptic digests of two fractions of rat brain protein separated by reversed-phase high-performance liquid chromatography (HPLC), indicating the potential application of 2-PP and 2-PMP for the highly sensitive determination of peptides in comprehensive proteome analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Accurate determination of aldehydes in amine catalysts or amines by 2,4-dinitrophenylhydrazine derivatization.

PubMed

Barman, Bhajendra N

2014-01-31

Carbonyl compounds, specifically aldehydes, present in amine catalysts or amines are determined by reversed-phase liquid chromatography using ultraviolet detection of their corresponding 2,4-dinitrophenylhydrazones. The primary focus has been to establish optimum conditions for determining aldehydes accurately because these add exposure concerns when the amine catalysts are used to manufacture polyurethane products. Concentrations of aldehydes determined by this method are found to vary with the pH of the aqueous amine solution and the derivatization time, the latter being problematic when the derivatization reaction proceeds slowly and not to completion in neutral and basic media. Accurate determination of aldehydes in amines through derivatization can be carried out at an effective solution pH of about 2 and with derivatization time of 20min. Hydrochloric acid has been used for neutralization of an amine. For complete derivatization, it is essential to protonate all nitrogen atoms in the amine. An approach for the determination of an adequate amount of acid needed for complete derivatization has been described. Several 0.2M buffer solutions varying in pH from 4 to 8 have also been used to make amine solutions for carrying out derivatization of aldehydes. These solutions have effective pHs of 10 or higher and provide much lower aldehyde concentrations compared to their true values. Mechanisms for the formation of 2,4-dinitrophenylhydrazones in both acidic and basic media are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

CANCER RISK ASSESSMENT FOR CHLOROFORM

EPA Science Inventory

Chloroform is a common chlorination by-product in drinking water. EPA has regulated chloroform as a probable human carcinogen under the Safe Drinking Water Act. The cancer risk estimate via ingestion was based on the 1985 Jorgenson study identifying kidney tumors in male Osborne ...

Determination of mustard and lewisite related compounds in abandoned chemical weapons (Yellow shells) from sources in China and Japan.

PubMed

Hanaoka, Shigeyuki; Nomura, Koji; Wada, Takeharu

2006-01-06

Knowledge of the states of the contents in chemical munitions that Japanese Imperial Forces abandoned at the end of World War II in Japan and China is gravely lacking. To unearth and recover these chemical weapons and detoxify the contents safely, it is essential to establish analytical procedures to definitely determine the CWA contents. We established such a procedure and applied it to the analysis of chemicals in the abandoned shells. Yellow shells are known to contain sulfur mustard, lewisite, or a mixture of both. Lewisite was analyzed without thiol derivatization, because it and its decomposition products yield the same substances in the derivatization. Analysis using our new procedure showed that both mustard and lewisite remained as the major components after the long abandonment of nearly 60 years. The content of mustard was 43% and that of lewisite 55%. The viscous material found was suggested to be mostly oligomers of mustard. Comparison of the components in the Yellow agents with mustard recovered in both Japan and China showed a difference in the impurities between the CWAs produced by the former Imperial navy and those by the former Imperial army.

Thin-layer chromatographic determination of erythromycin and other macrolide antibiotics in livestock products.

PubMed

Petz, M; Solly, R; Lymburn, M; Clear, M H

1987-01-01

A method is described for determination of 4 macrolide antibiotics in livestock products. Erythromycin, tylosin, oleandomycin, and spiramycin were extracted from animal tissues, milk, and egg with acetonitrile at pH 8.5. Cleanup was done by adding sodium chloride and dichloromethane, evaporating the organic layer, and subsequent acid/base partitioning. After the antibiotics were separated by thin-layer chromatography (TLC), they were reacted with xanthydrol and could be detected as purple spots down to 0.02 mg/kg without interference by other commonly used therapeutic drugs (23 were tested). Anisaldehyde-sulfuric acid, cerium sulfate-molybdic acid, phosphomolybdic acid, and Dragendorff's reagent proved to be less sensitive as visualizing agents. For quantitation, TLC plates were scanned at 525 nm. Recoveries were between 71 and 96% for erythromycin and tylosin in liver, muscle, and egg at the 0.1-0.5 mg/kg level and 51% for erythromycin in milk at the 0.02 mg/kg level (coefficient of variation = 10-18%). Bioautography with Bacillus subtilis was used to confirm results, in addition to TLC analysis of derivatized antibiotics and liquid chromatography with electrochemical detection. Various derivatization procedures for erythromycin were investigated for improved ultra-violet or fluorescence detection in liquid chromatography.

A monobromobimane-based assay to measure the pharmacokinetic profile of reactive sulphide species in blood

PubMed Central

Wintner, Edward A; Deckwerth, Thomas L; Langston, William; Bengtsson, Asa; Leviten, Dina; Hill, Paul; Insko, Michael A; Dumpit, Ronald; VandenEkart, Emily; Toombs, Christopher F; Szabo, Csaba

2010-01-01

Background and purpose: Hydrogen sulphide (H2S) is a labile, endogenous metabolite of cysteine, with multiple biological roles. The development of sulphide-based therapies for human diseases will benefit from a reliable method of quantifying H2S in blood and tissues. Experimental approach: Concentrations of reactive sulphide in saline and freshly drawn whole blood were quantified by reaction with the thio-specific derivatization agent monobromobimane, followed by reversed-phase fluorescence HPLC and/or mass spectrometry. In pharmacokinetic studies, male rats were exposed either to intravenous infusions of sodium sulphide or to H2S gas inhalation, and levels of available blood sulphide were measured. Levels of dissolved H2S/HS- were concomitantly measured using an amperometric sensor. Key results: Monobromobimane was found to rapidly and quantitatively derivatize sulphide in saline or whole blood to yield the stable small molecule sulphide dibimane. Extraction and quantification of this bis-bimane derivative were validated via reversed-phase HPLC separation coupled to fluorescence detection, and also by mass spectrometry. Baseline levels of sulphide in blood were in the range of 0.4–0.9 µM. Intravenous administration of sodium sulphide solution (2–20 mg·kg−1·h−1) or inhalation of H2S gas (50–400 ppm) elevated reactive sulphide in blood in a dose-dependent manner. Each 1 mg·kg−1·h−1 of sodium sulphide infusion into rats was found to be pharmacokinetically equivalent to approximately 30 ppm of H2S gas inhalation. Conclusions and implications: The monobromobimane derivatization method is a sensitive and reliable means to measure reactive sulphide species in whole blood. Using this method, we have established a bioequivalence between infused sodium sulphide and inhaled H2S gas. PMID:20590590

A monobromobimane-based assay to measure the pharmacokinetic profile of reactive sulphide species in blood.

PubMed

Wintner, Edward A; Deckwerth, Thomas L; Langston, William; Bengtsson, Asa; Leviten, Dina; Hill, Paul; Insko, Michael A; Dumpit, Ronald; VandenEkart, Emily; Toombs, Christopher F; Szabo, Csaba

2010-06-01

Hydrogen sulphide (H(2)S) is a labile, endogenous metabolite of cysteine, with multiple biological roles. The development of sulphide-based therapies for human diseases will benefit from a reliable method of quantifying H(2)S in blood and tissues. Concentrations of reactive sulphide in saline and freshly drawn whole blood were quantified by reaction with the thio-specific derivatization agent monobromobimane, followed by reversed-phase fluorescence HPLC and/or mass spectrometry. In pharmacokinetic studies, male rats were exposed either to intravenous infusions of sodium sulphide or to H(2)S gas inhalation, and levels of available blood sulphide were measured. Levels of dissolved H(2)S/HS(-) were concomitantly measured using an amperometric sensor. Monobromobimane was found to rapidly and quantitatively derivatize sulphide in saline or whole blood to yield the stable small molecule sulphide dibimane. Extraction and quantification of this bis-bimane derivative were validated via reversed-phase HPLC separation coupled to fluorescence detection, and also by mass spectrometry. Baseline levels of sulphide in blood were in the range of 0.4-0.9 microM. Intravenous administration of sodium sulphide solution (2-20 mg x kg(-1) x h(-1)) or inhalation of H(2)S gas (50-400 ppm) elevated reactive sulphide in blood in a dose-dependent manner. Each 1 mg x kg(-1) x h(-1) of sodium sulphide infusion into rats was found to be pharmacokinetically equivalent to approximately 30 ppm of H(2)S gas inhalation. The monobromobimane derivatization method is a sensitive and reliable means to measure reactive sulphide species in whole blood. Using this method, we have established a bioequivalence between infused sodium sulphide and inhaled H(2)S gas.

Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

PubMed

van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

2015-12-18

The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

Hit-to-lead development of the chamigrane endoperoxide merulin A for the treatment of African sleeping sickness.

PubMed

Navarro, Gabriel; Chokpaiboon, Supchar; De Muylder, Geraldine; Bray, Walter M; Nisam, Sean C; McKerrow, James H; Pudhom, Khanitha; Linington, Roger G

2012-01-01

Human African trypanosomiasis (HAT) is an infectious disease with a large global health burden occurring primarily in Central and Eastern Africa. Most current treatments have poor blood brain barrier (BBB) penetration, which prevent them from targeting the most lethal stage of the infection. In addition, current therapeutics suffer from a variety of limitations ranging from serious side effects to difficulties with treatment administration. Therefore it is of crucial importance to find new treatments that are safe, affordable, and effective against both sub-species of Trypanosoma brucei. Semi-synthetic derivatization of the fungally-derived natural product merulin A (1) has led to the discovery of new development candidates for the protozoan parasite T. brucei, the causative agent of HAT. Creation of an initial SAR library based around the merulin scaffold revealed several key features required for activity, including the endoperoxide bridge, as well as one position suitable for further derivatization. Subsequent synthesis of a 20-membered analogue library, guided by the addition of acyl groups that improve the drug-like properties of the merulin A core, resulted in the development of compound 12 with an IC(50) of 60 nM against T. brucei, and a selectivity index greater than 300-fold against HeLa and immortalized glial cells. We report the semi-synthetic optimization of the merulin class of endoperoxide natural products as development candidates against T. brucei. We have identified compounds with low nM antiparasitic activities and high selectivity indices against HeLa cells. These compounds can be produced economically in large quantities via a one step derivatization from the microbial fermentation broth isolate, making them encouraging lead candidates for further development.

Capillary electrophoresis determination of glucosamine in nutraceutical formulations after labeling with anthranilic acid and UV detection.

PubMed

Volpi, Nicola

2009-04-05

A new robust CE method for the determination of the glucosamine (GlcN) content in nutraceutical formulations is described after its derivatization with anthranilic acid (2-aminobenzoic acid, AA). The CE separation of derivatized GlcN with AA was performed on an uncoated fused-silica capillary tube (50 microm I.D.) using an operating pH 7.0 buffer of 150 mM boric acid/50 mM NaH2PO4 and UV detection at 214 nm. The method was validated for specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The detector response for GlcN was linear over the selected concentration range from 240 to 2400 pg (40-400 microg/mL) with a correlation coefficient greater than 0.980. The intra- and inter-day variations (CV%) were between 0.5 and 0.9 for migration time, and between 2.8 and 4.3 for peak area, respectively. The LOD and the LOQ of the method were approximately 200 and 500 pg, respectively. The intra- and inter-day accuracy was estimated to range from 2.8% to 5.1%, while the percent recoveries of GlcN in formulations were calculated to be about 100% after simple centrifugation for 10 min, lyophilization and derivatization with AA. The CE method was applied to the determination of GlcN content, in the form of GlcN-hydrochloride or GlcN-sulfate, of several nutraceutical preparations in the presence of other ingredients, i.e. chondroitin sulfate, vitamin C and/or methylsulfonylmethane (MSM) as well as salts and other agents. The quantitative results obtained were in total conformity with the label claims.

Simultaneous extraction and quantitation of several bioactive amines in cheese and chocolate.

PubMed

Baker, G B; Wong, J T; Coutts, R T; Pasutto, F M

1987-04-17

A method is described for simultaneous extraction and quantitation of the amines 2-phenylethylamine, tele-methylhistamine, histamine, tryptamine, m- and p-tyramine, 3-methoxytyramine, 5-hydroxytryptamine, cadaverine, putrescine, spermidine and spermine. This method is based on extractive derivatization of the amines with a perfluoroacylating agent, pentafluorobenzoyl chloride, under basic aqueous conditions. Analysis was done on a gas chromatograph equipped with an electron-capture detector and a capillary column system. The procedure is relatively rapid and provides derivatives with good chromatographic properties. Its application to analysis of the above amines in cheese and chocolate products is described.

Two choices for the functionalization of silica nanoparticles with gallic acid: characterization of the nanomaterials and their antimicrobial activity against Paenibacillus larvae

NASA Astrophysics Data System (ADS)

Vico, Tamara A.; Arce, Valeria B.; Fangio, María F.; Gende, Liesel B.; Bertran, Celso A.; Mártire, Daniel O.; Churio, María S.

2016-11-01

Silica nanoparticles attached to gallic acid were synthesized from 7-nm diameter fumed silica particles by different functionalization methods involving the condensation of hydroxyl or carboxyl groups. The particles were characterized by thermal analyses and UV-vis, FTIR, NMR, and EPR spectroscopies. In comparison to free gallic acid, enhanced stability and increased antimicrobial activity against Paenibacillus larvae were found for the functionalized nanoparticles. Thus, both derivatization strategies result in improved properties of the natural polyphenol as antimicrobial agent for the treatment of honeybee pathologies.

CONTROLLED, SHORT-TERM DERMAL AND INHALATION EXPOSURE TO CHLOROFORM

EPA Science Inventory

Studies were conducted to determine the uptake by humans of chloroform as a result of controlled short-term dermal and inhalation exposures. The approach used continuous real-time breath analysis to determine exhaled-breath profiles and evaluate chloroform kinetics in the huma...

Derivatization of amino acids with N,N-dimethyl-2,4-dinitro-5-fluorobenzylamine for liquid chromatography/electrospray ionization mass spectrometry.

PubMed

Liu, Zhongfa; Minkler, Paul E; Lin, De; Sayre, Lawrence M

2004-01-01

Derivatization, separation and identification of amino acids with a novel compound, N,N-dimethyl-2,4-dinitro-5-fluorobenzylamine (DMDNFB), using high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) was demonstrated. Compared to derivatization with 2,4-dinitrofluorobenzene (DNFB), DMDNFB-derivatized amino acids and dipeptides exhibit much larger ion current signals in the commonly used ESI positive mode, which was attributed to the introduction of the N,N-dimethylaminomethyl protonatable site. Copyright 2004 John Wiley & Sons, Ltd.

Derivatization reagents in liquid chromatography/electrospray ionization tandem mass spectrometry.

PubMed

Santa, Tomofumi

2011-01-01

Liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is one of the most prominent analytical techniques owing to its inherent selectivity and sensitivity. In LC/ESI-MS/MS, chemical derivatization is often used to enhance the detection sensitivity. Derivatization improves the chromatographic separation, and enhances the mass spectrometric ionization efficiency and MS/MS detectability. In this review, an overview of the derivatization reagents which have been applied to LC/ESI-MS/MS is presented, focusing on the applications to low molecular weight compounds. 2010 John Wiley & Sons, Ltd.

Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

PubMed

Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

2009-04-10

SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

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

PubMed

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

2008-02-01

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

Retreatability of two endodontic sealers, EndoSequence BC Sealer and AH Plus: a micro-computed tomographic comparison

PubMed Central

Oltra, Enrique; Cox, Timothy C.; LaCourse, Matthew R.; Johnson, James D.

2017-01-01

Objectives Recently, bioceramic sealers like EndoSequence BC Sealer (BC Sealer) have been introduced and are being used in endodontic practice. However, this sealer has limited research related to its retreatability. Hence, the aim of this study was to evaluate the retreatability of two sealers, BC Sealer as compared with AH Plus using micro-computed tomographic (micro-CT) analysis. Materials and Methods Fifty-six extracted human maxillary incisors were instrumented and randomly divided into 4 groups of 14 teeth: 1A, gutta-percha, AH Plus retreated with chloroform; 1B, gutta-percha, AH Plus retreated without chloroform; 2A, gutta-percha, EndoSequence BC Sealer retreated with chloroform; 2B, gutta-percha, EndoSequence BC Sealer retreated without chloroform. Micro-CT scans were taken before and after obturation and retreatment and analyzed for the volume of residual material. The specimens were longitudinally sectioned and digitized images were taken with the dental operating microscope. Data was analyzed using an ANOVA and a post-hoc Tukey test. Fisher exact tests were performed to analyze the ability to regain patency. Results There was significantly less residual root canal filling material in the AH Plus groups retreated with chloroform as compared to the others. The BC Sealer samples retreated with chloroform had better results than those retreated without chloroform. Furthermore, patency could be re-established in only 14% of teeth in the BC Sealer without chloroform group. Conclusion The results of this study demonstrate that the BC Sealer group had significantly more residual filling material than the AH Plus group regardless of whether or not both sealers were retreated with chloroform. PMID:28194360

Oil extraction from algae: A comparative approach.

PubMed

Valizadeh Derakhshan, Mehrab; Nasernejad, Bahram; Abbaspour-Aghdam, Farzin; Hamidi, Mohammad

2015-01-01

In this article, various methods including soxhlet, Bligh & Dyer (B&D), and ultrasonic-assisted B&D were investigated for the extraction of lipid from algal species Chlorella vulgaris. Relative polarity/water content and impolar per polar ratios of solvents were considered to optimize the relative proportions of each triplicate agent by applying the response surface method (RSM). It was found that for soxhlet, hexane-methanol (54-46%, respectively) with total lipid extraction of 14.65% and chloroform-methanol (54-46%, respectively) with the extraction of 19.87% lipid were the best set of triplicate where further addition of acetone to the first group and ethanol to the second group did not contributed to further extraction. In B&D, however, chloroform-methanol-water (50%-35%-15%, respectively) reached the all-time maximum of 24%. Osmotic shock as well as ultrasonication contributed to 3.52% of further extraction, which is considered to promote the total yield up to almost 15%. From the growth data and fatty acid analysis, the applied method was assessed to be appropriate for biodiesel production with regard to selectivity and extraction yield. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Ingestion, inhalation, and dermal exposures to chloroform and trichloroethene from tap water.

PubMed Central

Weisel, C P; Jo, W K

1996-01-01

Individuals are exposed to volatile compounds present in tap water by ingestion, inhalation, and dermal absorption. Traditional risk assessments for water often only consider ingestion exposure to toxic chemicals, even though showering has been shown to increase the body burden of certain chemicals due to inhalation exposure and dermal absorption. We collected and analyzed time-series samples of expired alveolar breath to evaluate changes in concentrations of volatile organic compounds being expired, which reflects the rate of change in the bloodstream due to expiration, metabolism, and absorption into tissues. Analysis of chloroform and trichloethene in expired breath, compounds regulated in water, was also used to determine uptake from tap water by each route (inhalation, ingestion, or absorption). Each route of exposure contributed to the total exposure of these compounds from daily water use. Further, the ingestion dose was completely metabolized before entering the bloodstream, whereas the dose from the other routes was dispersed throughout the body. Thus, differences in potential biologically effective doses depend on route, target organ, and whether the contaminant or metabolite is the biologically active agent. Images Figure 1. A Figure 1. B Figure 1. C Figure 2. A Figure 2. B PMID:8834861

Preliminary study on fractions' activities of red betel vine (Piper crocatum Ruiz & Pav) leaves ethanol extract toward Mycobacterium tuberculosis

NASA Astrophysics Data System (ADS)

Rachmawaty, Farida Juliantina; Julianto, Tatang Shabur; Tamhid, Hady Anshory

2018-04-01

This research aims to identify the antimycobacterial activity of fraction of red betel vine leaves ethanol extract (methanol fraction, ethyl acetate, and chloroform) toward M. tuberculosis. Red betel vine leaves ethanol extract was made with maceration method using ethanol solvent 70%. Resulted extract was then fractionated using Liquid Vacuum Chromatography (LVC) with methanol, ethyl acetate, and chloroform solvent. Each fractionation was exposed to M. tuberculosis with serial dilution method. Controls of fraction, media, bacteria, and isoniazid as standard drug were included in this research. The group of compound from the most active fraction was then identified. The research found that the best fraction for antimycobacterial activity toward M. tuberculosisis chloroform fraction. The compound group of chloroform fraction was then identified. The fraction contains flavonoid, tannin, alkaloid, and terpenoid. The fraction of methanol, ethyl acetate, and chloroform from red betel vine leaves has antimycobacterial activity toward M. tuberculosis. Chloroform fraction has the best antimycobacterial activity and it contains flavonoid, tannin, alkaloid, and terpenoid.

Chloroform Hydrodechlorination over Palladium–Gold Catalysts: A First-Principles DFT Study

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

Xu, Lang; Yao, Xiaoqian; Khan, Ahmad

2016-04-20

Hydrodechlorination is a promising method for treating toxic chlorocarbon compounds. Pd is among the most effective catalysts for chloroform hydrodechlorination, and experiments have shown that the Pd–Au alloy catalyst yields superior catalytic performance over pure Pd. In this paper, we examine the chloroform hydrodechlorination mechanism over Pd(1 1 1) and Pd ML/Au(1 1 1) surfaces using periodic, self-consistent density functional theory calculations (DFT, GGA–PW91) and maximum rate analysis. We suggest that the reaction occurs on both surfaces through complete dechlorination of chloroform followed by hydrogenation of CH* to methane, and that the initial dechlorination step is likely the rate-limiting step.more » Finally, on Pd(1 1 1), the chloroform dechlorination barrier is 0.24 eV higher than the desorption barrier, whereas on Pd ML/Au(1 1 1), the chloroform dechlorination barrier is 0.07 eV lower than the desorption barrier, which can explain the higher hydrodechlorination activity of the Pd–Au alloy catalyst.« less

Identification of light-independent inhibition of human immunodeficiency virus-1 infection through bioguided fractionation of Hypericum perforatum

PubMed Central

Maury, Wendy; Price, Jason P; Brindley, Melinda A; Oh, ChoonSeok; Neighbors, Jeffrey D; Wiemer, David F; Wills, Nickolas; Carpenter, Susan; Hauck, Cathy; Murphy, Patricia; Widrlechner, Mark P; Delate, Kathleen; Kumar, Ganesh; Kraus, George A; Rizshsky, Ludmila; Nikolau, Basil

2009-01-01

Background Light-dependent activities against enveloped viruses in St. John's Wort (Hypericum perforatum) extracts have been extensively studied. In contrast, light-independent antiviral activity from this species has not been investigated. Results Here, we identify the light-independent inhibition of human immunodeficiency virus-1 (HIV-1) by highly purified fractions of chloroform extracts of H. perforatum. Both cytotoxicity and antiviral activity were evident in initial chloroform extracts, but bioassay-guided fractionation produced fractions that inhibited HIV-1 with little to no cytotoxicity. Separation of these two biological activities has not been reported for constituents responsible for the light-dependent antiviral activities. Antiviral activity was associated with more polar subfractions. GC/MS analysis of the two most active subfractions identified 3-hydroxy lauric acid as predominant in one fraction and 3-hydroxy myristic acid as predominant in the other. Synthetic 3-hydroxy lauric acid inhibited HIV infectivity without cytotoxicity, suggesting that this modified fatty acid is likely responsible for observed antiviral activity present in that fraction. As production of 3-hydroxy fatty acids by plants remains controversial, H. perforatum seedlings were grown sterilely and evaluated for presence of 3-hydroxy fatty acids by GC/MS. Small quantities of some 3-hydroxy fatty acids were detected in sterile plants, whereas different 3-hydroxy fatty acids were detected in our chloroform extracts or field-grown material. Conclusion Through bioguided fractionation, we have identified that 3-hydroxy lauric acid found in field grown Hypericum perforatum has anti-HIV activity. This novel anti-HIV activity can be potentially developed into inexpensive therapies, expanding the current arsenal of anti-retroviral agents. PMID:19594941

Portuguese propolis disturbs glycolytic metabolism of human colorectal cancer in vitro

PubMed Central

2013-01-01

Background Propolis is a resin collected by bees from plant buds and exudates, which is further processed through the activity of bee enzymes. Propolis has been shown to possess many biological and pharmacological properties, such as antimicrobial, antioxidant, immunostimulant and antitumor activities. Due to this bioactivity profile, this resin can become an alternative, economic and safe source of natural bioactive compounds. Antitumor action has been reported in vitro and in vivo for propolis extracts or its isolated compounds; however, Portuguese propolis has been little explored. The aim of this work was to evaluate the in vitro antitumor activity of Portuguese propolis on the human colon carcinoma cell line HCT-15, assessing the effect of different fractions (hexane, chloroform and ethanol residual) of a propolis ethanol extract on cell viability, proliferation, metabolism and death. Methods Propolis from Angra do Heroísmo (Azores) was extracted with ethanol and sequentially fractionated in solvents with increasing polarity, n-hexane and chloroform. To assess cell viability, cell proliferation and cell death, Sulforhodamine B, BrDU incorporation assay and Anexin V/Propidium iodide were used, respectively. Glycolytic metabolism was estimated using specific kits. Results All propolis samples exhibited a cytotoxic effect against tumor cells, in a dose- and time-dependent way. Chloroform fraction, the most enriched in phenolic compounds, appears to be the most active, both in terms of inhibition of viability and cell death. Data also show that this cytotoxicity involves disturbance in tumor cell glycolytic metabolism, seen by a decrease in glucose consumption and lactate production. Conclusion Our results show that Portuguese propolis from Angra do Heroísmo (Azores) can be a potential therapeutic agent against human colorectal cancer. PMID:23870175

Neuroprotective effect of Alpinia galanga (L.) fractions on Aβ(25-35) induced amnesia in mice.

PubMed

Hanish Singh, J C; Alagarsamy, V; Diwan, Prakash V; Sathesh Kumar, S; Nisha, J C; Narsimha Reddy, Y

2011-10-31

The rhizomes of Alpinia galanga (L.) Willd (Zingiberaceae), a ginger substitute for flavouring food was traditionally used as nervine tonic and stimulant. This investigation is designed to screen cognitive improvement of Alpinia galanga (AG) fractions in Alzheimer's type of amnesia in mice induced by Aβ((25-35)). Alzheimer's disease induced mice treated with fractions (n-hexane, chloroform and ethyl acetate) of AG in 200 and 400mg/kg. Neurotoxicity was induced by intracerebroventricular injection of Aβ((25-35)) on the 14th day of 21 days drug treatment. Open field and water maze were carried to determine habituation memory and hippocampal memory. Na(+)/K(+)-ATPase, acetylcholinesterase (AChE) and antioxidant enzymes (SOD, GPx, catalase and vitamin C) were determined in brain tissue homogenate to estimate the brain biochemical changes and its anti-amnesic potential with intensity of oxidative stress signaling. Further bioactive (chloroform) fraction was eluted through column chromatography to identify the lead molecules. Increased habituation memory and decreased escape latency in behavioral parameter are the indicative of the cognitive enhancement after treatment with Alpinia galanga fractions. Increment in Na(+)/K(+)-ATPase and antioxidant activity depicts brain membrane integrity improvement and free radical scavenging property. AChE level was decreased to improve the cognition by enhancing cholinergic transmission. Anti-amnesic effect was exerted by various fractions of Alpinia galanga. Among all fractions, preeminent neuroprotection was exerted by chloroform fraction, which has compound, 1'δ-1'-acetoxyeugenol acetate and it may be a potential therapeutic agent for Alzheimer's type of amnesia. These results further motivate us to explore the activity of lead compound's anti-amnesic effect on transgenic mice model of AD. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Determination of triclosan in antiperspirant gels by first-order derivative spectrophotometry.

PubMed

Du, Lina; Li, Miao; Jin, Yiguang

2011-10-01

A first-order derivative UV spectrophotometric method was developed to determine triclosan, a broad-spectrum antimicrobial agent, in health care products containing fragrances which could interfere the determination as impurities. Different extraction methods were compared. Triclosan was extracted with chloroform and diluted with ethanol followed by the derivative spectrophotometric measurement. The interference of fragrances was completely eliminated. The calibration graph was found to be linear in the range of 7.5-45 microg x mL(-1). The method is simple, rapid, sensitive and proper to determine triclosan in fragrance-containing health care products.

Sterculia guttata seeds extractives--an effective mosquito larvicide.

PubMed

Katade, Sushama R; Pawar, Pushpa V; Wakharkar, Radhika D; Deshpande, Nirmala R

2006-08-01

The larvicidal activity of ethanol, chloroform and hexane soxhlet extracts obtained from S. guttata seeds was investigated against the IVth instar larvae of Dengue fever vector, Aedes aegypti and filarial vector, Culex quinquefasciatus. All extracts including fractions of ethanol extract exhibited 100% larval kill within 24 hr exposure period at 500 ppm concentration. Fraction A1 of ethanol was found to be most promising; its LC50 was 21.552 and 35.520 ppm against C. quinquefasciatus and A. aegypti respectively. Naturally occurring S. guttata seed derived fractions merit further study as potential mosquito larval control agents or lead compounds.

Investigating chloroperoxidase-catalyzed formation of chloroform from humic substances using stable chlorine isotope analysis.

PubMed

Breider, Florian; Hunkeler, Daniel

2014-01-01

Chloroperoxidase (CPO) is suspected to play an important role in the biosynthesis of natural chloroform. The aims of the present study are to evaluate the variability of the δ(37)Cl value of naturally produced chloroform and to better understand the reaction steps that control the chlorine isotope signature of chloroform. The isotope analyses have shown that the chlorination of the humic substances (HS) in the presence of high H3O(+) and Cl(-) concentrations induces a large apparent kinetic isotope effect (AKIE = 1.010-1.018) likely associated with the transfer of chlorine between two heavy atoms, whereas in the presence of low H3O(+) and Cl(-) concentrations, the formation of chloroform induces a smaller AKIE (1.005-1.006) likely associated with the formation of an HOCl-ferriprotoporphyrin IX intermediate. As the concentration of H3O(+) and Cl(-) in soils are generally at submillimolar levels, the formation of the HOCl-ferriprotoporphyrin IX intermediate is likely rate-limiting in a terrestrial environment. Given that the δ(37)Cl values of naturally occurring chloride tend to range between -1 and +1‰, the δ(37)Cl value of natural chloroform should vary between -5‰ and -8‰. As the median δ(37)Cl value of industrial chloroform is -3.0‰, the present study suggests that chlorine isotopic composition of chloroform might be used to discriminate industrial and natural sources in the environment.

A microfluidic device for the automated derivatization of free fatty acids to fatty acid methyl esters.

PubMed

Duong, Cindy T; Roper, Michael G

2012-02-21

Free fatty acid (FFA) compositions are examined in feedstock for biodiesel production, as source-specific markers in soil, and because of their role in cellular signaling. However, sample preparation of FFAs for gas chromatography-mass spectrometry (GC-MS) analysis can be time and labor intensive. Therefore, to increase sample preparation throughput, a glass microfluidic device was developed to automate derivatization of FFAs to fatty acid methyl esters (FAMEs). FFAs were delivered to one input of the device and methanolic-HCl was delivered to a second input. FAME products were produced as the reagents traversed a 29 μL reaction channel held at 55 °C. A Design of Experiment protocol was used to determine the combination of derivatization time (T(der)) and ratio of methanolic-HCl:FFA (R(der)) that maximized the derivatization efficiencies of tridecanoic acid and stearic acid to their methyl ester forms. The combination of T(der) = 0.8 min and R(der) = 4.9 that produced optimal derivatization conditions for both FFAs within a 5 min total sample preparation time was determined. This combination of T(der) and R(der) was used to derivatize 12 FFAs with a range of derivatization efficiencies from 18% to 93% with efficiencies of 61% for tridecanoic acid and 84% for stearic acid. As compared to a conventional macroscale derivatization of FFA to FAME, the microfluidic device decreased the volume of methanolic-HCl and FFA by 20- and 1300-fold, respectively. The developed microfluidic device can be used for automated preparation of FAMEs to analyze the FFA compositions of volume-limited samples.

Tandem MS Analysis of Selenamide-Derivatized Peptide Ions

NASA Astrophysics Data System (ADS)

Zhang, Yun; Zhang, Hao; Cui, Weidong; Chen, Hao

2011-09-01

Our previous study showed that selenamide reagents such as ebselen and N-(phenylseleno)phthalimide (NPSP) can be used for selective and rapid derivatization of protein/peptide thiols in high conversion yield. This paper reports the systematic investigation of MS/MS dissociation behaviors of selenamide-derivatized peptide ions upon collision induced dissociation (CID) and electron transfer dissociation (ETD). In the positive ion mode, derivatized peptide ions exhibit tag-dependent CID dissociation pathways. For instance, ebselen-derivatized peptide ions preferentially undergo Se-S bond cleavage upon CID to produce a characteristic fragment ion, the protonated ebselen ( m/z 276), which allows selective identification of thiol peptides from protein digest as well as selective detection of thiol proteins from protein mixture using precursor ion scan (PIS). In contrast, NPSP-derivatized peptide ions retain their phenylselenenyl tags during CID, which is useful in sequencing peptides and locating cysteine residues. In the negative ion CID mode, both types of tags are preferentially lost via the Se-S cleavage, analogous to the S-S bond cleavage during CID of disulfide-containing peptide anions. In consideration of the convenience in preparing selenamide-derivatized peptides and the similarity of Se-S of the tag to the S-S bond, we also examined ETD of the derivatized peptide ions to probe the mechanism for electron-based ion dissociation. Interestingly, facile cleavage of Se-S bond occurs to the peptide ions carrying either protons or alkali metal ions, while backbone cleavage to form c/z ions is severely inhibited. These results are in agreement with the Utah-Washington mechanism proposed for depicting electron-based ion dissociation processes.

Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under Acidic Conditions

EPA Science Inventory

In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and etha...

Development of a compound-specific isotope analysis method for acetone via 2,4-dinitrophenylhydrazine derivatization.

PubMed

Wen, Sheng; Feng, Yanli; Wang, Xinming; Sheng, Guoying; Fu, Jiamo; Bi, Xinhui

2004-01-01

A novel method has been developed for compound-specific isotope analysis for acetone via DNPH (2,4-dinitrophenylhydrazine) derivatization together with combined gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Acetone reagents were used to assess delta13C fractionation during the DNPH derivatization process. Reduplicate delta13C analyses were designed to evaluate the reproducibility of the derivatization, with an average error (1 standard deviation) of 0.17 +/- 0.05 per thousand, and average analytical error of 0.28 +/- 0.09 per thousand. The derivatization process introduces no isotopic fractionation for acetone (the average difference between the predicted and analytical delta13C values was 0.09 +/- 0.20 per thousand, within the precision limits of the GC/C/IRMS measurements), which permits computation of the delta13C values for the original underivatized acetone through a mass balance equation. Together with further studies of the carbon isotopic effect during the atmospheric acetone-sampling procedure, it will be possible to use DNPH derivatization for carbon isotope analysis of atmospheric acetone. Copyright (c) 2004 John Wiley & Sons, Ltd.

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.

Chemical derivatization for enhancing sensitivity during LC/ESI-MS/MS quantification of steroids in biological samples: a review.

PubMed

Higashi, Tatsuya; Ogawa, Shoujiro

2016-09-01

Sensitive and specific methods for the detection, characterization and quantification of endogenous steroids in body fluids or tissues are necessary for the diagnosis, pathological analysis and treatment of many diseases. Recently, liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) has been widely used for these purposes due to its specificity and versatility. However, the ESI efficiency and fragmentation behavior of some steroids are poor, which lead to a low sensitivity. Chemical derivatization is one of the most effective methods to improve the detection characteristics of steroids in ESI-MS/MS. Based on this background, this article reviews the recent advances in chemical derivatization for the trace quantification of steroids in biological samples by LC/ESI-MS/MS. The derivatization in ESI-MS/MS is based on tagging a proton-affinitive or permanently charged moiety on the target steroid. Introduction/formation of a fragmentable moiety suitable for the selected reaction monitoring by the derivatization also enhances the sensitivity. The stable isotope-coded derivatization procedures for the steroid analysis are also described. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physicochemical properties and biological activities of DEAE-derivatized Sphingomonas gellan.

PubMed

Yoo, Sang-Ho; Lee, Kyung Hee; Lee, Ji-Soo; Cha, Jaeho; Park, Cheon Seok; Lee, Hyeon Gyu

2005-08-10

Physicochemical characteristics and biological activities of Sphingomonas gellan (S-gellan) were investigated. The S-gellan weight fractions of Glc and GlcUA were 0.45 and 0.25, respectively, and the molar ratio of Glc:Rha:GlcUA was approximately 4:2:3. The S-gellan was chemically derivatized with diethylaminoethyl chloride-HCl (DEAE-HCl), and the resulting modified S-gellan contained both positive and negative charges. The elemental and IR analyses were conducted to confirm the successful incorporation of DEAE groups into S-gellan. A large increase in nitrogen fraction was observed from the derivatized S-gellan by elemental analysis. The IR absorption bands induced by C-H, C-N, and C-O-C stretching were noticeable at 2950, 1310-1380, and 1000-1150 cm(-1), respectively, resulting from the DEAE substitution. The characteristic CH3 and CH2 peaks originated from the DEAE group were detected in the 1H NMR spectrum of the derivatized S-gellan as well. The solubility of native S-gellan was improved almost twice from 40% to 75% after DEAE derivatization, while water holding capacity (WHC) drastically decreased from 10026% to 245%. Oil binding capacity (OBC) of S-gellan also significantly dropped from 1528% to 331% after the derivatization. The bile acid binding capacity of S-gellan was indirectly determined by measuring the holding capability of cholic acid inside the dialysis membrane (MWCO 12,000-14,000 Da). Once S-gellan was DEAE derivatized, there was substantial increase in the cholic acid retardation index (CRI). Up to 9 h of dialysis, the derivatized S-gellan released 29.3% less of cholic acid compared to the control group that did not contain S-gellan. From these results of the improved water solubility and stronger bile acid binding capacity, it would be suggested that the DEAE-derivatized S-gellan has more advantages than gellan itself for functional food applications.

THE ENHANCEMENT OF CHLOROFORM-INDUCED PLASMA PROTEOLYTIC ACTIVITY BY EPSILON AMINOCAPROIC ACID

PubMed Central

Donaldson, Virginia H.; Ratnoff, Oscar D.

1962-01-01

The proteolytic activity in chloroform-treated plasma euglobulins has been attributed to plasmin. Plasmin can digest both casein and fibrin. Epsilon aminocaproic acid, which inhibits the activation of plasminogen, the precursor of plasmin, by streptokinase, urokinase, and tissue activators enhanced the development of casein hydrolytic activity in a mixture of chloroform and plasma euglobulins. Fibrinolytic activity was also enhanced, but this was evident only if the epsilon aminocaproic acid was removed from the chloroform-treated euglobulins prior to assay. The reasons for the paradoxical enhancement of chloroform-induced casein hydrolysis by euglobulins containing epsilon aminocaproic acid are unclear. However, studies of optimal pH, heat stability, and the effect of ionic strength on the activation of the precursor of this proteolytic enzyme do not differentiate it from plasminogen. PMID:13887179

Theoretical study on the mechanism of the gas-phase elimination kinetics of alkyl chloroformates

NASA Astrophysics Data System (ADS)

Alcázar, Jackson J.; Marquez, Edgar; Mora, José R.; Cordova-Sintjago, Tania; Chuchani, Gabriel

2016-03-01

The theoretical calculations on the mechanism of the homogeneous and unimolecular gas-phase elimination kinetics of alkyl chloroformates- ethyl chloroformate (ECF), isopropyl chloroformate (ICF), and sec-butyl chloroformate (SCF) - have been carried out by using CBS-QB3 level of theory and density functional theory (DFT) functionals CAM-B3LYP, M06, MPW1PW91, and PBE1PBE with the basis sets 6-311++G(d,p) and 6-311++G(2d,2p). The chlorofomate compounds with alkyl ester Cβ-H bond undergo thermal decomposition producing the corresponding olefin, HCl and CO2. These homogeneous eliminations are proposed to undergo two different types of mechanisms: a concerted process, or via the formation of an unstable intermediate chloroformic acid (ClCOOH), which rapidly decomposes to HCl and CO2 gas. Since both elimination mechanisms may occur through a six-membered cyclic transition state structure, it is difficult to elucidate experimentally which is the most reasonable reaction mechanism. Theoretical calculations show that the stepwise mechanism with the formation of the unstable intermediate chloroformic acid from ECF, ICF, and SCF is favoured over one-step elimination. Reasonable agreements were found between theoretical and experimental values at the CAM-B3LYP/6-311++G(d,p) level.

Improved sample preparation of glyphosate and methylphosphonic acid by EPA method 6800A and time-of-flight mass spectrometry using novel solid-phase extraction.

PubMed

Wagner, Rebecca; Wetzel, Stephanie J; Kern, John; Kingston, H M Skip

2012-02-01

The employment of chemical weapons by rogue states and/or terrorist organizations is an ongoing concern in the United States. The quantitative analysis of nerve agents must be rapid and reliable for use in the private and public sectors. Current methods describe a tedious and time-consuming derivatization for gas chromatography-mass spectrometry and liquid chromatography in tandem with mass spectrometry. Two solid-phase extraction (SPE) techniques for the analysis of glyphosate and methylphosphonic acid are described with the utilization of isotopically enriched analytes for quantitation via atmospheric pressure chemical ionization-quadrupole time-of-flight mass spectrometry (APCI-Q-TOF-MS) that does not require derivatization. Solid-phase extraction-isotope dilution mass spectrometry (SPE-IDMS) involves pre-equilibration of a naturally occurring sample with an isotopically enriched standard. The second extraction method, i-Spike, involves loading an isotopically enriched standard onto the SPE column before the naturally occurring sample. The sample and the spike are then co-eluted from the column enabling precise and accurate quantitation via IDMS. The SPE methods in conjunction with IDMS eliminate concerns of incomplete elution, matrix and sorbent effects, and MS drift. For accurate quantitation with IDMS, the isotopic contribution of all atoms in the target molecule must be statistically taken into account. This paper describes two newly developed sample preparation techniques for the analysis of nerve agent surrogates in drinking water as well as statistical probability analysis for proper molecular IDMS. The methods described in this paper demonstrate accurate molecular IDMS using APCI-Q-TOF-MS with limits of quantitation as low as 0.400 mg/kg for glyphosate and 0.031 mg/kg for methylphosphonic acid. Copyright © 2012 John Wiley & Sons, Ltd.

In praise of anesthesia: Two case studies of pain and suffering during major surgical procedures with and without anesthesia in the United States Civil War-1861-65.

PubMed

Albin, Maurice S

2017-12-29

Background The United States Civil War (1861-1865) pitted the more populous industrialized North (Union) against the mainly agricultural slaveholding South (Confederacy). This conflict cost an enormous number of lives, with recent estimates mentioning a total mortality greater than 700,000 combatants [1]. Although sulfuric ether (ETH) and chloroform (CHL) were available since Morton's use of the former in 1846 and the employment of the latter in 1847, and even though inhalational agents were used in Crimean war (1853-1856) and the Mexican-American War (1846-1848), the United States Civil War gave military surgeons on both sides the opportunity to experience the use of these two agents because of the large number of casualties. Methods Research of historic archives illustrates the dramatic control of surgical pain made possible with introduction of two general anesthetic and analgesic drugs in 1846 and 1847. Results An appreciation of the importance of anesthesia during surgical procedures can be noted in the poignant and at times hair raising cases of two left arm amputations carried out under appalling circumstances during the United States Civil War. In the first-case the amputation was delayed for nearly five days after the wounding of Private Winchell who served in an elite sharpshooter brigade and was captured by the Confederate Army during battle. The amputation was performed without anesthesia and the voice of the Private himself narrates his dreadful experience. The postoperative course was incredible as he received no analgesia and survived a delirious comatose state lying on the ground in the intense summer heat. Thomas Jonathan "Stonewall" Jackson was a famous ascetic Confederate General who helped defeat the Union forces at the Battle of Chancellorsville on May 2, 1863. In the ensuing near-darkness, Jackson was fired upon by his own friendly troops where he suffered multiple gunshot wounds on his right hand as well as a ball in the upper humerus of the left arm similar to that of Private Winchell. Transported to a field hospital about thirty miles away, the evacuation was carried out under artillery fire and the General dropped from the stretcher at least twice before arriving at the field hospital. There, a team of surgeons operated on "Stonewall", using open drop chloroform, the surgery taking 50 min, anesthesia times of one hour with General Jackson awake and speaking with clarity shortly after the termination of the anesthesia. A brief explanation of the use of anesthetics in the military environment during the Crimean, Mexican American and the United States Civil War is also presented. Conclusion and implications Two case stories illustrate the profound improvement in surgical pain made possible with ether and chloroform only 160 years ago. Surgeons and patients nowadays have no ideas what these most important improvements in modern medicine means, unless "reliving" the true hell of pain surgery was before ether and chloroform.

Rapid analysis of aflatoxins B1, B2, and ochratoxin A in rice samples using dispersive liquid-liquid microextraction combined with HPLC.

PubMed

Lai, Xian-Wen; Sun, Dai-Li; Ruan, Chun-Qiang; Zhang, He; Liu, Cheng-Lan

2014-01-01

A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface derivatization strategy for combinatorial analysis of cell response to mixtures of protein domains.

PubMed

Chiang, Chunyi; Karuri, Stella W; Kshatriya, Pradnya P; Schwartz, Jeffrey; Schwarzbauer, Jean E; Karuri, Nancy W

2012-01-10

We report a robust strategy for conjugating mixtures of two or more protein domains to nonfouling polyurethane surfaces. In our strategy, the carbamate groups of polyurethane are reacted with zirconium alkoxide from the vapor phase to give a surface-bound oxide that serves as a chemical layer that can be used to bond organics to the polymer substrate. A hydroxyalkylphosphonate monolayer was synthesized on this layer, which was then used to covalently bind primary amine groups in protein domains using chloroformate-derived cross-linking. The effectiveness of this synthesis strategy was gauged by using an ELISA to measure competitive, covalent bonding of cell-binding (III(9-10)) and fibronectin-binding (III(1-2)) domains of the cell adhesion protein fibronectin. Cell adhesion, spreading, and fibronectin matrix assembly were examined on surfaces conjugated with single domains, a 1:1 surface mixture of III(1-2) and III(9-10), and a recombinant protein "duplex" containing both domains in one fusion protein. The mixture performed as well as or better than the other surfaces in these assays. Our surface activation strategy is amenable to a wide range of polymer substrates and free amino group-containing protein fragments. As such, this technique may be used to create biologically specific materials through the immobilization of specific protein groups or mixtures thereof on a substrate surface.

Determination of Carvedilol Enantiomers in Pharmaceutical Dosages by SBSE-HPLC Based on Diastereomer Formation.

PubMed

Taraji, Maryam; Talebpour, Zahra; Adib, Nuoshin; Karimi, Shima; Haghighi, Farideh; Aboul-Enein, Hassan Y

2015-09-01

A sensitive, selective and simple method for the simultaneous determination of carvedilol enantiomers in aqueous solution has been developed using stir bar sorptive extraction (SBSE) followed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. This method is based on the reaction of carvedilol enantiomers with (-)-menthyl chloroformate (MCF) after extraction by the SBSE method to produce diastereomeric derivatives. The separation was achieved by use of a C18 analytical column and the influence of mobile phase composition on the enantioseparation of carvedilol was studied. The applicability of two sorptive phases, poly(methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane, were tested for extraction of carvedilol enantiomers from aqueous samples. The obtained results showed excellent linear dynamic ranges and precisions for each of them. The least limit of detection for (S)- and (R)-carvedilol obtained 8 and 11 µg L(-1), respectively, using the PA-EG sorptive phase. Inter- and intra-mean recoveries were also satisfactory, ranging from 98 to 103%, with coefficient of variation in the range of 1-5% at three fortified levels using a PA-EG coated stir bar. The proposed SBSE (PA-EG)-MCF derivatization-HPLC-UV method was successfully applied to enantioselective analysis of carvedilol in water and pharmaceutical dosages, confirming the application of this method. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Synthesis and photochemical properties of a novel iron-sulfur-nitrosyl cluster derivatized with the pendant chromophore protoporphyrin IX.

PubMed

Conrado, Christa L; Wecksler, Stephen; Egler, Christian; Magde, Douglas; Ford, Peter C

2004-09-06

The novel Roussin red-salt ester (PPIX-RSE) with a pendant porphyrin chromophore was prepared and investigated as a precursor for the photochemical generation of nitric oxide. PPIX-RSE has the general formula Fe(2)(NO)(4)[(mu-S,mu-S')P] (where (S,S')P is the bis(2-thiolatoethyl) diester of protoporphyrin IX. The photoexcitation of PPIX-RSE with 436- or 546-nm light in an aerated chloroform solution led to the photodecomposition of the cluster with the respective quantum yields (5.2 +/- 0.7) x 10(-4) and (2.5 +/- 0.5 x 10(-4)) and the concomitant release of NO. PPIX-RSE is a significantly more effective NO generator at longer wavelength excitation than are other Fe(2)(mu-SR)(2)(NO)(4) esters for which R is a simple alkyl group such as CH(3)CH(2)- because of the much higher absorptivity of the pendant PPIX chromophore at these wavelengths and a modestly higher quantum yield. Fluorescence intensity and lifetime data indicate that the photoexcited porphyrin of PPIX-RSE is largely quenched by the energy transfer to the Fe(2)S(2)(NO)(4) cluster's core. However, a small fraction of this emission is not quenched, and it is proposed that PPIX-RSE may exist in solution as two conformers.

Amino acids implicated in plant defense are higher in Candidatus Liberibacter asiaticus-tolerant citrus varieties

PubMed Central

Killiny, Nabil; Hijaz, Faraj

2016-01-01

ABSTRACT Citrus Huanglongbing (HLB), also known as citrus greening, has been threatening the citrus industry since the early 1900's and up to this date there are no effective cures for this disease. Field observations and greenhouse controlled studies demonstrated that some citrus genotypes are more tolerant to Candidatus Liberibacter asiaticus (CLas) pathogen than others. However, the mechanisms underpinning tolerance has not been determined yet. The phloem sap composition of CLas-tolerant and sensitive citrus varieties was studied to identify metabolites that could be responsible for their tolerance to CLas. The citrus phloem sap was collected by centrifugation and was analyzed with gas chromatography-mass spectrometry after methyl chloroformate derivatization. Thirty-three metabolites were detected in the phloem sap of the studied varieties: twenty 20 amino acids, eight 8 organic acids, and five 5 fatty acids. Interestingly, the levels of most amino acids, especially those implicated in plantdefense to pathogens such as phenylalanine, tyrosine, tryptophan, lysine, and asparagine were higher in tolerant varieties. Although the level of organic acids varied between cultivars, this variation was not correlated with citrus resistance to CLas and could be cultivar specific. The fatty acids were found in trace amounts and in most cases their levels were not significantly different among varieties. Better understanding of the mechanisms underpinning citrus tolerance to CLas will help in developing economically tolerant varieties. PMID:27057814

Amino acids implicated in plant defense are higher in Candidatus Liberibacter asiaticus-tolerant citrus varieties.

PubMed

Killiny, Nabil; Hijaz, Faraj

2016-01-01

Citrus Huanglongbing (HLB), also known as citrus greening, has been threatening the citrus industry since the early 1900's and up to this date there are no effective cures for this disease. Field observations and greenhouse controlled studies demonstrated that some citrus genotypes are more tolerant to Candidatus Liberibacter asiaticus (CLas) pathogen than others. However, the mechanisms underpinning tolerance has not been determined yet. The phloem sap composition of CLas-tolerant and sensitive citrus varieties was studied to identify metabolites that could be responsible for their tolerance to CLas. The citrus phloem sap was collected by centrifugation and was analyzed with gas chromatography-mass spectrometry after methyl chloroformate derivatization. Thirty-three metabolites were detected in the phloem sap of the studied varieties: twenty 20 amino acids, eight 8 organic acids, and five 5 fatty acids. Interestingly, the levels of most amino acids, especially those implicated in plantdefense to pathogens such as phenylalanine, tyrosine, tryptophan, lysine, and asparagine were higher in tolerant varieties. Although the level of organic acids varied between cultivars, this variation was not correlated with citrus resistance to CLas and could be cultivar specific. The fatty acids were found in trace amounts and in most cases their levels were not significantly different among varieties. Better understanding of the mechanisms underpinning citrus tolerance to CLas will help in developing economically tolerant varieties.

Chromatographic finger print analysis of anti-inflammatory active extract fractions of aerial parts of Tribulus terrestris by HPTLC technique.

PubMed

Mohammed, Mona Salih; Alajmi, Mohamed Fahad; Alam, Perwez; Khalid, Hassan Subki; Mahmoud, Abelkhalig Muddathir; Ahmed, Wadah Jamal

2014-03-01

To develop HPTLC fingerprint profile of anti-inflammatory active extract fractions of Tribulus terrestris (family Zygophyllaceae). The anti-inflammatory activity was tested for the methanol and its fractions (chloroform, ethyl acetate, n-butanol and aqueous) and chloroform extract of Tribulus terrestris (aerial parts) by injecting different groups of rats (6 each) with carrageenan in hind paw and measuring the edema volume before and 1, 2 and 3 h after carrageenan injection. Control group received saline i.p. The extracts treatment was injected i.p. in doses of 200 mg/kg 1 h before carrageenan administration. Indomethacin (30 mg/kg) was used as standard. HPTLC studies were carried out using CAMAG HPTLC system equipped with Linomat IV applicator, TLC scanner 3, Reprostar 3, CAMAG ADC 2 and WIN CATS-4 software for the active fractions of chloroform fraction of methanol extract. The methanol extract showed good antiedematous effect with percentage of inhibition more than 72%, indicating its ability to inhibit the inflammatory mediators. The methanol extract was re-dissolved in 100 mL of distilled water and fractionated with chloroform, ethyl acetate and n-butanol. The four fractions (chloroform, ethyl acetate, n-butanol and aqueous) were subjected to anti-inflammatory activity. Chloroform fraction showed good anti-inflammatory activity at dose of 200 mg/kg. Chloroform fraction was then subjected to normal phase silica gel column chromatography and eluted with petroleum ether-chloroform, chloroform-ethyl acetate mixtures of increasing polarity which produced 15 fractions (F1-F15). Only fractions F1, F2, F4, F5, F7, F9, F11 and F14 were found to be active, hence these were analyzed with HPTLC to develop their finger print profile. These fractions showed different spots with different Rf values. The different chloroform fractions F1, F2, F4, F5, F7, F9, F11 and F14 revealed 4, 7, 7, 8, 9, 7, 7 and 6 major spots, respectively. The results obtained in this experiment strongly support and validate the traditional uses of this Sudanese medicinal plant.

Chromatographic finger print analysis of anti-inflammatory active extract fractions of aerial parts of Tribulus terrestris by HPTLC technique

PubMed Central

Mohammed, Mona Salih; Alajmi, Mohamed Fahad; Alam, Perwez; Khalid, Hassan Subki; Mahmoud, Abelkhalig Muddathir; Ahmed, Wadah Jamal

2014-01-01

Objective To develop HPTLC fingerprint profile of anti-inflammatory active extract fractions of Tribulus terrestris (family Zygophyllaceae). Methods The anti-inflammatory activity was tested for the methanol and its fractions (chloroform, ethyl acetate, n-butanol and aqueous) and chloroform extract of Tribulus terrestris (aerial parts) by injecting different groups of rats (6 each) with carrageenan in hind paw and measuring the edema volume before and 1, 2 and 3 h after carrageenan injection. Control group received saline i.p. The extracts treatment was injected i.p. in doses of 200 mg/kg 1 h before carrageenan administration. Indomethacin (30 mg/kg) was used as standard. HPTLC studies were carried out using CAMAG HPTLC system equipped with Linomat IV applicator, TLC scanner 3, Reprostar 3, CAMAG ADC 2 and WIN CATS-4 software for the active fractions of chloroform fraction of methanol extract. Results The methanol extract showed good antiedematous effect with percentage of inhibition more than 72%, indicating its ability to inhibit the inflammatory mediators. The methanol extract was re-dissolved in 100 mL of distilled water and fractionated with chloroform, ethyl acetate and n-butanol. The four fractions (chloroform, ethyl acetate, n-butanol and aqueous) were subjected to anti-inflammatory activity. Chloroform fraction showed good anti-inflammatory activity at dose of 200 mg/kg. Chloroform fraction was then subjected to normal phase silica gel column chromatography and eluted with petroleum ether-chloroform, chloroform-ethyl acetate mixtures of increasing polarity which produced 15 fractions (F1-F15). Only fractions F1, F2, F4, F5, F7, F9, F11 and F14 were found to be active, hence these were analyzed with HPTLC to develop their finger print profile. These fractions showed different spots with different Rf values. Conclusions The different chloroform fractions F1, F2, F4, F5, F7, F9, F11 and F14 revealed 4, 7, 7, 8, 9, 7, 7 and 6 major spots, respectively. The results obtained in this experiment strongly support and validate the traditional uses of this Sudanese medicinal plant. PMID:25182438

A Low-Cost Liquid-Chromatography System Using a Spectronic 20-Based Detector.

ERIC Educational Resources Information Center

Jezorek, John R.; And Others

1986-01-01

Describes the design and evaluation of a Spectronic 20-based detector as well as a simple system for postcolumn derivatization useful for metal-ion chromatographic detection. Both detection and derivatization can be performed in the ultra-violet (UV) mode using a low-cost UV-visible spectrophotometer and UV-region derivatization reagents. (JN)

Matrix effect in matrix-assisted laser desorption/ionization mass spectra of derivatized oligomeric polyols.

PubMed

Borisov, Roman S; Polovkov, Nikolai Yu; Zhilyaev, Dmitry I; Zaikin, Vladimir G

2013-01-30

Herein we describe a strong matrix effect observed in the matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectra of silylated glycerol alkoxylates and manifested in the loss of the silyl groups in the presence of carboxyl-containing matrices. Commercially available glycerol alkoxylates containing three end OH groups as well as three matrices - 2,5-dihydroxybenzoic acid (DHB), 3-indoleacrylic acid (IAA) and 1,8,9-anthracenetriol (dithranol) - were chosen for the investigation. N,O-Bis(trimethylsilyl)trifluoroacetamide containing 1% trimethylchlorosilane, acetic anhydride and a formylation mixture (formic acid/acetyl chloride) were used for derivatization. Initial oligomers and derivatized products were analyzed by MALDI-ToF-mass spectrometry (MS) on an Autoflex II instrument, equipped with a nitrogen laser (λ 337 nm), in positive ion reflectron mode. Only [M + Na](+) ions were observed for underivatized polymers and for completely derivatized polymers in the presence of DHB and dithranol, respectively. In the case of IAA the mass spectra revealed sets of peaks for underivatized, and for partially and completely derivatized oligomers. No similar 'matrix effect' was observed in the case of acylated glycerol alkoxylates (acyl = formyl, acetyl): only peaks for completely derivatized oligomers were obtained in all matrices: DHB, IAA and dithranol. Using 1,9-nonandiol, we showed that the 'matrix effect' was due to trans-silylation of carboxyl-containing matrices (DHB and IAA) during co-crystallization of silylated oligomers and matrices. The obtained results show that matrix molecules can participate as reactive species in MALDI-ToF-MS experiments. The matrix should be carefully chosen when a derivatization approach is applied because the analysis of spectra of the completely derivatized products is particularly desirable in the quantitative determination of functional end-groups. Copyright © 2012 John Wiley & Sons, Ltd.

Analysis of Organic Molecules Extracted from Mars Analogues and Influence of Their Mineralogy Using N-Methyl-N-(tert-butyldimethylsilyl)Trifluoroacetamide Derivatization Coupled with Gas Chromatography Mass Spectrometry in Preparation for the Sample Analysis at Mars Derivatization Experiment on the Mars Science Laboratory Mission

NASA Technical Reports Server (NTRS)

Stalport, F.; Glavin, D. P.; Eigenbrode, J. L.; Bish, D.; Blake, D.; Coll, P.; Szopa, C.; Buch, A.; McAdam, A.; Dworkin, J. P.;

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction for determining acidic herbicides by gas chromatography/mass spectrometry.

PubMed

Wu, Jingming; Lee, Hian Kee

2006-10-15

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction (LPME) for the trace determination of acidic herbicides (2,4-dichlorobenzoic acid, 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, 3,5-dichlorobenzoic acid, 2-(2,4,5-trichlorophenoxy)propionic acid) in aqueous samples by gas chromatography/mass spectrometry (GC/MS) was developed. Prior to GC injection port derivatization, acidic herbicides were converted into their ion-pair complexes with tetrabutylammonium chloride in aqueous samples and then extracted by 1-octanol impregnated in the hollow fiber. Upon injection, ion pairs of acidic herbicides were quantitatively derivatized to their butyl esters in the GC injection port. Thus, several parameters related to the derivatization process (i.e., injection temperature, purge-off time) were evaluated, and main parameters affecting the hollow fiber-protected LPME procedure such as extraction organic solvent, ion-pair reagent type, pH of aqueous medium, concentration of ion-pair reagent, sodium chloride concentration added to the aqueous medium, stirring speed, and extraction time profile, optimized. At the selected extraction and derivatization conditions, no matrix effects were observed. This method proved good repeatability (RSDs <12.3%, n = 6) and good linearity (r2 > or = 0.9939) for spiked deionized water samples for five analytes. The limits of detection were in the range of 0.51-13.7 ng x L(-1) (S/N =3) under GC/MS selected ion monitoring mode. The results demonstrated that injection port derivatization following ion-pair hollow fiber-protected LPME was a simple, rapid, and accurate method for the determination of trace acidic herbicides from aqueous samples. In addition, this method proved to be environmentally friendly since it completely avoided open derivatization with potentially hazardous reagents.

USE OF BIOLOGICALLY BASED COMPUTATIONAL MODELING IN MODE OF ACTION-BASED RISK ASSESSMENT – AN EXAMPLE OF CHLOROFORM

EPA Science Inventory

The objective of current work is to develop a new cancer dose-response assessment for chloroform using a physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model. The PBPK/PD model is based on a mode of action in which the cytolethality of chloroform occurs when the ...

Magnetoliposomes Loaded with Poly-Unsaturated Fatty Acids as Novel Theranostic Anti-Inflammatory Formulations

PubMed Central

Calle, Daniel; Negri, Viviana; Ballesteros, Paloma; Cerdán, Sebastián

2015-01-01

We describe the preparation, physico-chemical characterization and anti-inflammatory properties of liposomes containing the superparamagnetic nanoparticle Nanotex, the fluorescent dye Rhodamine-100 and omega-3 polyunsaturated fatty acid ethyl ester (ω-3 PUFA-EE), as theranostic anti-inflammatory agents. Liposomes were prepared after drying chloroform suspensions of egg phosphatidylcholine, hydration of the lipid film with aqueous phases containing or not Nanotex, Rhodamine-100 dye or ω-3 PUFA-EE, and eleven extrusion steps through nanometric membrane filters. This resulted in uniform preparations of liposomes of approximately 200 nm diameter. Extraliposomal contents were removed from the preparation by gel filtration chromatography. High Resolution Magic Angle Spinning 1H NMR Spectroscopy of the liposomal preparations containing ω-3 PUFA-EE revealed well resolved 1H resonances from highly mobile ω-3 PUFA-EE, suggesting the formation of very small (ca. 10 nm) ω-3 PUFA-EE nanogoticules, tumbling fast in the NMR timescale. Chloroform extraction of the liposomal preparations revealed additionally the incorporation of ω-3 PUFA-EE within the membrane domain. Water diffusion weighted spectra, indicated that the goticules of ω-3 PUFA-EE or its insertion in the membrane did not affect the average translational diffusion coefficient of water, suggesting an intraliposomal localization, that was confirmed by ultrafiltration. The therapeutic efficacy of these preparations was tested in two different models of inflammatory disease as inflammatory colitis or the inflammatory component associated to glioma development. Results indicate that the magnetoliposomes loaded with ω-3 PUFA-EE allowed MRI visualization in vivo and improved the outcome of inflammatory disease in both animal models, decreasing significantly colonic inflammation and delaying, or even reversing, glioma development. Together, our results indicate that magnetoliposomes loaded with ω-3 PUFA-EE may become useful anti-inflammatory agents for image guided drug delivery. PMID:25767616

Phytochemical analysis of Andrographis paniculata and Orthosiphon stamineus leaf extracts for their antibacterial and antioxidant potential.

PubMed

Malahubban, M; Alimon, A R; Sazili, A Q; Fakurazi, S; Zakry, F A

2013-09-01

Leaves of Andrographis paniculata and Orthosiphon stamineus were extracted with water, ethanol, methanol and chloroform to assess their potential as antibacterial and antioxidant agents. High performance liquid chromatography analysis showed that the methanolic extracts of A. paniculata and O. stamineus leaves gave the highest amounts of andrographolide and rosmarinic acid, respectively. These leaf extracts exhibited antimicrobial and antioxidant activities and, at the highest concentration tested (200 mg/mL), showed greater inhibitory effects against the Gram positive bacteria Bacillus cereus and Staphylococcus aureus than 10% acetic acid. Andrographis paniculata and O. stamineus methanolic and ethanolic leaf extracts also showed the strongest antioxidant activity as compared with the other extracts tested. The bioactive compounds present in these leaf extracts have the potential to be developed into natural antibacterial and antioxidant agents that may have applications in animal and human health.

Selective chloroform sensor using thiol functionalized reduced graphene oxide at room temperature

NASA Astrophysics Data System (ADS)

Midya, Anupam; Mukherjee, Subhrajit; Roy, Shreyasee; Santra, Sumita; Manna, Nilotpal; Ray, Samit K.

2018-02-01

This paper presents a highly selective chloroform sensor using functionalised reduced graphene oxide (RGO) as a sensing layer. Thiol group is covalently attached on the basal plan of RGO film by a simple one-step aryl diazonium chemistry to improve its selectivity. Several spectroscopic techniques like X-ray photoelectron, Raman and Fourier transform infrared spectroscopy confirm successful thiol functionalization of RGO. Finally, the fabricated chemiresistor type sensor is exposed to chloroform in the concentration range 200-800 ppm (parts per million). The sensor shows a 4.3% of response towards 800 ppm chloroform. The selectivity of the sensor is analyzed using various volatile organic compounds as well. The devices show enhanced response and faster recovery attributed to the physiosorption of chloroform onto thiol functionalized graphene making them attractive for 2D materials based sensing applications.

Bioactive plants from Argentina and Bolivia.

PubMed

Bardón, Alicia; Borkosky, Susana; Ybarra, María I; Montanaro, Susana; Cartagena, Elena

2007-04-01

Antibacterial and molluscicidal activities of methanol and chloroform extracts of 16 plant species belonging to the families Compositae and Melastomataceae were evaluated. The chloroform extract of Vernonanthura tweediana and the methanol extract of Senecio santelisis resulted to be very toxic to brine shrimp nauplii (LC(50)=1 microg/ml). Chloroform extracts of S. santelisis and Senecio leucostachys as well as the methanol extract of Wedelia subvaginata displayed molluscicidal effects on Biomphalaria peregrina showing LC(100)<100 microg/ml. Moderate antibacterial action was produced by the chloroform extracts of Flaveria bidentis, Grindelia scorzonerifolia and Vernonia incana against two strains of Staphylococcus aureus.

Self-Diffusion and Heteroassociation in an Acetone-Chloroform Mixture at 298 K

NASA Astrophysics Data System (ADS)

Golubev, V. A.; Gurina, D. L.; Kumeev, R. S.

2018-01-01

The self-diffusion coefficients of acetone and chloroform in a binary acetone-chloroform mixture at 298 K are determined via pulsed field gradient NMR spectroscopy. It is estimated that the hydrodynamic radii of the mixture's components, calculated using the Stokes-Einstein equation, grow as the concentrations of the components fall. It is shown that such behavior of hydrodynamic radii is due to acetone-chloroform heteroassociation. The hydrodynamic radii of monomers and heteroassociates in a 1: 1 ratio are determined along with the constant of heteroassociation, using the proposed model of an associated solution.

Separation of thiol and cyanide hydrolysis products of chemical warfare agents by capillary electrophoresis.

PubMed

Copper, Christine L; Collins, Greg E

2004-03-01

The fluorescence derivatizing agent, o-phthalaldehyde (OPA), has been applied to the separation and detection of cyanide and several structurally similar thiols by capillary electrophoresis (CE)-laser induced fluorescence (LIF). Of particular interest to this investigation was the separation of 2-dimethylaminoethanethiol, 2-diethylaminoethanethiol, and cyanide, each of which are hydrolysis products or hydrolysis product simulants of the chemical warfare (CW) agents O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX), O-isobutyl S-2-diethylaminoethyl methylphosphonothiolate (R-VX), and tabun (GA). Other structurally similar thiols simultaneously resolved by this method include 1-pentanethiol and 2-mercaptoethanol. Instrumental parameters were probed and optimum values for capillary length (50 cm) and inner diameter (75 microm), injection time (30 s) and field strength (15 kV) were determined. Sample stacking methods enabled detection limits of 9.3 microg/L for cyanide, 1.8 microg/L for 2-diethylaminoethanethiol, 35 microg/L for 2-dimethylaminoethanethiol, 15 microg/L for 2-mercaptoethanol, and 89 microg/L for 1-pentanethiol. The linearity of the method was verified over an order of magnitude and the reproducibility was found to be 3.0%.

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.

Chloroformate derivatization for tracing the fate of Amino acids in cells and tissues by multiple stable isotope resolved metabolomics (mSIRM).

PubMed

Yang, Ye; Fan, Teresa W-M; Lane, Andrew N; Higashi, Richard M

2017-07-11

Amino acids have crucial roles in central metabolism, both anabolic and catabolic. To elucidate these roles, steady-state concentrations of amino acids alone are insufficient, as each amino acid participates in multiple pathways and functions in a complex network, which can also be compartmentalized. Stable Isotope-Resolved Metabolomics (SIRM) is an approach that uses atom-resolved tracking of metabolites through biochemical transformations in cells, tissues, or whole organisms. Using different elemental stable isotopes to label multiple metabolite precursors makes it possible to resolve simultaneously the utilization of these precursors in a single experiment. Conversely, a single precursor labeled with two (or more) different elemental isotopes can trace the allocation of e.g. C and N atoms through the network. Such dual-label experiments however challenge the resolution of conventional mass spectrometers, which must distinguish the neutron mass differences among different elemental isotopes. This requires ultrahigh resolution Fourier transform mass spectrometry (UHR-FTMS). When combined with direct infusion nano-electrospray ion source (nano-ESI), UHR-FTMS can provide rapid, global, and quantitative analysis of all possible mass isotopologues of metabolites. Unfortunately, very low mass polar metabolites such as amino acids can be difficult to analyze by current models of UHR-FTMS, plus the high salt content present in typical cell or tissue polar extracts may cause unacceptable ion suppression for sources such as nano-ESI. Here we describe a modified method of ethyl chloroformate (ECF) derivatization of amino acids to enable rapid quantitative analysis of stable isotope labeled amino acids using nano-ESI UHR-FTMS. This method showed excellent linearity with quantifiable limits in the low nanomolar range represented in microgram quantities of biological specimens, which results in extracts with total analyte abundances in the low to sub-femtomole range. We have applied this method to profile amino acids and their labeling patterns in 13 C and 2 H doubly labeled PC9 cell extracts, cancerous and non-cancerous tissue extracts from a lung cancer patient and their protein hydrolysates as well as plasma extracts from mice fed with a liquid diet containing 13 C 6 -glucose (Glc). The multi-element isotopologue distributions provided key insights into amino acid metabolism and intracellular pools in human lung cancer tissues in high detail. The 13 C labeling of Asp and Glu revealed de novo synthesis of these amino acids from 13 C 6 -Glc via the Krebs cycle, specifically the elevated level of 13 C 3 -labeled Asp and Glu in cancerous versus non-cancerous lung tissues was consistent with enhanced pyruvate carboxylation. In addition, tracking the fate of double tracers, ( 13 C 6 -Glc +  2 H 2 -Gly or 13 C 6 -Glc +  2 H 3 -Ser) in PC9 cells clearly resolved pools of Ser and Gly synthesized de novo from 13 C 6 -Glc ( 13 C 3 -Ser and 13 C 2 -Gly) versus Ser and Gly derived from external sources ( 2 H 3 -Ser, 2 H 2 -Gly). Moreover the complex 2 H labeling patterns of the latter were results of Ser and Gly exchange through active Ser-Gly one-carbon metabolic pathway in PC9 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

USE OF SENSITIVITY ANALYSIS ON A PHYSIOLOGICALLY-BASED PHARMACOKINETIC (PBPK) MODEL FOR CHLOROFORM IN RATS TO DETERMINE AGE-RELATED TOXICITY

EPA Science Inventory

USE OF SENSITIVITY ANALYSIS ON A PHYSIOLOGICALLY BASED PHARMACOKINETIC (PBPK) MODEL FOR CHLOROFORM IN RATS TO DETERMINE AGE-RELATED TOXICITY.
CR Eklund, MV Evans, and JE Simmons. US EPA, ORD, NHEERL, ETD,PKB, Research Triangle Park, NC.

Chloroform (CHCl3) is a disinfec...

Immunotoxicological Profile of Chloroform in Female B6c3f1 Mice When Administered In Drinking Water

EPA Science Inventory

Chloroform can be formed as a disinfection by-product during water chlorination, one of the primary modalities for purifying municipal water supplies for human consumption. The goal of this study was to characterize the immunotoxic effects of chloroform in female B6C3F1 mice when...

Preserving ground water samples with hydrochloric acid does not result in the formation of chloroform

USGS Publications Warehouse

Squillace, Paul J.; Pankow, James F.; Barbash, Jack E.; Price, Curtis V.; Zogorski, John S.

1999-01-01

Water samples collected for the determination of volatile organic compounds (VOCs) are often preserved with hydrochloric acid (HCl) to inhibit the biotransformation of the analytes of interest until the chemical analyses can he performed. However, it is theoretically possible that residual free chlorine in the HCl can react with dissolved organic carbon (DOC) to form chloroform via the haloform reaction. Analyses of 1501 ground water samples preserved with HCl from the U.S. Geological Survey's National Water-Quality Assessment Program indicate that chloroform was the most commonly detected VOC among 60 VOCs monitored. The DOC concentrations were not significantly larger in samples with detectable chloroform than in those with no delectable chloroform, nor was there any correlation between the concentrations of chloroform and DOC. Furthermore, chloroform was detected more frequently in shallow ground water in urban areas (28.5% of the wells sampled) than in agricultural areas (1.6% of the wells sampled), which indicates that its detection was more related to urban land-use activities than to sample acidification. These data provide strong evidence that acidification with HCl does not lead to the production of significant amounts of chloroform in ground water samples. To verify these results, an acidification study was designed to measure the concentrations of all trihalomethanes (THMs) that can form as a result of HCl preservation in ground water samples and to determine if ascorbic acid (C6H8O6) could inhibit this reaction if it did occur. This study showed that no THMs were formed as a result of HCl acidification, and that ascorbic acid had no discernible effect on the concentrations of THMs measured.

Infectious bursal disease in New Brunswick.

PubMed

Ide, P R; Stevenson, R G

1973-10-01

A flock of four week old chickens experienced a disease of sudden onset in which the only symptoms were those of depression shortly before death, and in which the predominant histological lesion was necrosis of lymphocytes in the bursa of Fabricius.A virus, designated strain Sk-1, was isolated from pooled bursal tissue of affected birds and was serologically identified as a strain of the infectious bursal agent. This virus was chloroform resistant, did not hemagglutinate guinea pig or chicken erythrocytes and did not produce a cytopathic effect in chick embryo tissue cultures. Equivocal results were obtained in filtration studies but the agent was less than 100nm in diameter. Four week old chicks inoculated with strain Sk-1 developed microscopic lesions in the bursa of Fabricius which were similar to those seen in the original field specimens. Inoculated chick embryos exhibited characteristic macroscopic lesions and necrosis of vascular tissue was a common histological change.A limited serological survey of local poultry flocks indicated that infection by this agent had occurred in four of the ten flocks examined.

Easy and Fast Method for the Determination of Biogenic Amines in Fish and Fish Products with Liquid Chromatography Coupled to Orbitrap Tandem Mass Spectrometry.

PubMed

Kaufmann, Anton; Maden, Kathryn

2018-03-01

A quantitative method for the determination of biogenic amines was developed. The method is characterized by the virtual absence of sample cleanup and does not require a derivatization reaction. Diluted extracts are centrifuged, filtrated, and directly injected into an ultra-HPLC column, which is coupled to a single-stage high-resolution mass spectrometer (Orbitrap). The chromatography is based on a reversed-phase column and an eluent containing an ion-pairing agent (heptafluorobutyric acid). The high sensitivity of the instrument permits the injection of very diluted extracts, which ensures stable retention times and the virtual absence of signal suppression effects. In addition, the quantification of histamine (a regulated compound) is further aided by the use of an isotopically labeled internal standard. The method was validated for three fish-based matrixes. Both the sample processing and the analytical measurement are very fast; hence, the methodology is ideal for high-throughput work. In addition, the method is significantly more selective than conventional methods (i.e., derivatization followed by LC with UV/fluorescence (FL) detection) for biogenic amines. A comparison showed that LC-UV/FL methods can produce false-positive findings due to coeluting matrix compounds.

A macrocyclic polyamine as an anion receptor in the capillary electrochromatographic separation of carbohydrates.

PubMed

Liu, Chuen-Ying; Chen, Tse-Hsien; Misra, Tarun Kumar

2007-06-22

An analytical approach of the 32-membered macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N8) was described for the capillary electrochromatographic (CEC) separation of derivatized mono- and disaccharides. The column displayed reversal electroosmotic flow (EOF) at pH below 7.0, while a cathodic EOF was shown at pH above 7.0. The reductive amination of saccharides was carried out with p-aminobenzoic acid. Some parameters that affect the CEC separations were investigated. Several competitive ligands, such as Tris, EDTA and phosphate were also examined for the effect on the performance. We achieved a complete separation of all compounds as well as the excess derivatizing agent by using borate buffer (pH 9.0) in a mode of concentration gradient (60 mM inlet side and 70 mM outlet side). The relative standard deviation of the retention time measured for each sample was less than 4% in six continuous runs, suggesting that the bonded phase along with the gradient formed inside the column was quite stable. With the mixing modes of anion coordination, anion exchange, and shape discrimination, the interaction adequately accomplishes the separation of carbohydrates which are epimers or have different glycosidic linkage, although the electrophoretic migration is also involved in the separation mechanism.

Analysis of Reaction between α-Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of α-Lipoic Acid.

PubMed

Godlewska, Magdalena; Odachowska, Angelika; Turkowicz, Monika; Karpinska, Joanna

2015-01-01

The present study offers results of analysis concerning the course of reaction between reduced α-lipoic acid (LA) and 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT). In water environments, the reaction between CMQT and hydrophilic thiols proceeds very rapidly and the resultant products are stable. For the described analysis, optimum reaction conditions, such as concentration of the reducing agent, environment pH, and concentration of the reagent were carefully selected. The spectrophotometric assay was carried out measuring absorbance at λ = 348 nm (i.e., the spectral band of the obtained reaction product). Furthermore, the calibration curve of lipoic acid was registered. It was concluded that the Lambert-Beer law was observed within the range 1-10 μmol L(-1). Later, the reaction between LA and CMQT was used as precolumn derivatization in a chromatographic determination of the lipoic acid in the range 2.5-50 μmol L(-1). Practical applicability of the designed methods was evaluated by determining lipoic acid in Revitanerv pharmaceutical preparation which contains 300 mg LA in a single capsule. The error of the determination did not exceed 0.5% in relation to the declared value.

Analysis of Reaction between α-Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of α-Lipoic Acid

PubMed Central

Godlewska, Magdalena; Odachowska, Angelika; Turkowicz, Monika; Karpinska, Joanna

2015-01-01

The present study offers results of analysis concerning the course of reaction between reduced α-lipoic acid (LA) and 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT). In water environments, the reaction between CMQT and hydrophilic thiols proceeds very rapidly and the resultant products are stable. For the described analysis, optimum reaction conditions, such as concentration of the reducing agent, environment pH, and concentration of the reagent were carefully selected. The spectrophotometric assay was carried out measuring absorbance at λ = 348 nm (i.e., the spectral band of the obtained reaction product). Furthermore, the calibration curve of lipoic acid was registered. It was concluded that the Lambert-Beer law was observed within the range 1–10 μmol L−1. Later, the reaction between LA and CMQT was used as precolumn derivatization in a chromatographic determination of the lipoic acid in the range 2.5–50 μmol L−1. Practical applicability of the designed methods was evaluated by determining lipoic acid in Revitanerv pharmaceutical preparation which contains 300 mg LA in a single capsule. The error of the determination did not exceed 0.5% in relation to the declared value. PMID:26504616

Hydrazide and hydrazine reagents as reactive matrices for MALDI-MS to detect gaseous aldehydes.

PubMed

Shigeri, Yasushi; Ikeda, Shinya; Yasuda, Akikazu; Ando, Masanori; Sato, Hiroaki; Kinumi, Tomoya

2014-08-01

The reagents 19 hydrazide and 14 hydrazine were examined to function as reactive matrices for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to detect gaseous aldehydes. Among them, two hydrazide (2-hydroxybenzohydrazide and 3-hydroxy-2-naphthoic acid hydrazide) and two hydrazine reagents [2-hydrazinoquinoline and 2,4-dinitrophenylhydrazine (DNPH)] were found to react efficiently with carbonyl groups of gaseous aldehydes (formaldehyde, acetaldehyde and propionaldehyde); these are the main factors for sick building syndrome and operate as reactive matrices for MALDI-MS. Results from accurate mass measurements by JMS-S3000 Spiral-TOF suggested that protonated ion peaks corresponding to [M + H](+) from the resulting derivatives were observed in all cases with the gaseous aldehydes in an incubation, time-dependent manner. The two hydrazide and two hydrazine reagents all possessed absorbances at 337 nm (wavelength of MALDI nitrogen laser), with, significant electrical conductivity of the matrix crystal and functional groups, such as hydroxy group and amino group, being important for desorption/ionization efficiency in MALDI-MS. To our knowledge, this is the first report that gaseous molecules could be derivatized and detected directly in a single step by MALDI-MS using novel reactive matrices that were derivatizing agents with the ability to enhance desorption/ionization efficiency. Copyright © 2014 John Wiley & Sons, Ltd.

Theodore Roosevelt Chloroforming Uncle Sam "In the Hopeless Ward".

PubMed

Drew, Benjamin A; Bause, George S

2016-10-01

In March of 1905 in Judge magazine, Louis Dalrymple published his political cartoon of Theodore Roosevelt chloroforming "Uncle Sam." Having sampled a host of Democratic remedies, the 125-year-old Sam can expect that Roosevelt's chloroform will either cure him with major Republican surgery or kill him with Osler-linked euthanasia. Copyright © 2016 Elsevier Inc. All rights reserved.

THE FAILURE OF CHLOROFORM ADMINISTERED IN THE DRINKING WATER TO INDUCE RENAL TUBULAR CELL NEOPLASIA IN MALE F344/N RATS

EPA Science Inventory

The failure of chloroform administered in drinking water to induce renal tubular cell neoplasia in male F344/N rats

Chloroform (TCM) has been demonstrated to be a renal carcinogen in the male Osborne-
Mendel rat when administered either by corn oil gavage or in drin...

Kinetic Studies that Evaluate the Solvolytic Mechanisms of Allyl and Vinyl Chloroformate Esters

PubMed Central

D’Souza, Malcolm J.; Givens, Aaron F.; Lorchak, Peter A.; Greenwood, Abigail E.; Gottschall, Stacey L.; Carter, Shannon E.; Kevill, Dennis N.

2013-01-01

At 25.0 °C the specific rates of solvolysis for allyl and vinyl chloroformates have been determined in a wide mix of pure and aqueous organic mixtures. In all the solvents studied, vinyl chloroformate was found to react significantly faster than allyl chloroformate. Multiple correlation analyses of these rates are completed using the extended (two-term) Grunwald-Winstein equation with incorporation of literature values for solvent nucleophilicity (NT) and solvent ionizing power (YCl). Both substrates were found to solvolyze by similar dual bimolecular carbonyl-addition and unimolecular ionization channels, each heavily dependent upon the solvents nucleophilicity and ionizing ability. PMID:23549265

A RP-LC method with evaporative light scattering detection for the assay of simethicone in pharmaceutical formulations.

PubMed

Moore, Douglas E; Liu, Tina X; Miao, William G; Edwards, Alison; Elliss, Russell

2002-09-05

A reversed-phase liquid chromatographic method has been developed and validated for the determination of the polydimethylsiloxane (PDMS) component of Simethicone, which is used as an anti-foaming agent in pharmaceutical formulations. The method involves acidification to neutralise antacid components of the formulation, then a single extraction of the PDMS with dichloromethane. This is followed by separation with a reversed-phase column using an acetonitrile-chloroform solvent gradient, and quantification by an evaporative light scattering detector. An assay precision of 3% was achieved in intraday and interday determinations. No interference was found from the aluminium and magnesium hydroxide components of antacid formulations.

Smooth muscle relaxing flavonoids and terpenoids from Conyza filaginoides.

PubMed

Mata, R; Rojas, A; Acevedo, L; Estrada, S; Calzada, F; Rojas, I; Bye, R; Linares, E

1997-02-01

Activity-guided fractionation of the smooth muscle relaxing, chloroform-methanol (1:1) extract of Conyza filaginoides (D.C.) Hieron (Asteraceae) led to the isolation of three flavonoids (quercetin 3-glucoside, rutin, and pinostrobin), one sterol (alpha-spinasterol), a sesquiterpenoid (beta-caryophyllene 4,5-alpha-oxide), and two triterpenoids (erythrodiol and 3-beta-tridecanoyloxy-28-hydroxyolean-12-ene). 3-beta-Tridecanoyloxy-28-hydroxy-olean-12-ene is a new naturally occurring terpenoid. All the isolated compounds induced a concentration-dependent inhibition of the spontaneous contractions of rat ileum. The spasmolytic activity exhibited by the extract and active principles tends to support the traditional use of C filaginoides as an antispasmodic agent.

Simultaneous Solid Phase Extraction and Derivatization of Aliphatic Primary Amines Prior to Separation and UV-Absorbance Detection

PubMed Central

Felhofer, Jessica L.; Scida, Karen; Penick, Mark; Willis, Peter A.; Garcia, Carlos D.

2013-01-01

To overcome the problem of poor sensitivity of capillary electrophoresis-UV absorbance for the detection of aliphatic amines, a solid phase extraction and derivatization scheme was developed. This work demonstrates successful coupling of amines to a chromophore immobilized on a solid phase and subsequent cleavage and analysis. Although the analysis of many types of amines is relevant for myriad applications, this paper focuses on the derivatization and separation of amines with environmental relevance. This work aims to provide the foundations for future developments of an integrated sample preparation microreactor capable of performing simultaneous derivatization, preconcentration, and sample cleanup for sensitive analysis of primary amines. PMID:24054648

Applications of derivatization reactions to trace organic compounds during sample preparation based on pressurized liquid extraction.

PubMed

Carro, Antonia M; González, Paula; Lorenzo, Rosa A

2013-06-28

Pressurized liquid extraction (PLE) is an exhaustive technique used for the extraction of analytes from solid samples. Temperature, pressure, solvent type and volume, and the addition of other reagents notably influence the efficiency of the extraction. The analytical applications of this technique can be improved by coupling with appropriate derivatization reactions. The aim of this review is to discuss the recent applications of the sequential combination of PLE with derivatization and the approaches that involve simultaneous extraction and in situ derivatization. The potential of the latest developments to the trace analysis of environmental, food and biological samples is also analyzed. Copyright © 2013 Elsevier B.V. All rights reserved.

Selective determination of arginine-containing and tyrosine-containing peptides using capillary electrophoresis and laser-induced fluorescence detection.

PubMed

Cobb, K A; Novotny, M V

1992-01-01

The use of two different amino acid-selective fluorogenic reagents for the derivatization of peptides is investigated. One such scheme utilizes a selective reaction of benzoin with the guanidine moiety to derivatize arginine residues occurring in a peptide. The second scheme involves the formylation of tyrosine, followed by reaction with 4-methoxy-1,2-phenylenediamine. The use of capillary electrophoresis and laser-induced fluorescence detection allows enhanced efficiencies and sensitivities to be obtained for the separations of either arginine- or tyrosine-containing peptides. A helium-cadmium laser (325 nm) is ideally suited for the laser-based detection system due to a close match of the excitation maxima of derivatized peptides from both reactions. A detection limit of 270 amol is achieved for model arginine-containing peptides, while the detection limit for model tyrosine-containing peptides is measured at 390 amol. Both derivatization reactions are found to be useful for high-sensitivity peptide mapping applications in which only the peptides containing the derivatized amino acids are detected.

15N and13C NMR investigation of hydroxylamine-derivatized humic substances

USGS Publications Warehouse

Thorn, K.A.; Arterburn, J.B.; Mikita, M.A.

1992-01-01

Five fulvic and humic acid samples of diverse origins were derivatized with 15N-labeled hydroxylamine and analyzed by liquid-phase 15N NMR spectrometry. The 15N NMR spectra indicated that hydroxylamine reacted similarly with all samples and could discriminate among carbonyl functional groups. Oximes were the major derivatives; resonances attributable to hydroxamic acids, the reaction products of hydroxylamine with esters, and resonances attributable to the tautomeric equilibrium position between the nitrosophenol and monoxime derivatives of quinones, the first direct spectroscopic evidence for quinones, also were evident. The 15N NMR spectra also suggested the presence of nitriles, oxazoles, oxazolines, isocyanides, amides, and lactams, which may all be explained in terms of Beckmann reactions of the initial oxime derivatives. INEPT and ACOUSTIC 15N NMR spectra provided complementary information on the derivatized samples. 13C NMR spectra of derivatized samples indicated that the ketone/quinone functionality is incompletely derivatized with hydroxylamine. ?? 1991 American Chemical Society.

Separation-oriented derivatization of native fluorescent compounds through fluorous labeling followed by liquid chromatography with fluorous-phase.

PubMed

Sakaguchi, Yohei; Yoshida, Hideyuki; Todoroki, Kenichiro; Nohta, Hitoshi; Yamaguchi, Masatoshi

2009-06-15

We have developed a new and simple method based on "fluorous derivatization" for LC of native fluorescent compounds. This method involves the use of a column with a fluorous stationary phase. Native fluorescent analytes with target functional groups are precolumn derivatized with a nonfluorescent fluorous tag, and the fluorous-labeled analytes are retained in the column, whereas underivatized substances are not. Only the retained fluorescent analytes are detected fluorometrically at appropriate retention times, and retained substrates without fluorophores are not detected. In this study, biologically important carboxylic acids (homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid) and drugs (naproxen, felbinac, flurbiprofen, and etodolac) were used as model native fluorescent compounds. Experimental results indicate that the fluorous-phase column can selectively retain fluorous compounds including fluorous-labeled analytes on the basis of fluorous separation. We believe that separation-oriented derivatization presented here is the first step toward the introduction of fluorous derivatization in quantitative LC analysis.

Quantitative extraction and concentration of synthetic water-soluble acid dyes from aqueous media using a quinine-chloroform solution

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

Kobayashi, F.; Ozawa, N.; Hanai, J.

Twenty-one water-soluble acid dyes, including eleven azo, five triphenylmethane four xanthene, one naphthol derivatives, used at practical concentrations for food coloration, were quantitatively extracted from water and various carbonated beverages into a 0.1 M quinine-chloroform solution in the presence of 0.5 M boric acid by brief shaking. Quantitative extraction of these dyes was also accomplished by the 0.1 M quinine-chloroform solution made conveniently from chloroform, quinine hydrochloride, and sodium hydroxide added successively to water or beverages containing boric acid. Quinine acted as a countercation on the dyes having sulfonic and/or carboxylic acid group(s) to form chloroform-soluble ion-pair complexes. The diacidicmore » base alkaloid interacted with each acid group of mono-, di-, tri-, and tetrasulfonic acid dyes approximately in the ratio 0.8-0.9 to 1. The dyes in the chloroform solution were quantitatively concentrated into a small volume of sodium hydroxide solution also by brief shaking. The convenient quinine-chloroform method was applicable to the quantitative extraction of a mixture of 12 dyes from carbonated beverages, which are all currently used for food coloration. A high-pressure liquid chromatographic method is also presented for the systematic separation and determination of these 12 dyes following their concentration into the aqueous alkaline solution. The chromatogram was monitored by double-wavelength absorptiometry in the visible and ultraviolet ray regions.« less

Ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma.

PubMed

Xu, Xu; Su, Rui; Zhao, Xin; Liu, Zhuang; Zhang, Yupu; Li, Dan; Li, Xueyuan; Zhang, Hanqi; Wang, Ziming

2011-11-30

The ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0-110.8, 95.4-106.3, 95.0-108.3, and 95.7-107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n=5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination of SAs in liquid samples. Copyright © 2011 Elsevier B.V. All rights reserved.

The Influence of Mineralogy on Recovering Organic Acids from Mars Analogue Materials Using the One-Pot Derivatization Experiment on the Sample Analysis at Mars(SAM) Instrument Suite

NASA Technical Reports Server (NTRS)

Stalport, Fabien; Glavin, Daniel P.; Eigenbrode, J. L.; Bish, D.; Blake, D.; Coll, P.; Szopa, C.; Buch, A.; McAdam, A.; Dworkin, J. P.;

Microwave-assisted on-spot derivatization for gas chromatography-mass spectrometry based determination of polar low molecular weight compounds in dried blood spots.

PubMed

Sadones, Nele; Van Bever, Elien; Archer, John R H; Wood, David M; Dargan, Paul I; Van Bortel, Luc; Lambert, Willy E; Stove, Christophe P

2016-09-23

Dried blood spot (DBS) sampling and analysis is increasingly being applied in bioanalysis. Although the use of DBS has many advantages, it is also associated with some challenges. E.g. given the limited amount of available material, highly sensitive detection techniques are often required to attain sufficient sensitivity. In gas chromatography coupled to mass spectrometry (GC-MS), derivatization can be helpful to achieve adequate sensitivity. Because this additional sample preparation step is considered as time-consuming, we introduce a new derivatization procedure, i.e. "microwave-assisted on-spot derivatization", to minimize sample preparation of DBS. In this approach the derivatization reagents are directly applied onto the DBS and derivatization takes place in a microwave instead of via conventional heating. In this manuscript we evaluated the applicability of this new concept of derivatization for the determination of two polar low molecular weight molecules, gamma-hydroxybutyric acid (GHB) and gabapentin, in DBS using a standard GC-MS configuration. The method was successfully validated for both compounds, with imprecision and bias values within acceptance criteria (<20% at LLOQ, <15% at 3 other QC levels). Calibration lines were linear over the 10-100μg/mL and 1-30μg/mL range for GHB and gabapentin, respectively. Stability studies revealed no significant decrease of gabapentin and GHB in DBS upon storage at room temperature for at least 84 days. Furthermore, DBS-specific parameters, including hematocrit and volume spotted, were evaluated. As demonstrated by the analysis of GHB and gabapentin positive samples, "microwave-assisted on-spot derivatization" proved to be reliable, fast and applicable in routine toxicology. Moreover, other polar low molecular weight compounds of interest in clinical and/or forensic toxicology, including vigabatrin, beta-hydroxybutyric acid, propylene glycol, diethylene glycol, 1,4-butanediol and 1,2-butanediol, can also be detected using this method. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of NH2 concentration on 3-aminopropyl tri-ethoxy silane layers and cyclopropylamine plasma polymers by liquid-phase derivatization with 5-iodo 2-furaldehyde

NASA Astrophysics Data System (ADS)

Manakhov, Anton; Čechal, Jan; Michlíček, Miroslav; Shtansky, Dmitry V.

2017-08-01

The quantification of concentration of primary amines, e.g. in plasma polymerized layers is a very important task for surface analysis. However, the commonly used procedure, such as gas phase derivatization with benzaldehydes, shows several drawbacks, the most important of which are the side reaction effects. In the present study we propose and validate a liquid phase derivatization using 5-iodo 2-furaldehyde (IFA). It was demonstrated that the content of NH2 groups can be determined from the atomic concentrations measured by X-ray photoelectron spectroscopy (XPS), in particular from the ratio of I 3d and N 1s peak intensities. First, we demonstrate the method on a prototypical system such as 3-aminopropyl tri-ethoxy silane (APTES) layer. Here the XPS analysis carried out after reaction of APTES layer with IFA gives the fraction of primary amines (NH2/N) of 38.3 ± 7.9%. Comparing this value with that obtained by N 1s curve fitting of APTES layer giving 40.9 ± 9.5% of amine groups, it can be concluded that all primary amines were derivatized by reaction with IFA. The second system to demonstrate the method comprises cyclopropylamine (CPA) plasma polymers that were free from conjugated imines. In this case the method gives the NH2 fraction ∼8.5%. This value is closely matching the NH2/N ratio estimated by 4-trifluoromethyl benzaldehyde (TFBA) derivatization. The reaction of IFA with CPA plasma polymer exhibiting high density of conjugated imines revealed the NH2/N fraction of ∼10.8%. This value was significantly lower compared to 17.3% estimated by TFBA derivatization. As the overestimated density of primary amines measured by TFBA derivatization is probably related to the side reaction of benzaldehydes with conjugated imines, the proposed IFA derivatization of primary amines can be an alternative procedure for the quantification of surface amine groups.

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection.

PubMed

Richardson, Douglas D; Caruso, Joseph A

2007-06-01

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC-ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC-time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC-ICPMS.

Competition between roots and microorganisms for phosphorus: A novel 33P labeling approach

NASA Astrophysics Data System (ADS)

Zilla, Thomas; Kuzyakov, Yakov; Zavišiæ, Aljoša; Polle, Andrea

2015-04-01

While organic N mineralization exhibits clear seasonal uptake dynamics, knowledge about seasonal variation in microbial P uptake and mineralization is scarce. We hypothesize that the dynamics of P uptake and mineralization by microorganisms in temperate forest soils exhibit a seasonality anti-cyclic to plant P uptake. Therefore, the ratio of microbial P to labile P increases by the transition from acquiring ecosystems (in spring) to recycling ones (in fall). To investigate this, intact soil-plant mesocosms containing Ah horizon with 1 year old F. sylvatica were removed from the P-rich field site Bad Brueckenau and the P-depleted field site Luess in Germany. During incubation under controlled conditions, seasonal pulse labeling by 33P-orthophosphate was performed at 5 time points over the course of one year. 33P recovery in microbial compounds of organic and mineral soil horizons was determined 7 and 30 days after the labeling. This procedure will account for temporal changes in P allocation and also considers the rather slow P transport from the mycorrhiza into the plants and other microorganisms. For the first time we analyzed the 33P incorporation into total PLFA and consequently provide a new technique for the analysis of P uptake by microorganisms, which has clear advantages compared to P quantification after chloroform fumigation. Polar lipids are hereby extracted with a Frostegård-modified Bligh-and-Dyer buffer, i.e. a single phase mixture of chloroform, methanol and citrate buffer (0.8:1:2, v:v:v). Phospholipids (PLFA) are isolated and purified by solid phase extraction via a silica gel column chromatography. Subsequently, PLFA are hydrolyzed and the resulting fatty acids derivatized by methylation. The fatty acid methyl esters were extracted with n-hexane and measured by GC/MS to investigate the composition of the microbial community. The remaining extract, containing head groups, phosphate units and glycerol backbones, was used to determine 33P activity and recovery in the microbial membrane lipids with a multi-purpose scintillation counter. This approach offers the unique possibility to quantify P fluxes through the microbial network. For the first time, P cycling can be linked to changes in microbial community structure and activity in soils in situ.

Drawing the battle lines: tracing the "Science War" in the construction of the chloroform and human health risks debate.

PubMed

Driedger, S Michelle; Eyles, John

2003-04-01

The United States Environmental Protection Agency (US EPA) and the Chlorine Chemistry Council, the Chemical Manufacturers Association, and others have been embroiled in a legal challenge concerning the US EPA's "reversal" regarding the scientific assessment of chloroform's carcinogenicity. This issue arose during the US EPA's November 1998 promulgation of a Maximum Contaminant Level Goal for chloroform in the Stage 1 Final Rules for Disinfectants and Disinfection Byproducts in drinking water. In this paper we adopt a claimsmaking approach: to trace the development and outcome of the chloroform court challenge in the USA, to examine the construction of scientific knowledge claims concerning chloroform risk assessments, and to investigate how different interpretations of scientific uncertainties regarding the evidence are contested when such uncertainties are brought into a regulatory and judicial arena. This "science war" (Chlorine Chemistry Council and others v. US EPA and others) took place in the US Court of Appeals for the District of Columbia Circuit. The scientific "authority" in the construction of scientific claims in this dispute is based on the International Life Sciences Institute expert panel report on chloroform. Examining these science wars is important because they signal critical shifts in science policy agendas. The regulatory outcome of the chloroform science war in the United States can have profound implications for the construction and acceptance of scientific claims regarding drinking water in other jurisdictions (e.g., Canada). In this challenge, we argue that the actors involved in the dispute constructed "boundaries" around accepted and credible scientific claims.

Photochemical Production of Aldehydes and Ketones from Petroleum Films on Seawater

NASA Astrophysics Data System (ADS)

Tarr, M. A.; Rebet, K.; Monin, L.; Bastian, G.

2016-02-01

While numerous reports have demonstrated that sunlight results in oxygenation of petroleum in environmental systems, few details are available regarding the specific mechanisms of these reactions. Previous studies have not been able to identify specific chemicals formed when oil is subjected to photochemical transformation. In this study, we have utilized several petroleum samples to investigate the formation of aldehyde and ketone photoproducts. These samples included oil from the MC252 well (source of the Deepwater Horizon spill), surrogate oil provided by BP to represent the MC252 oil, and residual fuel oil (NIST 2717a). Thin films of oil ( 100 μm) were placed over water and irradiated with a solar simulator for the equivalent of 1.5-12 days. After irradiation, the water was carefully separated from the oil and derivatized with 2,4-dinitrophenylhydrazine, a selective derivatization agent for aldehydes and ketones. The derivatized material was then analyzed by HPLC. Additional analysis by electrospray MS was also performed, and absorbance and fluorescence spectra of the underivatized aqueous phase were recorded. For all oils, exposure to sunlight resulted in release of aldehydes and ketones to the aqueous phase. The amount of released photoproducts was proportional to the length of solar exposure, but no production was seen for dark controls. Despite some similarities, the pattern of product formation varied from oil to oil. Addition of dispersant (Corexit 9500a or 9527a) resulted in larger amounts of aldehydes and ketones detected in the aqueous phase after solar irradiation of the oil. Electrospray mass spectrometry was utilized in an attempt to provide structural information about the aldehydes and ketones formed. Results of this study demonstrate that aldehydes and ketones are important photoproducts resulting from solar irradiation of oil on water. These products will affect the transport and bioavailability of oil spilled in aquatic systems.

Methyl Chloroform Elimination from the Production of Space Shuttle Sold Rocket Motors

NASA Technical Reports Server (NTRS)

Golde, Rick P.; Burt, Rick; Key, Leigh

1997-01-01

Thiokol Space Operations manufactures the Reusable Solid Rocket Motors used to launch America's fleet of Space Shuttles. In 1989, Thiokol used more than 1.4 Mlb of methyl chloroform to produce rocket motors. The ban placed by the Environmental Protection Agency on the sale of methyl chloroform had a significant effect on future Reusable Solid Rocket Motor production. As a result, changes in the materials and processes became necessary. A multiphased plan was established by Thiokol in partnership with NASA's Marshall Space Flight Center to eliminate the use of methyl chloroform in the Reusable Solid Rocket Motor production process. Because of the extensive scope of this effort, the plan was phased to target the elimination of the majority of methyl chloroform use (90 percent) by January 1, 1996, the 3 Environmental Protection Agency deadline. Referred to as Phase I, this effort includes the elimination of two large vapor degreasers, grease diluent processes, and propellant tooling handcleaning using methyl chloroform. Meanwhile, a request was made for an essential use exemption to allow the continued use of the remaining 10 percent of methyl chloroform after the 1996 deadline, while total elimination was pursued for this final, critical phase (Phase II). This paper provides an update to three previous presentations prepared for the 1993, 1994, and 1995 CFC/Halon Alternative Conferences, and will outline the overall Ozone Depleting Compounds Elimination Program from the initial phases through the final testing and implementation phases, including facility and equipment development. Processes and materials to be discussed include low-pressure aqueous wash systems, high-pressure water blast systems- environmental shipping containers, aqueous and semi-aqueous cleaning solutions, and bond integrity and inspection criteria. Progress toward completion of facility implementation and lessons learned during the scope of the program, as well as the current development efforts and basic requirements of future methyl chloroform handcleaning elimination, will also be outlined.

The role of renal proximal tubule P450 enzymes in chloroform-induced nephrotoxicity: Utility of renal specific P450 reductase knockout mouse models

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

Liu, Senyan; Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York, Albany, NY 12201; Yao, Yunyi

The kidney is a primary target for numerous toxic compounds. Cytochrome P450 enzymes (P450) are responsible for the metabolic activation of various chemical compounds, and in the kidney are predominantly expressed in proximal tubules. The aim of this study was to test the hypothesis that renal proximal tubular P450s are critical for nephrotoxicity caused by chemicals such as chloroform. We developed two new mouse models, one having proximal tubule-specific deletion of the cytochrome P450 reductase (Cpr) gene (the enzyme required for all microsomal P450 activities), designated proximal tubule-Cpr-null (PTCN), and the other having proximal tubule-specific rescue of CPR activity withmore » the global suppression of CPR activity in all extra-proximal tubular tissues, designated extra-proximal tubule-Cpr-low (XPT-CL). The PTCN, XPT-CL, Cpr-low (CL), and wild-type (WT) mice were treated with a single oral dose of chloroform at 200 mg/kg. Blood, liver and kidney samples were obtained at 24 h after the treatment. Renal toxicity was assessed by measuring BUN and creatinine levels, and by pathological examination. The blood and tissue levels of chloroform were determined. The severity of toxicity was less in PTCN and CL mice, compared with that of WT and XPT-CL mice. There were no significant differences in chloroform levels in the blood, liver, or kidney, between PTCN and WT mice, or between XPT-CL and CL mice. These findings indicate that local P450-dependent activities play an important role in the nephrotoxicity induced by chloroform. Our results also demonstrate the usefulness of these novel mouse models for studies of chemical-induced kidney toxicity. - Highlights: • New mouse models were developed with varying P450 activities in the proximal tubule. • These mouse models were treated with chloroform, a nephrotoxicant. • Studies showed the importance of local P450s in chloroform-induced nephrotoxicity.« less

Underivatized oxysterols and nanoLC-ESI-MS: A mismatch.

PubMed

Roberg-Larsen, Hanne; Vesterdal, Caroline; Wilson, Steven Ray; Lundanes, Elsa

2015-07-01

Due to their non-charged character, liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) measurements of oxysterols are often performed after derivatization with e.g. charged Girard reagents. However, derivatization reactions are time-consuming and may require numerous steps to remove excess reagent. In addition, extensive sample handling can be associated with cholesterol autoxidation, resulting in analyte artifacts and hence false positives. Nano scale liquid chromatography in combination with electrospray-mass spectrometry (nanoLC-ESI-MS) is a powerful tool for analyzing limited samples, due to substantially increased sensitivity compared to conventional LC-ESI-MS. The signal enhancement may compensate for the poor ionization of the oxysterols; hence we have explored the possibility to quantify oxysterols without derivatization using nanoLC-ESI-MS. Non-derivatized oxysterols and nanoLC were however not compatible, due to persistent and large carry-over. This was attributed to the extended contribution of surface to volume ratio in such miniaturized systems and interactions with the materials of the nanoLC instrumentation (e.g. adsorption to the fused silica tubing). Two contemporary MS instruments (Q-Exactive™ hybrid quadrupole-Orbitrap and TSQ Quantiva™ triple quadrupole) were used. However, both the MS and MS/MS spectra of non-derivatized oxysterols were ambiguous and/or unrepeatable for both of the instruments employed. Derivatizing oxysterols is more cumbersome, but provides more selective and reliable results, and Girard derivatization+nanoLC-ESI-MS continues to be our recommended choice for measuring oxysterols in very limited samples. These investigations also indicate that extra care should be taken to remove lipids prior to nanoLC of other analytes, as adsorbed oxysterols, etc. can compromise analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

Review of in situ derivatization techniques for enhanced bioanalysis using liquid chromatography with mass spectrometry.

PubMed

Baghdady, Yehia Z; Schug, Kevin A

2016-01-01

Accurate and specific analysis of target molecules in complex biological matrices remains a significant challenge, especially when ultra-trace detection limits are required. Liquid chromatography with mass spectrometry is often the method of choice for bioanalysis. Conventional sample preparation and clean-up methods prior to the analysis of biological fluids such as liquid-liquid extraction, solid-phase extraction, or protein precipitation are time-consuming, tedious, and can negatively affect target recovery and detection sensitivity. An alternative or complementary strategy is the use of an off-line or on-line in situ derivatization technique. In situ derivatization can be incorporated to directly derivatize target analytes in their native biological matrices, without any prior sample clean-up methods, to substitute or even enhance the extraction and preconcentration efficiency of these traditional sample preparation methods. Designed appropriately, it can reduce the number of sample preparation steps necessary prior to analysis. Moreover, in situ derivatization can be used to enhance the performance of the developed liquid chromatography with mass spectrometry-based bioanalysis methods regarding stability, chromatographic separation, selectivity, and ionization efficiency. This review presents an overview of the commonly used in situ derivatization techniques coupled to liquid chromatography with mass spectrometry-based bioanalysis to guide and to stimulate future research. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Derivatization and Validation Strategy for Determining the Spatial Localization of Endogenous Amine Metabolites in Tissues using MALDI Imaging Mass Spectrometry

PubMed Central

Manier, M. Lisa; Spraggins, Jeffrey M.; Reyzer, Michelle L.; Norris, Jeremy L.; Caprioli, Richard M.

2014-01-01

Imaging mass spectrometry (IMS) studies increasingly focus on endogenous small molecular weight metabolites and consequently bring special analytical challenges. Since analytical tissue blanks do not exist for endogenous metabolites, careful consideration must be given to confirm molecular identity. Here we present approaches for the improvement in detection of endogenous amine metabolites such as amino acids and neurotransmitters in tissues through chemical derivatization and matrix-assisted laser desorption/ionization (MALDI) IMS. Chemical derivatization with 4-hydroxy-3-methoxycinnamaldehyde (CA) was used to improve sensitivity and specificity. CA was applied to the tissue via MALDI sample targets precoated with a mixture of derivatization reagent and ferulic acid (FA) as a MALDI matrix. Spatial distributions of chemically derivatized endogenous metabolites in tissue were determined by high-mass resolution and MSn imaging mass spectrometry. We highlight an analytical strategy for metabolite validation whereby tissue extracts are analyzed by high-performance liquid chromatography (HPLC)-MS/MS to unambiguously identify metabolites and distinguish them from isobaric compounds. PMID:25044893

Purification of Derivatized Oligosaccharides by Solid Phase Extraction for Glycomic Analysis

PubMed Central

Zhang, Qiwei; Li, Henghui; Feng, Xiaojun; Liu, Bi-Feng; Liu, Xin

2014-01-01

Profiling of glycans released from proteins is very complex and important. To enhance the detection sensitivity, chemical derivatization is required for the analysis of carbohydrates. Due to the interference of excess reagents, a simple and reliable purification method is usually necessary for the derivatized oligosaccharides. Various SPE based methods have been applied for the clean-up process. To demonstrate the differences among these methods, seven types of self-packed SPE cartridges were systematically compared in this study. The optimized conditions were determined for each type of cartridge and it was found that microcrystalline cellulose was the most appropriate SPE material for the purification of derivatized oligosaccharide. Normal phase HPLC analysis of the derivatized maltoheptaose was realized with a detection limit of 0.12 pmol (S N−1 = 3) and a recovery over 70%. With the optimized SPE method, relative quantification analysis of N-glycans from model glycoproteins were carried out accurately and over 40 N-glycans from human serum samples were determined regardless of the isomers. Due to the high stability and sensitivity, microcrystalline cellulose cartridge showed potential applications in glycomics analysis. PMID:24705408

Effect of AOT Microemulsion Composition on the Hydrodynamic Diameter and Electrophoretic Mobility of Titanium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Shaparenko, N. O.; Beketova, D. I.; Demidova, M. G.; Bulavchenko, A. I.

2018-05-01

The hydrodynamic diameter and electrophoretic mobility of titania nanoparticles in AOT microemulsions are studied depending on their water content (from 0 to 1.5 vol %), chloroform content in n-decane-chloroform mixture (from 0 to 30 vol %) and temperature (from 0 to 60°C). Considerable changes in diameter (from 20 to 400 nm) are detected upon adding water to the microemulsion. The electrophoretic mobility grows by 2-3 times upon adding chloroform, or as the temperature falls. The observed features allow us to halve the time of electrophoretic concentration for 140 nm TiO2 nanoparticles, and to concentrate 14 nm nanoparticles that do not exhibit electrophoretic mobility in the absence of chloroform.

Development and application of denuder sampling techniques with in situ derivatization for the determination of hydrogenbromide in volcanic plumes

NASA Astrophysics Data System (ADS)

Gutmann, Alexandra; Rüdiger, Julian; Hoffmann, Thorsten

2016-04-01

The composition of gases in volcanic plumes shifts with subsurface processes inside volcanoes. For monitoring volcanic activity by studying volcanic plumes it is essential to understand the chemical reactions inside the volcanic plume (Bobrowski and Platt, 2013). Measurements of BrO/SO2-ratio already enable insights into magmatic processes (Bobrowski and Giuffrida, 2012). Both, BrO and SO2, are measurable by Remote Sensing Techniques at a safe distance. Models suggest not a direct emission of BrO but formation due to photochemical and multiphase reactions in the gas and particle phase. These model presume HBr as first emitted species (Gerlach, 2004). So HBr is an important connecting link between easily measurable BrO/SO2-ratios and conclusions on a volcanic system. It is of high importance to know if there is a variation in the amount of HBr transformed into BrO and to gain knowledge on the factor of its dependence. Apart from depletion of surrounded ozone also decreasing or depletion of emitted HBr or even HCl could be responsible for the shift (Bobrowski and Giuffrida, 2012). Knowledge about complex processes in volcanic plumes will simplify interpretation and predictions. In this study, first applications of coated gas diffusion denuder (similar to Huang and Hoffmann, 2008) to derivatize gaseous HBr were successful. Due to the lack of adequate remote sensing techniques an in situ method was developed and will be presented in detail. The epoxide of oleic acid was determined as a suitable derivatization agent. The reaction with HBr gives 10-bromo-9-hydroxyoctadecanoic acid. Other hydrogenhalogens give corresponding products. Derivatized analytes were removed from denuder by solvent elution and subsequent analysed with gas chromatography-mass spectrometry. A limit of quantification below 1 ng was achieved. The method was applied on volcanic gas plumes at Mt. Etna in Italy in July and August 2015. The results showed HBr in higher ppt-range. These first proof-of-principle investigations showed the suitability of the method for halogenhalides-analysis. References Bobrowski, N. and Giuffrida, G.: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009, Solid Earth, 3, 433-445, doi:10.5194/se-3-433-2012, 2012. Bobrowski, N. and Platt, U.: Den Himmel betrachten, die Hölle verstehen. Telegramm aus dem Inneren der Erde., Ruperto Carola, 2013, 2013. Gerlach, T. M.: Volcanic sources of tropospheric ozone-depleting trace gases, Geochem. Geophys. Geosyst., 5, n/a, doi:10.1029/2004GC000747, 2004. Huang, R.-J. and Hoffmann, T.: A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-containing halogen species, Journal of Chromatography A, 1210, 135-141, doi:10.1016/j.chroma.2008.08.003, 2008.

Development and application of gas diffusion denuder sampling techniques with in situ derivatization for the determination of hydrogen halides in volcanic plumes

NASA Astrophysics Data System (ADS)

Gutmann, Alexandra; Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2017-04-01

Volcanoes emit large amounts of gases into the atmosphere. The gas composition in volcanic plumes vary, driven by subsurface processes (such as magma rising) as well as by chemical reactions within the plume after mixing with ambient air. The knowledge of the gas composition can be a useful tool to monitor volcanic activity changes. However, to use the plume composition as a monitoring parameter, it is essential to understand the chemical reactions inside volcanic plumes, in particular when interpretation of volcanic activity changes is based on reactive gas species, such as bromine monoxide or molecular halogens. Changes in BrO/SO2-ratios, measured by UV spectrometers, have already been interpreted in connection with increasing volcanic activity prior to eruptions. But the abundance of BrO changes as a function of the reaction time, and therefore with distance from the vent, as well as the spatial position in the plume. Actually model and field studies assume a non-direct emission of BrO, but its formation due to photochemical and multiphase reactions involving gas and particle phase of volcanic emission mixed with the surrounding atmosphere. However, same models presume HBr as initially emitted species. Therefore, HBr is an important species linking BrO to geophysical processes in volcanic systems. Due to the lack of analytical methods for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr, etc.) there are still large uncertainties about the magnitude of volcanic halogen emissions, and in the understanding of the bromine chemistry in volcanic plumes. Since the concentrations of hydrogen halides are not directly accesable by remote sensing techniques, an in situ method with coated gas diffusion denuder was developed. The method uses selective derivatization reaction of gaseous hydrogen halides with an organic compound for the enrichment and immobilization. For this task 5,6-Epoxy-5,6-dihydro-1,10-phenanthrolin was identified as a suitable derivatization agent. The reaction with HBr results in the formation of 5-Bromo-5,6-dihydro-6-hydroxy-1,10-phenanthrolin. Other hydrogen halides give corresponding products. Using a denuder based sampling system with in situ derivatization it is also possible to differentiate even between gaseous and particulate hydrogen bromine. The derivatized analytes were analyzed with high pressure liquid chromatography-mass spectrometry. We applied this approach to measure hydrogen halide mixing ratios (ppt to ppb range depending on plume age) in the plumes of different volcanoes: Stromboli, Italy; Masaya, Nicaragua; Turrialba, Costa Rica. The results of this measurements will be presented. Samples were taken at various distances to the emission source and have been compared with complementary data (e.g. SO2 from alkaline traps or gas sensors). Furthermore, the sampling method has been applied on an unmanned aerial vehicle for downwind sample collection.

Superhydrophobic aerogel that does not require per-fluoro compounds or contain any fluorine

DOEpatents

Kissel, David J.; Brinker, Charles Jeffrey

2015-05-26

Provided are superhydrophobic coatings, devices and articles including superhydrophobic coatings, and methods for preparing the superhydrophobic coatings. The exemplary superhydrophobic device can include a substrate component and one or more superhydrophobic coatings disposed over the substrate component, wherein at least one of the one or more superhydrophobic coatings has a water contact angle of at least about 150.degree. and a contact angle hysteresis of less than about 1.degree.. The one or more superhydrophobic coatings can include an ultra high water content acid catalyzed polysilicate gel, the polysilicate gel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

Antimycobacterial activity of selected medicinal plants traditionally used in Sudan to treat infectious diseases.

PubMed

Abuzeid, Nadir; Kalsum, Sadaf; Koshy, Richin John; Larsson, Marie; Glader, Mikaela; Andersson, Henrik; Raffetseder, Johanna; Pienaar, Elsje; Eklund, Daniel; Alhassan, Muddathir S; AlGadir, Haidar A; Koko, Waleed S; Schön, Thomas; Ahmed Mesaik, M; Abdalla, Omer M; Khalid, Asaad; Lerm, Maria

2014-11-18

The emergence of multidrug-resistant strains of Mycobacterium tuberculosis underscores the need for continuous development of new and efficient methods to determine the susceptibility of isolates of Mycobacterium tuberculosis in the search for novel antimycobacterial agents. Natural products constitute an important source of new drugs, and design and implementation of antimycobacterial susceptibility testing methods are necessary to evaluate the different extracts and compounds. In this study we have explored the antimycobacterial properties of 50 ethanolic extracts from different parts of 46 selected medicinal plants traditionally used in Sudan to treat infectious diseases. Plants were harvested and ethanolic extracts were prepared. For selected extracts, fractionation with hydrophilic and hydrophobic solvents was undertaken. A luminometry-based assay was used for determination of mycobacterial growth in broth cultures and inside primary human macrophages in the presence or absence of plant extracts and fractions of extracts. Cytotoxicity was also assessed for active fractions of plant extracts. Of the tested extracts, three exhibited a significant inhibitory effect on an avirulent strain of Mycobacterium tubercluosis (H37Ra) at the initial screening doses (125 and 6.25µg/ml). These were bark and leaf extracts of Khaya senegalensis and the leaf extract of Rosmarinus officinalis L. Further fractions of these plant extracts were prepared with n-hexane, chloroform, ethyl acetate, n-butanol, ethanol and water, and the activity of these extracts was retained in hydrophobic fractions. Cytotoxicity assays revealed that the chloroform fraction of Khaya senegalensis bark was non-toxic to human monocyte-derived macrophages and other cell types at the concentrations used and hence, further analysis, including assessment of IC50 and intracellular activity was done with this fraction. These results encourage further investigations to identify the active compound(s) within the chloroform fraction of Khaya senegalensis bark. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Ophthalmic acid accumulation in an Escherichia coli mutant lacking the conserved pyridoxal 5'-phosphate-binding protein YggS.

PubMed

Ito, Tomokazu; Yamauchi, Ayako; Hemmi, Hisashi; Yoshimura, Tohru

2016-12-01

Escherichia coli YggS is a highly conserved pyridoxal 5'-phosphate (PLP)-binding protein whose biochemical function is currently unknown. A previous study with a yggS-deficient E. coli strain (ΔyggS) demonstrated that YggS controls l-Ile- and l-Val-metabolism by modulating 2-ketobutyrate (2-KB), l-2-aminobutyrate (l-2-AB), and/or coenzyme A (CoA) availability in a PLP-dependent fashion. In this study, we found that ΔyggS accumulates an unknown metabolite as judged by amino acid analyses. LC/MS and MS/MS analyses of the compound with propyl chloroformate derivatization, and co-chromatography analysis identified this compound as γ-l-glutamyl-l-2-aminobutyryl-glycine (ophthalmic acid), a glutathione (GSH) analogue in which the l-Cys moiety is replaced by l-2-AB. We also determine the metabolic consequence of the yggS mutation. Absence of YggS initially increases l-2-AB availability, and then causes ophthalmic acid accumulation and CoA limitation in the cell. The expression of a γ-glutamylcysteine synthetase and a glutathione synthetase in a ΔyggS background causes high-level accumulation of ophthalmic acid in the cells (∼1.2 nmol/mg cells) in a minimal synthetic medium. This opens the possibility of a first fermentative production of ophthalmic acid. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Liquid chromatography/electrospray ionization/isotopic dilution mass spectrometry analysis of n-(phosphonomethyl) glycine and mass spectrometry analysis of aminomethyl phosphonic acid in environmental water and vegetation matrixes.

PubMed

Grey, L; Nguyen, B; Yang, P

2001-01-01

A liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) method was developed for the analysis of glyphosate (n-phosphonomethyl glycine) and its metabolite, aminomethyl phosphonic acid (AMPA) using isotope-labelled glyphosate as a method surrogate. Optimized parameters were achieved to derivatize glyphosate and AMPA using 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer prior to a reversed-phase LC analysis. Method spike recovery data obtained using laboratory and real world sample matrixes indicated an excellent correlation between the recovery of the native and isotope-labelled glyphosate. Hence, the first performance-based, isotope dilution MS method with superior precision, accuracy, and data quality was developed for the analysis of glyphosate. There was, however, no observable correlation between the isotope-labelled glyphosate and AMPA. Thus, the use of this procedure for the accurate analysis of AMPA was not supported. Method detection limits established using standard U.S. Environmental Protection Agency protocol were 0.06 and 0.30 microg/L, respectively, for glyphosate and AMPA in water matrixes and 0.11 and 0.53 microg/g, respectively, in vegetation matrixes. Problems, solutions, and the method performance data related to the analysis of chlorine-treated drinking water samples are discussed. Applying this method to other environmental matrixes, e.g., soil, with minimum modifications is possible, assuring accurate, multimedia studies of glyphosate concentration in the environment and the delivery of useful multimedia information for regulatory applications.

Development and validation of an EI-GC-MS method for the determination of benzodiazepine drugs and their metabolites in blood: applications in clinical and forensic toxicology.

PubMed

Papoutsis, Ioannis I; Athanaselis, Sotirios A; Nikolaou, Panagiota D; Pistos, Constantinos M; Spiliopoulou, Chara A; Maravelias, Constantinos P

2010-08-01

Benzodiazepines are used widely in daily clinical practice, due to their multiple pharmacological actions. The frequent problems associated with the wide use of benzodiazepines, as well as the multiple incidents of poisonings, led to the necessity for the development of a precise, sensitive and rapid method for the simultaneous determination of the 23 most commonly used benzodiazepines (diazepam, nordiazepam, oxazepam, bromazepam, alprazolam, lorazepam, medazepam, flurazepam, fludiazepam, tetrazepam, chlordiazepoxide, clobazam, midazolam, flunitrazepam, 7-amino-flunitrazepam, triazolam, prazepam, nimetazepam, nitrazepam, temazepam, lormetazepam, clonazepam, camazepam) in blood. A gas chromatographic method combined with mass spectrometric detection was developed, optimized and validated for the determination of the above substances. This method includes liquid-liquid extraction with chloroform at pH 9 and two stages of derivatization using tetramethylammonium hydroxide and propyliodide (propylation), as well as a mixture of triethylamine:propionic anhydride (propionylation). The recoveries were higher than 74% for all the benzodiazepines. The calibration curves were linear within the dynamic range of each benzodiazepine with a correlation coefficient higher than 0.9981. The limits of detection and quantification for each analyte were statistically calculated from the relative calibration curves. Accuracy and precision were also calculated and were found to be less than 8.5% and 11.1%, respectively. The developed method was successfully applied for the investigation of both forensic and clinical toxicological cases of accidental and suicidal poisoning. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Muscarinic receptor subtype selectivity of novel heterocyclic QNB analogues

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

Baumgold, J.; Cohen, V.I.; Paek, R.

1991-01-01

In an effort at synthesizing centrally-active subtype-selective antimuscarinic agents, the authors derivatized QNB (quinuclidinyl benzilate), a potent muscarinic antagonist, by replacing one of the phenyl groups with less lipophilic heterocyclic moieties. The displacement of ({sup 3}H)-N-methyl scopolamine binding by these novel compounds to membranes from cells expressing ml - m4 receptor subtypes was determined. Most of the novel 4-bromo-QNB analogues were potent and slightly selective for ml receptors. The 2-thienyl derivative was the most potent, exhibiting a 2-fold greater potency than BrQNB at ml receptors, and a 4-fold greater potency than BrQNB at ml receptors, and a 4-fold greater potencymore » at m2 receptors. This compound was also considerably less lipophilic than BrQNB as determined from its retention time on C18 reverse phase HPLC. This compound may therefore be useful both for pharmacological studies and as a candidate for a radioiodinated SPECT imaging agent for ml muscarinic receptors in human brain.« less

The nitric oxide prodrug JS-K and its structural analogues as cancer therapeutic agents.

PubMed

Maciag, Anna E; Saavedra, Joseph E; Chakrapani, Harinath

2009-09-01

Nitric oxide (NO) prodrugs of the diazeniumdiolate class are routinely used as reliable sources of nitric oxide in chemical and biological laboratory settings. O(2)-(2,4-dinitrophenyl) diazeniumdiolates, which are derivatized forms of ionic diazeniumdiolates, have been found to show potent anti-proliferative activity in a variety of cancer cells, presumably through the effects of NO. One important member of this class of diazeniumdiolates, O(2)-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K), has shown promise as a novel cancer therapeutic agent in a number of animal models. This review describes the developments in chemical and biochemical characterization and structure-activity relationship of JS-K and its analogues. In addition, some molecular mechanistic insights into the observed anti-proliferative activity of JS-K are discussed. Finally, a structural motif is presented for O(2)-(aryl) diazeniumdiolate nitric oxide prodrugs that show potency comparable with that of JS-K.

Chloroform in the hydrologic system--sources, transport, fate, occurrence, and effects on human health and aquatic organisms

USGS Publications Warehouse

Ivahnenko, Tamara; Barbash, Jack E.

2004-01-01

Chloroform is one of the volatile organic compounds (VOCs) detected most frequently in both ground and surface water. Because it is also one of the four trihalomethanes (THMs) produced in the highest concentrations during the chlorination of drinking water and wastewater, the frequent detection of this compound in ground and surface water of the United States is presumed to be caused primarily by the input of chlorinated water to the hydrologic system. Although anthropogenic sources of the compound are substantial, they are currently estimated to constitute only 10 percent of the total global input to the hydrologic system. Natural sources of the compound include volcanic gases, biomass burning, marine algae, and soil microorganisms. Under most conditions (except in the presence of unusually high bromide concentrations), chloroform is the THM produced in the highest concentrations during chlorination. Furthermore, in most cases where more than one THM is produced from chlorination, the relative concentrations among the different compounds usually decrease with increasing bromination (chloroform > dichlorobromomethane > chlorodibromomethane > bromoform). This phenomenon is presumed to be responsible for the common observation that when more than one THM is detected during investigations of the occurrence of these compounds in the hydrologic system, this same trend is typically observed among their relative concentrations or, for a uniform reporting limit, their relative frequencies of detection. This pattern could provide a valuable means for distinguishing between chlorinated water and other potential sources of chloroform in the environment. Chloroform has been widely detected in national, regional, and local studies of VOCs in ground, surface, source, and drinking waters. Total THM (TTHM) concentrations of the compound, however, were typically less than the Maximum Contaminant Level (MCL) of 80 ?g/L (micrograms per liter) established by the U.S. Environmental Protection Agency (USEPA) for TTHMs. In the studies that compared land-use settings, frequencies of detection of chloroform were higher beneath urban and residential areas than beneath agricultural or undeveloped areas. Because chloroform is a suspected human carcinogen, its presence in drinking water is a potential human health concern. Liver damage, however, is known to occur at chloroform exposures lower than those required to cause cancer, an observation that has been considered by the USEPA as the basis for setting a new, non-zero Maximum Contaminant Level Goal of 70 ?g/L for the compound. As part of its National Water-Quality Assessment Program, the U.S. Geological Survey has been assembling and analyzing data on the occurrence of VOCs (including chloroform) in ground and surface water on a national scale from studies conducted between 1991 and the present. This report presents a summary of current (2004) information on the uses, sources, formation, transport, fate, and occurrence of chloroform, as well as its effects on human health and aquatic organisms.

Combination cancer chemotherapy with one compound: pluripotent bradykinin antagonists.

PubMed

Stewart, John M; Gera, Lajos; Chan, Daniel C; York, Eunice J; Simkeviciene, Vitalija; Bunn, Paul A; Taraseviciene-Stewart, Laimute

2005-08-01

Lung and prostate cancers are major health problems worldwide. Treatments with standard chemotherapy agents are relatively ineffective. Combination chemotherapy gives better treatment than a single agent because the drugs can inhibit the cancer in different pathways, but new therapeutic agents are needed for the treatment of both tumor types. Bradykinin (BK) antagonists offer advantages of combination therapy in one compound. These promising multitargeted anti-cancer compounds selectively stimulate apoptosis in cancers and also inhibit both angiogenesis and matrix metalloprotease (MMP) action in treated lung and prostate tumors in nude mice. The highly potent, metabolism-resistant bradykinin antagonist peptide dimer, B-9870 [SUIM-(DArg-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-Arg)2] (SUIM=suberimidyl; Hyp=4-hydroxyproline; Igl=alpha-(2-indanyl)glycine; Oic=octahydroindole-2-carboxylic acid) and its non-peptide mimetic, BKM-570 [2,3,4,5,6-pentafluorocinnamoyl-(o-2,6-dichlorobenzyl)-L-tyrosine-N-(4-amino-2,2,6,6-tetramethylpiperidyl)amide] are superior to the widely used but toxic chemotherapeutic drugs cisplatin and taxotere. In certain combinations, they act synergistically with standard anti-cancer drugs. Due to its structure and biological activity, BKM-570 is an attractive lead compound for derivatization and evaluation for lung and prostate cancer drugs.

Chloroform ingestion causing severe gastrointestinal injury, hepatotoxicity and dermatitis confirmed with plasma chloroform concentrations.

PubMed

Jayaweera, Dushan; Islam, Shawkat; Gunja, Naren; Cowie, Chris; Broska, James; Poojara, Latesh; Roberts, Michael S; Isbister, Geoffrey K

2017-02-01

Poisoning due to chloroform ingestion is rare. The classic features of acute chloroform toxicity include central nervous system (CNS) and respiratory depression, and delayed hepatotoxicity. A 30-year-old female ingested 20-30 mL of 99% chloroform solution, which caused rapid loss of consciousness, transient hypotension and severe respiratory depression requiring endotracheal intubation and ventilation. She was alert by 12 h and extubated 16 h post-overdose. At 38-h post-ingestion, her liver function tests started to rise and she was commenced on intravenous acetylcysteine. Her alanine transaminase (1283 U/L), aspartate transaminase (734 U/L) and international normalized ratio (2.3) peaked 67- to 72-h post-ingestion. She also developed severe abdominal pain, vomiting and diarrhoea. An abdominal CT scan was consistent with severe enterocolitis, and an upper gastrointestinal endoscopy showed erosive oesophagitis, severe erosive gastritis and ulceration. She was treated with opioid analgesia, proton pump inhibitors, sucralfate and total parenteral nutrition. Secretions caused a contact dermatitis of her face and back. Nine days post-ingestion she was able to tolerate food. Her liver function tests normalized and the dermatitis resolved. Chloroform was measured using headspace gas chromatograph mass spectrometry, with a peak concentration of 2.00 μg/mL, 4 h 20 min post-ingestion. The concentration-time data fitted a 1-compartment model with elimination half-life 6.5 h. In addition to early CNS depression and delayed hepatotoxicity, we report severe gastrointestinal injury and dermatitis with chloroform ingestion. Recovery occurred with good supportive care, acetylcysteine and management of gastrointestinal complications.

Genotoxicity of drinking water disinfection by-products (bromoform and chloroform) by using both Allium anaphase-telophase and comet tests.

PubMed

Khallef, Messaouda; Liman, Recep; Konuk, Muhsin; Ciğerci, İbrahim Hakkı; Benouareth, Djameleddine; Tabet, Mouna; Abda, Ahlem

2015-03-01

Genotoxic effects of bromoform and chloroform, disinfection by-products of the chlorination of drinking water, were examined by using mitotic index (MI), mitotic phase, chromosome aberrations (CAs) and comet assay on root meristematic cells of Allium cepa. Different concentrations of bromoform (25, 50, 75 and 100 μg/mL) and chloroform (25, 50, 100 and 200 μg/mL) were introduced to onion tuber roots. Distilled water was used as a negative control and methyl methansulfonate (MMS-10 μg/mL) as positive control. All obtained data were subjected to statistical analyses by using SPSS 15.0 for Windows software. For comparison purposes, Duncan multiple range tests by using one-way analysis of variance were employed and p < 0.05 was accepted as significant value. Exposure of both chemicals (except 25 μg/mL applications of bromoform) significantly decreased MI. Bromoform and chloroform (except 25 μg/mL applications) increased total CAs in Allium anaphase-telophase test. A significant increase in DNA damage was also observed at all concentrations of both bromoform and chloroform examined by comet assay. The damages were higher than that of positive control especially at 75-100 μg/mL for bromoform and 100-200 μg/mL for chloroform.

Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under ...

EPA Pesticide Factsheets

In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and ethanol. The TBAB is composed of pelleted diatomaceous earth filter media inoculated with filamentous fungi species, which served as the principle biodegrading microorganism. The removal efficiencies of 5 ppmv of chloroform mixed with different ratios of ethanol as cometabolite (25, 50, 100, 150, and 200 ppmv) ranged between 69.9 and 80.9%. The removal efficiency, reaction rate kinetics, and the elimination capacity increased proportionately with an increase in the cometabolite concentration. The carbon recovery from the TBAB amounted to 69.6% of the total carbon input. It is postulated that the remaining carbon contributed to excess biomass yield within the system. Biomass control strategies such as starvation and stagnation were employed at different phases of the experiment. The chloroform removal kinetics provided a maximum reaction rate constant of 0.0018 s−1. The highest ratio of chemical oxygen demand (COD)removal/nitrogenutilization was observed at 14.5. This study provides significant evidence that the biodegradation of a highly chlorinated methane can be favored by cometabolism in a fungi-based TBAB. Chloroform is volatile hazardous chemical emitted from publicly owned treatment

Characterization of the extracellular bactericidal factors of rat alveolar lining material.

PubMed Central

Coonrod, J D; Lester, R L; Hsu, L C

1984-01-01

The surfactant fraction (55,000-g pellet) of leukocyte-free rat bronchoalveolar lavage fluid contains factors that rapidly kill and lyse pneumococci. These factors were purified and identified biochemically by using a quantitative bactericidal test to monitor fractionation procedures. 91% of the antipneumococcal activity of rat surfactant was recovered in chloroform after extraction of rat surfactant with chloroform-methanol (Bligh-Dyer procedure). After chromatography on silicic acid with chloroform, acetone, and methanol, all detectable antibacterial activity (approximately 80% of the initial activity) eluted with the neutral lipids in chloroform. When rechromatographed on silicic acid with hexane, hexane-chloroform, and chloroform, the antibacterial activity eluted with FFA. Thin-layer chromatography (TLC) established that the antibacterial activity was confined to the FFA fraction. Gas-liquid chromatography showed that the fatty acid fraction contained a mixture of long-chain FFA (C12 to C22) of which 66.7% were saturated and 32.4% were unsaturated. The quantity of TLC-purified FFA needed to kill 50% of 10(8) pneumococci under standardized conditions (one bactericidal unit) was 10.6 +/- 0.5 micrograms. Purified FFA acted as detergents, causing release of [3H]choline from pneumococcal cell walls and increased bacterial cell membrane permeability, evidenced by rapid unloading of 3-O-[3H]methyl-D-glucose. FFA acting as detergents appear to account for the bactericidal and bacteriolytic activity of rat pulmonary surfactant for pneumococci. PMID:6548228

Description of trihalomethane levels in three UK water suppliers.

PubMed

Whitaker, Heather; Nieuwenhuijsen, Mark J; Best, Nicola; Fawell, John; Gowers, Alison; Elliot, Paul

2003-01-01

Samples of drinking water are routinely analysed for four trihalomethanes (THMs), which are indicators of by-products of disinfection with chlorine, by UK water suppliers to demonstrate compliance with regulations. The THM data for 1992-1993 to 1997-1998 for three water suppliers in the north and midlands of England were made available for a UK epidemiological study of the association between disinfection by-products and adverse birth outcomes. This paper describes the THM levels in these three supply regions and discusses possible sources of variation. THM levels varied between different suppliers' water, and average THM levels were within the regulatory limits. Chloroform was the predominant THM in all water types apart from the ground water of one supplier. The supplier that distributed more ground and lowland surface water had higher dibromochloromethane (DBCM) and bromoform levels and lower chloroform levels than the other two suppliers. In the water of two suppliers, seasonal fluctuations in bromodichloromethane (BDCM) and DBCM levels were found with levels peaking in the summer and autumn. In the other water supplier, chloroform levels followed a similar seasonal trend whereas BDCM and DBCM levels did not. For all three water suppliers, chloroform levels declined throughout 1995 when there was a drought period. There was a moderate positive correlation between the THMs most similar in their structure (chloroform and BDCM, BDCM and DBCM, and DBCM and bromoform) and a slight negative correlation between chloroform and bromoform levels.

Optimization and validation of a minicolumn method for determining aflatoxins in copra meal.

PubMed

Arim, R H; Aguinaldo, A R; Tanaka, T; Yoshizawa, T

1999-01-01

A minicolumn (MC) method for determining aflatoxins in copra meal was optimized and validated. The method uses methanol-4% KCl solution as extractant and CuSO4 solution as clarifying agent. The chloroform extract is applied to an MC that incorporates "lahar," an indigenous material, as substitute for silica gel. The "lahar"-containing MC produces a more distinct and intense blue fluoresence on the Florisil layer than an earlier MC. The method has a detection limit of 15 micrograms total aflatoxins/kg sample. Confirmatory tests using 50% H2SO4 and trifluoroacetic acid in benzene with 25% HNO3 showed that copra meal samples contained aflatoxins and no interfering agents. The MC responses of the copra meal samples were in good agreement with their behavior in thin-layer chromatography. This modified MC method is accurate, giving linearity-valid results; rapid, being done in 15 min; economical, using low-volume reagents; relatively safe, having low-exposure risk of analysts to chemicals; and simple, making its field application feasible.

In vitro antifungal activity of extracts obtained from Hypericum perforatum adventitious roots cultured in a mist bioreactor against planktonic cells and biofilm of Malassezia furfur.

PubMed

Simonetti, Giovanna; Tocci, Noemi; Valletta, Alessio; Brasili, Elisa; D'Auria, Felicia Diodata; Idoux, Alicia; Pasqua, Gabriella

2016-01-01

Xanthone-rich extracts from Hypericum perforatum root cultures grown in a Mist Bioreactor as antifungal agents against Malassezia furfur. Extracts of Hypericum perforatum roots grown in a bioreactor showed activity against planktonic cells and biofilm of Malassezia furfur. Dried biomass, obtained from roots grown under controlled conditions in a ROOTec mist bioreactor, has been extracted with solvents of increasing polarity (i.e. chloroform, ethyl acetate and methanol). The methanolic fraction was the richest in xanthones (2.86 ± 0.43 mg g(-1) DW) as revealed by HPLC. The minimal inhibitory concentration of the methanol extract against M. furfur planktonic cells was 16 μg mL(-1). The inhibition percentage of biofilm formation, at a concentration of 16 μg mL(-1), ranged from 14% to 39%. The results show that H. perforatum root extracts could be used as new antifungal agents in the treatment of Malassezia infections.

Quantitation of low molecular weight sugars by chemical derivatization-liquid chromatography/multiple reaction monitoring/mass spectrometry.

PubMed

Han, Jun; Lin, Karen; Sequria, Carita; Yang, Juncong; Borchers, Christoph H

2016-07-01

A new method for the separation and quantitation of 13 mono- and disaccharides has been developed by chemical derivatization/ultra-HPLC/negative-ion ESI-multiple-reaction monitoring MS. 3-Nitrophenylhydrazine (at 50°C for 60 min) was shown to be able to quantitatively derivatize low-molecular weight (LMW) reducing sugars. The nonreducing sugar, sucrose, was not derivatized. A pentafluorophenyl-bonded phase column was used for the chromatographic separation of the derivatized sugars. This method exhibits femtomole-level sensitivity, high precision (CVs of ≤ 4.6%) and high accuracy for the quantitation of LMW sugars in wine. Excellent linearity (R(2) ≥ 0.9993) and linear ranges of ∼500-fold for disaccharides and ∼1000-4000-fold for monosaccharides were achieved. With internal calibration ((13) C-labeled internal standards), recoveries were between 93.6% ± 1.6% (xylose) and 104.8% ± 5.2% (glucose). With external calibration, recoveries ranged from 82.5% ± 0.8% (ribulose) to 105.2% ± 2.1% (xylulose). Quantitation of sugars in two red wines and two white wines was performed using this method; quantitation of the central carbon metabolism-related carboxylic acids and tartaric acid was carried out using a previously established derivatization procedure with 3-nitrophenylhydrazine as well. The results showed that these two classes of compounds-both of which have important organoleptic properties-had different compositions in red and white wines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of oxidized coal surfaces: Quarterly report, May 1987-July 1987

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

Hercules, D.M.

1987-01-01

Work has progressed in the areas of (1) exploration or derivatization reactions for ambient temperature in-situ derivatization of aldehydes, ketones, and phenols on carbon surfaces; (2) analysis of these derivatives by secondary ion mass spectrometry (SIMS) and laser mass spectrometry (LMS); (3) derivatization and analysis of a naturally weathered coal; (4) construction of a reactor for controlled low temperature oxidation of coal; and (5) design of a protocol for handling coal samples. Specific derivatization reactions studied in this period included reactions of Girard's reagent, 2,4-dinitrophenylhydrazine and bisulfite with aldehydes and ketones and 4-triethylammonium-2-butene (TAB), trimethylsilyl ethers (TMS) and dimethylsilyl ethersmore » (DMS) with phenols and alcohols. Positive ion SIMS analysis of Girard's reagent derivatives and TAB derivatives on a silver support yielded molecular ion species (e.g., cations from the salts) for a wide range of carbonyl and phenolic compounds, respectively. Comparison of negative ion LMS spectra of naturally weathered Illinois No. 6 coal before and after treatment with 2,4-dinitrophenylhydrazine reveals the presence of two high mass ions in the spectrum of treated coal that are not present in the spectra of either the untreated coal or the derivatizing reagent. This provides both evidence for carbonyl functionality on the surface of naturally weathered Illinois No. 6 coal and support for the feasibility of in-situ derivatization and analysis of organic components in the coal matrix. 5 refs.« less

A novel amino acid analysis method using derivatization of multiple functional groups followed by liquid chromatography/tandem mass spectrometry.

PubMed

Sakaguchi, Yohei; Kinumi, Tomoya; Yamazaki, Taichi; Takatsu, Akiko

2015-03-21

We have developed a novel amino acid analysis method using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups). The amino, carboxyl, and phenolic hydroxyl groups of the amino acids were derivatized with 1-bromobutane so that the hydrophobicities and basicities of the amino acids were improved. The derivatized amino acids, including amino group-modified amino acids, could be detected with high sensitivity using liquid chromatography/tandem mass spectrometry (LC-MS/MS). In this study, 17 amino acids obtained by hydrolyzing proteins and 4 amino group-modified amino acids found in the human body (N,N-dimethylglycine, N-formyl-L-methionine, L-pyroglutamic acid, and sarcosine) were selected as target compounds. The 21 derivatized amino acids could be separated using an octadecyl-silylated silica column within 20 min and simultaneously detected. The detection limits for the 21 amino acids were 5.4-91 fmol, and the calibration curves were linear over the range of 10-100 nmol L(-1) (r(2) > 0.9984) with good repeatability. A confirmatory experiment showed that our proposed method could be applied to the determination of a protein certified reference material using the analysis of 12 amino acids combined with isotope dilution mass spectrometry. Furthermore, the proposed method was successfully applied to a stable isotope-coded derivatization method using 1-bromobutane and 1-bromobutane-4,4,4-d3 for comparative analysis of amino acids in human serum.

Enhanced detectability of fluorinated derivatives of N,N-dialkylamino alcohols and precursors of nitrogen mustards by gas chromatography coupled to Fourier transform infrared spectroscopy analysis for verification of chemical weapons convention.

PubMed

Garg, Prabhat; Purohit, Ajay; Tak, Vijay K; Dubey, D K

2009-11-06

N,N-Dialkylamino alcohols, N-methyldiethanolamine, N-ethyldiethanolamine and triethanolamine are the precursors of VX type nerve agents and three different nitrogen mustards respectively. Their detection and identification is of paramount importance for verification analysis of chemical weapons convention. GC-FTIR is used as complimentary technique to GC-MS analysis for identification of these analytes. One constraint of GC-FTIR, its low sensitivity, was overcome by converting the analytes to their fluorinated derivatives. Owing to high absorptivity in IR region, these derivatives facilitated their detection by GC-FTIR analysis. Derivatizing reagents having trimethylsilyl, trifluoroacyl and heptafluorobutyryl groups on imidazole moiety were screened. Derivatives formed there were analyzed by GC-FTIR quantitatively. Of these reagents studied, heptafluorobutyrylimidazole (HFBI) produced the greatest increase in sensitivity by GC-FTIR detection. 60-125 folds of sensitivity enhancement were observed for the analytes by HFBI derivatization. Absorbance due to various functional groups responsible for enhanced sensitivity were compared by determining their corresponding relative molar extinction coefficients ( [Formula: see text] ) considering uniform optical path length. The RSDs for intraday repeatability and interday reproducibility for various derivatives were 0.2-1.1% and 0.3-1.8%. Limit of detection (LOD) was achieved up to 10-15ng and applicability of the method was tested with unknown samples obtained in international proficiency tests.

Determination of glyoxal and methylglyoxal in environmental and biological matrices by stir bar sorptive extraction with in-situ derivatization.

PubMed

Neng, N R; Cordeiro, C A A; Freire, A P; Nogueira, J M F

2007-10-26

Stir bar sorptive extraction with in-situ derivatization using 2,3-diaminonaphthalene (DAN) followed by liquid desorption and high performance liquid chromatography with diode array detection (SBSE(DAN)in-situ-LD-HPLC-DAD) was developed for the determination of glyoxal (Gly) and methylglyoxal (MGly) in environmental and biological matrices. DAN proved very good specificity as in-situ derivatising agent for Gly and MGly in aqueous media, allowing the formation of adducts with remarkable sensitivity, selectivity and the absence of photodegradation. Assays performed on spiked (1.0 microg L(-1)) water samples, under convenient experimental conditions, yielded recoveries of 96.2+/-7.9% for Gly and 96.1+/-6.4% for MGly. The analytical performance showed good accuracy, suitable precision (<12.0%), low detection limits (15 ng L(-1) for Gly and 25 ng L(-1) for MGly adducts) and excellent linear dynamic ranges (r2>0.99) from 0.1 to 120.0 microg L(-1). By using the standard addition method, the application of the present method to tap and swimming-pool water, beer, yeast cells suspension and urine samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, showing to be easy to implement, reliable, sensitive and with a low sample volume requirement to monitor Gly and MGly in environmental and biological matrices.

Chemometric studies for the characterization and differentiation of microorganisms using in situ derivatization and thermal desorption ion mobility spectrometry.

PubMed

Ochoa, Mariela L; Harrington, Peter B

2005-02-01

Whole-cell bacteria were characterized and differentiated by thermal desorption ion mobility spectrometry and chemometric modeling. Principal component analysis was used to evaluate the differences in the ion mobility spectra of whole-cell bacteria and the fatty acid methyl esters (FAMEs) generated in situ after derivatization of the bacterial lipids. Alternating least squares served to extract bacterial peaks from the complex ion mobility spectra of intact microorganisms and, therefore, facilitated the characterization of bacterial strains, species, and Gram type. In situ thermal hydrolysis/methylation with tetramethylammonium hydroxide was necessary for the differentiation of Escherichia coli strains, which otherwise could not be distinguished by spectra acquired with the ITEMISER ion mobility spectrometer. The addition of the methylating agent had no effect on Gram-positive bacteria, and therefore, they could not be differentiated by genera. The classification of E. coli strains was possible by analysis of the IMS spectra from the FAMEs generated in situ. By using the fuzzy multivariate rule-building expert system and cross-validation, a correct classification rate of 96% (22 out of 23 spectra) was obtained. Chemometric modeling on bacterial ion mobility spectra coupled to thermal hydrolysis/methylation proved a simple, rapid (2 min/sample), inexpensive, and sensitive technique to characterize and differentiate intact microorganisms. The ITEMISER ion mobility spectrometer could detect as few as 4 x 10(6) cells/sample.

Analysis and differentiation of paper samples by capillary electrophoresis and multivariate analysis.

PubMed

Fernández de la Ossa, Ma Ángeles; Ortega-Ojeda, Fernando; García-Ruiz, Carmen

2014-11-01

This work reports an investigation for the analysis of different paper samples using CE with laser-induced detection. Papers from four different manufactures (white-copy paper) and four different paper sources (white and recycled-copy papers, adhesive yellow paper notes and restaurant serviettes) were pulverized by scratching with a surgical scalpel prior to their derivatization with a fluorescent labeling agent, 8-aminopyrene-1,3,6-trisulfonic acid. Methodological conditions were evaluated, specifically the derivatization conditions with the aim to achieve the best S/N signals and the separation conditions in order to obtain optimum values of sensitivity and reproducibility. The best conditions, in terms of fastest, and easiest sample preparation procedure, minimal sample consumption, as well as the use of the simplest and fastest CE-procedure for obtaining the best analytical parameters, were applied to the analysis of the different paper samples. The registered electropherograms were pretreated (normalized and aligned) and subjected to multivariate analysis (principal component analysis). A successful discrimination among paper samples without entanglements was achieved. To the best of our knowledge, this work presents the first approach to achieve a successful differentiation among visually similar white-copy paper samples produced by different manufactures and paper from different paper sources through their direct analysis by CE-LIF and subsequent comparative study of the complete cellulose electropherogram by chemometric tools. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A modified LC-MS/MS method to simultaneously quantify glycerol and mannitol concentrations in human urine for doping control purposes.

PubMed

Dong, Ying; Yan, Kuan; Ma, Yanhua; Yang, Zhiyong; Zhao, Jun; Ding, Jinglin

2016-06-01

Glycerol and mannitol have the potential to act as plasma volume expanders and have been prohibited as masking agents by the World Anti-Doping Agency (WADA) accordingly. In this study, an improved strategy was developed and validated for the determination of urinary glycerol and mannitol levels simultaneously using a liquid chromatography/tandem mass spectrometry technique within 7min in an initial testing procedure. For confirmation, mannitol and all possible hexitols (allitol, altritol, galactitol, iditol and sorbitol) that can occur in human urine were baseline separated. This method made use of the derivatization of glycerol and mannitol by benzoyl chloride followed by analysis via LC-ESI-MS/MS with limited sample preparation. The limit of detection (LOD) for glycerol and mannitol was lower than 50ng/mL. The limit of quantitation (LOQ) for both substances was below 150ng/mL. The assay was linear from 0.15 to 1000μg/mL for glycerol and mannitol in human urine. The coefficients of variation of all inter- and intra-assay determinations at three concentration levels (0.5, 500, 900μg/mL) were better than 13% for glycerol and under 15% for mannitol. The method also afforded satisfactory results in terms of accuracy, derivatization yield, extraction recovery, matrix effect and specificity for both substances. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 177.1595 - Polyetherimide resin.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... Polyetherimide resin identified in paragraph (a) of this section shall have an intrinsic viscosity in chloroform... Viscosity of ULTEM Polyetherimide Using Chloroform as the Solvent,” which is incorporated by reference...

Breakable mesoporous silica nanoparticles for targeted drug delivery

NASA Astrophysics Data System (ADS)

Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A.; Robinet, Eric; de Cola, Luisa

2016-03-01

``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. Electronic supplementary information (ESI) available: Full experimental procedures, additional SEM and TEM images of particles, complete UV-Vis and PL-monitored characterization of the breakdown of the particles, SAXS, N2 adsorption, cytotoxicity assays. See DOI: 10.1039/c5nr09112h

Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins.

PubMed

Singh, Varoon; Garg, Prabhat; Chinthakindi, Sridhar; Tak, Vijay; Dubey, Devendra Kumar

2014-02-14

Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC-MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL(-1). The LOD and LOQ ranged from 2 to 6ngmL(-1) and 5 to 19ngmL(-1) respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of Diacetyl in Beer by a Precolumn Derivatization-HPLC-UV Method Using 4-(2,3-Dimethyl-6-quinoxalinyl)-1,2-benzenediamine as a Derivatizing Reagent.

PubMed

Wang, Ji-Yu; Wang, Xin-Jie; Hui, Xian; Hua, Shui-Hong; Li, Heng; Gao, Wen-Yun

2017-03-29

Diacetyl is an important flavoring compound in many foods, especially in beer. In the present study, we developed and validated a new precolumn derivatization HPLC-UV method for the determination of diacetyl using 4-(2,3-dimethyl-6-quinoxalinyl)-1,2-benzenediamine as a novel derivatizing reagent. After derivatization with the reagent at a pH value 4.0 at ambient temperature for 10 min, diacetyl was analyzed on an ODS column and detected at 254 nm. The results show that the correlation coefficient of the method is 0.9991 in the range of 0.10 to 100.0 μM diacetyl, and the limit of detection is 0.02 μM. The method was further evaluated in the analysis of beer samples with the recoveries ranging from 94.4 to 102.6% and RSDs from 1.36 to 3.33%. The concentrations of diacetyl in 8 beer samples were determined in the range of 0.19 to 0.42 μM. The method established in this study may be well suitable for the determination of diacetyl in beer.

Simultaneous Determination of Oleanolic Acid and Ursolic Acid by in Vivo Microdialysis via UHPLC-MS/MS Using Magnetic Dispersive Solid Phase Extraction Coupling with Microwave-Assisted Derivatization and Its Application to a Pharmacokinetic Study of Arctiumlappa L. Root Extract in Rats.

PubMed

Zheng, Zhenjia; Zhao, Xian-En; Zhu, Shuyun; Dang, Jun; Qiao, Xuguang; Qiu, Zhichang; Tao, Yanduo

2018-04-18

Simultaneous detection of oleanolic acid and ursolic acid in rat blood by in vivo microdialysis can provide important pharmacokinetics information. Microwave-assisted derivatization coupled with magnetic dispersive solid phase extraction was established for the determination of oleanolic acid and ursolic acid by liquid chromatography tandem mass spectrometry. 2'-Carbonyl-piperazine rhodamine B was first designed and synthesized as the derivatization reagent, which was easily adsorbed onto the surface of Fe 3 O 4 /graphene oxide. Simultaneous derivatization and extraction of oleanolic acid and ursolic acid were performed on Fe 3 O 4 /graphene oxide. The permanent positive charge of the derivatization reagent significantly improved the ionization efficiencies. The limits of detection were 0.025 and 0.020 ng/mL for oleanolic acid and ursolic acid, respectively. The validated method was shown to be promising for sensitive, accurate, and simultaneous determination of oleanolic acid and ursolic acid. It was used for their pharmacokinetics study in rat blood after oral administration of Arctiumlappa L. root extract.

Phloroglucinol Degradation in the Rumen Promotes the Capture of Excess Hydrogen Generated from Methanogenesis Inhibition.

PubMed

Martinez-Fernandez, Gonzalo; Denman, Stuart E; Cheung, Jane; McSweeney, Christopher S

2017-01-01

Strategies to manage metabolic hydrogen ([H]) in the rumen should be considered when reducing ruminant methane (CH 4 ) emissions. However, little is known about the use of dietary treatments to stimulate rumen microorganisms capable of capturing the [H] available when CH 4 is inhibited in vivo . The effects of the phenolic compound phloroglucinol on CH 4 production, [H] flows and subsequent responses in rumen fermentation and microbial community composition when methanogenesis is inhibited were investigated in cattle. Eight rumen fistulated Brahman steers were randomly allocated in two groups receiving chloroform as an antimethanogenic compound for 21 days. Following that period one group received chloroform + phloroglucinol for another 16 days, whilst the other group received only chloroform during the same period. The chloroform treatment resulted in a decrease in CH 4 production and an increase in H 2 expelled with a shift in rumen fermentation toward higher levels of propionate and formate and lower levels of acetate at day 21 of treatment. Bacterial operational taxonomic units (OTUs) assigned to Prevotella were promoted whilst Archaea and Synergistetes OTUs were decreased with the chloroform treatment as expected. The shift toward formate coincided with increases in Ruminococcus flavefaciens , Butyrivibrio fibrisolvens , and Methanobrevibacter ruminantium species. The addition of chloroform + phloroglucinol in the rumen resulted in a decrease of H 2 expelled (g) per kg of DMI and moles of H 2 expelled per mol of CH 4 decreased compared with the chloroform only treated animals. A shift toward acetate and a decrease in formate were observed for the chloroform + phloroglucinol-treated animals at day 37. These changes in the rumen fermentation profile were accompanied by a relative increase of OTUs assigned to Coprococcus spp., which could suggest this genus is a significant contributor to the metabolism of this phenolic compound in the rumen. This study demonstrates for the first time in vivo that under methanogenesis inhibition, H 2 gas accumulation can be decreased by redirecting [H] toward alternative sinks through the nutritional stimulation of specific microbial groups. This results in the generation of metabolites of value for the host while also helping to maintain a low H 2 partial pressure in the methane-inhibited rumen.

Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography-fluorescence detection.

PubMed

Muniraj, Sarangapani; Yan, Cheing-Tong; Shih, Hou-Kung; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2012-11-19

A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ng mL(-1)) based on SN(-1)=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Process for derivatizing carbon nanotubes with diazonium species and compositions thereof

NASA Technical Reports Server (NTRS)

Bahr, Jeffrey L. (Inventor); Tour, James M. (Inventor); Yang, Jiping (Inventor)

2011-01-01

Methods for the chemical modification of carbon nanotubes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications, and sensor devices. The methods of derivatization include electrochemical induced reactions, thermally induced reactions, and photochemically induced reactions. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes.

Characterization of oxidized coal surfaces: Quarterly report, January 1987-April 1987

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

Hercules, D.M.

1987-04-01

The work has focused on exploration of ambient temperature in-situ derivatization of aldehydes and ketones on carbon surfaces. 2,4-Dinitrophenylhydrazine, bisulfite, -ylium dichloro-iodate, and iminium perchlorate derivatizations were performed on a set of model aldehydes and ketones. Positive and negative ion laser mass spectra (LMS) of the 2,4-dinitrophenylhydrazine derivatives were obtained on zinic which is a common metal support used for LMS analysis. Although positive ion spectra were informative, negative ion spectra were more satisfactory as most compounds yielded molecular ion species in negative ion analysis. Spectra of selected preformed derivatives placed on charcoal and of benzaldehyde derivatized on charcoal weremore » also obtained. Molecular ion species that can be distinguished readily from carbon background ions were observed. Thus, the results established that in-situ derivatization followed by analysis is indeed possible. 3 refs., 8 figs.« less

Reduction mechanism of sulfur in lithium-sulfur battery: From elemental sulfur to polysulfide

DOE PAGES

Zheng, Dong; Yang, Xuran; Zhang, Xiaoqing; ...

2015-10-30

In this study, the polysulfide ions formed during the first reduction wave of sulfur in Li–S battery were determined through both in-situ and ex-situ derivatization of polysulfides. By comparing the cyclic voltammetric results with and without the derivatization reagent (methyl triflate) as well as the in-situ and ex-situ derivatization results under potentiostatic condition, in-situ derivatization was found to be more appropriate than its ex-situ counterpart, since subsequent fast chemical reactions between the polysulfides and sulfur may occur during the timeframe of ex-situ procedures. It was found that the major polysulfide ions formed at the first reduction wave of elemental sulfurmore » were the S 4 2– and S 5 2– species, while the widely accepted reduction products of S 8 2– and S 6 2– for the first reduction wave were in low abundance.« less

Fluorination, Defluorination, Derivatization and Solvation of Single-Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Margrave, John L.

1999-10-01

Direct fluorination has been used to create fluoronanotubes which have active sites for derivatizing carbon nanotubes. A new technique using hydrazine and its derivatives has been used for defluorination of fluoronanotubes. The products include N2 and HF. Fluorinated species can be derivatized with R-Li or Grignard Reagents to form inorganic fluorides and derivatized products e.g., methyl, butyl or hexyl-nanotubes, (NH2)x-nanotubes, etc. Mass-spectra IR and Raman spectra along with electron microprobe analyses have been utilized, along with AFM, SEM and TEM to characterize the products. ``Fluorotubes" can be solvated as individual tubes in various alcohol solvents via ultrasonication. These solutions persist long enough (over a week) to permit solution phase chemistry to be carried out on the fluorotubes. For example, the solvated fluorotubes can be precipitated out of solution with hydrazine to yield normal, unfluorinated SWNTs or they can be reacted with sodium methoxide to yield methoxylated SWNTs.

Sedaxicenes: potential new antifungal ferrocene-based agents?

PubMed

Rubbiani, R; Blacque, O; Gasser, G

2016-04-21

Fungal infections are a group of diseases spread all over the world with an extremely high morbidity. Worryingly, although several pathogenic fungi were found to develop resistance towards traditional therapy, research towards the discovery of novel antimycotic agents is very limited. Considering the promising results obtained with the ferrocene-based drug candidates Ferroquine and Ferrocifen as antimalarial and anticancer drug candidates, respectively, we envisaged derivatizing the organic scaffold of a new broad-spectrum fungicide, namely sedaxane, with a ferrocenyl moiety in order to obtain new metal-based antifungal agents. The new ferrocenyl sedaxane derivatives called herein Sedaxicenes (, and ) were characterized using different analytical techniques and the structures were confirmed by X-ray crystallography. As expected for antimycotic agents, , and were found to have a low or even no toxicity towards human cells (IC50 > 100 μM). Interestingly, while the parent drug did not display any mycotoxicity (EC50 > 100 μM), complex was found to have some antifungal activity with an IC50 value of 43 μM under the same experimental conditions. In order to investigate the possible redox-mediated mode of action of , we synthesized the ruthenocene analogue of , namely . Ruthenocene is known to have a completely different electrochemical behaviour from ferrocene although both the compounds are isostructural. As anticipated, complex was found to induce an increase of the reactive oxygen species level in S. cerevisiae, contrary to its analogue and to the parent compound sedaxane.

Determination of Glyphosate, its Degradation Product Aminomethylphosphonic Acid, and Glufosinate, in Water by Isotope Dilution and Online Solid-Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry

USGS Publications Warehouse

Meyer, Michael T.; Loftin, Keith A.; Lee, Edward A.; Hinshaw, Gary H.; Dietze, Julie E.; Scribner, Elisabeth A.

2009-01-01

The U.S. Geological Survey method (0-2141-09) presented is approved for the determination of glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate in water. It was was validated to demonstrate the method detection levels (MDL), compare isotope dilution to standard addition, and evaluate method and compound stability. The original method USGS analytical method 0-2136-01 was developed using liquid chromatography/mass spectrometry and quantitation by standard addition. Lower method detection levels and increased specificity were achieved in the modified method, 0-2141-09, by using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The use of isotope dilution for glyphosate and AMPA and pseudo isotope dilution of glufosinate in place of standard addition was evaluated. Stable-isotope labeled AMPA and glyphosate were used as the isotope dilution standards. In addition, the stability of glyphosate and AMPA was studied in raw filtered and derivatized water samples. The stable-isotope labeled glyphosate and AMPA standards were added to each water sample and the samples then derivatized with 9-fluorenylmethylchloroformate. After derivatization, samples were concentrated using automated online solid-phase extraction (SPE) followed by elution in-line with the LC mobile phase; the compounds separated and then were analyzed by LC/MS/MS using electrospray ionization in negative-ion mode with multiple-reaction monitoring. The deprotonated derivatized parent molecule and two daughter-ion transition pairs were identified and optimized for glyphosate, AMPA, glufosinate, and the glyphosate and AMPA stable-isotope labeled internal standards. Quantitative comparison between standard addition and isotope dilution was conducted using 473 samples analyzed between April 2004 and June 2006. The mean percent difference and relative standard deviation between the two quantitation methods was 7.6 plus or minus 6.30 (n = 179), AMPA 9.6 plus or minus 8.35 (n = 206), and glufosinate 9.3 plus or minus 9.16 (n = 16). The analytical variation of the method, comparison of quantitation by isotope dilution and multipoint linear regressed standard curves, and method detection levels were evaluated by analyzing six sets of distilled-water, groundwater, and surface-water samples spiked in duplicate at 0.0, 0.05, 0.10 and 0.50 microgram per liter and analyzed on 6 different days during 1 month. The grand means of the normalized concentration percentage recovery for glyphosate, AMPA, and glufosinate among all three matrices and spiked concentrations ranged from 99 to 114 plus or minus 2 to 7 percent of the expected spiked concentration. The grand mean of the percentage difference between concentrations calculated by standard addition and linear regressed multipoint standard curves ranged from 8 to 15 plus or minus 2 to 9 percent for the three compounds. The method reporting levels calculated from all the 0.05- microgram per liter spiked samples were 0.02 microgram per liter for all three compounds. Compound stability experiments were conducted on 10 samples derivatized four times for periods between 136 to 269 days. The glyphosate and AMPA concentrations remained relatively constant in samples held up to 136 days before derivatization. The half life of glyphosate varied from 169 to 223 days in the underivatized samples. Derivatized samples were analyzed the day after derivitization, and again 54 and 64 days after derivatization. The derivatized samples analyzed at days 52 and 64 were within 20 percent of the concentrations of the derivatized samples analyzed the day after derivatization.

One drop chemical derivatization--DESI-MS analysis for metabolite structure identification.

PubMed

Lubin, Arnaud; Cabooter, Deirdre; Augustijns, Patrick; Cuyckens, Filip

2015-07-01

Structural elucidation of metabolites is an important part during the discovery and development process of new pharmaceutical drugs. Liquid Chromatography (LC) in combination with Mass Spectrometry (MS) is usually the technique of choice for structural identification but cannot always provide precise structural identification of the studied metabolite (e.g. site of hydroxylation and site of glucuronidation). In order to identify those metabolites, different approaches are used combined with MS data including nuclear magnetic resonance, hydrogen/deuterium exchange and chemical derivatization followed by LC-MS. Those techniques are often time-consuming and/or require extra sample pre-treatment. In this paper, a fast and easy to set up tool using desorption electrospray ionization-MS for metabolite identification is presented. In the developed method, analytes in solution are simply dried on a glass plate with printed Teflon spots and then a single drop of derivatization mixture is added. Once the spot is dried, the derivatized compound is analyzed. Six classic chemical derivatizations were adjusted to work as a one drop reaction and applied on a list of compounds with relevant functional groups. Subsequently, two successive reactions on a single spot of amoxicillin were tested and the methodology described was successfully applied on an in vitro incubated alprazolam metabolite. All reactions and analyses were performed within an hour and gave useful structural information by derivatizing functional groups, making the method a time-saving and efficient tool for metabolite identification if used in addition or in some cases as an alternative to common methods. Copyright © 2015 John Wiley & Sons, Ltd.

Determination of residual 4-nitrobenzaldehyde in chloramphenicol and its pharmaceutical formulation by HPLC with UV/Vis detection after derivatization with 3-nitrophenylhydrazine.

PubMed

Luo, Lan; Gu, Congcong; Li, Mingxian; Zheng, Xiangyuan; Zheng, Feng

2018-04-21

4-Nitrobenzaldehyde is the synthetic raw material and an important photodegradation product of chloramphenicol. With a structural "alert" of human genotoxic potential and reported mutagenicity, this compound should be controlled in drug substances as a potential genotoxic impurity. However, current analysis methods require complex pre-treatment processes and/or lack sufficient specificity and sensitivity. Nitrophenylhydrazine is a common carbonyl derivatization reagent used to determine the residual aromatic aldehydes in drug samples. In the present study, we report an unexpected advantage of 3-nitrophenylhydrazine hydrochloride as a derivatization reagent in the derivatization high-performance liquid chromatography-ultraviolet detection method to determine 4-nitrobenzaldehyde in chloramphenicol samples. Compared with other nitro-substituted phenylhydrazines, 3-nitrophenylhydrazine hydrochloride can minimize drug matrix and derivatization reagent interferences, since the maximum absorption wavelength of its derivative is significantly red-shifted to 397 nm. The derivatization conditions have been optimized in terms of reaction efficiency, including reaction temperature, time, and diluting solvent, through a design of experiments. As a result, after reaction with 500 μg mL -1 of 3-nitrophenylhydrazine hydrochloride in acetonitrile-water (70:30, v/v) at 60 °C for 30 min, the developed HPLC method could be used to determine 4-nitrobenzaldehyde with a limit of detection of 0.009 μg mL -1 . The method was then validated and applied for the determination of residual 4-nitrobenzaldehyde in chloramphenicol and its eye-drop samples. Copyright © 2018. Published by Elsevier B.V.

In-capillary derivatization with o-phthalaldehyde in the presence of 3-mercaptopropionic acid for the simultaneous determination of monosodium glutamate, benzoic acid, and sorbic acid in food samples via capillary electrophoresis with ultraviolet detection.

PubMed

Aung, Hnin-Pwint; Pyell, Ute

2016-06-03

For the rapid simultaneous determination of monosodium glutamate (MSG), benzoic acid (BA), and sorbic acid (SA) in canned food and other processed food samples, we developed a method that combines in-capillary derivatization with separation by capillary electrophoresis. This method employs the rapid derivatization of MSG with o-phthalaldehyde (OPA) in the presence of 3-mercaptopropionic acid (3-MPA) and enables the detection of the resulting OPA-MSG derivative and of non-derivatized BA and SA at 230nm. The composition of the background electrolyte and the parameters of derivatization and separation are as follows: 25mM borax containing 5mM OPA and 6mM 3-MPA, separation voltage 25mV, injection at 30mbar for 20s, and column temperature 25°C. Because of the high reaction rate and suitably adapted effective electrophoretic mobilities, band broadening due to the derivatization reaction at the start of the separation process is kept to a minimum. The optimized method is validated with respect to LOD, LOQ, linearity, recovery, and precision. This method can be applied to real samples such as soy, fish, oyster and sweet and sour chili sauces after application of appropriate clean-up steps. Mechanisms of zone broadening and zone focusing are discussed showing the validity of the employed theoretical approach regarding the dependence of the peak shape for OPA-MSG on the concentration of MSG in the sample. Copyright © 2016 Elsevier B.V. All rights reserved.

A rational approach to heavy-atom derivative screening

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

Joyce, M. Gordon; Radaev, Sergei; Sun, Peter D., E-mail: psun@nih.gov

2010-04-01

In order to overcome the difficulties associated with the ‘classical’ heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom-derivative screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification. Despite the development in recent times of a range of techniques for phasing macromolecules, the conventional heavy-atom derivatization method still plays a significant role in protein structure determination. However, this method has become less popular in modern high-throughput oriented crystallography, mostly owing to its trial-and-error nature, which often results in lengthy empirical searches requiring large numbers of well diffracting crystals. In addition, the phasingmore » power of heavy-atom derivatives is often compromised by lack of isomorphism or even loss of diffraction. In order to overcome the difficulties associated with the ‘classical’ heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom derivative-screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification. The method includes three basic steps: (i) the selection of likely reactive compounds for a given protein and specific crystallization conditions based on pre-defined heavy-atom compound reactivity profiles, (ii) screening of the chosen heavy-atom compounds for their ability to form protein adducts using mass spectrometry and (iii) derivatization of crystals with selected heavy-metal compounds using the quick-soak method to maximize diffraction quality and minimize non-isomorphism. Overall, this system streamlines the process of heavy-atom compound identification and minimizes the problem of non-isomorphism in phasing.« less

[Determination of fumonisins B1 and B2 in corn by high performance liquid chromatography with post-column derivatization method].

PubMed

Zhang, Xiaoxu; Xiao, Zhiyong; Zhang, Hongyan; Yang, Lili; Ma, Liyan

2012-08-01

A high performance liquid chromatography-fluorescence detection with post-column derivatization method was developed to detect fumonisin B1 (FB1) and fumonisin B2 (FB2) in corn. Several factors, such as the pH of derivatization buffer, concentration and flow rate of derivatization reagents, excitation wavelength, emission wavelength, which affected the detection of fumonisins were optimized. The separation was performed on a ZORBAX SB C18 column operated at 40 degrees C with the gradient elution by two mobile phases of 0.1 mol/L sodium dihydrogen phosphate solution (pH 3.3) and methanol at a flow rate of 0.8 mL/min. The derivatization was performed at ambient temperature. The o-phthalaldehyde (OPA) flow rate was 0.4 mL/min. The results showed that the optimum conditions were pH 10.5 of the derivatization reagent, OPA concentration at 2 g/L, and excitation wavelength of 335 nm, emission wavelength of 440 nm. The linear plots of FB1 and FB2 were obtained between 0.2 to 20 mg/L, with the correlation coefficients above 0.999 for both FB1 and FB2. The limits of detection of fumonisins B1 and B2 were 0.02 mg/kg. The mean recoveries at the three spiked levels of 0.1 - 4.0 mg/kg were 82.5% - 89.8%. This method is accurate, simple, rapid and suitable for the determination of fumonisins B1 and B2 in corn.

Phytochemical Constituents and Antimicrobial Activity of the Ethanol and Chloroform Crude Leaf Extracts of Spathiphyllum cannifolium (Dryand. ex Sims) Schott.

PubMed

Dhayalan, Arunachalam; Gracilla, Daniel E; Dela Peña, Renato A; Malison, Marilyn T; Pangilinan, Christian R

2018-01-01

The study investigated the medicinal properties of Spathiphyllum cannifolium (Dryand. ex Sims) Schott as a possible source of antimicrobial compounds. The phytochemical constituents were screened using qualitative methods and the antibacterial and antifungal activities were determined using agar well diffusion method. One-way analysis of variance and Fisher's least significant difference test were used. The phytochemical screening showed the presence of sterols, flavonoids, alkaloids, saponins, glycosides, and tannins in both ethanol and chloroform leaf extracts, but triterpenes were detected only in the ethanol leaf extract. The antimicrobial assay revealed that the chloroform leaf extract inhibited Candida albicans, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa , whereas the ethanol leaf extract inhibited E. coli , S. aureus , and B. subtilis only. The ethanol and chloroform leaf extracts exhibited the highest zone of inhibition against B. subtilis . The antifungal assay showed that both the leaf extracts have no bioactivity against Aspergillus niger and C. albicans . Results suggest that chloroform is the better solvent for the extraction of antimicrobial compounds against the test organisms used in this study. Findings of this research will add new knowledge in advancing drug discovery and development in the Philippines.

Acaricidal activity of extracts of neem (Azadirachta indica) oil against the larvae of the rabbit mite Sarcoptes scabiei var. cuniculi in vitro.

PubMed

Du, Yong-Hua; Jia, Ren-Yong; Yin, Zhong-Qiong; Pu, Zhong-Hui; Chen, Jiao; Yang, Fan; Zhang, Yu-Qun; Lu, Yang

2008-10-20

The acaricidal activity of the petroleum ether extract, the chloroform extract and the acetic ether extract of neem (Azadirachta indica) oil against Sarcoptes scabiei var. cuniculi larvae was tested in vitro. A complementary log-log (CLL) model was used to analyze the data of the toxicity tests. The results showed that at all test time points, the petroleum ether extract demonstrated the highest activity against the larvae of S. scabiei var. cuniculi, while the activities of the chloroform extract and the acetic ether extract were similar. The activities of both the petroleum ether extract and the chloroform extract against the larvae showed the relation of time and concentration dependent. The median lethal concentration (LC50) of the petroleum ether extract (1.3 microL/mL) was about three times that of the chloroform extract (4.1 microL/mL) at 24 h post-treatment. At the concentrations of 500.0 microL/mL, the median lethal time (LT50) of the petroleum ether extract and the chloroform extract was 8.4 and 9.6 h, respectively.

Comparison of different amino acid derivatives and analysis of rat brain microdialysates by liquid chromatography tandem mass spectrometry.

PubMed

Uutela, Päivi; Ketola, Raimo A; Piepponen, Petteri; Kostiainen, Risto

2009-02-09

The efficiencies of three derivatisation reagents that react with either the amine (9-fluorenylmethyl chloroformate (FMOC)) or the carboxylic acid group (butanol) of amino acid or with both types of functional groups (propyl chloroformate) were compared in the analysis of amino acids by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). Separation of 20 amino acids derivatised with these three reagents was studied on reversed-phase chromatography. Linearity, repeatability and limits of detection of the LC-ESI-MS/MS method were determined by analysing FMOC-, butanol- and propyl chloroformate-derivatised lysine, beta-aminobutyric acid, threonine and glutamic acid. The limits of detection for the derivatised amino acids (7.5-75fmol) were as much as 2-60 times lower than those of the corresponding underivatised molecules. The best linearity was observed for amino acids derivatised with propyl chloroformate or butanol (r(2)=0.996-0.999, range=100-8500nmolL(-1)). Propyl chloroformate was the best suited of the reagents tested for the analysis of amino acids with LC-MS/MS and was used for the analysis of amino acids in rat brain microdialysis samples.

Electrophoretic deposition of silicon substituted hydroxyapatite coatings from n-butanol-chloroform mixture.

PubMed

Xiao, Xiu Feng; Liu, Rong Fang; Tang, Xiao Lian

2008-01-01

Silicon Substituted Hydroxyapatite (Si-HA) coatings were prepared on titanium substrates by electrophoretic deposition (EPD). The stability of Si-HA suspension in n-butanol and chloroform mixture has been studied by electricity conductivity and sedimentation test. The microstructure, shear strength and bioactivity in vitro has been tested. The stability of Si-HA suspension containing n-butanol and chloroform mixture as medium is better than that of pure n-butanol as medium. The good adhesion of the particles with the substrate and good cohesion between the particles were obtained in n-butanol and chloroform mixture. Adding triethanolamine (TEA) as additive into the suspension is in favor of the formation of uniform and compact Si-HA coatings on the titanium substrates by EPD. The shear strength of the coatings can reach 20.43 MPa after sintering at 700 degrees C for 2 h, when the volume ratio of n-butanol: chloroform is 2:1 and the concentration of TEA is 15 ml/L. Titanium substrates etched in H(2)O(2)/NH(3) solution help to improve the shear strength of the coatings. After immersion in simulated body fluid for 7 days, Si-HA coatings have the ability to induce the bone-like apatite formation.

21 CFR 700.18 - Use of chloroform as an ingredient in cosmetic products.

Code of Federal Regulations, 2010 CFR

2010-04-01

... animals. Studies conducted by the National Cancer Institute have demonstrated that the oral administration of chloroform to mice and rats induced hepatocellular carcinomas (liver cancer) in mice and renal...

21 CFR 700.18 - Use of chloroform as an ingredient in cosmetic products.

Code of Federal Regulations, 2011 CFR

2011-04-01

... animals. Studies conducted by the National Cancer Institute have demonstrated that the oral administration of chloroform to mice and rats induced hepatocellular carcinomas (liver cancer) in mice and renal...

21 CFR 700.18 - Use of chloroform as an ingredient in cosmetic products.

Code of Federal Regulations, 2013 CFR

2013-04-01

... animals. Studies conducted by the National Cancer Institute have demonstrated that the oral administration of chloroform to mice and rats induced hepatocellular carcinomas (liver cancer) in mice and renal...

21 CFR 700.18 - Use of chloroform as an ingredient in cosmetic products.

Code of Federal Regulations, 2012 CFR

2012-04-01

... animals. Studies conducted by the National Cancer Institute have demonstrated that the oral administration of chloroform to mice and rats induced hepatocellular carcinomas (liver cancer) in mice and renal...

21 CFR 700.18 - Use of chloroform as an ingredient in cosmetic products.

Code of Federal Regulations, 2014 CFR

2014-04-01

... animals. Studies conducted by the National Cancer Institute have demonstrated that the oral administration of chloroform to mice and rats induced hepatocellular carcinomas (liver cancer) in mice and renal...

Mass spectrometer having a derivatized sample presentation apparatus

DOEpatents

Nelson, Randall W.

2000-07-25

A mass spectrometer having a derivatized sample presentation apparatus is provided. The sample presentation apparatus has a complex bound to the surface of the sample presentation apparatus. This complex includes a molecule which may chemically modify a biomolecule.

Modeling the interaction of ozone with chloroform and bromoform under conditions close to stratospheric

NASA Astrophysics Data System (ADS)

Strokova, N. E.; Yagodovskaya, T. V.; Savilov, S. V.; Lukhovitskaya, E. E.; Vasil'ev, E. S.; Morozov, I. I.; Lunin, V. V.

2013-02-01

The reactions of ozone with chloroform and bromoform are studied using a flow gas discharge vacuum unit under conditions close to stratospheric (temperature range, 77-250 K; pressure, 10-3-0.1 Torr in the presence of nitrate ice). It is shown that the reaction with bromoform begins at 160 K; the reaction with chloroform, at 190 K. The reaction products are chlorine and bromine oxides of different composition, identified by low-temperature FTIR spectroscopy. The presence of nitrate ice raises the temperature of reaction onset to 210 K.

Durable polymer-aerogel based superhydrophobic coatings, a composite material

DOEpatents

Kissel, David J; Brinker, Charles Jeffrey

2014-03-04

Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

Durable polymer-aerogel based superhydrophobic coatings: a composite material

DOEpatents

Kissel, David J.; Brinker, Charles Jeffrey

2016-02-02

Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

Developing A New Sampling and Analysis Method for Hydrazine and Monomethyl Hydrazine

NASA Technical Reports Server (NTRS)

Allen, John R.

2002-01-01

Solid phase microextraction (SPME) will be used to develop a method for detecting monomethyl hydrazine (MMH) and hydrazine (Hz). A derivatizing agent, pentafluorobenzoyl chloride (PFBCl), is known to react readily with MMH and Hz. The SPME fiber can either be coated with PFBCl and introduced into a gaseous stream containing MMH, or PFBCl and MMH can react first in a syringe barrel and after a short equilibration period a SPME is used to sample the resulting solution. These methods were optimized and compared. Because Hz and MMH can degrade the SPME, letting the reaction occur first gave better results. Only MMH could be detected using either of these methods. Future research will concentrate on constructing calibration curves and determining the detection limit.

Targeted Delivery of Glucan Particle Encapsulated Gallium Nanoparticles Inhibits HIV Growth in Human Macrophages

PubMed Central

Soto, Ernesto R.; O'Connell, Olivia; Dikengil, Fusun; Peters, Paul J.; Clapham, Paul R.

2016-01-01

Glucan particles (GPs) are hollow, porous 3–5 μm microspheres derived from the cell walls of Baker's yeast (Saccharomyces cerevisiae). The 1,3-β-glucan outer shell provides for receptor-mediated uptake by phagocytic cells expressing β-glucan receptors. GPs have been used for macrophage-targeted delivery of a wide range of payloads (DNA, siRNA, protein, small molecules, and nanoparticles) encapsulated inside the hollow GPs or bound to the surface of chemically derivatized GPs. Gallium nanoparticles have been proposed as an inhibitory agent against HIV infection. Here, macrophage targeting of gallium using GPs provides for more efficient delivery of gallium and inhibition of HIV infection in macrophages compared to free gallium nanoparticles. PMID:27965897

Chemically modified electrodes by nucleophilic substitution of chlorosilylated platinum oxide surfaces

NASA Astrophysics Data System (ADS)

Chen, Chun-Hsien; Hutchison, James H.; Postlethwaite, Timothy A.; Richardson, John N.; Murray, R. W.

1994-07-01

Chlorosilylated platinum oxide electrode surfaces can be generated by reaction of SiCl4 vapor with an electrochemically prepared monolayer of platinum oxide. A variety of nucleophilic agents (such as alcohols, amines, thiols, and Grignard reagents) can be used to displace chloride and thereby functionalize the metal surface. Electroactive surfaces prepared with ferrocene methanol as the nucleophile show that derivatization by small molecules can achieve coverages on the order of a full monolayer. Surfaces modified with long-chain alkyl groups efficiently block electrode reactions of redox probes dissolved in the contacting solution, but other electrochemical (double layer capacitance and surface coverage) and contact angle measurements suggest that these molecule films are not highly ordered, self-assembled monolayers.

Chloroform

Integrated Risk Information System (IRIS)

Chloroform ; CASRN 67 - 66 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

21 CFR 177.1595 - Polyetherimide resin.

Code of Federal Regulations, 2013 CFR

2013-04-01

... shall have an intrinsic viscosity in chloroform at 25 °C (77 °F) of not less than 0.35 deciliter per gram as determined by a method titled “Intrinsic Viscosity of ULTEM Polyetherimide Using Chloroform as...

21 CFR 177.1595 - Polyetherimide resin.

Code of Federal Regulations, 2012 CFR

2012-04-01

... shall have an intrinsic viscosity in chloroform at 25 °C (77 °F) of not less than 0.35 deciliter per gram as determined by a method titled “Intrinsic Viscosity of ULTEM Polyetherimide Using Chloroform as...

21 CFR 177.1595 - Polyetherimide resin.

Code of Federal Regulations, 2011 CFR

2011-04-01

... shall have an intrinsic viscosity in chloroform at 25 °C (77 °F) of not less than 0.35 deciliter per gram as determined by a method titled “Intrinsic Viscosity of ULTEM Polyetherimide Using Chloroform as...

Surface Structures Formed by a Copper(II) Complex of Alkyl-Derivatized Indigo

PubMed Central

Honda, Akinori; Noda, Keisuke; Tamaki, Yoshinori; Miyamura, Kazuo

2016-01-01

Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II) ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM) analysis revealed that the copper(II) complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed. PMID:28773957

Process for derivatizing carbon nanotubes with diazonium species

NASA Technical Reports Server (NTRS)

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

LC-MS n Analysis of Isomeric Chondroitin Sulfate Oligosaccharides Using a Chemical Derivatization Strategy

NASA Astrophysics Data System (ADS)

Huang, Rongrong; Pomin, Vitor H.; Sharp, Joshua S.

2011-09-01

Improved methods for structural analyses of glycosaminoglycans (GAGs) are required to understand their functional roles in various biological processes. Major challenges in structural characterization of complex GAG oligosaccharides using liquid chromatography-mass spectrometry (LC-MS) include the accurate determination of the patterns of sulfation due to gas-phase losses of the sulfate groups upon collisional activation and inefficient on-line separation of positional sulfation isomers prior to MS/MS analyses. Here, a sequential chemical derivatization procedure including permethylation, desulfation, and acetylation was demonstrated to enable both on-line LC separation of isomeric mixtures of chondroitin sulfate (CS) oligosaccharides and accurate determination of sites of sulfation by MS n . The derivatized oligosaccharides have sulfate groups replaced with acetyl groups, which are sufficiently stable to survive MS n fragmentation and reflect the original sulfation patterns. A standard reversed-phase LC-MS system with a capillary C18 column was used for separation, and MS n experiments using collision-induced dissociation (CID) were performed. Our results indicate that the combination of this derivatization strategy and MS n methodology enables accurate identification of the sulfation isomers of CS hexasaccharides with either saturated or unsaturated nonreducing ends. Moreover, derivatized CS hexasaccharide isomer mixtures become separable by LC-MS method due to different positions of acetyl modifications.

2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography.

PubMed

Faraji, Mohammad; Hamdamali, Mohammadrezza; Aryanasab, Fezzeh; Shabanian, Meisam

2018-07-13

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L -1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L -1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L -1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). Copyright © 2018. Published by Elsevier B.V.

Demonstration of hydrazide tagging for O-glycans and a central composite design of experiments optimization using the INLIGHT™ reagent.

PubMed

King, Samuel R; Hecht, Elizabeth S; Muddiman, David C

2018-02-01

The INLIGHT™ strategy for N-linked glycan derivatization has been shown to overcome many of the challenges associated with glycan analysis. The hydrazide tag reacts efficiently with the glycans, increasing their non-polar surface area, allowing for reversed-phase separations and increased ionization efficiency. We have taken the INLIGHT™ strategy and adopted it for use with O-linked glycans. A central composite design was utilized to find optimized tagging conditions (45% acetic acid, 0.1 μg/μL tag concentration, 37 C, 1.75 h). Derivatization at optimized conditions was much quicker than any hydrazide derivatization strategy used previously. Human immunoglobulin A (IgA) and bovine submaxillary mucin (BSM) were then deglycosylated through hydrazinolysis and the removed glycans were tagged under optimum conditions. XIC of tagged glycans and MS2 data show successful hydrazide tagging of O-linked glycans for the first time. Graphical abstract The INLIGHT™ hydrazide tag was optimized using a central composite design for derivatization of O-linked glycans. Two glycoprotein standards were deglycosylated through hydrazinolysis and tagged at the optimized conditions. MS/MS data shows INLIGHT™ derivatization of glycans demonstrating successful hydrazide tagging of O-glycans for the first time.

LC-MSn Analysis of Isomeric Chondroitin Sulfate Oligosaccharides Using a Chemical Derivatization Strategy

PubMed Central

Huang, Rongrong; Pomin, Vitor H.; Sharp, Joshua S.

2011-01-01

Improved methods for structural analyses of glycosaminoglycans (GAGs) are required to understand their functional roles in various biological processes. Major challenges in structural characterization of complex GAG oligosaccharides using liquid chromatography-mass spectrometry (LC-MS) include the accurate determination of the patterns of sulfation due to gas-phase losses of the sulfate groups upon collisional activation and inefficient on-line separation of positional sulfation isomers prior to MS/MS analyses. Here, a sequential chemical derivatization procedure including permethylation, desulfation, and acetylation was demonstrated to enable both on-line LC separation of isomeric mixtures of chondroitin sulfate (CS) oligosaccharides and accurate determination of sites of sulfation by MSn. The derivatized oligosaccharides have sulfate groups replaced with acetyl groups, which are sufficiently stable to survive MSn fragmentation and reflect the original sulfation patterns. A standard reversed-phase LC-MS system with a capillary C18 column was used for separation, and MSn experiments using collision-induced dissociation (CID) were performed. Our results indicate that the combination of this derivatization strategy and MSn methodology enables accurate identification of the sulfation isomers of CS hexasaccharides with either saturated or unsaturated nonreducing ends. Moreover, derivatized CS hexasaccharide isomer mixtures become separable by LC-MS method due to different positions of acetyl modifications. PMID:21953261

In situ Analysis of Organic Compounds on Mars using Chemical Derivatization and Gas Chromatography Mass Spectrometry

NASA Technical Reports Server (NTRS)

Glavin, D. P.; Buch, A.; Cabane, M.; Coll, P.; Navarro-Gonzalez, R.; Mahaffy, P. R.

2005-01-01

One of the core science objectives of NASA's 2009 Mars Science Laboratory (MSL) mission is to determine the past or present habitability of Mars. The search for key organic compounds relevant to terrestrial life will be an important part of that assessment. We have developed a protocol for the analysis of amino acids and carboxylic acids in Mars analogue materials using gas chromatography mass spectrometry (GCMS). As shown, a variety of carboxylic acids were readily identified in soil collected from the Atacama Desert in Chile at part-per-billion levels by GCMS after extraction and chemical derivatization using the reagent N,N-tert.-butyl (dimethylsilyl) trifluoroacetamide (MTBSTFA). Several derivatized amino acids including glycine and alanine were also detected by GCMS in the Atacama soil at lower concentrations (chromatogram not shown). Lacking derivatization capability, the Viking pyrolysis GCMS instruments could not have detected amino acids and carboxylic acids, since these non-volatile compounds require chemical transformation into volatile species that are stable in a GC column. We are currently optimizing the chemical extraction and derivatization technique for in situ GCMS analysis on Mars. Laboratory results of analyses of Atacama Desert samples and other Mars analogue materials using this protocol will be presented.

Antitubercular activity of the semi-polar extractives of Uvaria rufa.

PubMed

Macabeo, Allan Patrick G; Tudla, Florie A; Krohn, Karsten; Franzblau, Scott G

2012-10-01

To investigate the inhibitory activity of the chloroform extract, petroleum ether and chloroform sub-extracts, lead-acetate treated chloroform extract, fractions and secondary metabolites of Uvaria rufa (U. rufa) against Mycobacterium tuberculosis (M. tuberculosis) H(37)Rv. The antituberculosis susceptibility assay was carried out using the colorimetric Microplate Alamar blue assay (MABA). In addition, the cytotoxicity of the most active fraction was evaluated using the VERO cell toxicity assay. The in vitro inhibitory activity against M. tuberculosis H(37)Rv increased as purification progressed to fractionation (MIC up to 23 μg/mL). The chloroform extract and its sub-extracts showed moderate toxicity while the most active fraction from chloroform sub-extract exhibited no cytotoxicity against VERO cells. Meanwhile, the lead acetate-treated crude chloroform extract and its fractions showed complete inhibitions (100%) with MIC values up to 8 μg/mL. Phytochemical screening of the most active fraction showed, in general, the presence of terpenoids, steroids and phenolic compounds. Evaluation of the antimycobacterial activity of known secondary metabolites isolated showed no promising inhibitory activity against the test organism. The present results demonstrate the potential of U. rufa as a phytomedicinal source of compounds that may exhibit promising antituberculosis activity. In addition, elimination of polar pigments revealed enhanced inhibition against M. tuberculosis H(37)Rv. While several compounds known for this plant did not show antimycobacterial activity, the obtained results are considered sufficient reason for further study to isolate the metabolites from U. rufa responsible for the antitubercular activity. Copyright © 2012 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Laboratory Evaluations of the Fractions Efficacy of Annona senegalensis (Annonaceae) Leaf Extract on Immature Stage Development of Malarial and Filarial Mosquito Vectors.

PubMed

Lame, Younoussa; Nukenine, Elias Nchiwan; Pierre, Danga Yinyang Simon; Elijah, Ajaegbu Eze; Esimone, Charles Okechukwu

2015-12-01

Within the framework to control mosquitoes, ovicidal, larvicidal and pupicidal activity of Annona senegalensis leaf extract and its 4 fractions against Anopheles gambiae and Culex quinquefasciatus were evaluated in the laboratory conditions. Ovicidal test was performed by submitting at least 100 eggs of mosquitoes to 125, 250, 500, 1000 and 2000 ppm concentrations, while larvicidal and pupicidal effects were assessed by submitting 25 larvae or pupae to the concentrations of 2500, 1250, 625 and 312.5 ppm of plant extract or fractions of A. senegalensis. The eggs of An. gambiae were most affected by N-hexane (0.00% hatchability) and chloroform (03.67% hatchability) fractions compared to Cx. quinquefasciatus where at least 25 % hatchability were recorded at 2000 ppm. For larvicidal test, N-hexane (LC50= 298.8 ppm) and chloroform (LC50= 418.3 ppm) fractions were more effective than other fractions on An. gambiae larvae while, a moderate effectiveness was also observed with N-hexane (LC50= 2087.6 ppm), chloroform (LC50= 9010.1 ppm) fractions on Cx. quinquefasciatus larvae. The highest mortality percent of the pupae were also recorded with N-hexane and chloroform fractions on An. gambiae at 2500 ppm. As for Cx. quinquefasciatus only 50 % and 36 % mortality were recorded with N-hexane and chloroform fractions respectively. The extract of A. senegalensis was toxic on immature stage of mosquito species tested. By splitting methanolic crude extract, only N-hexane and chloroform fractions were revealed to possess a mosquitocidal effects and could be considered and utilized for future immature mosquito vectors control.

Carcinogenicity of by-products of disinfection in mouse and rat liver

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

Herren-Freund, S.L.; Pereira, M.A.

1986-11-01

By-products of disinfection were tested for initiating and/or promoting activity in rat liver by using the rat liver foci bioassay. The assay uses an increased incidence of ..gamma..-glutamyltranspeptidase-positive foci (GGT foci) as an indicator of carcinogenicity. The by-products of disinfection, including chloramine, halogenated humic acids, halogenated ethanes, halogenated acetonitriles, halogenated methanes, halogenated ethylene, and N-Cl piperidine, did not initiate GGT foci, which would indicate that they are not capable of initiating carcinogenesis. Chloroform and halogenated benzenes were tested in this assay for their ability to promote the occurrence of GGT foci and tumors initiated by diethylnitrosamine (DENA). Chloroform either hadmore » no effect or inhibited the occurrence of GGT foci when administered subsequent to a single dose of DENA. However, when the chloroform was administered in drinking water concurrently with weekly doses of DENA, it enhanced the formation of liver tumors. Of 20 halogenated benzenes tested, only 1,2,4,5-tetrachlorobenzene and hexachlorobenzene promoted the occurrence of DENA-initiated GGT foci. Thus in rat liver, the tested by-products of drinking water disinfection did not demonstrate tumor-initiating activity, although a few appeared to possess tumor-promoting activity. Chloroform was also tested for tumor-promoting activity in 15-days-old Swiss mice initiated with ethylnitrosourea (ENU). ENU at 5 and 20 ..mu..g/g caused a dose-dependent increase in liver tumors. In male mice, chloroform inhibited both spontaneous and ENU-induced liver tumors. When administered in the drinking water, chloroform inhibited, whereas phenobarbital promoted, hepatocarcinogenesis in mice.« less

Phloroglucinol Degradation in the Rumen Promotes the Capture of Excess Hydrogen Generated from Methanogenesis Inhibition

PubMed Central

Martinez-Fernandez, Gonzalo; Denman, Stuart E.; Cheung, Jane; McSweeney, Christopher S.

2017-01-01

Strategies to manage metabolic hydrogen ([H]) in the rumen should be considered when reducing ruminant methane (CH4) emissions. However, little is known about the use of dietary treatments to stimulate rumen microorganisms capable of capturing the [H] available when CH4 is inhibited in vivo. The effects of the phenolic compound phloroglucinol on CH4 production, [H] flows and subsequent responses in rumen fermentation and microbial community composition when methanogenesis is inhibited were investigated in cattle. Eight rumen fistulated Brahman steers were randomly allocated in two groups receiving chloroform as an antimethanogenic compound for 21 days. Following that period one group received chloroform + phloroglucinol for another 16 days, whilst the other group received only chloroform during the same period. The chloroform treatment resulted in a decrease in CH4 production and an increase in H2 expelled with a shift in rumen fermentation toward higher levels of propionate and formate and lower levels of acetate at day 21 of treatment. Bacterial operational taxonomic units (OTUs) assigned to Prevotella were promoted whilst Archaea and Synergistetes OTUs were decreased with the chloroform treatment as expected. The shift toward formate coincided with increases in Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, and Methanobrevibacter ruminantium species. The addition of chloroform + phloroglucinol in the rumen resulted in a decrease of H2 expelled (g) per kg of DMI and moles of H2 expelled per mol of CH4 decreased compared with the chloroform only treated animals. A shift toward acetate and a decrease in formate were observed for the chloroform + phloroglucinol-treated animals at day 37. These changes in the rumen fermentation profile were accompanied by a relative increase of OTUs assigned to Coprococcus spp., which could suggest this genus is a significant contributor to the metabolism of this phenolic compound in the rumen. This study demonstrates for the first time in vivo that under methanogenesis inhibition, H2 gas accumulation can be decreased by redirecting [H] toward alternative sinks through the nutritional stimulation of specific microbial groups. This results in the generation of metabolites of value for the host while also helping to maintain a low H2 partial pressure in the methane-inhibited rumen. PMID:29051749

METHOD DEVELOPMENT FOR THE DETERMINATION OF FORMALDEHYDE IN SAMPLES OF ENVIRONMENTAL ORIGIN

EPA Science Inventory

An analytical method was developed for the determination of formaldehyde in samples of environmental origin. After a review of the current literature, five candidate methods involving chemical derivatization were chosen for evaluation. The five derivatization reagents studied wer...

DETERMINATION OF ALIPHATIC AMINES IN WATER USING DERIVATIZATION WITH FLUORESCEIN ISOTHIOCYANATE AND CAPILLARY ELECTROPHORESIS/LASER-INDUCED FLUORESCENCE DETECTION.

EPA Science Inventory

Detection-oriented derivatization of aliphatic amines and amine functional groups in coumpounds of environmental interest was studied using fluorescein isothiocyanate (FITC) with separation/determination by capillary electrophoresis/laser-induced fluorescence. Determinative level...

Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization

PubMed Central

Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

2014-01-01

An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded ‘fixed charge’ sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptides with S,S′-dimethylthiobutanoylhydroxysuccinimide ester iodide (DMBNHS), followed by analysis using capillary HPLC-ESI-MS, yielded an average 2.5-fold increase in ionization efficiencies and a significant increase in the presence and/or abundance of higher charge state precursor ions compared to the non-derivatized phosphopeptides. Notably, 44% of the phosphopeptides (22 of 50) in their underivatized states yielded precursor ions whose maximum charge states corresponded to +2, while only 8% (4 of 50) remained at this maximum charge state following DMBNHS derivatization. Quantitative analysis was achieved by measuring the abundances of the diagnostic product ions corresponding to the neutral losses of ‘light’ (S(CH3)2) and ‘heavy’ (S(CD3)2) dimethylsulfide exclusively formed upon CID-MS/MS of isobaric stable isotope labeled forms of the DMBNHS derivatized phosphopeptides. Under these conditions, the phosphate group stayed intact. Access for a greater number of peptides to provide enhanced phosphopeptide sequence identification and phosphorylation site characterization was achieved via automated data-dependent CID-MS3 or ETD-MS/MS analysis due to the formation of the higher charge state precursor ions. Importantly, improved sequence coverage was observed using ETD-MS/MS following introduction of the sulfonium ion fixed charge, but with no detrimental effects on ETD fragmentation efficiency. PMID:21952753

Identification and Quantitation of Malonic Acid Biomarkers of In-Born Error Metabolism by Targeted Metabolomics

NASA Astrophysics Data System (ADS)

Ambati, Chandra Shekar R.; Yuan, Furong; Abu-Elheiga, Lutfi A.; Zhang, Yiqing; Shetty, Vivekananda

2017-05-01

Malonic acid (MA), methylmalonic acid (MMA), and ethylmalonic acid (EMA) metabolites are implicated in various non-cancer disorders that are associated with inborn-error metabolism. In this study, we have slightly modified the published 3-nitrophenylhydrazine (3NPH) derivatization method and applied it to derivatize MA, MMA, and EMA to their hydrazone derivatives, which were amenable for liquid chromatography- mass spectrometry (LC-MS) quantitation. 3NPH was used to derivatize MA, MMA, and EMA, and multiple reaction monitoring (MRM) transitions of the corresponding derivatives were determined by product-ion experiments. Data normalization and absolute quantitation were achieved by using 3NPH derivatized isotopic labeled compounds 13C2-MA, MMA-D3, and EMA-D3. The detection limits were found to be at nanomolar concentrations and a good linearity was achieved from nanomolar to millimolar concentrations. As a proof of concept study, we have investigated the levels of malonic acids in mouse plasma with malonyl-CoA decarboxylase deficiency (MCD-D), and we have successfully applied 3NPH method to identify and quantitate all three malonic acids in wild type (WT) and MCD-D plasma with high accuracy. The results of this method were compared with that of underivatized malonic acid standards experiments that were performed using hydrophilic interaction liquid chromatography (HILIC)-MRM. Compared with HILIC method, 3NPH derivatization strategy was found to be very efficient to identify these molecules as it greatly improved the sensitivity, quantitation accuracy, as well as peak shape and resolution. Furthermore, there was no matrix effect in LC-MS analysis and the derivatized metabolites were found to be very stable for longer time.

Towards a rational approach for heavy-atom derivative screening in protein crystallography

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

Agniswamy, Johnson; Joyce, M. Gordon; Hammer, Carl H.

2008-04-01

Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity of more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity ofmore » more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Met-, Cys- and His-containing peptides were derivatized against Hg, Au and Pt compounds, while Tyr-, Glu-, Asp-, Asn- and Gln-containing peptides were assessed against Pb compounds. A total of 1668 reactive conditions were examined using mass spectrometry and were compiled into heavy-atom reactivity tables. The results showed that heavy-atom derivatization reactions are highly linked to buffer and pH, with the most accommodating buffer being MES at pH 6. A group of 21 compounds were identified as most successful irrespective of ligand or buffer/pH conditions. To assess the applicability of the peptide heavy-atom reactivity to proteins, lysozyme crystals were derivatized with a list of peptide-reactive compounds that included both known and new compounds for lysozyme derivatization. The results showed highly consistent heavy-atom reactivities between the peptides and lysozyme.« less

The interaction of insulin with phospholipids

PubMed Central

Perry, M. C.; Tampion, W.; Lucy, J. A.

1971-01-01

1. A simple two-phase chloroform–aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of 125I-labelled insulin in this system was determined after incubation at 37°C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized 125I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin–phospholipid or insulin–amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin–phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [14C]glucose between the two phases as a monitor of phospholipid–insulin interactions. The ability of phospholipids to solubilize [14C]glucose in chloroform increased in the order phosphatidylcholine

Antimutagenic, antigenotoxic and antioxidant activities of Acacia salicina extracts (ASE) and modulation of cell gene expression by H2O2 and ASE treatment.

PubMed

Bouhlel, Ines; Valenti, Kita; Kilani, Soumaya; Skandrani, Ines; Ben Sghaier, Mohamed; Mariotte, Anne-Marie; Dijoux-Franca, Marie-Genevieve; Ghedira, Kamel; Hininger-Favier, Isabelle; Laporte, François; Chekir-Ghedira, Leila

2008-08-01

The total oligomers flavonoids (TOF), chloroform, petroleum ether and aqueous extracts from Acacia salicina, were investigated for the antioxidative, cytotoxic, antimutagenic and antigenotoxic activities. The viability of K562 cells were affected by all extracts after 48 h exposure. Our results showed that A. salicina extracts have antigenotoxic and/or antimutagenic activities. TOF and chloroform extracts exhibit antioxidant properties, expressed by the capacity of these extracts to inhibit xanthine oxidase activity. To further explore the mechanism of action of A. salicina extracts, we characterized expression profiles of genes involved in antioxidant protection and DNA repair in the human lymphoblastic cell line K562 exposed to H2O2. Transcription of several genes related to the thioredoxin antioxidant system and to the DNA base-excision repair pathway was up-regulated after incubation with chloroform, TOF and petroleum ether extracts. Moreover genes involved in the nucleotide-excision repair pathway and genes coding for catalase and Mn-superoxide-dismutase, two important antioxidant enzymes, were induced after incubation with the chloroform extract. Taken together, these observations provide evidence that the chloroform and TOF extracts of A. salicina leaves contain bioactive compounds that are able to protect cells against the consequences of an oxidative stress.

Effect of casting solvent on crystallinity of ondansetron in transdermal films.

PubMed

Pattnaik, Satyanarayan; Swain, Kalpana; Mallick, Subrata; Lin, Zhiqun

2011-03-15

The purpose of the present investigation is to assess the influence of casting solvent on crystallinity of ondansetron hydrochloride in transdermal polymeric matrix films fabricated using povidone and ethyl cellulose as matrix forming polymers. Various casting solvents like chloroform (CHL), dichloromethane (DCM), methanol (MET); and mixture of chloroform and ethanol (C-ETH) were used for fabrication of the transdermal films. Analytical tools like scanning electron microscopy (SEM), X-ray diffraction (XRD) studies, differential scanning calorimetry (DSC), etc. were utilized to characterize the crystalline state of ondansetron in the film. Recrystallisation was observed in all the transdermal films fabricated using the casting solvents other than chloroform. Long thin slab-looking, long wire-like or spherulite-looking crystals with beautiful impinged boundaries were observed in SEM. Moreover, XRD revealed no crystalline peaks of ondansetron hydrochloride in the transdermal films prepared using chloroform as casting solvent. The significantly decreased intensity and sharpness of the DSC endothermic peaks corresponding to the melting point of ondansetron in the formulation (specifically in CHL) indicated partial dissolution of ondansetron crystals in the polymeric films. The employed analytical tools suggested chloroform as a preferred casting solvent with minimum or practically absence of recrystallization indicating a relatively amorphous state of ondansetron in transdermal films. Copyright © 2011 Elsevier B.V. All rights reserved.

Charged derivatization and on-line solid phase extraction to measure extremely low cortisol and cortisone levels in human saliva with liquid chromatography-tandem mass spectrometry.

PubMed

Magda, Balázs; Dobi, Zoltán; Mészáros, Katalin; Szabó, Éva; Márta, Zoltán; Imre, Tímea; Szabó, Pál T

2017-06-05

The aim of this study was to develop a sensitive, reliable and high-throughput liquid chromatography - electrospray ionization - mass spectrometric (LC-ESI-MS/MS) method for the simultaneous quantitation of cortisol and cortisone in human saliva. Derivatization with 2-hydrazino-1-methylpyridine (HMP) was one of the most challenging aspects of the method development. The reagent was reacting with cortisol and cortisone at 60°C within 1h, giving mono- and bis-hydrazone derivatives. Investigation of derivatization reaction and sample preparation was detailed and discussed. Improvement of method sensitivity was achieved with charged derivatization and use of on-line solid phase extraction (on-line SPE). The lower limit of quantitation (LLOQ) was 5 and 10pg/ml for cortisol and cortisone, respectively. The developed method was subsequently applied to clinical laboratory measurement of cortisol and cortisone in human saliva. Copyright © 2017 Elsevier B.V. All rights reserved.

Exposure Assessment of Acetamide in Milk, Beef, and Coffee Using Xanthydrol Derivatization and Gas Chromatography/Mass Spectrometry

PubMed Central

2017-01-01

Acetamide has been classified as a possible human carcinogen, but uncertainties exist about its levels in foods. This report presents evidence that thermal decomposition of N-acetylated sugars and amino acids in heated gas chromatograph injectors contributes to artifactual acetamide in milk and beef. An alternative gas chromatography/mass spectrometry protocol based on derivatization of acetamide with 9-xanthydrol was optimized and shown to be free of artifactual acetamide formation. The protocol was validated using a surrogate analyte approach based on d3-acetamide and applied to analyze 23 pasteurized whole milk, 44 raw sirloin beef, and raw milk samples from 14 different cows, and yielded levels about 10-fold lower than those obtained by direct injection without derivatization. The xanthydrol derivatization procedure detected acetamide in every food sample tested at 390 ± 60 ppb in milk, 400 ± 80 ppb in beef, and 39 000 ± 9000 ppb in roasted coffee beans. PMID:29186951

Optimization of a Precolumn OPA Derivatization HPLC Assay for Monitoring of l-Asparagine Depletion in Serum during l-Asparaginase Therapy.

PubMed

Zhang, Mei; Zhang, Yong; Ren, Siqi; Zhang, Zunjian; Wang, Yongren; Song, Rui

2018-06-06

A method for monitoring l-asparagine (ASN) depletion in patients' serum using reversed-phase high-performance liquid chromatography with precolumn o-phthalaldehyde and ethanethiol (ET) derivatization is described. In order to improve the signal and stability of analytes, several important factors including precipitant reagent, derivatization conditions and detection wavelengths were optimized. The recovery of the analytes in biological matrix was the highest when 4% sulfosalicylic acid (1:1, v/v) was used as a precipitant reagent. Optimal fluorescence detection parameters were determined as λex = 340 nm and λem = 444 nm for maximal signal. The signal of analytes was the highest when the reagent ET and borate buffer of pH 9.9 were used in the derivatization solution. And the corresponding derivative products were stable up to 19 h. The validated method had been successfully applied to monitor ASN depletion and l-aspartic acid, l-glutamine, l-glutamic acid levels in pediatric patients during l-asparaginase therapy.

Reagent Precoated Targets for Rapid In-Tissue Derivatization of the Anti-Tuberculosis Drug Isoniazid Followed by MALDI Imaging Mass Spectrometry

NASA Astrophysics Data System (ADS)

Manier, M. Lisa; Reyzer, Michelle L.; Goh, Anne; Dartois, Veronique; Via, Laura E.; Barry, Clifton E.; Caprioli, Richard M.

2011-08-01

Isoniazid (INH) is an important component of front-line anti-tuberculosis therapy with good serum pharmacokinetics but unknown ability to penetrate tuberculous lesions. However, endogenous background interferences hinder our ability to directly analyze INH in tissues. Chemical derivatization has been successfully used to measure isoniazid directly from tissue samples using matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS). MALDI targets were pretreated with trans-cinnamaldehyde (CA) prior to mounting tissue slices. Isoniazid present in the tissues was efficiently derivatized and the INH-CA product measured by MS/MS. Precoating of MALDI targets allows the tissues to be directly thaw-mounted and derivatized, thus simplifying the preparation. A time-course series of tissues from tuberculosis infected/INH dosed animals were assayed and the MALDI MS/MS response correlates well with the amount of INH determined to be in the tissues by high-performance liquid chromatography (HPLC)-MS/MS.

Process for making polymers comprising derivatized carbon nanotubes and compositions thereof

NASA Technical Reports Server (NTRS)

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

The present invention incorporates new processes for blending derivatized carbon nanotubes into polymer matrices to create new polymer/composite materials. When modified with suitable chemical groups using diazonium chemistry, the nanotubes can be made chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as mechanical strength) to the properties of the composite material as a whole. To achieve this, the derivatized (modified) carbon nanotubes are physically blended with the polymeric material, and/or, if desired, allowed to react at ambient or elevated temperature. These methods can be utilized to append functionalities to the nanotubes that will further covalently bond to the host polymer matrix, or directly between two tubes themselves. Furthermore, the nanotubes can be used as a generator of polymer growth, wherein the nanotubes are derivatized with a functional group that is an active part of a polymerization process, which would also result in a composite material in which the carbon nanotubes are chemically involved.

The competition of charge remote and charge directed fragmentation mechanisms in quaternary ammonium salt derivatized peptides--an isotopic exchange study.

PubMed

Cydzik, Marzena; Rudowska, Magdalena; Stefanowicz, Piotr; Szewczuk, Zbigniew

2011-12-01

Derivatization of peptides as quaternary ammonium salts (QAS) is a promising method for sensitive detection by electrospray ionization tandem mass spectrometry (Cydzik et al. J. Pept. Sci. 2011, 17, 445-453). The peptides derivatized by QAS at their N-termini undergo fragmentation according to the two competing mechanisms - charge remote (ChR) and charge directed (ChD). The absence of mobile proton in the quaternary salt ion results in ChR dissociation of a peptide bond. However, Hofmann elimination of quaternary salt creates an ion with one mobile proton leading to the ChD fragmentation. The experiments on the quaternary ammonium salts with deuterated N-alkyl groups or amide NH bonds revealed that QAS derivatized peptides dissociate according to the mixed ChR-ChD mechanism. The isotopic labeling allows differentiation of fragments formed according to ChR and ChD mechanisms. © The Author(s) 2011. This article is published with open access at Springerlink.com

A simultaneous derivatization of 3-monochloropropanediol and 1,3-dichloropropane with hexamethyldisilazane-trimethylsilyl trifluoromethanesulfonate at room temperature for efficient analysis of food sample analysis.

PubMed

Lee, Bai Qin; Wan Mohamed Radzi, Che Wan Jasimah Bt; Khor, Sook Mei

2016-02-05

This paper reports the application of hexamethyldisilazane-trimethylsilyl trifluoromethanesulfonate (HMDS-TMSOTf) for the simultaneous silylation of 3-monochloro-1,2-propanediol (3-MCPD) and 1,3-dicholoropropanol (1,3-DCP) in solid and liquid food samples. 3-MCPD and 1,3-DCP are chloropropanols that have been established as Group 2B carcinogens in clinical testing. They can be found in heat-processed food, especially when an extended high-temperature treatment is required. However, the current AOAC detection method is time-consuming and expensive. Thus, HMDS-TMSOTf was used in this study to provide a safer, and cost-effective alternative to the HFBI method. Three important steps are involved in the quantification of 3-MCPD and 1,3-DCP: extraction, derivatization and quantification. The optimization of the derivatization process, which involved focusing on the catalyst volume, derivatization temperature, and derivatization time was performed based on the findings obtained from both the Box-Behnken modeling and a real experimental set up. With the optimized conditions, the newly developed method was used for actual food sample quantification and the results were compared with those obtained via the standard AOAC method. The developed method required less samples and reagents but it could be used to achieve lower limits of quantification (0.0043mgL(-1) for 1,3-DCP and 0.0011mgL(-1) for 3-MCPD) and detection (0.0028mgL(-1) for 1,3-DCP and 0.0008mgL(-1) for 3-MCPD). All the detected concentrations are below the maximum tolerable limit of 0.02mgL(-1). The percentage of recovery obtained from food sample analysis was between 83% and 96%. The new procedure was validated with the AOAC method and showed a comparable performance. The HMDS-TMSOTf derivatization strategy is capable of simultaneously derivatizing 1,3-DCP and 3-MCPD at room temperature, and it also serves as a rapid, sensitive, and accurate analytical method for food samples analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous Analysis of 3-MCPD and 1,3-DCP in Asian Style Sauces Using QuEChERS Extraction and Gas Chromatography-Triple Quadrupole Mass Spectrometry.

PubMed

Genualdi, Susan; Nyman, Patricia; DeJager, Lowri

2017-02-01

Acid hydrolyzed vegetable protein (aHVP) is used for flavoring a wide variety of foods and also in the production of nonfermented soy sauce. During the production of aHVP, chloropropanols including 3-monochloropropane-1,2-diol (3-MCPD) and 1,3 dichloropropane-2-ol (1,3-DCP) can be formed through the reaction of the hydrochloric acid catalyst and residual fat and the reaction of 3-MCPD with acetic acid, respectively. 3-MCPD is a carcinogen, and 1,3-DCP has been classified as a genotoxic carcinogen. The European Union (EU) has set a maximum concentration of 0.02 mg/kg of 3-MCPD in aHVP, and the Food and Drug Administration (FDA) set a guidance limit of 1 mg/kg of 3-MCPD in aHVP. 1,3-DCP is not an approved food additive, and the Joint FAO/WHO Expert Committee on Food Additives (JEFCA) has set a limit at 0.005 mg/kg, which is close to the estimated method detection limit. Currently there are few analytical methods for the simultaneous determination of 3-MCPD and 1,3-DCP without derivatization due to differences in their physical chemical properties and reactivity. A new method was developed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) with direct analysis of the extract without derivatization using gas chromatography-triple quadrupole mass spectrometry (GC-QQQ). Additionally, a market sampling of 60 soy sauce samples was performed in 2015 to determine if concentrations have changed since the FDA limit was set in 2008. The sampling results were compared between the new QuEChERS method and a method using phenylboronic acid (PBA) as a derivatizing agent for 3-MCPD analysis. The concentrations of 3-MCPD detected in soy sauce samples collected in 2015 (

Simultaneous Analysis of 3-MCPD and 1,3-DCP in Asian Style Sauces Using QuEChERS Extraction and Gas Chromatography–Triple Quadrupole Mass Spectrometry

PubMed Central

Genualdi, Susan; Nyman, Patricia; DeJager, Lowri

2017-01-01

Acid hydrolyzed vegetable protein (aHVP) is used for flavoring a wide variety of foods and also in the production of nonfermented soy sauce. During the production of aHVP, chloropropanols including 3-monochloropropane-1,2-diol (3-MCPD) and 1,3 dichloropropane-2-ol (1,3-DCP) can be formed through the reaction of the hydrochloric acid catalyst and residual fat and the reaction of 3-MCPD with acetic acid, respectively. 3-MCPD is a carcinogen, and 1,3-DCP has been classified as a genotoxic carcinogen. The European Union (EU) has set a maximum concentration of 0.02 mg/kg of 3-MCPD in aHVP, and the Food and Drug Administration (FDA) set a guidance limit of 1 mg/kg of 3-MCPD in aHVP. 1,3-DCP is not an approved food additive, and the Joint FAO/WHO Expert Committee on Food Additives (JEFCA) has set a limit at 0.005 mg/kg, which is close to the estimated method detection limit. Currently there are few analytical methods for the simultaneous determination of 3-MCPD and 1,3-DCP without derivatization due to differences in their physical chemical properties and reactivity. A new method was developed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) with direct analysis of the extract without derivatization using gas chromatography–triple quadrupole mass spectrometry (GC-QQQ). Additionally, a market sampling of 60 soy sauce samples was performed in 2015 to determine if concentrations have changed since the FDA limit was set in 2008. The sampling results were compared between the new QuEChERS method and a method using phenylboronic acid (PBA) as a derivatizing agent for 3-MCPD analysis. The concentrations of 3-MCPD detected in soy sauce samples collected in 2015 (

Metabolic alterations in the nymphal instars of Diaphorina citri induced by Candidatus Liberibacter asiaticus, the putative pathogen of huanglongbing.

PubMed

Killiny, Nabil; Jones, Shelley E

2018-01-01

Currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. The disease is caused by the Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). The pathogen is transmitted in a persistent propagative circulative manner within its vector, the Asian citrus psyllid, Diaphorina citri. Exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of CLas and to designing an artificial medium for culturing the pathogen. It has been shown that the nymphal stages have a greater role in transmission mainly because they feed on plants more actively than adults. In this study, we carried out an untargeted comparative metabolomic analysis for healthy and CLas-infected 4th / 5th instar nymphs. The metabolic analysis was performed using trimethylsilylation and methyl chloroformate derivatization followed by Gas Chromatography-Mass Spectrometry (GC-MS). Overall, the changes in the nymph metabolism due to the infection with CLas were more pronounced than in adults, as we previously published. Nymphs reared on CLas-infected Valencia sweet orange were higher in many metabolites, mainly those of the TCA cycle, C16 and C18 fatty acids, glucose, sucrose, L-proline, L-serine, pyroglutamic acid, saccharic acid, threonic acid and myo-inositol than those reared on healthy plants. In contrast, CLas-infected nymphs were lower in putrescine, glycine, L -phenylalanine, L -tyrosine, L -valine, and chiro-inositol. The information provided from this study may contribute in acceleration of the availability of CLas in culture and consequent screening of antibacterial compounds to discover a definitive solution for huanglongbing.

Metabolic alterations in the nymphal instars of Diaphorina citri induced by Candidatus Liberibacter asiaticus, the putative pathogen of huanglongbing

PubMed Central

Jones, Shelley E.

2018-01-01

Currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. The disease is caused by the Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). The pathogen is transmitted in a persistent propagative circulative manner within its vector, the Asian citrus psyllid, Diaphorina citri. Exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of CLas and to designing an artificial medium for culturing the pathogen. It has been shown that the nymphal stages have a greater role in transmission mainly because they feed on plants more actively than adults. In this study, we carried out an untargeted comparative metabolomic analysis for healthy and CLas-infected 4th / 5th instar nymphs. The metabolic analysis was performed using trimethylsilylation and methyl chloroformate derivatization followed by Gas Chromatography-Mass Spectrometry (GC-MS). Overall, the changes in the nymph metabolism due to the infection with CLas were more pronounced than in adults, as we previously published. Nymphs reared on CLas-infected Valencia sweet orange were higher in many metabolites, mainly those of the TCA cycle, C16 and C18 fatty acids, glucose, sucrose, L-proline, L-serine, pyroglutamic acid, saccharic acid, threonic acid and myo-inositol than those reared on healthy plants. In contrast, CLas-infected nymphs were lower in putrescine, glycine, L -phenylalanine, L -tyrosine, L -valine, and chiro-inositol. The information provided from this study may contribute in acceleration of the availability of CLas in culture and consequent screening of antibacterial compounds to discover a definitive solution for huanglongbing. PMID:29370262

Collection and chemical composition of phloem sap from Citrus sinensis L. Osbeck (sweet orange).

PubMed

Hijaz, Faraj; Killiny, Nabil

2014-01-01

Through utilizing the nutrient-rich phloem sap, sap feeding insects such as psyllids, leafhoppers, and aphids can transmit many phloem-restricted pathogens. On the other hand, multiplication of phloem-limited, uncultivated bacteria such as Candidatus Liberibacter asiaticus (CLas) inside the phloem of citrus indicates that the sap contains all the essential nutrients needed for the pathogen growth. The phloem sap composition of many plants has been studied; however, to our knowledge, there is no available data about citrus phloem sap. In this study, we identified and quantified the chemical components of phloem sap from pineapple sweet orange. Two approaches (EDTA enhanced exudation and centrifugation) were used to collect phloem sap. The collected sap was derivatized with methyl chloroformate (MCF), N-methyl-N- [tert-butyl dimethylsilyl]-trifluroacetamide (MTBSTFA), or trimethylsilyl (TMS) and analyzed with GC-MS revealing 20 amino acids and 8 sugars. Proline, the most abundant amino acid, composed more than 60% of the total amino acids. Tryptophan, tyrosine, leucine, isoleucine, and valine, which are considered essential for phloem sap-sucking insects, were also detected. Sucrose, glucose, fructose, and inositol were the most predominant sugars. In addition, seven organic acids including succinic, fumaric, malic, maleic, threonic, citric, and quinic were detected. All compounds detected in the EDTA-enhanced exudate were also detected in the pure phloem sap using centrifugation. The centrifugation technique allowed estimating the concentration of metabolites. This information expands our knowledge about the nutrition requirement for citrus phloem-limited bacterial pathogen and their vectors, and can help define suitable artificial media to culture them.

Collection and Chemical Composition of Phloem Sap from Citrus sinensis L. Osbeck (Sweet Orange)

PubMed Central

Hijaz, Faraj; Killiny, Nabil

2014-01-01

Through utilizing the nutrient-rich phloem sap, sap feeding insects such as psyllids, leafhoppers, and aphids can transmit many phloem-restricted pathogens. On the other hand, multiplication of phloem-limited, uncultivated bacteria such as Candidatus Liberibacter asiaticus (CLas) inside the phloem of citrus indicates that the sap contains all the essential nutrients needed for the pathogen growth. The phloem sap composition of many plants has been studied; however, to our knowledge, there is no available data about citrus phloem sap. In this study, we identified and quantified the chemical components of phloem sap from pineapple sweet orange. Two approaches (EDTA enhanced exudation and centrifugation) were used to collect phloem sap. The collected sap was derivatized with methyl chloroformate (MCF), N-methyl-N- [tert-butyl dimethylsilyl]-trifluroacetamide (MTBSTFA), or trimethylsilyl (TMS) and analyzed with GC-MS revealing 20 amino acids and 8 sugars. Proline, the most abundant amino acid, composed more than 60% of the total amino acids. Tryptophan, tyrosine, leucine, isoleucine, and valine, which are considered essential for phloem sap-sucking insects, were also detected. Sucrose, glucose, fructose, and inositol were the most predominant sugars. In addition, seven organic acids including succinic, fumaric, malic, maleic, threonic, citric, and quinic were detected. All compounds detected in the EDTA-enhanced exudate were also detected in the pure phloem sap using centrifugation. The centrifugation technique allowed estimating the concentration of metabolites. This information expands our knowledge about the nutrition requirement for citrus phloem-limited bacterial pathogen and their vectors, and can help define suitable artificial media to culture them. PMID:25014027

Determination of intracellular glutathione and cysteine using HPLC with a monolithic column after derivatization with monobromobimane.

PubMed

Conlan, Xavier A; Stupka, Nicole; McDermott, Geoffrey P; Francis, Paul S; Barnett, Neil W

2010-05-01

An optimized high-performance liquid chromatography (HPLC) method is used to show that, as myoblasts differentiate into multinucleated muscle fibers, there is a shift to a more oxidized cell redox state. The HPLC method incorporated derivatization with monobromobimane for the determination of the reduced (GSH) and oxidized (GSSG) forms of glutathione and the reduced (Cys) and oxidized (CysSS) forms of cysteine. The derivatization was optimized to improve the sensitivity of the approach; the limits of detection for glutathione and cysteine were 3 x 10(-8) and 5 x 10(-8) M, respectively. 2009 John Wiley & Sons, Ltd.

Analysis of L-serine-O-phosphate in cerebrospinal spinal fluid by derivatization-liquid chromatography/mass spectrometry.

PubMed

McNaney, Colleen A; Benitex, Yulia; Luchetti, David; Labasi, Jeffrey M; Olah, Timothy V; Morgan, Daniel G; Drexler, Dieter M

2014-05-01

L-serine-O-phosphate (L-SOP), the precursor of L-serine, is a potent agonist against the group III metabotropic glutamate receptors (mGluRs) and, thus, is of interest as a potential biomarker for monitoring modulation of neurotransmitter release. So far, no reports are available on the analysis of L-SOP in cerebrospinal fluid (CSF). Here a novel method is presented to determine L-SOP levels in CSF employing precolumn derivatization with (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP) coupled to liquid chromatography/mass spectrometry (derivatization-LC/MS, d-LC/MS). Copyright © 2014 Elsevier Inc. All rights reserved.

Hydroxypyridinone Derivatives: A Fascinating Class of Chelators with Therapeutic Applications - An Update.

PubMed

Chaves, Sílvia; Piemontese, Luca; Hiremathad, Asha; Santos, Maria A

2018-01-01

Hydroxypyridinones (HPs) are a family of N-heterocyclic metal chelators, which have been an attractive target in the development of a variety of new pharmaceutical drugs, due to their high metal chelating efficacy/specificity and easy derivatization to tune the desired biological properties. In fact, along the last decades, hydroxypyridinone derivatives, but mostly 3-hydroxy-4-pyridinone (3,4-HP), have been intensively used in drug design, following either a multitarget approach, in which one chelating unity is extrafunctionalized (hybridized) to enable the interaction with other important specific biological sites, or a polydenticity approach, in which more than one chelating moiety is conveniently attached to one scaffold, to increase the metal chelating efficacy. This review represents an update of the most recent publications (2014-2016) in mono-HP hybrids, namely as potential anti-Alzheimer's drugs, inhibitors of metalloenzymes and anti-microbials, and also polychelating compounds (poly- HP), in view of potential application, such as anti-microbial/biostatic agents, luminescent biosensors or diagnostic agents. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Efficient Bioconjugation of Protein Capture Agents to Biosensor Surfaces Using Aniline-Catalyzed Hydrazone Ligation

PubMed Central

Byeon, Ji-Yeon; Limpoco, F. T.; Bailey, Ryan C.

2010-01-01

Aniline-catalyzed hydrazone ligation between surface immobilized hydrazines and aldehyde-modified antibodies is shown to be an efficient method for attaching protein capture agents to model oxide-coated biosensor substrates. Silicon photonic microring resonators are used to directly evaluate the efficiency of this surface bioconjugate reaction at various pHs and in the presence or absence of aniline as a nucleophilic catalyst. It is found that aniline significantly increases the net antibody loading for surfaces functionalized over a pH range from 4.5 to 7.4, allowing derivatization of substrates with reduced incubation time and sample consumption. This increase in antibody loading directly results in more sensitive antigen detection when functionalized microrings are employed in a label-free immunoassay. Furthermore, these experiments also reveal an interesting pH dependent non-covalent binding trend that plays an important role in dictating the amount of antibody attached onto the substrate, highlighting the competing contributions of the bioconjugate reaction rate and the dynamic interactions that control opportunities for a solution-phase biomolecule to react with a substrate-bound reagent. PMID:20809595

Derivatizations of Sgc8-c aptamer to prepare metallic radiopharmaceuticals as imaging diagnostic agents: Syntheses, isolations, and physicochemical characterizations.

PubMed

Sicco, Estefanía; Báez, Jessica; Margenat, Jimena; García, Fernanda; Ibarra, Manuel; Cabral, Pablo; Moreno, María; Cerecetto, Hugo; Calzada, Victoria

2018-03-01

Aptamers, oligonucleotides with the capability to bind to a target through non-covalent bonds with high affinity and specificity, have a great number of advantages as scaffold to prepare molecular imaging agents. In this sense, we have performed post-SELEX modifications of a truncated aptamer, Sgc8-c, which bind to protein tyrosine kinase 7 to obtain a specific molecular targeting probe for in vivo diagnosis and in vivo therapy. Herein, we describe the synthetic efforts to prepare conjugates between Sgc8-c and different metallic ions chelator moieties in short times, high purities, and adequate yields. The selected chelator moieties, derived from 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, 2-benzyl-1,4,7-triazacyclononane-1,4,7-triacetic acid, and 6-hydrazinonicotinic acid, were covalently attached at the 5'-aptamer position yielding the expected products which were stable in aqueous solution up to 75°C and in typical aptamer storage conditions at least for 30 days. © 2017 John Wiley & Sons A/S.

LC-QTOF-MS-based targeted metabolomics of arginine-creatine metabolic pathway-related compounds in plasma: application to identify potential biomarkers in pediatric chronic kidney disease.

PubMed

Benito, Sandra; Sánchez, Alicia; Unceta, Nora; Andrade, Fernando; Aldámiz-Echevarria, Luis; Goicolea, M Aránzazu; Barrio, Ramón J

2016-01-01

Chronic kidney disease (CKD) is a major epidemiologic problem which causes several disturbances in adults and in pediatrics. Despite being a worldwide public health problem, information available for CKD in the pediatric population is scarce. For that reason, an ion-pair reversed-phase liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) method has been developed and validated in order to analyze 16 amino acids, amino acid derivatives, and analogous compounds related to the arginine-creatine metabolic pathway that are suspicious of being increased or decreased in plasma from patients with CKD. The analytical method involved the addition of dithiothreitol, a reducing agent which reduces disulfide and thus giving total aminothiol concentration, as well as a simple precipitation of plasma proteins. Moreover, despite amino acids being usually derivatized to improve their retention time and to enhance their signal, for this method, an ion-pairing reagent was used, thus avoiding the need for derivatization. Subsequently, analysis of plasma from pediatric patients suffering from CKD and control pediatrics was carried out. As a result, glycine, citrulline, creatinine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were significantly increased in patients with CKD, regardless of their creatinine level, whereas in addition to these compounds dimethylglycine was also increased when CKD patients had plasma creatinine concentrations above 12 μg mL(-1), thus all are suggested as potential biomarkers for renal impairment.

Capture of the volatile carbonyl metabolite of flecainide on 2,4-dinitrophenylhydrazine cartridge for quantitation by stable-isotope dilution mass spectrometry coupled with chromatography

PubMed Central

Prokai, Laszlo; Szarka, Szabolcs; Wang, Xiaoli; Prokai-Tatrai, Katalin

2012-01-01

Carbonyl compounds are common byproducts of many metabolic processes. These volatile chemical entities are usually derivatized before mass spectrometric analysis to enhance the sensitivity of their detections. The classically used reagent for this purpose is 2,4-dinitrophenylhydrazine (DNPH) that forms the corresponding hydrazones. When DNPH is immobilized on specific cartridges it permits solvent-free collection and simultaneous derivatization of aldehydes and ketones from gaseous samples. The utility of this approach was tested by assembling a simple apparatus for the in vitro generation of trifluoroacetaldehyde (TFAA) and its subsequent capture on the attached DNPH cartridge. TFAA was generated via cytochrome P450-catalyzed dealkylation of flecainide, an antiarrhythmic agent, in pooled human liver microsomes. Stable-isotope dilution mass spectrometry coupled with GC and LC using negative chemical ionization (NCI) and electrospray ionization (ESI) was evaluated for quantitative analyses. To eliminate isotope effects observed with the use of deuterium-labeled DNPH, we selected its 15N4-labeled analog to synthesize the appropriate TFAA adduct, as internal standard. Quantitation by GC–NCI-MS using selected-ion monitoring outperformed LC–ESI-MS methods considering limits of detection and linearity of the assays. The microsomal metabolism of 1.5 μmol of flecainide for 1.5 h resulted in 2.6 ± 0.5 μg TFAA-DNPH, corresponding to 9.3 ± 1.7 nmol TFAA, captured by the cartridge. PMID:22342210

Capture of the volatile carbonyl metabolite of flecainide on 2,4-dinitrophenylhydrazine cartridge for quantitation by stable-isotope dilution mass spectrometry coupled with chromatography.

PubMed

Prokai, Laszlo; Szarka, Szabolcs; Wang, Xiaoli; Prokai-Tatrai, Katalin

2012-04-06

Carbonyl compounds are common byproducts of many metabolic processes. These volatile chemicals are usually derivatized before mass spectrometric analysis to enhance the sensitivity of their detections. The classically used reagent for this purpose is 2,4-dinitrophenylhydrazine (DNPH) that forms the corresponding hydrazones. When DNPH is immobilized on specific cartridges it permits solvent-free collection and simultaneous derivatization of aldehydes and ketones from gaseous samples. The utility of this approach was tested by assembling a simple apparatus for the in vitro generation of trifluoroacetaldehyde (TFAA) and its subsequent capture on the attached DNPH cartridge. TFAA was generated via cytochrome P450-catalyzed dealkylation of flecainide, an antiarrhythmic agent, in pooled human liver microsomes. Stable-isotope dilution mass spectrometry coupled with GC and LC using negative chemical ionization (NCI) and electrospray ionization (ESI) was evaluated for quantitative analyses. To eliminate isotope effects observed with the use of deuterium-labeled DNPH, we selected its (15)N(4)-labeled analog to synthesize the appropriate TFAA adduct, as internal standard. Quantitation by GC-NCI-MS using selected-ion monitoring outperformed LC-ESI-MS methods considering limits of detection and linearity of the assays. The microsomal metabolism of 1.5 μmol of flecainide for 1.5h resulted in 2.6 ± 0.5 μg TFAA-DNPH, corresponding to 9.3 ± 1.7 nmol TFAA, captured by the cartridge. Copyright © 2012 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.

Geraniol (2,6-dimethyl-2,6-octadien-8-ol) reactions with ozone and OH radical: Rate constants and gas-phase products

NASA Astrophysics Data System (ADS)

Forester, Crystal D.; Ham, Jason E.; Wells, J. R.

The bimolecular rate constants, kOH+geraniol, (231±58)×10 -12 cm 3 molecule -1 s -1 and k+geraniol, (9.3±2.3)×10 -16 cm 3 molecule -1 s -1, were measured using the relative rate technique for the reaction of the hydroxyl radical (OH) and ozone (O 3) with 2,6-dimethyl-2,6-octadien-8-ol (geraniol) at (297±3) K and 1 atmosphere total pressure. To more clearly define part of geraniol's indoor environment degradation mechanism, the products of the geraniol+OH and geraniol+O 3 reactions were also investigated. The identified geraniol+OH and geraniol+O 3 reaction products were: acetone, hydroxyacetaldehyde (glycolaldehyde, HC( dbnd O)CH 2OH), ethanedial (glyoxal, HC( dbnd O)C( dbnd O)H), and 2-oxopropanal (methylglyoxal, CH 3C( dbnd O)C( dbnd O)H). The use of derivatizing agents O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) were used to propose 4-oxopentanal as the other major geraniol+OH and geraniol+O 3 reaction product. The elucidation of this other reaction product was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible geraniol+OH and geraniol+O 3 reaction mechanisms based on previously published volatile organic compound+OH and volatile organic compound+O 3 gas-phase reaction mechanisms.

Determination of herbicides in environmental water samples by simultaneous in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction and silylation followed by GC-MS.

PubMed

Suárez, Ruth; Clavijo, Sabrina; González, Alba; Cerdà, Víctor

2018-03-01

An on-line, fast, simple, selective, and sensitive method has been developed for the determination of three herbicides belonging to the following families: triazines (atrazine), chloroacetamide (alachlor), and phenoxy (2,4-dichlorophenoxyacetic acid) in water samples. The method involves an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction along with simultaneous silylation prior to their determination by gas chromatography with mass spectrometry. Extraction, derivatization, and preconcentration have been simultaneously performed using acetone as dispersive solvent, N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide as derivatization agent and trichloroethylene as extraction solvent. After stirring for 180 s, the sedimented phase was transferred to a rotary micro-volume injection valve (3 μL) and introduced by an air stream into gas chromatograph with mass spectrometry detector. Recovery and enrichment factors were 87.2-111.2% and 7.4-10.4, respectively. Relative standard deviations were in the ranges of 6.6-7.4 for intraday and 9.2-9.6 for interday precision. The detection limits were in the range of 0.045-0.03 μg/L, and good linearity was observed up to 200 μg/L, with R 2 ranging between 0.9905 and 0.9964. The developed method was satisfactorily applied to assess the occurrence of the studied herbicides in groundwater samples. The recovery test was also performed with values between 77 and 117%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel HPLC fluorescence method for the quantification of methylphenidate in human plasma

PubMed Central

Zhu, Hao-Jie; Wang, Jun-Sheng; Patrick, Kennerly S.; Donovan, Jennifer L.; DeVane, C. Lindsay; Markowitz, John S.

2007-01-01

A number of analytical methods have been established to quantify methylphenidate (MPH). However, to date no HPLC methods are applicable to human pharmacokinetic studies without the use of mass spectrometry (MS) detection. We developed a sensitive and reliable HPLC-fluorescence method for the determination of MPH in human plasma using 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride (DIB-Cl) as the derivatizing agent. An established GC-MS method was adopted in this study as a comparator assay. MPH was derivatized DIB-Cl, and separated isocratically on a C18 column using a HPLC system with fluorescence detection (λex: 330 nm, λem: 460 nm). The lower limit of determination was found to be 1 ng/mL. A linear calibration curve was obtained over the concentrations ranging from 1 to 80 ng/mL (r=0.998). The relative standard deviations of intra-day and inter-day variations were ≤ 9.10 % and ≤ 7.58 %, respectively. The accuracy ranged between 92.59 % and 103.06 %. The method was successfully applied to the pharmacokinetic study of a subject who received a single oral dose (0.3 mg/kg) of immediate-release MPH and yielded consistent results with that of the GC-MS method. This method is the first HPLC assay with non-MS detection providing sufficient reliability and sensitivity for both pre-clinical and clinical studies of MPH. PMID:17804308

Electrochemically protected copper(I)-catalyzed azide-alkyne cycloaddition.

PubMed

Hong, Vu; Udit, Andrew K; Evans, Richard A; Finn, M G

2008-06-16

The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has found broad application in myriad fields. For the most demanding applications that require high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu(I) oxidation state in the presence of air. This simple procedure efficiently achieves excellent yields of CuAAC products from both small-molecule and protein substrates without the use of potentially damaging chemical reducing agents. A new water-soluble carboxylated version of the popular tris(benzyltriazolylmethyl)amine (TBTA) ligand is also described. Cyclic voltammetry revealed reversible or quasi-reversible electrochemical redox behavior of copper complexes of the TBTA derivative (2; E(1/2)=60 mV vs. Ag/AgCl), sulfonated bathophenanthroline (3; E(1/2)=-60 mV), and sulfonated tris(benzimidazoylmethyl)amine (4; E(1/2) approximately -70 mV), and showed catalytic turnover to be rapid relative to the voltammetry time scale. Under the influence of a -200 mV potential that was established by using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically protected bioconjugations in air were performed by using bacteriophage Qbeta that was derivatized with azide moieties at surface lysine residues. Complete derivatization of more than 600 reactive sites per particle was demonstrated within 12 h of electrolysis with substoichiometric quantities of Cu3.

Targeting of Arenavirus RNA Synthesis by a Carboxamide-Derivatized Aromatic Disulfide with Virucidal Activity

PubMed Central

Sepúlveda, Claudia S.; García, Cybele C.; Levingston Macleod, Jesica M.

2013-01-01

Several arenaviruses can cause severe hemorrhagic fever (HF) in humans, representing a public health threat in endemic areas of Africa and South America. The present study characterizes the potent virucidal activity of the carboxamide-derivatized aromatic disulfide NSC4492, an antiretroviral zinc finger-reactive compound, against Junín virus (JUNV), the causative agent of Argentine HF. The compound was able to inactivate JUNV in a time and temperature-dependent manner, producing more than 99 % reduction in virus titer upon incubation with virions at 37°C for 90 min. The ability of NSC4492-treated JUNV to go through different steps of the multiplication cycle was then evaluated. Inactivated virions were able to bind and enter into the host cell with similar efficiency as control infectious particles. In contrast, treatment with NSC4492 impaired the capacity of JUNV to drive viral RNA synthesis, as measured by quantitative RT-PCR, and blocked viral protein expression, as determined by indirect immunofluorescence. These results suggest that the disulfide NSC4492 targets on the arenavirus replication complex leading to impairment in viral RNA synthesis. Additionally, analysis of VLP produced in NSC4492-treated cells expressing JUNV matrix Z protein revealed that the compound may interact with Z resulting in an altered aggregation behavior of this protein, but without affecting its intrinsic self-budding properties. The potential perspectives of NSC4492 as an inactivating vaccinal compound for pathogenic arenaviruses are discussed. PMID:24278404

High-performance liquid chromatography determination of ketone bodies in human plasma by precolumn derivatization with p-nitrobenzene diazonium fluoroborate.

PubMed

Yamato, Susumu; Shinohara, Kumiko; Nakagawa, Saori; Kubota, Ai; Inamura, Katsushi; Watanabe, Gen; Hirayama, Satoshi; Miida, Takashi; Ohta, Shin

2009-01-01

We developed and validated a sensitive and convenient high-performance liquid chromatography (HPLC) method for the specific determination of ketone bodies (acetoacetate and D-3-hydroxybutyrate) in human plasma. p-Nitrobenzene diazonium fluoroborate (diazo reagent) was used as a precolumn derivatization agent, and 3-(2-hydroxyphenyl) propionic acid was used as an internal standard. After the reaction, excess diazo reagent and plasma proteins were removed by passing through a solid-phase cartridge (C(18)). The derivatives retained on the cartridge were eluted with methanol, introduced into the HPLC system, and then detected with UV at 380 nm. A calibration curve for acetoacetate standard solution with a 20-microl injection volume showed good linearity in the range of 1 to 400 microM with a 0.9997 correlation coefficient. For the determination of D-3-hydroxybutyrate, it was converted to acetoacetate before reaction with the diazo reagent by an enzymatic coupling method using D-3-hydroxybutyrate dehydrogenase and lactate dehydrogenase. A calibration curve for D-3-hydroxybutyrate standard solution also showed good linearity in the range of 1.5 to 2000 microM with a 0.9988 correlation coefficient. Analytical recoveries of acetoacetate and D-3-hydroxybutyrate in human plasma were satisfactory. The method was successfully applied to samples from diabetic patients, and results were consistent with those obtained using the thio-NAD enzymatic cycling method used in clinical laboratories.

[Simultaneous determination of six fluorescent whitening agents in plastic and paper packaging materials by high performance liquid chromatography].

PubMed

Zhang, Juzhou; Ji, Shuilin; Cai, Huimei; Li, Jing; Wang, Yongxin; Wang, Jingqiu

2017-11-08

A novel analytical method was developed for the simultaneous determination of six fluorescent whitening agents (FWAs:FWA 135, FWA 184, FWA 185, FWA 199, FWA 378 and FWA 393) in paper and plastic food packaging materials by high performance liquid chromatography with fluorescence detection (HPLC-FLD). The sample was extracted with mixed solution of chloroform and acetonitrile (3:7, v/v), then cleaned up by HLB solid phase extraction column. Qualitative and quantitative analyses were carried out by HPLC. The sample was separated on a Phenomenex C18 column using acetonitrile and 5 mmol/L ammonium acetate aqueous solution as mobile phases. The results indicated that the linear range of FWA393 was 15-1500 μg/L and the linear ranges of the other five FWAs were 5-500 μg/L with correlation coefficients greater than 0.999. The recoveries in spiked samples were between 80.4% and 125.0% with RSDs ( n =6) of 1%-13%. Furthermore, this method was applied to analyze 12 samples in the market to verify the practicality of the method. The method showed the advantages of simplicity, high recovery and good precision, and is suitable for the detection of the six fluorescent whitening agents in food packaging materials.

Extraction-spectrophotometric determination of tris(2-chloroethyl)amine using phthaleins.

PubMed

Rozsypal, Tomas; Halamek, Emil

2017-06-01

Procedures for the extraction-spectrophotometric determination of tris(2-chloroethyl)amine, an alkylating agent known as a drug as well as a chemical warfare agent (nitrogen mustard HN-3), with 7 acid-base indicators of a triphenylmethane lactone type, phthaleins, were developed. Representatives of phthaleins without an oxygen bridge (thymolphthalein, o-cresolphthalein, naphtholphthalein) and with an oxygen bridge (fluorescein, 2',7'-dichlorofluorescein, eosin B and eosin Y) were used. The methods were based on the formation of ion pair complexes. Chloroform was used as a non-polar solvent for an extraction. The conditions to determine were optimized for the optimal pH of the buffer and the concentration of a phthalein as a reagent. The dependence on the reaction time in a water phase and the stoichiometry of extraction products were studied. The detection limits and the limits of the determination of separate procedures and conditional extraction constants were determined. Comparison with the spectrophotometric method of the group determination of alkyl halides and acyl halides using alkaline ethanol-water solution of thymolphthalein, the so-called T-135 agent, was conducted. While studying the selectivity, the possible interference of bis(2-chloroethyl)sulphide and 3 nitrogen mustards in the proposed procedures were verified. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A rapid gas chromatographic injection-port derivatization method for the tandem mass spectrometric determination of patulin and 5-hydroxymethylfurfural in fruit juices.

PubMed

Marsol-Vall, Alexis; Balcells, Mercè; Eras, Jordi; Canela-Garayoa, Ramon

2016-07-01

A novel method consisting of injection-port derivatization coupled to gas chromatography-tandem mass spectrometry is described. The method allows the rapid assessment of 5-hydroxymethylfurfural (HMF) and patulin content in apple and pear derivatives. The chromatographic separation of the compounds was achieved in a short chromatographic run (12.2min) suitable for routine controls of these compounds in the fruit juice industry. The optimal conditions for the injection-port derivatization were at 270°C, 0.5min purge-off, and a 1:2 sample:derivatization reagent ratio (v/v). These conditions represent an important saving in terms of derivatization reagent consumption and sample preparation time. Quality parameters were assessed for the target compounds, giving LOD of 0.7 and 1.6μg/kg and LOQ of 2 and 5μg/kg for patulin and HMF, respectively. These values are below the maximum patulin concentration in food products intended for infants and young children. Repeatability (%RSD n=5) was below 12% for both compounds. In addition, the method linearity ranged between 25 and 1000μg/kg and between 5 and 192μg/kg for HMF and patulin, respectively. Finally, the method was applied to study HMF and patulin content in various fruit juice samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasound-assisted emulsification microextraction combined with injection-port derivatization for the determination of some chlorophenoxyacetic acids in water samples.

PubMed

Yamini, Yadollah; Saleh, Abolfazl

2013-07-01

An efficient method based on ultrasound-assisted emulsification microextraction followed by injection-port derivatization GC analysis was developed to determine 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) in natural water samples. In this procedure, 12.5 μL of 1-undecanol was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample of the analytes located inside an ultrasonic water bath. The resulting emulsion was centrifuged, and 1 μL of the separated organic solvent together with 1 μL of the derivatization reagent were injected into a GC equipped with a flame ionization detector. Several factors that influence the derivatization and extraction were optimized. Under the optimal conditions, the LODs were 0.33 and 1.7 μg/L for MCPA and 2,4-D, respectively. Preconcentration factors of 670 and 836 were obtained for MCPA and 2,4-D, respectively. The precision of the proposed method was evaluated in terms of repeatability, which was <5.7% (n = 5). The applicability of the proposed method was evaluated by extraction and determination of chlorophenoxyacetic acids from some natural waters, which indicated that the matrices of natural waters have no significant effect on the extraction and derivatization efficiency of this method. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The natural chlorine cycle - Formation of the carcinogenic and greenhouse gas compound chloroform in drinking water reservoirs.

PubMed

Forczek, Sándor T; Pavlík, Milan; Holík, Josef; Rederer, Luděk; Ferenčík, Martin

2016-08-01

Chlorine cycle in natural ecosystems involves formation of low and high molecular weight organic compounds of living organisms, soil organic matter and atmospherically deposited chloride. Chloroform (CHCl3) and adsorbable organohalogens (AOX) are part of the chlorine cycle. We attempted to characterize the dynamical changes in the levels of total organic carbon (TOC), AOX, chlorine and CHCl3 in a drinking water reservoir and in its tributaries, mainly at its spring, and attempt to relate the presence of AOX and CHCl3 with meteorological, chemical or biological factors. Water temperature and pH influence the formation and accumulation of CHCl3 and affect the conditions for biological processes, which are demonstrated by the correlation between CHCl3 and ΣAOX/Cl(-) ratio, and also by CHCl3/ΣAOX, CHCl3/AOXLMW, CHCl3/ΣTOC, CHCl3/TOCLMW and CHCl3/Cl(-) ratios in different microecosystems (e.g. old spruce forest, stagnant acidic water, humid and warm conditions with high biological activity). These processes start with the biotransformation of AOX from TOC, continue via degradation of AOX to smaller molecules and further chlorination, and finish with the formation of small chlorinated molecules, and their subsequent volatilization and mineralization. The determined concentrations of chloroform result from a dynamic equilibrium between its formation and degradation in the water; in the Hamry water reservoir, this results in a total amount of 0.1-0.7 kg chloroform and 5.2-15.4 t chloride. The formation of chloroform is affected by Cl(-) concentration, by concentrations and ratios of biogenic substrates (TOC and AOX), and by the ratios of the substrates and the product (feedback control by chloroform itself). Copyright © 2016 Elsevier Ltd. All rights reserved.

Formation and transformation of chloroform during managed aquifer recharge (MAR).

PubMed

Liu, Dan; Liang, Xiujuan; Zhang, Wenjing; Wang, Zhuo; Ma, Tianyi; Li, Fulin; Chen, Xuequn

2018-05-09

Chlorination is an effective method to protect the safety of groundwater systems during managed aquifer recharge. However, chlorination leads to the formation of disinfection by-products, whose behavior in aquifers remains unclear and has caused public concern. In this study, an in-site test was performed on an anoxic aquifer in Shouguang City, China, to investigate the formation and transformation of chloroform during managed aquifer recharge. The field tests showed that the formation of chloroform in groundwater caused by the recharge of chlorinated water, and that the fate of chloroform was affected by adsorption and biodegradation. The retardation factor was 1.27, and the half-life was 29 days. The formation and transformation of chloroform during continuous recharge under different hydrochemical conditions was further investigated by batch experiments. These experiments showed that the formation of chloroform increased with contact time, tended to be stable after 10 h, and was facilitated by high chloride/TOC ratios, high pH, and low ionic strength (IS) for a given contact time. The adsorption experiments showed that the process accords with the pseudo-second-order kinetic equations and the Freundlich model. The adsorption capacity was pH dependent (1.01-1.66 μg/g at pH 5 and 2.17-3.05 μg/g at pH 9). Increasing the IS promotes adsorption. The results from biodegradation experiments indicated that the biodegradation was well fitted by the Monod equation. The retardation factor in the batch experiments was close to that of the field test, but the half-life was less than the field test. This is mainly due to the difference in the concentration of dissolved oxygen. Copyright © 2018 Elsevier Ltd. All rights reserved.

The early steps of chloroform anaesthesia in Turkey during the Ottoman Empire in the 19th century.

PubMed

Ulman, Yesim Isil

2005-04-01

The aim of this study was to research the pioneering steps for the employment of chloroform in Turkey in comparison with the developments in the West i.e. in the United States and in Europe. The development of anaesthesiology in the West started in the first half of the 19th century. As an anaesthetic substance, ether was first employed in a medical operation by R. Liston in December 1846. But taking into consideration of its bronchially irritant effect, British gynaecologist Dr. J.Y. Simpson preferred to utilize chloroform in obstetrical operations in 1847. The paper aims at shedding light on the earlier steps for modern anaesthesiology in Turkey in that sense. The survey used evaluation of archival documents, first hand-original sources such as the annual medical reports of the Medical School, books, official journals, and newspapers of the time, and also secondary sources concerned with the subject. In view of the findings of the survey, chloroform, as an anaesthetic material, began to be administered surgically in Turkey much earlier than it was already known. It was experienced and used in operations at the surgical clinic of the Imperial School of Medicine at the Capital city, Istanbul in 1848. The Crimean War (1853-1855) induced to the prevalent surgical use of chloroform in Istanbul on the soldiers back from the front. In other words, it was evidenced that surgeons started to make use of this anaesthetic substance in the Ottoman Empire, shortly after it was put into medical practice in Europe. This study deals with that phenomenal progress of chloroform anaesthesia in the medical history in Turkey during the second half of the 19th century.

Dissolution of root canal sealer cements in volatile solvents.

PubMed

Whitworth, J M; Boursin, E M

2000-01-01

There are few published data on the solubility profiles of endodontic sealers in solvents commonly employed in root canal retreatment. This study tested the hypothesis that root canal sealer cements are insoluble in the volatile solvents chloroform and halothane. Standardized samples (n = 5) of glass ionomer (Ketac Endo), zinc oxide-eugenol (Tubli-Seal EWT), calcium hydroxide (Apexit) and epoxy resin (AH Plus) based sealers were immersed in chloroform or halothane for 30 s, 1 min, 5 min and 10 min. Mean loss of weight was plotted against time of exposure, and differences in behaviour assessed by multiple paired t-tests (P < 0.01). Clear differences were shown in the solubility profiles of major classes of root canal sealer cements in two common volatile solvents. In comparison with other classes of material, Ketac Endo was the least soluble in chloroform and halothane (P < 0.01), with less than 1% weight loss after 10 min exposure to either solvent. Apexit had low solubility with 11.6% and 14.19% weight loss after 10 min exposure to chloroform and halothane, respectively. The difference between solvents was not significant (P > 0.01). Tubli-Seal EWT was significantly less soluble in halothane than chloroform (5.19% and 62.5% weight loss after 10 min exposure, respectively (P < 0.01)). Its solubility in halothane was not significantly different from that of Apexit. AH Plus was significantly more soluble than all other materials in both chloroform and halothane (96% and 68% weight loss after 10 min exposure, respectively (P < 0.01)). There are significant differences in the solubility profiles of major classes of root canal sealer in common organic solvents. Efforts should continue to find a more universally effective solvent for use in root canal treatment.

Laboratory Evaluations of the Fractions Efficacy of Annona senegalensis (Annonaceae) Leaf Extract on Immature Stage Development of Malarial and Filarial Mosquito Vectors

PubMed Central

Lame, Younoussa; Nukenine, Elias Nchiwan; Pierre, Danga Yinyang Simon; Elijah, Ajaegbu Eze; Esimone, Charles Okechukwu

2015-01-01

Background: Within the framework to control mosquitoes, ovicidal, larvicidal and pupicidal activity of Annona senegalensis leaf extract and its 4 fractions against Anopheles gambiae and Culex quinquefasciatus were evaluated in the laboratory conditions. Methods: Ovicidal test was performed by submitting at least 100 eggs of mosquitoes to 125, 250, 500, 1000 and 2000 ppm concentrations, while larvicidal and pupicidal effects were assessed by submitting 25 larvae or pupae to the concentrations of 2500, 1250, 625 and 312.5 ppm of plant extract or fractions of A. senegalensis. Results: The eggs of An. gambiae were most affected by N-hexane (0.00% hatchability) and chloroform (03.67% hatchability) fractions compared to Cx. quinquefasciatus where at least 25 % hatchability were recorded at 2000 ppm. For larvicidal test, N-hexane (LC50= 298.8 ppm) and chloroform (LC50= 418.3 ppm) fractions were more effective than other fractions on An. gambiae larvae while, a moderate effectiveness was also observed with N-hexane (LC50= 2087.6 ppm), chloroform (LC50= 9010.1 ppm) fractions on Cx. quinquefasciatus larvae. The highest mortality percent of the pupae were also recorded with N-hexane and chloroform fractions on An. gambiae at 2500 ppm. As for Cx. quinquefasciatus only 50 % and 36 % mortality were recorded with N-hexane and chloroform fractions respectively. Conclusion: The extract of A. senegalensis was toxic on immature stage of mosquito species tested. By splitting methanolic crude extract, only N-hexane and chloroform fractions were revealed to possess a mosquitocidal effects and could be considered and utilized for future immature mosquito vectors control. PMID:26623434

Bilateral Olfactory Mucosa Damage Induces the Disappearance of Olfactory Glomerulus and Reduces the Expression of Extrasynaptic α5GABAARs in the Hippocampus in Early Postnatal Sprague Dawley Rats.

PubMed

Zheng, Xiaomin; Liang, Liang; Hei, Changchun; Yang, Wenjuan; Zhang, Tingyuan; Wu, Kai; Qin, Yi; Chang, Qing

2018-04-17

Chloroform-induced olfactory mucosal degeneration has been reported in adult rats following gavage. We used fixed-point chloroform infusions on different postnatal days (PNDs) to investigate the effects of early olfactory bilateral deprivation on the main olfactory bulbs in Sprague Dawley rats. The experimental groups included rats infused with chloroform (5 μl) or saline (sham, 5 μl) on PNDs 3 and 8, and rats not receiving infusions (control) (n = 6 in all groups). Rats receiving chloroform on PND 3 showed significant hypoevolutism when compared to those in other groups (P < 0.05). There was a complete disappearance and a significant reduction in the size of olfactory glomeruli in the PND 3 and 8 groups, respectively, when compared to the respective sham groups. Rats receiving chloroform on PND 3 had significant memory impairment (P < 0.01) and increased levels of learned helplessness (P < 0.05), as measured using the Morris water maze and tail suspension tests, respectively. GABA A receptor alpha5 subunit (α5GABA A R) expression in hippocampal neurons was significantly lower in rats receiving chloroform on PND 3 than in rats in other groups (P < 0.01), as measured using immunohistochemistry and polymerase chain reaction. There was thus a critical period for the preservation of regenerative ability in olfactory receptor neurons, during which damage and olfactory deprivation led to altered rhinencephalon structure and disappearance of olfactory glomeruli, which induced hypoevolutism. Olfactory deprivation after the critical period had no significant effect on olfactory receptor neuron regeneration, leading to reduced developmental and behavioral effects in Sprague Dawley rats.

Isolation and serological differentiation of a herpesvirus from bobwhite quail (Colinus virginianus, L. 1758).

PubMed

Kaleta, E F; Marschall, H J; Glünder, G; Stiburek, B

1980-01-01

An infectious agent was isolated from the liver of bobwhite quails (Colinus virginianus, L. 1758). The agent was sensitive to chloroform and its multiplication was inhibited by 5-iodine-2-deoxy-uridine. It passed filters with a pore diameter of 220 nm and more but not 100 nm filters. Electron microscopic examination revealed numerous nucleocapsids with hollow capsomeres and few enveloped particles in the supernatant fluids of infected cultures. The nucleocapsids were calculated to have 162 capsomeres on their surface. Using the plaque reduction method for neutralization tests no serological cross reactions could be detected between the quail isolate and sera against Marek's disease virus, turkey herpes-virus (HV), duck enteritis HV, infectious laryngotracheitis HV, amazon parrot HV, great horned owl HV, eagle owl HV, snowy owl HV, falcon HV, pigeon HV, Lake Victoria Cormorant HV, and stork HV. The isolate from bobwhite quail did only cross-react with antiserum against crane HV. It is concluded that the isolated virus is a member of the avian herpesvirus group and it is proposed to tentatively term it herpesvirus colinum (from Colinus virginianus = bobwhite quail).

Antimicrobial Activities of Three Medicinal Plants and Investigation of Flavonoids of Tripleurospermum disciforme.

PubMed

Tofighi, Zahra; Molazem, Maryam; Doostdar, Behnaz; Taban, Parisa; Shahverdi, Ahmad Reza; Samadi, Nasrin; Yassa, Narguess

2015-01-01

Rosa damascena, Tripleurospermum disciforme and Securigera securidaca were used as disinfectant agents and for treatment of some disease in folk medicine of Iran. The antimicrobial effects of different fractions of seeds extract of S. securidaca, petals extract of R. damascena and aerial parts extract of T. disciforme were examined against some gram positive, gram negative and fungi by cup plate diffusion method. The petroleum ether and chloroform fractions of S. securidaca showed antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa, while its methanol fraction had no antibacterial effects. R. damascena petals extract demonstrated antibacterial activities against Bacillus cereus, Staphylococcus epidermidis, S. aureus and Pseudomonas aeruginosa. T. disciforme aerial parts extract exhibited antimicrobial effects only against S. aureus and S. epidermidis. None of the fractions had any antifungal activities. Therefore, present study confirmed utility of these plants as disinfectant agents. Six flavonoids were isolated from T. disciforme: Luteolin, Quercetin-7-O-glucoside, Kaempferol, Kaempferol-7-O-glucoside, Apigenin and Apigenin-7-O-glucoside. The flavonoids and the antimicrobial activity of T. disciforme are reported for the first time.

Antimicrobial Activities of Three Medicinal Plants and Investigation of Flavonoids of Tripleurospermum disciforme

PubMed Central

Tofighi, Zahra; Molazem, Maryam; Doostdar, Behnaz; Taban, Parisa; Shahverdi, Ahmad Reza; Samadi, Nasrin; Yassa, Narguess

2015-01-01

Rosa damascena, Tripleurospermum disciforme and Securigera securidaca were used as disinfectant agents and for treatment of some disease in folk medicine of Iran. The antimicrobial effects of different fractions of seeds extract of S. securidaca, petals extract of R. damascena and aerial parts extract of T. disciforme were examined against some gram positive, gram negative and fungi by cup plate diffusion method. The petroleum ether and chloroform fractions of S. securidaca showed antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa, while its methanol fraction had no antibacterial effects. R. damascena petals extract demonstrated antibacterial activities against Bacillus cereus, Staphylococcus epidermidis, S. aureus and Pseudomonas aeruginosa. T. disciforme aerial parts extract exhibited antimicrobial effects only against S. aureus and S. epidermidis. None of the fractions had any antifungal activities. Therefore, present study confirmed utility of these plants as disinfectant agents. Six flavonoids were isolated from T. disciforme: Luteolin, Quercetin-7-O-glucoside, Kaempferol, Kaempferol-7-O-glucoside, Apigenin and Apigenin-7-O-glucoside. The flavonoids and the antimicrobial activity of T. disciforme are reported for the first time. PMID:25561928

Identification of linoleic acid, a main component of the n-hexane fraction from Dryopteris crassirhizoma, as an anti-Streptococcus mutans biofilm agent.

PubMed

Jung, Ji-Eun; Pandit, Santosh; Jeon, Jae-Gyu

2014-01-01

Dryopteris crassirhizoma is a semi-evergreen plant. Previous studies have shown the potential of this plant as an agent for the control of cariogenic biofilms. In this study, the main antibacterial components of the plant were identified by correlating gas chromatography-mass spectrometry data with the antibacterial activity of chloroform and n-hexane fractions and then evaluating the activity of the most potent antibacterial component against Streptococcus mutans UA159 biofilms. The most potent antibacterial component was linoleic acid, a main component of the n-hexane fraction. Linoleic acid reduced viability in a dose dependent manner and reduced biofilm accumulation during initial and mature biofilm formation. Furthermore, when the biofilms were briefly treated with linoleic acid (10 min/treatment, a total of six times), the dry weight of the biofilms was significantly diminished. In addition, the anti-biofilm activity of the n-hexane fraction was similar to that of linoleic acid. These results suggest that the n-hexane fraction of D. crassirhizoma and linoleic acid may be useful for controlling cariogenic biofilms.

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

2011-12-01

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

Water-based alkyl ketene dimer ink for user-friendly patterning in paper microfluidics.

PubMed

Hamidon, Nurul Nadiah; Hong, Yumiao; Salentijn, Gert Ij; Verpoorte, Elisabeth

2018-02-13

We propose the use of water-based alkyl ketene dimer (AKD) ink for fast and user-friendly patterning of paper microfluidic devices either manually or using an inexpensive XY-plotter. The ink was produced by dissolving hydrophobic AKD in chloroform and emulsifying the solution in water. The emulsification was performed in a warm water bath, which led to an increased rate of the evaporation of chloroform. Subsequent cooling led to the final product, an aqueous suspension of fine AKD particles. The effects of surfactant and AKD concentrations, emulsification procedure, and cooling approach on final ink properties are presented, along with an optimized protocol for its formulation. This hydrophobic agent was applied onto paper using a plotter pen, after which the paper was heated to allow spreading of AKD molecules and chemical bonding with cellulose. A paper surface patterned with the ink (10 g L -1 AKD) yielded a contact angle of 135.6° for water. Unlike organic solvent-based solutions of AKD, this AKD ink does not require a fume hood for its use. Moreover, it is compatible with plastic patterning tools, due to the effective removal of chloroform in the production process to less than 2% of the total volume. Furthermore, this water-based ink is easy to prepare and use. Finally, the AKD ink can also be used for the fabrication of so-called selectively permeable barriers for use in paper microfluidic networks. These are barriers that stop the flow of water through paper, but are permeable to solvents with lower surface energies. We applied the AKD ink to confine and preconcentrate sample on paper, and demonstrated the use of this approach to achieve higher detection sensitivities in paper spray ionization-mass spectrometry (PSI-MS). Our patterning approach can be employed outside of the analytical lab or machine workshop for fast prototyping and small-scale production of paper-based analytical tools, for use in limited-resource labs or in the field. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Phytochemical Screening, Alpha-Glucosidase Inhibition, Antibacterial and Antioxidant Potential of Ajuga bracteosa Extracts.

PubMed

Hafeez, Kokab; Andleeb, Saiqa; Ghousa, Tahseen; Mustafa, Rozina G; Naseer, Anum; Shafique, Irsa; Akhter, Kalsoom

2017-01-01

Ajuga bracteosa, a medicinal herb, is used by local community to cure a number of diseases such as inflammation, jaundice bronchial asthma, cancer and diabetes. The aim of present work was to evaluate the antioxidant potential, in vitro antidiabetic and antimicrobial effects of A. bracteosa. n-hexane, ethyl acetate, chloroform, acetone, methanol and aqueous extracts of Ajuga bracteosa roots, were prepared via maceration. Antibacterial activity was carried out by agar well diffusion method. Quantitative and qualitative phytochemical screening was done. The antioxidant activity was determined by iron (II) chelating activity, iron reducing power, DPPH, and ABTS free radical scavenging methods, Antidiabetic activity was evaluated through inhibition of α-glucosidase assay. Phytochemical analysis showed the presence of phenols, flavonoids, tannins, saponins, quinines, terpenoids, xanthoproteins, glycosides, carbohydrates, steroids, phytosterols and amino acids. DPPH and ABTS potential values were recorded as 61.92% to 88.84% and 0.11% to 38.82%, respectively. Total phenolic and total flavonoid contents were expressed as gallic acid and rutin equivalents. Total iron content was expressed as FeSO4 equivalents. Chloroform and n-hexane extracts showed significant enzyme inhibition potential with IC50 values of 29.92 μg/ml and 131.7 μg/ml respectively. Aqueous extract showed maximum inhibition of E. coli, S. typhimurium, E. amnigenus, S. pyogenes, and S. aureus, (18.0±1.0 mm, 12.5±0.7 mm, 17.0±0.0 mm, 11.0±0.0 mm and 15.3±2.0 mm mm), respectively. Similarly, n-hexane extract showed maximum inhibition of E. coli, E. amnigenus, S. aureus (11.6±1.5 mm; 11.3±1.5 mm; 13.3±0.5 mm). This study also shows that n-hexane, chloroform, ethyl acetate and aqueous extracts of A. bracteosa root possess α-glucosidase inhibitory activities and therefore it may be used as hypoglycemic agents in the management of postprandial hyperglycemia. Ajuga bracteosa root extracts may provide a basis for development of antioxidant, antimicrobial and antidiabetic drugs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Antimicrobial and anti-inflammatory activities of Pleurostylia capensis Turcz (Loes) (celastraceae).

PubMed

Razwinani, Mapula; Tshikalange, Thilivhali Emmanuel; Motaung, Shirley C K M

2014-01-01

Pleurostylia capensis is a large tree that can reach the maximum height of 20 m long, and it have been traditionally used as cosmetic, for steam bath, ritual body wash, and as a purgative to treat symptoms of witchcraft. Using ethanol, chloroform, dichloromethane (DCM), ethyl acetate (EA), and water extracts, leaves, bark and roots of Pleurostylia capensis were investigated scientifically for their effectiveness in antimicrobial, antioxidant and anti-inflammatory activities using standard methods. The extracts were evaluated for antimicrobial activity against Gram positive (Staphylococcus aureus, Bacillus cereus, and Mycobacterium smegmatis), Gram negative (Escherichia coli, Klebsiella pneumonia, Klebsiella oxytoca, Streptococcus pyogenes, Pseudomonas aeruginosa and Salmonella typhimurium), and Candida albicans. The antioxidant activity was investigated using 2, 2-diphenlyl-1-picrylhadrazyl (DPPH), free radical scavenging assay. The anti-inflammatory activity of P. capensis extracts was evaluated against both cyclooxygenase enzymes (COX 1 and 2). The ethyl acetate extracts of P. capensis showed a strong antimicrobial activity against B. cereus, K. pneumonia, S. pyogenes, and M. smegmatis with MIC value of 0.39 and 0.78 mg/ml. While the ethanol bark extract was most active against M. smegmatis with MIC value of 0.78 mg/ml; the least potent activity was observed with dichloromethane, chloroform and water extracts, with an MIC value ranging from 1.56 mg/ml to 50.0 mg/ml. The plant extracts proved to be good antioxidant agent, whereas extracts of ethanol were the most active, with IC50 ranging from 1.00 to 1.74 µg/ml, which is lower, and in close range to Vitamin C (1.40 µg/ml). Its moderation to potent inhibitory activity was observed in all extracts. Ethanol and dichloromethane extracts were among the most potent when compared to water and petroleum ether extracts. The water extracts showed to be nontoxic on the Hek cell line with an IC50 value of 204.0, and 207.3 µg/ml (roots and bark) respectively. The dichloromethane, ethyl acetate, chloroform and ethanol extracts showed to be toxic on the Hek cell, with IC50 range from 5.94 to 42.91µg/ml. The results obtained indicate the effectiveness of these plants.

IRIS Assessment Plan for Chloroform (Scoping and Problem Formulation Materials)

EPA Science Inventory

In September 2017, EPA released the draft IRIS Assessment Plan (IAP) for Chloroform for public review and comment. ...

IRIS Assessment Plan for Chloroform (Scoping and Problem Formulation Materials)

EPA Science Inventory

In September 2017, EPA released the draft IRIS Assessment Plan (IAP) for Chloroform for public review and comment. Th...

Did the use of chloroform by Queen Victoria influence its acceptance in obstetric practice?

PubMed

Connor, H; Connor, T

1996-10-01

Examination of contemporaneous publications suggests that the use of chloroform by Queen Victoria in 1853 did not result in the major breakthrough in the acceptability of obstetric anaesthesia with which the event has been credited by some later writers.

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1-Butanol + Chloroform + Benzene) and its Binary Constituents (1-Butanol + Chloroform and 1-Butanol + Benzene)

NASA Astrophysics Data System (ADS)

Smiljanić, Jelena D.; Kijevčanin, Mirjana Lj.; Djordjević, Bojan D.; Grozdanić, Dušan K.; Šerbanović, Slobodan P.

2008-04-01

Densities ρ of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister equation for all binary mixtures and to the Nagata and Tamura equation for the ternary system. The Radojković et al. equation has been used to predict excess molar volumes of the ternary mixtures. Also, V E data of the binary systems were correlated by the van der Waals (vdW1) and Twu Coon Bluck Tilton (TCBT) mixing rules coupled with the Peng Robinson Stryjek Vera (PRSV) equation of state. The prediction and correlation of V E data for the ternary system were performed by the same models.

Application of the Grunwald-Winstein Equations to Studies of Solvolytic Reactions of Chloroformate and Fluoroformate Esters

PubMed Central

D’Souza, Malcolm J.; Kevill, Dennis N.

2014-01-01

Chloroformates are important laboratory and industrial chemicals with almost one hundred listed in the catalogs of leading suppliers. They are, for example, of prime importance as protecting groups in peptide synthesis. In some instances, the more stable fluoroformate is preferred. In recent years, the specific rates of solvolysis (k) for chloroformates and fluoroformates in solvents of widely ranging nucleophilicity and ionizing power have been studied. Analysis of these rates using the extended (two-term) Grunwald-Winstein equation has led to important information concerning reaction mechanism. Also assisting in this effort have been studies of kinetic solvent isotope effects (KSIE), of leaving group effects (especially kF/kCl ratios), and of entropies of activation from studies of specific rate variations with temperature. For solvolyses of chloroformate esters, two mechanisms (addition-elimination and ionization) are commonly encountered. For solvolyses of fluoroformates, mainly because of a strong C–F bond, the ionization pathway is rare and the addition-elimination pathway is in most situations the one encountered. PMID:25364780

Analysis of phytochemical constituents of Eucalyptus citriodora L. responsible for antifungal activity against post-harvest fungi.

PubMed

Javed, S; Shoaib, A; Mahmood, Z; Mushtaq, S; Iftikhar, S

2012-01-01

In vitro antifungal activity and phytochemical constituents of essential oil, aqueous, methanol and chloroform extract of Eucalyptus citriodora Hook leaves were investigated. A qualitative phytochemical analysis was performed for the detection of alkaloids, cardiac glycosides, flavonoids, saponins, sterols, tannins and phenols. Methanolic extract holds all identified biochemical constituents except for the tannin. While these biochemical constituents were found to be absent in essential oil, aqueous and chloroform extracts with the exception of sterols, cardiac glycosides and phenols in essential oil and sterols and phenols in aqueous and chloroform extracts. Antimycotic activity of four fractions of E. citriodora was investigated through agar-well diffusion method against four post-harvest fungi, namely, Aspergillus flavus Link ex Gray, Aspergillus fumigatus Fres., Aspergillus nidulans Eidam ex Win and Aspergillus terreus Thom. The results revealed maximum fungal growth inhibition by methanolic extract (14.5%) followed by essential oil (12.9%), chloroform extract (10.15%) and aqueous extract (10%).

Derivatization of castor oil based estolide esters: Preparation of epoxides and cyclic carbonates

USDA-ARS?s Scientific Manuscript database

Estolides that are based on castor oil and oleic acid are versatile starting points for the production of industrial fluids with new properties. A variety of unsaturated estolides were derivatized by epoxidation with hydrogen peroxide. The epoxidized estolides were further modified using supercritic...

APPLICATION OF DNPH DERIVATIZATION WITH LC/MS TO THE IDENTIFICATION OF POLAR CARBONYL DRINKING WATER DISINFECTION BY-PRODUCTS IN DRINKING WATER

EPA Science Inventory

A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for analyzing and identifying highly polar aldehydes and ketones in ozonated drinking wa...

Volumetric determination of uranium using titanous sulfate as reductant before oxidimetric titration

USGS Publications Warehouse

Wahlberg, James S.; Skinner, Dwight L.; Rader, Lewis F.

1956-01-01

A new method for determining uranium in samples containing 0.05 percent or more U3O8, using titanous sulfate as reducing agent, is much shorter, faster, and has fewer interferences than conventional methods using reductor columns. The sample is dissolved with sulfuric, nitric, perchloric, and hydrofluoric acids. Elements that would otherwise form insoluble fluorides are kept in solution by complexing the fluoride ion with boric acid. A precipitation is made with cupferron to remove interfering elements. The solution is filtered to remove the precipitated cupferrates instead of extracting them with chloroform as is usually done. Filtration is preferred to extraction because any niobium that may be in solution forms an insoluble cupferrate that may be removed by filtering but is very difficult to extract with chloroform. Excess cupferron is destroyed by oxidizing with nitric and perchloric acids, and evaporating to dense fumes of sulfuric acid. The uranium is reduced to U(IV) by the addition of titanous sulfate, with cupric sulfate used as an indicator of the completeness of the reduction. Metallic copper is formed when all the uranium is reduced. The reduced copper is then reoxidized by the addition of mercuric perchlorate, an excess of ferric sulfate added, and the solution titrated immediately with standard ceric sulfate with ferroin as an indicator. Precision of the method compared favorable with methods in common use, both for uranium ores and for most types of uranium-rich materials.

Assessment of Soil-Gas and Soil Contamination at the Former Military Police Range, Fort Gordon, Georgia, 2009-2010

USGS Publications Warehouse

Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir B.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

2011-01-01

Soil gas and soil were assessed for organic and inorganic contaminants at the former military police range at Fort Gordon, Georgia, from May to September 2010. The assessment evaluated organic contaminants in soil-gas samplers and inorganic contaminants in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers deployed and collected from May 20 to 24, 2010, identified masses above method detection level for total petroleum hydrocarbons, gasoline-related and diesel-related compounds, and chloroform. Most of these detections were in the southwestern quarter of the study area and adjacent to the road on the eastern boundary of the site. Nine of the 11 chloroform detections were in the southern half of the study area. One soil-gas sampler deployed adjacent to the road on the southern boundary of the site detected a mass of tetrachloroethene greater than, but close to, the method detection level of 0.02 microgram. For soil-gas samplers deployed and collected from September 15 to 22, 2010, none of the selected organic compounds classified as chemical agents and explosives were detected above method detection levels. Inorganic concentrations in the five soil samples collected at the site did not exceed the U.S. Environmental Protection Agency regional screening levels for industrial soil and were at or below background levels for similar rocks and strata in South Carolina.

Piperolein B and piperchabamide D isolated from black pepper (Piper nigrum L.) as larvicidal compounds against the diamondback moth (Plutella xylostella).

PubMed

Hwang, Ki Seon; Kim, Young Kook; Park, Kee Woong; Kim, Young Tae

2017-08-01

There is growing demand for the development of alternative pest control agents that are effective as well as non-toxic to human health and the environment. Plant protection products derived from plant extracts are an eco-friendly alternative to synthetic pesticides. The aim of this study was to identify larvicidal compounds isolated from a natural source against Plutella xylostella L. In a larvicidal activity assay, several solvent fractions from the methanol extract of Piper nigrum L. fruit showed larvicidal effects against P. xylostella. Screening results indicated that chloroform extract was the most effective against P. xylostella larvae. Two compounds with insecticidal activity in the chloroform fraction were identified as piperolein B and piperchabamide D by spectroscopic analyses, including mass spectrometry and NMR, and by comparison to published data. At applications of 0.1 mg mL -1 concentration, piperolein B and piperchabamide D, respectively, induced 96.7 ± 5.8% and 79.2 ± 16.6% mortality rates of P. xylostella larvae 4 days post-application. Our results demonstrate that piperolein B and piperchabamide D isolated from P. nigrum are the major constituents of the extract demonstrating insecticidal properties for the control of P. xylostella larvae. These plant-derived compounds should become useful alternatives to synthetic chemicals after studying their insecticidal mechanisms. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Chloroform-Methanol Residue of Coxiella burnetii Markedly Potentiated the Specific Immunoprotection Elicited by a Recombinant Protein Fragment rOmpB-4 Derived from Outer Membrane Protein B of Rickettsia rickettsii in C3H/HeN Mice

PubMed Central

Gong, Wenping; Wang, Pengcheng; Xiong, Xiaolu; Jiao, Jun; Yang, Xiaomei; Wen, Bohai

2015-01-01

The obligate intracellular bacteria, Rickettsia rickettsii and Coxiella burnetii, are the potential agents of bio-warfare/bio-terrorism. Here C3H/HeN mice were immunized with a recombinant protein fragment rOmp-4 derived from outer membrane protein B, a major protective antigen of R. rickettsii, combined with chloroform-methanol residue (CMR) extracted from phase I C. burnetii organisms, a safer Q fever vaccine. These immunized mice had significantly higher levels of IgG1 and IgG2a to rOmpB-4 and interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), two crucial cytokines in resisting intracellular bacterial infection, as well as significantly lower rickettsial loads and slighter pathological lesions in organs after challenge with R. rickettsii, compared with mice immunized with rOmpB-4 or CMR alone. Additionally, after challenge with C. burnetii, the coxiella loads in the organs of these mice were significantly lower than those of mice immunized with rOmpB-4 alone. Our results prove that CMR could markedly potentiate enhance the rOmpB-4-specific immunoprotection by promoting specific and non-specific immunoresponses and the immunization with the protective antigen of R. rickettsii combined with CMR of C. burnetii could confer effective protection against infection of R. rickettsii or C. burnetii. PMID:25909586

Molecular dynamics study of a heteroditopic-calix[4]diquinone-assisted transfer of KCl and dopamine through a water-chloroform liquid-liquid interface.

PubMed

Santos, Sérgio M; Costa, Paulo J; Lankshear, Michael D; Beer, Paul D; Félix, Vítor

2010-09-02

The ability of two heteroditopic calix[4]diquinone receptors to transport a KCl ion-pair and a dopamine zwitterion through a water-chloroform interface was investigated via molecular dynamics (MD) simulations. Gas-phase conformational analysis has been carried on KCl and dopamine receptor binding associations and the lowest energy structures found in both cases show that the recognition of KCl and dopamine zwitterion occurs through multiple and cooperative N-H...anion and O...cation bonding interactions, with the receptor adopting equivalent folded conformations stabilized by pi-stacking interactions. The unconstrained MD simulations performed on KCl and dopamine complexes inserted in either the chloroform or water phase revealed that receptors are preferentially located at the interface with the hydrophobic tert-butyl groups of the calix[4]diquinone moiety immersed in the chloroform bulk while the polar anion binding cavity is directed toward the water phase. When the KCl complex is placed in chloroform, the release of the ion-pair occurs only after the first contact with the water interface, being a nonsimultaneous event, with the chloride anion leaving the receptor before the potassium cation. The dopamine, via the -NH(3)(+) binding entity, remains bound to the receptor during the entire time of the MD simulation (10 ns). In contrast, when both complexes were inserted in the water bulk, the full release of KCl and dopamine are fast events. The potentials of mean force (PMFs), associated with the migration of the complexes from chloroform to water through the interface, were calculated from steered molecular dynamics (SMD) simulations. The PMFs for the free KCl and zwitterionic dopamine migrations were also obtained for comparison purposes. The transport of KCl from water to chloroform (the reverse path) mediated by the receptor has a free energy barrier estimated in 6.50 kcal mol(-1), which is 3.0 kcal mol(-1) smaller than that found for the free KCl. The transport of dopamine complex along the reverse path is characterized by downhill energy profile, with a small free energy barrier of 6.56 kcal mol(-1).

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin.

PubMed

Bach, Sandra M; Fortuna, Mario A; Attarian, Rodgoun; de Trimarco, Juliana T; Catalán, César A N; Av-Gay, Yossef; Bach, Horacio

2011-02-01

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.

Phytochemical analysis of Gymnema sylvestre and evaluation of its antimicrobial activity.

PubMed

Chodisetti, Bhuvaneswari; Rao, Kiranmayee; Giri, Archana

2013-01-01

Gymnema sylvestre (CS 149), known to be a rich source of saponins and other valuable phytochemicals, has been analysed for antimicrobial activity. The chloroform extracts of aerial and root parts of G. sylvestre exhibited higher antimicrobial activity as compared to diethyl ether and acetone. The root extracts of chloroform have shown competitive minimum inhibitory concentration and minimum bactericidal concentration values in the range of 0.04-1.28 mg mL(-1) and 0.08-2.56 mg/mL, respectively, towards the pathogens. The GC-MS analysis of chloroform extracts has shown the presence of compounds like eicosane, oleic acid, stigmasterol and vitamin E.

JBIR-12, a novel antioxidative agent from Penicillium sp. NBRC 103941.

PubMed

Izumikawa, Miho; Nagai, Aya; Doi, Takayuki; Takagi, Motoki; Shin-Ya, Kazuo

2009-04-01

In the course of our screening program for active compounds from fungal metabolites, we isolated JBIR-12 (1) as a free radical scavenger from the culture broth of Penicillium sp. NBRC 103941. Structure elucidation of 1 was carried out using methylated and/or acetylated derivatives of 1. As a consequence, the structure of 1 was determined to be a novel highly oxygenated tetrahydronaphthalene species attached to an acyl chain moiety on the basis of NMR and other spectroscopic data. It was interesting that 1 was spontaneously methylated when left in methanol. Furthermore, isomerization or rearrangements could occur during the derivatization of 1. Compound 1 exhibited potent radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical with an IC(50) value of 75 microM.

Systematic Review Protocol for the IRIS Chloroform Assessment (Inhalation) (Preliminary Assessment Materials)

EPA Science Inventory

In January 2018, EPA released the Systematic Review Protocol for the IRIS Chloroform Assessment (Inhalation). As part of developing a draft IRIS assessment, EPA presents a methods document, referred to as the protocol, for conducting a chemical-specific systematic revie...

PHYSIOLOGICALLY BASED PHARMACOKINEITC (PBPK) MODELING OF METABOLIC INHIBITION FOR INTERACTION BETWEEN TRICHLOROETHYLENE AND CHLOROFORM

EPA Science Inventory

Trichloroethylene (TCE) and chloroform (CHCl3) are two of the most common environmental contaminants found in water. PBPK models have been increasingly used to predict target dose in internal tissues from available environmental exposure concentrations. A closed inhalation (or g...

Factors associated with sources, transport, and fate of chloroform and three other trihalomethanes in untreated groundwater used for drinking water

USGS Publications Warehouse

Carter, Janet M.; Moran, Michael J.; Zogorski, John S.; Price, Curtis V.

2012-01-01

Multiple lines of evidence for indicating factors associated with the sources, transport, and fate of chloroform and three other trihalomethanes (THMs) in untreated groundwater were revealed by evaluating low-level analytical results and logistic regression results for THMs. Samples of untreated groundwater from wells used for drinking water were collected from 1996-2007 from 2492 wells across the United States and analyzed for chloroform, bromodichloromethane, dibromochloromethane, and bromoform by a low-level analytical method implemented in April 1996. Using an assessment level of 0.02 μg/L, chloroform was detected in 36.5% of public-well samples and 17.6% of domestic-well samples, with most concentrations less than 1 μg/L. Brominated THMs occurred less frequently than chloroform but more frequently in public-well samples than domestic-well samples. For both public and domestic wells, THMs occurred most frequently in urban areas. Logistic regression analyses showed that the occurrence of THMs was related to nonpoint sources such as urban land use and to point sources like septic systems. The frequent occurrence and concentration distribution pattern of THMs, as well as their frequent co-occurrence with other organic compounds and nitrate, all known to have anthropogenic sources, and the positive associations between THM occurrence and dissolved oxygen and recharge indicate the recycling of water that contains THMs and other anthropogenic contaminants.

An overview of heavy-atom derivatization of protein crystals

PubMed Central

Pike, Ashley C. W.; Garman, Elspeth F.; Krojer, Tobias; von Delft, Frank; Carpenter, Elisabeth P.

2016-01-01

Heavy-atom derivatization is one of the oldest techniques for obtaining phase information for protein crystals and, although it is no longer the first choice, it remains a useful technique for obtaining phases for unknown structures and for low-resolution data sets. It is also valuable for confirming the chain trace in low-resolution electron-density maps. This overview provides a summary of the technique and is aimed at first-time users of the method. It includes guidelines on when to use it, which heavy atoms are most likely to work, how to prepare heavy-atom solutions, how to derivatize crystals and how to determine whether a crystal is in fact a derivative. PMID:26960118

Suppression of Pulmonary Host Defenses and Enhanced Susceptibility to Respiratory bacterial Infection in mice Following Inhalation Exposure to Trichloroethylene and Chloroform

EPA Science Inventory

Numerous epidemiologic studies have associated episodes of increased air pollution with increased incidence of respiratory disease, including pneumonia, croup, and bronchitis. Trichloroethylene (TCE) and chloroform are among 33 hazardous air pollutants identified by the U.S. Env...

Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon

EPA Science Inventory

Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2–persulfate binary mixtur...

Comparative Study on the Performance of Anaerobic and Aerobic Biotrickling Filter for Removal of Chloroform

EPA Science Inventory

Use of biotrickling filter (BTF) for gas phase treatment of volatile trihalomethanes (THMs) stripped from water treatment plants could be an attractive treatment option. The aim of this study is to use laboratory-scale anaerobic BTF to treat gaseous chloroform (recalcitrant to bi...

Quantification of protein carbonylation.

PubMed

Wehr, Nancy B; Levine, Rodney L

2013-01-01

Protein carbonylation is the most commonly used measure of oxidative modification of proteins. It is most often measured spectrophotometrically or immunochemically by derivatizing proteins with the classical carbonyl reagent 2,4 dinitrophenylhydrazine (DNPH). We present protocols for the derivatization and quantification of protein carbonylation with these two methods, including a newly described dot blot with greatly increased sensitivity.

[Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry].

PubMed

Gao, Yonggang; Zhang, Yanyan; Gao, Jianguo; Zhang, Huiling; Zheng, Lisha; Chen, Jing

2012-10-01

A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N = 3) was 10 microg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials.

Determination of picomolar concentrations of carbonyl compounds in natural waters, including seawater, by liquid chromatography

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

Kieber, R.; Mopper, K.

1990-10-01

Low molecular weight carbonyl compounds in natural waters were determined at picomolar to nanomolar levels by derivatization with 2,4-dinitrophenylhydrazine followed by liquid chromatography. The uniqueness of the method is attributed to the extremely low blanks obtained and the minimal sample preparation involved. The detection limit for direct injection of derivatized natural water samples is 0.5 nM for aldehydes and 5 nM for ketones with a precision of {approximately}7% RSD at the 30 nM level for aldehydes. The detection limit can be further lowered by using off-line cartridge enrichment in which derivatized natural water is passed through a C18 extraction cartridge.more » Recoveries for the enrichment method were 95-105% for a sample volume of 20 mL and for concentrations of carbonyl compounds in the 1-30 nM range. A field procedure for storage of derivatized sample extracts for extended periods is also presented. Applications of enrichment and sample storage techniques to marine and estuarine waters are presented.« less

An optimized two-step derivatization method for analyzing diethylene glycol ozonation products using gas chromatography and mass spectrometry.

PubMed

Yu, Ran; Duan, Lei; Jiang, Jingkun; Hao, Jiming

2017-03-01

The ozonation of hydroxyl compounds (e.g., sugars and alcohols) gives a broad range of products such as alcohols, aldehydes, ketones, and carboxylic acids. This study developed and optimized a two-step derivatization procedure for analyzing polar products of aldehydes and carboxylic acids from the ozonation of diethylene glycol (DEG) in a non-aqueous environment using gas chromatography-mass spectrometry. Experiments based on Central Composite Design with response surface methodology were carried out to evaluate the effects of derivatization variables and their interactions on the analysis. The most desirable derivatization conditions were reported, i.e., oximation was performed at room temperature overnight with the o-(2,3,4,5,6-pentafluorobenzyl) hydroxyl amine to analyte molar ratio of 6, silylation reaction temperature of 70°C, reaction duration of 70min, and N,O-bis(trimethylsilyl)-trifluoroacetamide volume of 12.5μL. The applicability of this optimized procedure was verified by analyzing DEG ozonation products in an ultrafine condensation particle counter simulation system. Copyright © 2016. Published by Elsevier B.V.

Simultaneous Determination of Food-Related Biogenic Amines and Precursor Amino Acids Using in Situ Derivatization Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction by Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry.

PubMed

He, Yongrui; Zhao, Xian-En; Wang, Renjun; Wei, Na; Sun, Jing; Dang, Jun; Chen, Guang; Liu, Zhiqiang; Zhu, Shuyun; You, Jinmao

2016-11-02

A simple, rapid, sensitive, selective, and environmentally friendly method, based on in situ derivatization ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using multiple reaction monitoring (MRM) mode has been developed for the simultaneous determination of food-related biogenic amines and amino acids. A new mass-spectrometry-sensitive derivatization reagent 4'-carbonyl chloride rosamine (CCR) was designed, synthesized, and first reported. Parameters and conditions of in situ DUADLLME and UHPLC-MS/MS were optimized in detail. Under the optimized conditions, the in situ DUADLLME was completed speedily (within 1 min) with high derivatization efficiencies (≥98.5%). With the cleanup and concentration of microextraction step, good analytical performance was obtained for the analytes. The results showed that this method was accurate and practical for quantification of biogenic amines and amino acids in common food samples (red wine, beer, wine, cheese, sausage, and fish).

Simultaneous derivatization/preconcentration of volatile aldehydes with a miniaturized fiber-packed sample preparation device designed for gas chromatographic analysis.

PubMed

Saito, Yoshihiro; Ueta, Ikuo; Ogawa, Mitsuhiro; Jinno, Kiyokatsu

2006-10-01

A novel in-needle sample preparation device has been developed for the determination of volatile aldehydes in gaseous samples. The needle device is designed for the gas chromatographic (GC) analysis of aldehydes and ketones commonly found in typical in-house environments. In order to prepare the extraction device, a bundle of polymer-coated filaments was longitudinally packed into a specially designed needle. Derivatization reactions were prompted by 2,4-dinitrophenylhydrazine (NDPH) included in the needle, and so the aldehydes and ketones were derivatized to the corresponding hydrazones and extracted with the extraction needle. A reproducible extraction needle preparation process was established, along with a repeatable derivatization/extraction process that ensures the successful determination of aldehydes. The storage performance of the extraction needle was also evaluated at room temperature for three days. The results demonstrate the successful application of the fiber-packed extraction device to the preparation of a gaseous sample of aldehydes, and the future possibility of applying the extraction device to the analysis of in-house environments.

HPLC-MRM relative quantification analysis of fatty acids based on a novel derivatization strategy.

PubMed

Cai, Tie; Ting, Hu; Xin-Xiang, Zhang; Jiang, Zhou; Jin-Lan, Zhang

2014-12-07

Fatty acids (FAs) are associated with a series of diseases including tumors, diabetes, and heart diseases. As potential biomarkers, FAs have attracted increasing attention from both biological researchers and the pharmaceutical industry. However, poor ionization efficiency, extreme diversity, strict dependence on internal standards and complicated multiple reaction monitoring (MRM) optimization protocols have challenged efforts to quantify FAs. In this work, a novel derivatization strategy based on 2,4-bis(diethylamino)-6-hydrazino-1,3,5-triazine was developed to enable quantification of FAs. The sensitivity of FA detection was significantly enhanced as a result of the derivatization procedure. FA quantities as low as 10 fg could be detected by high-performance liquid chromatography coupled with triple-quadrupole mass spectrometry. General MRM conditions were developed for any FA, which facilitated the quantification and extended the application of the method. The FA quantification strategy based on HPLC-MRM was carried out using deuterated derivatization reagents. "Heavy" derivatization reagents were used as internal standards (ISs) to minimize matrix effects. Prior to statistical analysis, amounts of each FA species were normalized by their corresponding IS, which guaranteed the accuracy and reliability of the method. FA changes in plasma induced by ageing were studied using this strategy. Several FA species were identified as potential ageing biomarkers. The sensitivity, accuracy, reliability, and full coverage of the method ensure that this strategy has strong potential for both biomarker discovery and lipidomic research.

Constant pressure-assisted head-column field-amplified sample injection in combination with in-capillary derivatization for enhancing the sensitivity of capillary electrophoresis.

PubMed

Yan, Na; Zhou, Lei; Zhu, Zaifang; Zhang, Huige; Zhou, Ximin; Chen, Xingguo

2009-05-15

In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the "head column". Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5kV, 45s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10min for derivatization reaction under 35 degrees C, then the capillary temperature was cooled to 25 degrees C and the derivatives were immediately separated and determined under 25 degrees C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method.

Dispersive liquid-liquid microextraction combined with microwave-assisted derivatization for determining lipoic acid and its metabolites in human urine.

PubMed

Tsai, Chia-Ju; Chen, Yen-Ling; Feng, Chia-Hsien

2013-10-04

This study explored dispersive liquid-liquid microextraction for extraction and concentration of lipoic acid in human urine. To improve the detection of lipoic acid by both capillary liquid chromatography (CapLC) with UV detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), microwave-assisted derivatization with 4-bromomethyl-6,7-dimethoxycoumarin was performed to render lipoic acid chromophores for UV detection and also high ionization efficiency in MALDI. All parameters that affected lipoic acid extraction and derivatization from urine were investigated and optimized. In the analyses of human urine samples, the two methods had a linear range of 0.1-20 μM with a correlation coefficient of 0.999. The detection limits of CapLC-UV and MALDI-TOF MS were 0.03 and 0.02 μM (S/N ≧ 3), respectively. The major metabolites of lipoic acid, including 6,8-bismethylthio-octanoic acid, 4,6-bismethylthio-hexanoic acid, and 2,4-bismethylthio-butanoic acid were also extracted by dispersive liquid-liquid microextraction and detected by MALDI-TOF MS. The minor metabolites (undetectable by MALDI-TOF MS), bisnorlipoic acid and tetranorlipoic acid were also extracted by dispersive liquid-liquid microextraction and identified with an LTQ Orbitrap mass spectrometer. After dispersive liquid-liquid microextraction and microwave-assisted derivatization, all lipoic acid derivatizations and metabolites were structurally confirmed by LTQ Orbitrap. Copyright © 2013 Elsevier B.V. All rights reserved.

Suicide inactivation of hydroxylamine oxidoreductase of Nitrosomonas europaea by organohydrazines.

PubMed

Logan, M S; Hooper, A B

1995-07-18

In the presence of a suitable electron acceptor such as mammalian cytochrome c, hydroxylamine oxidoreductase (HAO) from the chemolithotrophic bacterium Nitrosomonas europaea catalyzes the oxidation of hydroxylamine or hydrazine to nitrite or dinitrogen, respectively. Each subunit of HAO contains 7 c-hemes and a chromophore of the active site called heme P460, a c-heme bridged from a methylene carbon to a ring carbon of a tyrosine of the peptide chain. Reaction with either substrate results in reduction of several c-hemes of HAO. The reaction of organohydrazines with HAO was investigated in this work. HAO was inactivated by (phenyl-, (methyl-, or (hydroxyethyl)hydrazine. The process followed first order kinetics and was inhibited by the substrates, hydroxylamine or hydrazine. Complete loss of enzyme activity and absorbancy characteristic of native heme P460 of HAO occurred at a 1:1 ratio of phenylhydrazine and HAO. HAO was covalently derivatized by two molecules of [14C]-phenylhydrazine per subunit. Heme P460 was derivatized with high affinity, and an amino acid residue was derivatized with lower affinity. c-Hemes were not derivatized except for the partial reaction of (hydroxyethyl)hydrazine with one heme. As with hydroxylamine and hydrazine, incubation with organohydrazines resulted in reduction of c-heme of HAO. Derivatized minus native optical difference spectra of ferric or ferrous HAO revealed changes in the optical properties of heme P460 which were generally similar to shifts seen in the reaction of the heme of other hemoproteins with organohydrazines.(ABSTRACT TRUNCATED AT 250 WORDS)

Qualitative and quantitative evaluation of derivatization reagents for different types of protein-bound carbonyl groups.

PubMed

Bollineni, Ravi Chand; Fedorova, Maria; Hoffmann, Ralf

2013-09-07

Mass spectrometry (MS) of 'carbonylated proteins' often involves derivatization of reactive carbonyl groups to facilitate their enrichment, identification and quantification. Among the many reported reagents, 2,4-dinitrophenylhydrazine (DNPH), biotin hydrazide (BHZ) and O-(biotinylcarbazoylmethyl) hydroxylamine (ARP) are the most frequently used. Despite their common use in carbonylation research, their reactivity towards protein-bound carbonyls has not been quantitatively evaluated in detail, to the best of our knowledge. Thus we studied the reactivity and specificity of these reagents towards different classes of reactive carbonyl groups (e.g. aldehydes, ketones and lactams), each being represented by a synthetic peptide carrying an accordingly modified residue. All three tagging reagents were selective for aliphatic aldehydes and ketones. Lactams and carbonyl-containing tryptophan oxidation products, however, were labelled only at low levels or not at all. Whereas DNPH derivatization was efficient under the published standard conditions, the derivatization conditions for BHZ and ARP had to be altered. Acidic conditions provided quantitative labelling yields for ARP. Peptides derivatized with DNPH, BHZ and ARP fragmented efficiently in tandem mass spectrometry, when the experimental conditions were chosen carefully for each reagent. Importantly, the tested carbonylated peptides did not cross-react with amino groups in other proteins present during sample preparations or enzymatic digestion. Thus, it appears favourable to digest proteins first and then derivatise the reactive carbonyl groups more efficiently at the peptide level under acidic conditions. The carbonylated model peptides used in this study might be valid internal standards for carbonylation proteomics.

Dried blood spot on-card derivatization: an alternative form of sample handling to overcome the instability of thiorphan in biological matrix.

PubMed

Mess, Jean-Nicholas; Taillon, Marie-Pierre; Côté, Cynthia; Garofolo, Fabio

2012-12-01

Thiorphan, the active metabolite of racecadotril, can undergo oxidation in biological matrices such as blood and plasma. In bioanalysis, a general approach for the stabilization of such a molecule is to derivatize the thiol group to a more stable thioether, often requiring complex handling procedures at the clinical site. In this research, the concept of dried blood spot (DBS) on-card derivatization was evaluated to stabilize thiorphan. DBS cards were in-house pre-treated with 2-bromo-3'-methoxyacetophenone and left to dry prior to blood spotting. Thiorphan was shown to be effectively derivatized to thiorphan-methoxyacetophenone once applied on the in-house pre-treated cards. Thiorphan-methoxyacetophenone was extracted by soaking a 6 mm DBS punch in methanol containing the internal standard (thiorphan-methoxyacetophenone-D₅). Chromatographic separation was achieved on a Waters XBridge C₁₈ column with a gradient elution of 5 mM NH₄HCO₃ and methanol in 2.5 min and detection by ESI(+)/MS/MS. A linear (weighted 1/x²) relationship was obtained over a concentration range of 5.00-600.00 ng/mL. The assay met regulatory guidelines acceptance criteria for sensitivity, selectivity, precision and accuracy, matrix effect, recovery, dilution integrity and multiple stability evaluations. The DBS on-card derivatization has shown to be an easy and reliable alternative form of sample collection for the quantification of thiorphan. Copyright © 2012 John Wiley & Sons, Ltd.

Simultaneous identification and quantification of bisphenol A and 12 bisphenol analogues in environmental samples using precolumn derivatization and ultra high performance liquid chromatography with tandem mass spectrometry.

PubMed

Wang, Zhonghe; Yu, Jing; Yao, Jiaxi; Wu, Linlin; Xiao, Hang; Wang, Jun; Gao, Rong

2018-02-10

A method for the identification and quantification of bisphenol A and 12 bisphenol analogues in river water and sediment samples combining liquid-liquid extraction, precolumn derivatization, and ultra high-performance liquid chromatography coupled with tandem mass spectrometry was developed and validated. Analytes were extracted from the river water sample using a liquid-liquid extraction method. Dansyl chloride was selected as a derivatization reagent. Derivatization reaction conditions affecting production of the dansyl derivatives were tested and optimized. All the derivatized target compounds were well separated and eluted in 10 min. Dansyl chloride labeled compounds were analyzed using a high-resolution mass spectrometer with electrospray ionization in the positive mode, and the results were confirmed and quantified in the parallel reaction monitoring mode. The method validation results showed a satisfactory level of sensitivity. Linearity was assessed using matrix-matched standard calibration, and good correlation coefficients were obtained. The limits of quantification for the analytes ranged from 0.005 to 0.02 ng/mL in river water and from 0.15 to 0.80 ng/g in sediment. Good reproducibility of the method in terms of intra- and interday precision was achieved, yielding relative standard deviations of less than 10.1 and 11.6%, respectively. Finally, this method was successfully applied to the analysis of real samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved conventional and microwave-assisted silylation protocols for simultaneous gas chromatographic determination of tocopherols and sterols: Method development and multi-response optimization.

PubMed

Poojary, Mahesha M; Passamonti, Paolo

2016-12-09

This paper reports on improved conventional thermal silylation (CTS) and microwave-assisted silylation (MAS) methods for simultaneous determination of tocopherols and sterols by gas chromatography. Reaction parameters in each of the methods developed were systematically optimized using a full factorial design followed by a central composite design. Initially, experimental conditions for CTS were optimized using a block heater. Further, a rapid MAS was developed and optimized. To understand microwave heating mechanisms, MAS was optimized by two distinct modes of microwave heating: temperature-controlled MAS and power-controlled MAS, using dedicated instruments where reaction temperature and microwave power level were controlled and monitored online. Developed methods: were compared with routine overnight derivatization. On a comprehensive level, while both CTS and MAS were found to be efficient derivatization techniques, MAS significantly reduced the reaction time. The optimal derivatization temperature and time for CTS found to be 55°C and 54min, while it was 87°C and 1.2min for temperature-controlled MAS. Further, a microwave power of 300W and a derivatization time 0.5min found to be optimal for power-controlled MAS. The use of an appropriate derivatization solvent, such as pyridine, was found to be critical for the successful determination. Catalysts, like potassium acetate and 4-dimethylaminopyridine, enhanced the efficiency slightly. The developed methods showed excellent analytical performance in terms of linearity, accuracy and precision. Copyright © 2016 Elsevier B.V. All rights reserved.

A smog chamber comparison of a microfluidic derivatization measurement of gas-phase glyoxal and methylglyoxal with other analytical techniques

NASA Astrophysics Data System (ADS)

Pang, X.; Lewis, A. C.; Richard, A.; Baeza-Romero, M. T.; Adams, T. J.; Ball, S. M.; Daniels, M. J. S.; Goodall, I. C. A.; Monks, P. S.; Peppe, S.; Ródenas García, M.; Sánchez, P.; Muñoz, A.

2013-06-01

A microfluidic lab-on-a-chip derivatization technique has been developed to measure part per billion volume (ppbV) mixing ratios of gaseous glyoxal (GLY) and methylglyoxal (MGLY), and the method compared with other techniques in a smog chamber experiment. The method uses o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) as a derivatization reagent and a microfabricated planar glass micro-reactor comprising an inlet, gas and fluid splitting and combining channels, mixing junctions, and a heated capillary reaction microchannel. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the micro-reactor result in a fast and highly efficient derivatization reaction, generating an effluent stream ready for direct introduction to a gas chromatograph-mass spectrometer (GC-MS). A linear response for GLY was observed over a calibration range 0.7 to 400 ppbV, and for MGLY of 1.2 to 300 ppbV, when derivatized under optimal reaction conditions. The method detection limits (MDLs) were 80 pptV and 200 pptV for GLY and MGLY respectively, calculated as 3 times the standard deviation of the S/N of the blank sample chromatograms. These MDLs are below or close to typical concentrations in clean ambient air. The feasibility of the technique was assessed by applying the methodology under controlled conditions to quantify of α-dicarbonyls formed during the photo-oxidation of isoprene in a large scale outdoor atmospheric simulation chamber (EUPHORE). Good general agreement was seen between microfluidic measurements and Fourier Transform Infra Red (FTIR), Broad Band Cavity Enhanced Absorption Spectroscopy (BBCEAS) and a detailed photochemical chamber box modelling calculation for both GLY and MGLY. Less good agreement was found with Proton-Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) and Solid Phase Microextraction (SPME) derivatization methods for MGLY measurement.

Automated Online Solid-Phase Derivatization for Sensitive Quantification of Endogenous S-Nitrosoglutathione and Rapid Capture of Other Low-Molecular-Mass S-Nitrosothiols.

PubMed

Wang, Xin; Garcia, Carlos T; Gong, Guanyu; Wishnok, John S; Tannenbaum, Steven R

2018-02-06

S-Nitrosothiols (RSNOs) constitute a circulating endogenous reservoir of nitric oxide and have important biological activities. In this study, an online coupling of solid-phase derivatization (SPD) with liquid chromatography-mass spectrometry (LC-MS) was developed and applied in the analysis of low-molecular-mass RSNOs. A derivatizing-reagent-modified polymer monolithic column was prepared and adapted for online SPD-LC-MS. Analytes from the LC autosampler flowed through the monolithic column for derivatization and then directly into the LC-MS for analysis. This integration of the online derivatization, LC separation, and MS detection facilitated system automation, allowing rapid, laborsaving, and sensitive detection of RSNOs. S-Nitrosoglutathione (GSNO) was quantified using this automated online method with good linearity (R 2 = 0.9994); the limit of detection was 0.015 nM. The online SPD-LC-MS method has been used to determine GSNO levels in mouse samples, 138 ± 13.2 nM of endogenous GSNO was detected in mouse plasma. Besides, the GSNO concentrations in liver (64.8 ± 11.3 pmol/mg protein), kidney (47.2 ± 6.1 pmol/mg protein), heart (8.9 ± 1.8 pmol/mg protein), muscle (1.9 ± 0.3 pmol/mg protein), hippocampus (5.3 ± 0.9 pmol/mg protein), striatum (6.7 ± 0.6 pmol/mg protein), cerebellum (31.4 ± 6.5 pmol/mg protein), and cortex (47.9 ± 4.6 pmol/mg protein) were also successfully quantified. When the derivatization was performed within 8 min, followed by LC-MS detection, samples could be rapidly analyzed compared with the offline manual method. Other low-molecular-mass RSNOs, such as S-nitrosocysteine and S-nitrosocysteinylglycine, were captured by rapid precursor-ion scanning, showing that the proposed method is a potentially powerful tool for capture, identification, and quantification of RSNOs in biological samples.

A novel mass spectrometric method for formaldehyde in children's personal-care products and water via derivatization with acetylacetone.

PubMed

Backe, Will J

2017-06-30

New legislation in the state of Minnesota prohibits the sale of children's personal-care products (PCPs) that contain more than 500 ng/mg formaldehyde. Previous attempts to quantify formaldehyde in PCPs use nonspecific derivatization procedures that employ harsh reagents and/or nonspecific detection. Derivatization of formaldehyde by acetylacetone occurs under mild conditions and is specific for formaldehyde but it has not been investigated using high-performance liquid chromatography/tandem mass-spectrometry (HPLC/MS/MS). To determine formaldehyde, PCPs were dissolved and then interferences were minimized by graphitized-carbon solid-phase extraction. Formaldehyde was derivatized to 3,5-diacetyl-1,4-dihydrolutidine (DDL) using an acetylacetone solution. Post-derivatization, samples were diluted and analyzed by HPLC/MS/MS. Quantification was performed by isotopic dilution. Product-ion spectra were acquired for DDL and D 12 -DDL. The mass shifts between the two product-ion spectra were used to assign fragment structures. To confirm molecular formulas, high-resolution accurate-mass analysis of the DDL product ions was performed by quadrupole time-of-flight MS. Structures were proposed for all product ions of DDL above 10% relative intensity. Method accuracy ranged between 96-104% for all matrices at all concentrations tested. Method precision was less than 4% relative standard deviation. The reporting limit was 10 ng/mg in PCPs and 100 μg/L in water. Twenty children's PCPs were tested to demonstrate the method and formaldehyde was reported in five from 23-1500 ng/mg. Of those five, two samples contained formaldehyde above the Minnesota regulatory limit. The developed method allows for the accurate quantification of formaldehyde in PCPs at levels below those required by a new regulation on children's products in Minnesota. The method includes a derivatization procedure that is newly adapted to HPLC/MS/MS; therefore, structures were proposed for the product ions of the derivative (DDL). Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

THE INFLUENCE OF ADVANCED AGE ON THE HEPATIC AND RENAL TOXICITY OF CHLOROFORM

EPA Science Inventory

THE INFLUENCE OF ADVANCED AGE ON THE HEPATIC AND RENAL TOXICITY OF CHLOROFORM (CHC13). A McDonald, Y M Sey and J E Simmons. NHEERL, ORD, U.S. EPA, RTP, NC.
Disinfection, by chlorination or by ozonation followed by treatment with either chlorine or chloramine, of water containi...

HEPATOTOXIC EVALUATION OF THE BINARY INTERACTIONS OF BROMODICHLOROMETHANE WITH CHLOROFORM, CHLORODIBROMOMETHANE AND BROMOFORM

EPA Science Inventory

HEPATOTOXIC EVALUATION OF THE BINARY INTERACTIONS OF BROMODICHLOROMETHANE (BDCM) WITH CHLOROFORM (CHC13), CHLORODIBROMOMETHANE (CDBM) AND BROMOFORM (CHBr3). Y M Se'', C Gennings2, A McDonald', L K Teuschler3, A Hamm2and J E Simmons .'NHEERL, ORD, U.S. EPA, RTP, NC; 2MCV, VCU, Ric...

The effect of chloroform, orange oil and eucalyptol on root canal transportation in endodontic retreatment.

PubMed

Karataş, Ertuğrul; Kol, Elif; Bayrakdar, İbrahim Şevki; Arslan, Hakan

2016-04-01

The purpose of the present study was to assess the effect of solvents on root canal transportation in endodontic retreatment. Sixty extracted human permanent mandibular first molars with curved root canals were selected. All of the root canals were prepared using Twisted File Adaptive instruments (SybronEndo, Orange, CA, USA) and filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the cold lateral compaction technique. The teeth were assigned to four retreatment groups as follows (n = 15): eucalyptol, chloroform, orange oil and control. The canals were scanned using cone-beam computed tomography scanning before and after instrumentation. The chloroform group showed a significantly higher mean transportation value than the orange oil and control groups at the 3 and 5 mm levels (P = 0.011 and P = 0.003, respectively). There was no significant difference among the orange oil, eucalyptol and control groups in terms of canal transportation (P > 0.61). The chloroform led to more canal transportation than the eucalyptol and orange oil during endodontic retreatment. © 2015 Australian Society of Endodontology.

Solubility of Lead Sulfate in Water and in Sodium Sulfate Solutions: An Experiment in Atomic Absorption Spectrophotometry.

ERIC Educational Resources Information Center

Lehman, Thomas A.; Everett, Wayne W.

1982-01-01

Describes a set of undergraduate laboratory experiments which provide experience in deuteration and derivatization procedures applied to infrared spectroscopy. Basic skills in vacuum-line technique are also taught while measuring infrared spectra of deuterated solid samples and demonstrating the value of derivatization as an aid to interpreting…

High-sensitivity chemical derivatization NMR analysis for condition monitoring of aged elastomers.

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

Assink, Roger Alan; Celina, Mathias C.; Skutnik, Julie Michelle

2004-06-01

An aged polybutadiene-based elastomer was reacted with trifluoroacetic anhydride (TFAA) and subsequently analyzed via 19F NMR spectroscopy. Derivatization between the TFAA and hydroxyl functionalities produced during thermo-oxidative aging was achieved, resulting in the formation of trifluoroester groups on the polymer. Primary and secondary alcohols were confirmed to be the main oxidation products of this material, and the total percent oxidation correlated with data obtained from oxidation rate measurements. The chemical derivatization appears to be highly sensitive and can be used to establish the presence and identity of oxidation products in aged polymeric materials. This methodology represents a novel condition monitoringmore » approach for the detection of chemical changes that are otherwise difficult to analyze.« less

Quantification of phytochelatins in Chlamydomonas reinhardtii using ferrocene-based derivatization.

PubMed

Bräutigam, Anja; Bomke, Susanne; Pfeifer, Thorben; Karst, Uwe; Krauss, Gerd-Joachim; Wesenberg, Dirk

2010-08-01

A method for the identification and quantification of canonic and isoforms of phytochelatins (PCs) from Chlamydomonas reinhardtii was developed. After disulfide reduction with tris(2-carboxyethyl)phosphine (TCEP) PCs were derivatized with ferrocenecarboxylic acid (2-maleimidoyl)ethylamide (FMEA) in order to avoid oxidation of the free thiol functions during analysis. Liquid chromatography (LC) coupled to electrospray mass spectrometry (ESI-MS) and inductively coupled plasma-mass spectrometry (ICP-MS) was used for rapid and quantitative analysis of the precolumn derivatized PCs. PC(2-4), CysGSH, CysPC(2-4), CysPC(2)desGly, CysPC(2)Glu and CysPC(2)Ala were determined in the algal samples depending on the exposure of the cells to cadmium ions.