Close The Infona portal uses cookies, i.e. strings of text saved by a browser on the users device. The portal can access those files and use them to remember the users data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser. ...
Gas chromatography mass spectrometry (GC/MS)-based fecal metabonomics represents a powerful systems biology approach for elucidating metabolic biomarkers of lower gastrointestinal tract (GIT) diseases. Unlike metabolic profiling of fecal water, the profiling of complete fecal material remains under-explored. Here, a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) method was developed and validated for the global metabonomic profiling of human feces. Fecal and fecal water metabotypes were also profiled and compared. Additionally, the unclear influence of blood in stool on the fecal metabotype was investigated unprecedentedly. Eighty milligram of lyophilized feces was ultrasonicated with 1mL of methanol:water (8:2) for 30min, followed by centrifugation, drying of supernatant, oximation and trimethylsilylation for 45min. Lyophilized feces demonstrated a more comprehensive metabolic coverage than fecal water, based on the number of chromatographic peaks. Principal component analysis ...
Abstract. We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for ...
QP-2010s Gas Chromatograph/Mass Spectrometer from Shimadzu,Shimadzus GCMS-QP2010s Gas Chromatograph/Mass Spectrometer, utilizing many of the high-end features of the GCMS-QP2010 Plus, offers high throughput and excellent productivity, providing users with an excellent performance-to-cost ratio. Like the GCMS-QP2010 Plus, the GCMS-QP2010s features patented,biological,biology supply,biology supplies,biology product
TY - UNPB. T1 - VOCCluster: Untargeted Metabolomics Feature Clustering Approach for Clinical Breath Gas Chromatography-Mass Spectroscopy Data. AU - Alkhalifah, Yaser. AU - Phillips, Iain. AU - Soltoggio, Andrea. AU - Darnley, Kareen. AU - Nailon, William Henry. AU - McLaren, Duncan. AU - Eddleston, Michael. AU - Thomas, Paul AU - Salman, Dahlia. PY - 2019/2/18. Y1 - 2019/2/18. M3 - Working paper. T3 - ChemRxiv. BT - VOCCluster: Untargeted Metabolomics Feature Clustering Approach for Clinical Breath Gas Chromatography-Mass Spectroscopy Data. ER - ...
The Canadian Forest Service promotes the sustainable development of Canadas forests and the competitiveness of the Canadian forest sector
Comprehensive two-dimensional gas chromatography (GC×GC) is a high resolution and high sensitivity technique. It is especially suitable for the separation and identification of analytes in complex mixtures. Focused on the characterization of complex mixtures, a series of method and application studies using GC×GC have been carried out. Although comprehensive two-dimensional gas chromatography (GC×GC) can offer high resolution and sensitivity compared with traditional one-dimensional gas chromatography (1DGC), sample preparation is still essential for trace component analysis. An on-column cold trap device was used as a part of GC×GC or GC×GC combined with time-of-flight mass spectrometry (TOFMS) systems. The on-column cold trap device using a homemade double layer CO2 jet was mounted on the GC×GC or GC×GC-TOFMS, and performed at -60 ℃-70 cryogenic ℃temperature. Based on large volume injection, the trace compounds were focused at the head of column by cold trap and stationary phase, ...
TY - JOUR. T1 - Principles and applications of comprehensive two-dimensional gas chromatography. AU - Marriott, Philip. AU - Shellie, Robert. PY - 2002/1/1. Y1 - 2002/1/1. N2 - This issue of Trends in Analytical Chemistry celebrates 50 years of gas chromatography (GC) - the greatest enabling technology for chemical analysis of volatile compounds. However, what may be considered the most powerful separation tool in GC - comprehensive two-dimensional gas chromatography (GC×GC) - is a development born of the 1990s. It was first described and almost fully established in the last decade of the twentieth century. The coming decades can be expected to see it flourish into a major operating mode of GC, when applications and fundamental principles will be further expanded, and, most importantly, its universal acceptance will be unquestioned. This article describes why the pioneers of GC×GC have so much faith in the new opportunities afforded by this exciting technology.. AB - This issue of Trends in ...
A sensitive and specific assay for the quantitative determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma specimens is described. Electron capture/negative ion chemical ionization gas chromatography/mass spectrometry is used to determine the extracted plasma concentrati...
The composition and changes of the fungal population and of the metabolites present in grapes and in ferments of Vitis vinifera L. cv. Corvina, one of the major components of the Amarone musts, were dissected aiming at the identification of constant characteristics possibly influenced by the productive process. The fungal populations and metabolomic profiles were analyzed in three different vintages. 454-pyrosequencing on the ribosomal ITS1 region has been used to identify the fungal population present in Corvina grapes and fresh must. Samples were also subjected to metabolomics analysis measuring both free volatile compounds and glycosylated aroma precursors through an untargeted approach with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Albeit strongly dependent on the climate, both the mycobiota and metabolome of Corvina grapes and fresh musts show some characteristics recursive in different vintages. Such persistent characteristics are likely determined ...
Qiu YQ,Lu X,Pang T,et al. Study of traditional Chinese medicine volatile oils from different geographical origins by comprehensive two-dimensional gas chromatography - time-of-flight mass spectrometry (GC×GC-TOFMS) in combination with multivariate analysis[J]. Journal of Pharmaceutical and Biomedical Analysis,2007,43:1721-1727 ...
App Note for Enhanced Detection and Separation of Anabolic Steroids for Anti-Doping Control Screening by Comprehensive TwoDimensional Gas Chromatography Time-of-Flight Mass Spectrometry (GCxGC-TOFMS)
This article aims to investigate the use and benefits of using comprehensive two-dimensional gas chromatography (GC x GC) and structure-activity relationship modeling for screening and prioritization of organic contaminants in complex matrices. The benefit of applying comprehensive screening techniques to samples with high organic contaminant content is primarily that compounds with diverse physicochemical properties can be analyzed simultaneously. Here, a heavily contaminated industrial area was surveyed for organic pollutants by analyzing soil, sediment, and surface water samples. The hazard of the pollutants were ranked using SARs. The water samples were liquid-liquid extracted using dichloromethane and directly analyzed by GC x GC-time-of-flight mass spectrometry (GC x GC-TofMS). Soil and sediment samples were extracted with dichloromethane in an ultrasonic bath and subjected to gel permeation chromatography to eliminate lipids and humic matter. The low molecular weight fraction was then ...
The investigation of naturally volatile and derivatized metabolites in biological tissues by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry...
TY - JOUR. T1 - Gas chromatographic mass spectrometric detection of dihydroxy fatty acids preserved in the bound phase of organic residues of archaeological pottery vessels. AU - Hansel, Fabricio A.. AU - Bull, Ian D.. AU - Evershed, Richard P.. PY - 2011/7/15. Y1 - 2011/7/15. N2 - A methodology is presented for the determination of dihydroxy fatty acids preserved in the bound phase of organic residues preserved in archaeological potsherds. The method comprises saponification, esterification, silica gel column chromatographic fractionation, and analysis by gas chromatography/mass spectrometry. The electron ionisation mass spectra of the trimethylsilyl ether methyl ester derivatives are characterised by fragment ions arising from cleavage of the bond between the two vicinal trimethylsiloxy groups. Other significant fragment ions are [M-15](+.), [M-31](+.), m/z 147 and ions characteristic of vicinal disubstituted (trimethylsiloxy) TMSO- groups (Delta(7,8), Delta(9,10), Delta(11,12) and ...
This study examined whether 4-ABP-Hb adducts in RBC (as biomarkers of environmental tobacco smoke exposure) collected several years before the onset of a number of tobacco-related cancers and respiratory diseases may be predictive of disease risk among never smokers or former smokers.. Because of the limited amount of Hb available for the analysis of 4-ABP adducts, the analytic method was improved to obtain samples free of compounds interfering with the analysis. A mixed cation exchange/reverse-phase extraction cartridges for isolation of the analyte and high-resolution gas chromatography-negative ion chemical ionization-mass spectrometry with selective ion monitoring for quantitation was used for analysis and proved suitable for 4-ABP-Hb adduct measurement. Overall, the adduct levels were in good agreement with previous studies, which used larger amounts of Hb (8, 10, 20).. Elevated adduct levels are likely to reflect higher exposure to environmental tobacco smoke, as indicated by the moderate ...
Next, a model was developed that permitted a systematic investigation of peak shape in fluidic modulation. In the case of a non-focusing modulator for comprehensive two-dimensional gas chromatography, the systematic distortions induced when the modulator loads the second-dimension column give rise to a characteristic peak shape. Depending on the operating conditions this systematic distortion can be the dominant component of the second-dimension elution profiles. Understanding the factors that cause different peak shape observations provides a rugged approach to method development. It is shown that low flow ratio can lead to significant peak skewing and increasing the flow ratio reduces the magnitude of peak skewing. Validation of the peak shape model is made by comparison with experimental data ...
Close The Infona portal uses cookies, i.e. strings of text saved by a browser on the users device. The portal can access those files and use them to remember the users data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser. ...
Directory of patents related to Isotope-ratio-monitoring Gas Chromatography-mass Spectrometry Apparatus And Method (3 patents): Isotope-ratio-monitoring gas chromatography-mass spectrometry apparatus and method.; Isotope-ratio-monitoring gas chromatography-mass spectrometry apparatus and method; Isotope-ratio-monitoring gas chromatography-mass spectrometry apparatus and method
High-molecular weight compounds previously were found to be important secondary products from autoxidation of polyunsaturated fatty esters. The contribution of dimers to oxidative deterioration was investigated by analyzing their volatile thermal decomposition products by capillary gas chromatography-mass spectrometry. Dimers were isolated by gel permeation chromatography from autoxidized linolenate and from the corresponding monohydroperoxides, cyclic peroxides and dihydroperoxides. Major volatile decomposition products identified from these oxidative dimers were similar to those formed from the corresponding monomeric hydroperoxides. However, dimers from linolenate hydroperoxides produced more propanal and methyl 9-oxononanoate than the corresponding monomers but less methyl octanoate and much less or no 2,4-heptadienal and 2,4,7-decatrienal. Significant differences in minor volatile products also were observed between dimeric and monomeric products of methyl linolenate oxidation compounds. ...
Time of flight mass spectrometry identifies the elements of a compound by subjecting a sample of ions to a strong electrical field. Illuminating emerging analytical techniques in high-resolution mass spectrometry, Liquid Chromatography Time-of-Flight Mass Spectrometry shows readers how to analyze unknown and emerging contaminants-such as antibiotics, steroids, analgesics-using advanced mass spectrometry techniques. The text combines theoretical discussion with concrete examples, making it suitable for analytical chemists, environmental chemists, organic chemists, medicinal chemists, university research chemists, and graduate and post-doctorate students.. ...
Developing atherosclerotic lesions in hypercholesterolemic rabbits are depleted in zinc, while iron accumulates. This study examined the influence of zinc supplementation on the development of atherosclerosis and used isotope dilution gas chromatography-mass spectrometry techniques to measure biomarkers of oxidative lipid damage in atherosclerotic rabbit aorta. Our previous method for F2-isoprostane measurement was adapted to include the quantitation of cholesterol oxidation products in the same sample. Two groups of New Zealand white rabbits were fed a high cholesterol (1% w/w) diet and one group was also supplemented with zinc (1 g/kg) for 8 weeks. Controls were fed a normal diet. Zinc supplementation did not significantly alter the increase in total plasma cholesterol levels observed in animals fed high cholesterol. However, in cholesterol-fed animals zinc supplementation significantly reduced the accumulation of total cholesterol levels in aorta which was accompanied by a significant reduction in
TY - JOUR. T1 - Determination of bromide in whole blood and urine from humans using gas chromatography-mass spectrometry. AU - Kage, Shigetoshi. AU - Kudo, Keiko. AU - Ikeda, Hideaki. AU - Tsujita, Akira. AU - Ikeda, Noriaki. PY - 2005/3/25. Y1 - 2005/3/25. N2 - We devised a sensitive and simple method for determination of bromide in whole blood and urine from humans using gas chromatography-mass spectrometry. Bromide was alkylated with pentafluorobenzyl p-toluenesulphonate in the mixture of acetone and phosphate buffer (pH 6.8). The derivative obtained was analyzed using gas chromatography-mass spectrometry with the positive-ion EI mode. The lower limit of detection for the compound was 1 mg/l. The calibration curve for bromide was linear over the concentration range from 2 to 100 mg/l. With use of this method, levels of bromide in whole blood and urine were determined in cases of poisoning by inhaled brominated hydrocarbons.. AB - We devised a sensitive and simple method for determination of ...
Volatile organic compounds were quantified during two aircraft-based field campaigns using highly automated, whole air samplers with expedited post-flight analysis via a new custom-built, field-deployable gas chromatography-mass spectrometry instrument. During flight, air samples were pressurized with a stainless steel bellows compressor into electropolished stainless steel canisters. The air samples were analyzed using a novel gas chromatograph system designed specifically for field use which eliminates the need for liquid nitrogen. Instead, a Stirling cooler is used for cryogenic sample pre-concentration at temperatures as low as 165 degrees C. The analysis system was fully automated on a 20 min cycle to allow for unattended processing of an entire flight of 72 sample canisters within 30 h, thereby reducing typical sample residence times in the canisters to less than 3 days. The new analytical system is capable of quantifying a wide suite of C2 to C10 organic compounds at part-per-trillion ...
Since its first bench-top gas chromatograph/mass spectrometer (GC/MS) was sold in 1979, Shimadzu has been a leader in design innovations, such as our front access ion source, high efficiency ion optics, 20,000 u/second scan speed, and post-quadrupole focusing lenses.. Together, these innovations provide unparalleled instrument performance and simplified operation and maintenance. With the addition of the GCMS-TQ8040 triple quadrupole GC-MS/MS, Shimadzu offers a comprehensive series of GC/MS and GC-MS/MS instruments for every application.. Based on the UFMS (Ultra-Fast Mass Spectrometry) features and flexibility of the systems, a full range of solutions for multidimensional analysis, including Comprehensive GC (GCxGC) as well as MDGC is possible as well.. ...
The efficacy of a newly developed gas chromatography-negative ion chemical ionization-mass spectrometry-selected ion monitoring (GC-NICI-MS-SIM) assay for measuring globin adducts of benzo[a]pyrene (B[a]P) and chrysene diol epoxides in human was evaluated. In this pilot study, smokers and nonsmokers were selected as exposed and nonexposed groups. Using [2H12]r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyren e ([2H12]trans,anti-B[a]P-tetraol) as an internal standard, B[a]P-tetraols released from globin after hydrolysis and derivatization were quantified by GC-NICI-MS-SIM. Levels of trans-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrochrysene (chrysene-DE)-globin adducts were estimated by assuming that the recovery and the MS response of the perdeuterated B[a]P-tetraol internal standard reflected the recovery and MS response of chrysene tetraols. The assay was found to be reproducible and sensitive enough to detect both analytes in all samples. The mean levels of B[a]P-tetraols released ...
The current methodology used in quality control of Ecuadorian beverages such as Pájaro azúl, Puro and Pata de vaca is carried out by using conventional gas chromatography; however, it does not allow the fingerprinting of these Ecuadorian spirit beverages and their possible cases of adulteration. In order to overcome this drawback, comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS) was combined with multivariate data analysis, revealing that compounds like citronellal, citronellol, geraniol, methyl anthranilate, (−)-trans-α-bergamotene, (−)-cis-α-bergamotene and d-limonene can be considered key elements for pattern recognition of these traditional beverages and product adulteration cases. Thus, the two-dimensional chromatographic fingerprints obtained by GC × GC-MS coupled with chemometric analysis, using Principal Component Analysis and Fisher-ratio can be considered as a potential strategy for adulteration recognition, and it may used as a quality assurance system
Savareear, Benjamin, Jacobs, Matthew R and Shellie, Robert A 2014, Multiplexed dual first-dimension comprehensive two-dimensional gas chromatography-mass spectrometry with contra-directional thermal modulation, Journal of Chromatography A, vol. 1365, pp. 183-190, doi: 10.1016/j.chroma.2014.09.014. ...
Ionization mode. • electron ionization. • positive / negative chemical ionization. • Mass range : 1.6 ~ 1,050 amu. • Mass scan speed : max. 12,500 amu/sec. • Detector : triple-axis HED-electron multiplier. • Vacuum pumping system : 262 L/sec. • Library : wiley 8th with NIST 2008 MS library. ...
Ionization mode. • electron ionization. • positive / negative chemical ionization. • Mass range : 1.6 ~ 1,050 amu. • Mass scan speed : max. 12,500 amu/sec. • Detector : triple-axis HED-electron multiplier. • Vacuum pumping system : 262 L/sec. • Library : wiley 8th with NIST 2008 MS library. ...
A survey is made of investigations into the adsorption of polar and labile substances on surfaces within gas chromatographic equipment and of the methods which have been developed to minimize it. A description is given of a gas chromatograph-mass spectrometer in which such methods have been applied for the analysis of trace quantities of sulphur compounds.
was isolated from this hydrocarbon-contaminated wastewater and examined for its ability to utilize hexadecane. This strain was capable to grow on n-hexadecane as the sole source of carbon and energy. The ability of the isolate to degrade nhexadecane was assessed by growth assays and gas chromatography/mass spectrometry analysis. Using GC analysis, it was shown that the strain KSS1060 was able to degrade 62 % of n-hexadecane within 6 days, which mostly (51.6 %) occurred within the first 24 h. Identification of this hexadecane-degrader bacterium was carried out using 16S rDNA sequence analysis. Additionally, characterization of chemical composition of wastewater samples by the use of gas chromatography/mass spectrometry analysis indicated the presence of Hexanal, Benzene methanol, Indanol, 1,2-benzenedicarboxylic acid diethyl ester, diisobutyl phthalate, and Phenol,4,4-(1- methylethylidene) in the major constituents of wastewater. In conclusion, this study can focus on more costefficient ...
In chromatography-based metabonomic research, retention time (RT) alignment of chromatographic peaks poses a challenge for the accurate profiling of biomarkers. Although a number of RT alignment software has been reported, the performance of these software packages have not been comprehensively evaluated. This study aimed to evaluate the RT alignment accuracy of publicly available and commercial RT alignment software. Two gas chromatography/mass spectrometry (GC/MS) datasets acquired from a mixture of standard metabolites and human bladder cancer urine samples, were used to assess three publicly available software packages, MetAlign, MZmine and TagFinder, and two commercial applications comprising the Calibration feature and Statistical Compare of ChromaTOF software. The overall RT alignment accuracies in aligning standard compounds mixture were 93, 92, 74, 73 and 42% for Calibration feature, MZmine, MetAlign, Statistical Compare and TagFinder, respectively. Additionally, unique trends were ...
We compared the value of plasma samples with that of 24-hour urine samples in identifying patients with pheochromocytoma among those with hypertension. We employed specific gas chromatographic-mass spectrometric analysis of both urine and plasma for simultaneous assay of norepinephrine and its neuronal metabolite 3,4-dihydroxyphenylglycol (DHPG). The study population consisted of 1086 patients with hypertension, among them 25 patients with proved pheochromocytoma. Reference ranges for free norepinephrine and DHPG in plasma and urine were established. Measurement of free norepinephrine in 24-hour urine samples provided the best index of a pheochromocytoma. This technique had 100 percent sensitivity and 98 percent specificity among 1192 urine samples, as compared with 82 percent sensitivity and 95 percent specificity among 358 plasma samples. Simultaneous measurement of norepinephrine and DHPG in urine further improved specificity (to 99 percent), but the use of the ratio of norepinephrine to DHPG reduced
Quality Environmental Test Chambers manufacturers & exporter - buy Hplc Gas Chromatograph Mass Spectrometry Analyzer Machine GLPC / GC from China manufacturer.
In this paper, automated sample preparation, retention time locked gas chromatography-mass spectrometry (GC-MS) and data analysis methods for the metabolomics study were evaluated. A miniaturized and automated derivatisation method using sequential oximation and silylation was applied to a polar extract of 4 types (2 types×2 ages) of Arabidopsis thaliana, a popular model organism often used in plant sciences and genetics. Automation of the derivatisation process offers excellent repeatability, and the time between sample preparation and analysis was short and constant, reducing artifact formation. Retention time locked (RTL) gas chromatography-mass spectrometry was used, resulting in reproducible retention times and GC-MS profiles. Two approaches were used for data analysis. XCMS followed by principal component analysis (approach 1) and AMDIS deconvolution combined with a commercially available program (Mass Profiler Professional) followed by principal component analysis (approach 2) were compared.
UMESC Publications. Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue Idowu, O. R., Kijak, P. J., Meinertz, J. R., and Schmidt, L. J., 2004, Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue: Journal of Association of Official Analytical Chemists International, v. 87, no. 5, p. 1098-1108.. Abstract. Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA ...
Public tender in Salisbury. Supply of two Agilent 7890B Series gas chromatography mass spectrometry flame photometric detection systems. Supply of two Agilent 7890B Series gas chromatography mass spectrometry flame photometric detection systems. voluntary ex ante transparency notice
The current research work was designed to investigate the impact of the biofield energy treatment on the isotopic abundance ratios in resorcinol. The post Evaluation of the Isotopic Abundance Ratio in Biofield Energy Treated Resorcinol Using Gas Chromatography-Mass Spectrometry Technique appeared first on Sciworthy.. ...
Part I - Fluorinated Compounds A method has been developed for the extraction, concentration, and determination of two unique fluorinated compounds from the sediments of Lake Ontario. These compounds originated from a common industrial landfill, and have been carried to Lake Ontario by the Niagara River. Sediment samples from the Mississauga basin of Lake Ontario have been evaluated for these compounds and a depositional trend was established. The sediments were extracted by accelerated solvent extraction (ASE) and then underwent clean-up, fractionation, solvent exchange, and were concentrated by reduction under nitrogen gas. The concentrated extracts were analyzed by gas chromatography - electron capture negative ionization - mass spectrometry. The depositional profile determined here is reflective of the operation of the landfill and shows that these compounds are still found at concentrations well above background levels. These increased levels have been attributed to physical disturbances of ...
Comprehensive two-dimensional (2D) separations are highly beneficial in the characterization of complex samples. The research presented in this dissertation involves the analysis of the small polar molecules comprising the yeast metabolome using commercially available GCxGC-TOFMS instrumentation. The studies described herein are some of the first on metabolomic data using GCxGC-TOFMS and the analysis required a tremendous amount of procedural and software method development. A proof of principle experiment was performed using fermenting and respiring yeast cells. Initially, principal component analysis (PCA) was performed on three selective mass channels (m/z ) to identify the metabolite locations exhibiting changes between sample types. Twenty-six metabolite peaks were reported. Following proof that the GCxGCTOFMS is applicable to the study of yeast metabolite data, an extensive study was performed to determine the ability of GCxGC-TOFMS to detect metabolites and ultimately be utilized to ...
The enhanced resolution of comprehensive two-dimensional gas chromatography (GCxGC) was combined with the increased resolving power, speed, and mass accuracy of the Pegasus® HRTs mass analyzer to confidently characterize molecules in light cycle oil (LCO) and vacuum gas oil (VGO). Optimized chromatographic and mass spectrometry parameters were implemented to improve data acquisition, processing, and heteroatomic speciation of these light to midlevel petroleum fractions. Software tools were utilized to process the data and facilitate robust compound identifications. GCxGC-HRT data was processed using comprehensive Peak Find and resulted in comprehensive characterization of molecules in LCO and VGO samples. Compound classes consisted of, but were not limited to alkanes, cycloalkanes, aromatics, benzothiophenes, and carbazoles. Selective processing of alkylbenzothiophenes and dibenzothiophenes was conducted by retrospectively processing data using rapid two-dimensional, accurate mass Target Analyte
The conviction rate in drug facilitated sexual assault (DFSA) cases is known to be very low. In addition, the potential impact of toxicological results on the case is often not well understood by the judicial authorities. The aims of this study were (1) to obtain more knowledge concerning the prevalence of incapacitating substances in DFSA cases, (2) to create a more efficient DFSA analysis strategy taking background information into account, and (3) to evaluate the potential impact of systematic toxicological analysis (STA) on the final judicial outcome. This small-scale epidemiological study (n = 79) demonstrates that commonly-used illicit drugs, psychoactive medicines and ethanol are more prevalent in DFSA cases in contrast to the highly mediatized date rape drugs. Additionally, via case examples, the interest of performing STA-to prove incapacitation of the victim-in judicial procedures with mutual-consent discussions has been demonstrated as it led to increased convictions. However, more
Slater, C., Hardieck, M., Preston, T. and Weaver, L.T. (1998) Analysis of tert.-butyldimethylsilyl [1-13C]palmitic acid in stool samples by gas chromatography-mass spectrometry with electron impact ionisation: comparison with combustion isotope-ratio mass spectrometry. Journal of Chromatography B: Biomedical Sciences and Applications, 716(1-2), pp. 1-6. (doi:10.1016/S0378-4347(98)00280-1) ...
This study was conducted at the Horticulture Department of Cukurova University, Adana, Turkey, in 2010 to determine the volatile aroma compounds of Morchella mushroom. Fresh samples of Morchella esculenta (Sample 1) and Morchella elata (Sample 2) were collected from Canakkale (Sample 1) and Mersin (Sample 2) provinces in Turkey in the spring of 2010. Volatile aroma compounds were analyzed by headspace gas chromatography mass spectrometry (HS-GC/MS). A total of 31 aroma compounds were identified in the 2 analyzed samples: 7 alcohols, 7 esters, 7 ketones, 3 acids, 2 aldehydes, 1 terpene, phenol, 1-propanamine, geranyl linalool, and quinoline. Seventeen aroma components were identified in Sample 1, and 18 compounds were found in Sample 2. Phenol was determined as the major aroma compound in both Sample 1 and Sample 2, at 50.888% and 58.293% content, respectively. Alcohols, especially 1-octen-3-ol, were detected as the second major aroma components in Sample 1 and Sample 2, at 15.500% and 5.660% ...
New Gas Chromatography Mass Spectrometry (GC-MS) Systems | GMI, Dont waste your money on your next Gas Chromatography System purchase. Download GMIs Gas Chromatography Guide and become an expert on acquiring excellent quality equipment by learning how to:   Select the right system based on expected throughput. Differentiate sample introduction systems to suit your required injection techniques. Pick out the proper GC Column for your Gas Chromatograph equipment. Choose between detector types according to selectivity or dependency. Dont waste your time and money on the wrong equipment. Download the guide today, click here.   Browse through and learn more about a specific New Gas Chromatography, Detector or System by clicking on the product name below. For any inquiries and/or concerns, just contact our new lab equipment experts via our hotline at 1-800-745-2710 or email us at [email protected]
TY - JOUR. T1 - Profile of volatile metabolites in urine by gas chromatography-mass spectrometry. AU - Zlatkis, Albert. AU - Bertsch, Wolfgang. AU - Lichtenstein, H. A.. AU - Tishbee, Arye. AU - Shunbo, Farid. AU - Liebich, M.. AU - Coscia, A. M.. AU - Fleischer, N.. PY - 1973. Y1 - 1973. N2 - Profiles of volatile metabolites of 150 urine samples from normal individuals and 40 samples from subjects with diabetes mellitus have been studied by gas chromatography and mass spectrometry. The technique involves adsorption of the urinary headspace volatiles on Tenax GC, heat desorption with helium, trapping on a cooled precolumn, and chromatography on 100-m × 0.50-mm i.d. nickel columns. Individual profiles were observed over a period of 2 months. Characteristic constituents in normal urines are 2-butanone, 2-pentanone, 4-heptanone, dimethyl disulfide, several alkyl furans, pyrrole, and carvone. In subjects with diabetes mellitus under insulin treatment, high concentrations of pyrazines, ...
This standard is developed for the purposes of enforcing the Law of the Peoples Republic of China on Environmental Protection, protecting the environment, safeguarding the public health, and setting standards for PCBs in soil and sediment. This standard specifies the gas chromatography-mass spectrometry method for the determination of PCBs in soil and sediment. It is the original version.. ...
We Have Recent Updates of Liquid Chromatography-Mass Spectroscopy Market in Sample [email protected] https://www.orbisresearch.com/contacts/request-sample/4701902?utm_source=PoojaB. This report is an in-depth analysis of the Liquid Chromatography-Mass Spectroscopy market categorized based on the end user, derivatives,and geographical regions such as America, APAC, Europe, and MEA.Competitorsin the Liquid Chromatography-Mass Spectroscopy market are studied in detail in the report. It offers key details of the vendors in the Liquid Chromatography-Mass Spectroscopy market. To help enterprises, investors, and other market players improve their position in the Liquid Chromatography-Mass Spectroscopy market, this Liquid Chromatography-Mass Spectroscopy market report provides a detailed analysis of the market leaders. Moreover, it gives a brief overview of the competencies and ability of these companies in the Liquid Chromatography-Mass Spectroscopy to grow in future and dominate the market. The ...
Abstract. During the MINOS campaign in August 2001 comprehensive two-dimensional gas chromatography (GC x GC) was applied to the in situ measurements of atmospheric volatile organic compounds (VOCs) at the Finokalia ground station, Crete. The measurement system employs a thermal desorption unit for on-line sampling and injection, and a GC x GC separation system equipped with a flame ionization detector (FID) for detection. The system was optimized to resolve C7-C14 organic components. Two-dimensional chromatograms from measurements of Finokalia air samples show several hundred well-separated peaks. To facilitate peak identification, cartridge samples collected at Finokalia were analyzed using the same GC x GC system coupled with a time-of-flight mass spectrometer (TOF-MS). The resulting mass spectra were deconvoluted and compared to spectra from a database for tentative peak identification. About 650 peaks have been identified in the two-dimensional plane, with significant signal/noise ratios ...
TY - JOUR. T1 - Advances in the application of comprehensive two-dimensional gas chromatography in metabolomics. AU - Higgins Keppler, Emily A.. AU - Jenkins, Carrie L.. AU - Davis, Trenton J.. AU - Bean, Heather. N1 - Funding Information: The growth of the field of metabolomics is reflected by the recent investments by the National Institutes of Health (NIH) into the Common Fund Metabolomics program, which supports technology development, infrastructure, training, and an international repository for metabolomics data, the Metabolomics Workbench ( metabolomicsworkbench.org ) [59] . The goal is to generate publicly accessible metabolomics data, following the models of data sharing for genomics and transcriptomics via the GenBank and Gene Expression Omnibus (GEO) databases, respectively. Currently, depositing metabolomics data into public repositories is only encouraged under the NIH Data Sharing policies; however, it is possible that in the near future journal publishers may require data sharing ...
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of the bacterium Staphylococcus aureus characterized by its multi-drug resistance to penicillins, clindamycin, tetracyclines, macrolides, aminoglycosides, fluoroquinolones, etc. Chromolaena odorata R.M. King & H. Rob is a potential and promising plant that should be exploited for the management of diseases caused by MRSA because its fractions have anti-MRSA activities. The aim of this work was to screen and identify the chemical constituents of the anti-MRSA fractions of C. odorata leaves. Materials and Methods: Seven isolates of MRSA and methicillin-susceptible S. aureus(MSSA) and a control strain S. aureus NCIBB 8588 were used for this study. Fresh leaves of C. odorata were collected from Igbinedion University, Okada environs, Edo State, Nigeria. The fractions obtained were analyzed with a Gas Chromatography-Mass Spectrometry (GC-MS) analyzer to identify their chemical constituents. Results: A total of eight fractions ...
Liquid Chromatography Time-of-Flight Mass Spectrometry (LC-TOFMS) is an analytical platform that is widely used in the study of biological mixtures in the rapidly growing fields of proteomics and metabolomics. The development of statistical methods for the analysis of the very large data-sets that are typically produced in LC-TOFMS experiments is a very active area of research. However, the theoretical basis on which these methods are built is currently rather thin and as a result, inferences regarding the samples analysed are generally drawn in a somewhat qualitative fashion. This thesis concerns the development of a statistical formalism that can be used to describe and analyse the data produced in an LC-TOFMS experiment. This is done through the derivation of a number of probability distributions, each corresponding to a different level of approximation of the distribution of the empirically obtained data. Using such probabilistic models, statistically rigorous methods are developed and ...
The antiprotozoal and antioxidant activities of Viola tricolor and Laurus nobilis have been reported recently. Thus, the existing study pursued to assess the growth inhibition effect of methanolic extract of V. tricolor (MEVT) and acetonic extract of L. nobilis (AELN) against five Babesia parasites and Theileria equi in vitro and in vivo. MEVT and AELN suppressed Babesia bovis, B. bigemina, B. divergens, B. caballi, and T. equi growth at half-maximal inhibitory concentration (IC50) values of 75.7 ± 2.6, 43.3 ± 1.8, 67.6 ± 2.8, 48 ± 3.8, 54 ± 2.1 μg/mL, and 86.6 ± 8.2, 33.3 ± 5.1, 62.2 ± 3.3, 34.5 ± 7.5 and 82.2 ± 9.3 μg/mL, respectively. Qualitative phytochemical estimation revealed that both extracts containing multiple bioactive constituents and significant amounts of flavonoids and phenols. The toxicity assay revealed that MEVT and AELN affected the mouse embryonic fibroblast (NIH/3 T3) and Madin-Darby bovine kidney (MDBK) cell viability with half-maximum effective concentrations (EC50)
TY - JOUR. T1 - Simultaneous determination of phencyclidine and monohydroxylated metabolites in urine of man by gas chromatography-mass fragmentography with methane chemical ionization. AU - Cone, Edward J.. AU - Buchwald, William. AU - Yousefnejad, David. PY - 1981/5/8. Y1 - 1981/5/8. N2 - Phencyclidine and monohydroxy metabolites were measured in human urine using gas chromatography-mass fragmentography with methane chemical ionization. Samples were extracted either untreated or following acid hydrolysis, derivatized with heptafluorobutyric anhydride, separated on a 3% SE-30 column and analyzed by mass fragmentography. The assay was sensitive to ca. 0.01 μg/ml for phencyclidine and ca. 0.05 μg/ml for the metabolites. Urine samples from five human subjects enrolled in a methadone maintenance program who had ingested phencyclidine were analyzed. The phencyclidine concentration ranged from 0.3 to 23.7 μg/ml. The concentrations of metabolites ranged from 0 to 1.8 μg/ml. A new monohydroxy ...
TY - JOUR. T1 - Gas chromatographic-mass spectrometric fragmentation study of flavonoids as their trimethylsilyl derivatives. T2 - Analysis of flavonoids, sugars, carboxylic and amino acids in model systems and in citrus fruits. AU - Füzfai, Zs. AU - Molnár-Perl, I.. PY - 2007/5/11. Y1 - 2007/5/11. N2 - The fragmentation patterns and quantitation possibilities of three anthocyanidins (pelargonidin, cyanidin, malvidin), one flavonol (quercetin), two flavones (apigenin, luteolin) and two flavanones (naringenin, hesperetin) have been investigated as trimethylsilyl and as trimethylsilyl (oxime) derivatives by gas chromatography-mass spectrometry. Results proved that anthocyanidins and flavanones form trimethylsilyl (oximes), while flavonol and flavones provide simple trimethylsilyl derivatives. In all cases, characteristic fragments of high masses are formed proper for quantitation purposes. Hydrolysis conditions for naringin, hesperidin and rutin have been optimized, resulting in the quantitative ...
TY - JOUR. T1 - Improved separation of the 209 polychlorinated biphenyl congeners using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. AU - Focant, Jean François. AU - Sjödin, Andreas. AU - Patterson, Donald G.. N1 - Funding Information: J.-F. Focant is financially supported by the Oak Ridge Institute for Science and Education (ORISE), a Department of Energy (DOE) facility managed by Oak Ridge Associated Universities (ORAU). PY - 2004/6/25. Y1 - 2004/6/25. N2 - The separation of the 209 polychlorinated biphenyl (PCB) congeners has been studied using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS). Four column combinations based on thermally stable phases, DB-1/HT-8, DB-XLB/HT-8, DB-XLB/BPX-50, and HT-8/BPX-50, have been investigated. The HT-8/BPX-50 set produced the best separation. The distribution of the 100 to 150 ms wide peaks was highly structured in the chromatographic space and based on the ...
Pellizzari, E., Bunch, J. E., Bursey, J. T., Berkley, R. E., Sawicki, E., & Krost, K. (1976). Estimation of N-Nitrosodimethylamine Levels in Ambient Air by Capillary Gas-Liquid Chromatography/Mass Spectrometry. Analytical Letters, 9, 579 ...
TY - JOUR. T1 - Electron impact ionization of tetramethylsilane (TMS). AU - Basner, R.. AU - Foest, R.. AU - Schmidt, M.. AU - Sigeneger, F.. AU - Kurunczi, P.. AU - Becker, K.. AU - Deutsch, H.. N1 - Funding Information: This work was supported by a NATO Collaborative Research Grant (CRG-920089). Funding Information: We thank Mrs Haeder for invaluable technical assistance. Two of us (P.K. and K.B.) would like to acknowledge partial financial support from the U.S. National Science Foundation (NSF) through grant PHY-9401874. P.K. and K.B. would also like to thank their collaborators in Greifswald for their hospitality and support during several visits.. PY - 1996. Y1 - 1996. N2 - We studied the electron impact ionization of tetramethylsilane (TMS), Si(CH3)4, which is utilized in plasma polymerization applications, using various mass spectrometric techniques. Absolute partial cross-sections for the formation of the parent ion and 15 fragment ions were measured in a high resolution double-focusing ...
Comparison of extraction methods for quantitation of methionine and selenomethionine in yeast by species specific isotope dilution gas chromatography-mass spectrometry
Phytosterols are potential endocrine-disrupting compounds. Quantification of phytosterols was carried out in sediments from four coastal zones and two rivers in south-central Chile. Sterol concentrations were determined by capillary gas chromatography-mass spectrometry and the sources of sedimentary organic matter were determined using sterol ratios and lipid biomarkers. Total sterol concentrations (0.03 to 10.4 μg g-1) were within the range reported for other marine ecosystems and the β-sitosterol concentration (0.01 to 2.01 μg g-1) was lower than previously reported for the upwelling system off Peru. Some coastal stations adjacent to the rivers had β-sitosterol of terrestrial origin. High concentrations of β-sitosterol were also found in sediments from more oceanic stations, supporting the notion that this sterol can also be produced by phytoplankton. No differences in the sterol concentration between the coastal zones were found. However, significant differences were found between almost ...
article{191ea318-159e-43da-9392-05ee7bf33a0d, author = {Wady, Loay and Bunte, Annicka and Pehrson, Christina and Larsson, Lennart}, issn = {1872-8359}, language = {eng}, number = {3}, pages = {325--332}, publisher = {Elsevier}, series = {Journal of Microbiological Methods}, title = {Use of gas chromatography-mass spectrometry/solid phase microextraction for the identification of MVOCs from moldy building materials.}, url = {http://dx.doi.org/10.1016/S0167-7012(02)00190-2}, volume = {52}, year = {2003 ...
TY - JOUR. T1 - Screening for anabolic steroids and related compounds in illegal cocktails by liquid chromatography/time-of-flight mass spectrometry and liquid chromatography/quadrupole time-of-flight tandem mass spectrometry with accurate mass measurement. AU - Nielen, M.W.F.. AU - Vissers, J.P.C.. AU - Fuchs, R.E.M.. AU - van Velde, J.W.. AU - Lommen, A.. PY - 2001. Y1 - 2001. N2 - Findings of illegal hormone preparations such as syringes, bottles, cocktails, and so on, are an important information source for the nature of the current abuse of anabolic steroids and related compounds as growth-promoting agents in cattle. A new screening method for steroids in cocktails is presented based on liquid chromatography (LC) with diode-array UV-absorbance detection and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS). Accurate mass measurements were performed at a mass resolution of 4000 using continuous introduction of a lock mass through a second (electro)sprayer. Similar ...
Large and ever-increasing numbers of chemicals, including large quantities of a broad spectrum of organic compounds are used in modern society. More than 30 000 of the more than 100 000 chemical substances registered in the EU are estimated to be daily used, of which many will be discharged into the waste-streams handled by municipal sewage treatment plants (STPs). The main objective of the work underlying this thesis was to improve understanding of the relationships between the characteristics of sewage contaminants and their sewage treatment efficiency. Further objectives were to examine the relationships between socio-economic uses of chemicals and sludge quality, and the effects of regulatory actions on sludge quality.. The quality of the sewage sludge and the levels and distribution patterns of the sludge contaminants, both within and between the STPs, seem to remain quite constant over time. The overall findings indicate that the levels of contaminants in sewage sludge seem to be largely ...
Methods Patients with sterile brain injury requiring intubation and ventilation on the intensive care unit were eligible for inclusion. Serial clinical and breath data were obtained three times a week, from admission up to a maximum of 10 days. Bronchial lavage for semiquantitative culture was collected immediately prior to breath sampling. Breath samples were collected in triplicate for off-line analysis by thermal-desorption/gas chromatography/time-of-flight mass spectrometry. Breath data were recorded as retention time/mass ion pairs, and analysed (pathogen present vs absent) by ANOVA-mean centre principal component analysis.. ...
AIMS: This study compared serum metabolites of demented patients (Alzheimers disease and vascular dementia) and controls, and explored serum metabolite profiles of nondemented individuals 5 years preceding the diagnosis.. METHODS: Cognitively healthy participants were followed up for 5-20 years. Cognitive assessment, serum sampling, and diagnosis were completed every 5 years. Multivariate analyses were conducted on the metabolite profiles generated by gas chromatography/time-of-flight mass spectrometry.. RESULTS: A significant group separation was found between demented patients and controls, and between incident cases and controls. Metabolites that contributed in both analyses were 3,4-dihydroxybutanoic acid, docosapentaenoic acid, and uric acid.. CONCLUSIONS: Serum metabolite profiles are altered in demented patients, and detectable up to 5 years preceding the diagnosis. Blood sampling can make an important contribution to the early prediction of conversion to dementia.. ...
TY - CHAP. T1 - Polar Lipid Profiling by Supercritical Fluid Chromatography/Mass Spectrometry Method. AU - Yamada, Takayuki. AU - Nagasawa, Yumiko. AU - Taguchi, Kaori. AU - Fukusaki, Eiichiro. AU - Bamba, Takeshi. PY - 2015/4/15. Y1 - 2015/4/15. N2 - Polar lipids, such as phospholipids (PLs) and sphingolipids, are abundant in plant oils and are the major component of biological membranes. These lipids also play important physiological roles in cellular signaling. High-throughput simultaneous analyses for all types of lipids, including polar lipids, are favorable to elucidate the function of individual lipid molecular species or to distinguish among phenotypes. The research field aimed at comprehensive lipid profiling is called lipidomics. Because of the diversity of chemical structures and the wide range of polarities in lipids, a powerful separation technique is required for comprehensive lipid profiling. Supercritical Fluid Chromatography (SFC)/Mass Spectrometry (MS) is the ideal tool for ...
Persistence Market Research has studied the overall performance of the global liquid chromatography-mass spectroscopy market and have observed that the market is likely to show significant growth owing to a rising demand for liquid chromatography-mass spectroscopy systems across various applications.
Article Improved derivatization protocol for simultaneous determination of alkylphenol ethoxylates and brominated flame retardants followed by gas chromatography-mass spectrometry analyses. An improved derivatization protocol for the simultaneous det...
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Centers RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.. ...
Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasma, and human adipose tissue, were cleaned up by one of the following three cleanup procedures: (1) continuous liquid-liquid extraction steam distillation; (2) gel-permeation chromatography; and (3) adsorption on activated carbon followed by elution with toluene. The third procedure was used only for the examination of planar polychlorinated aromatic hydrocarbons in environmental samples. Using these techniques, the authors have found evidence for contamination of fish samples with polychloronaphthalenes, polychlorostyrenes, polychlorobiphenyls, polychlorodibenzofurans, and polychlorodibenzodioxins among other chemicals. The polychlorodibenzodioxins appeared only in the spectra of extracts of fish obtained from the ...
A simple, rapid and sensitive method based on microextraction in packed syringe (MEPS), in combination with gas chromatography-mass spectrometry (GC-MS) was developed. Polyaniline (PANI) nanowires network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI na ...
Humulene is one of the components of the essential oil from the flowering cone of the hops plant, Humulus lupulus, from which it derives its name. The concentration of humulene varies among different varieties of the plant but can be up to 40% of the essential oil.[3] Humulene and its reaction products in the brewing process of beer gives many beers their hoppy aroma. Noble hop varieties have been found to have higher levels of humulene, while other bitter hop varieties contain low levels.[4][unreliable source?] Multiple epoxides of humulene are produced in the brewing process. In a scientific study involving gas chromatography-mass spectrometry analysis of samples and a trained sensory panel, it was found that the hydrolysis products of humulene epoxide II specifically produces a hoppy aroma in beer.[5][6] α-Humulene has been found in many aromatic plants on all continents, often together with its isomer β-caryophyllene. Proven α-humulene emitters into the atmosphere are pine trees,[7] ...
This study was performed to investigate the effectiveness of garlic and onion compared to butylated hydroxy toluene (BHT) on retarding oxidation of cold infused sunflower oil stored for 6 months. Garlic and onion powders or their essential oils were added to sunflower oil in a wide range of concentrations. Sensory evaluation of the flavored oil samples was carried out. Panelists preferred significantly the sunflower oil flavored by cold infusion with garlic and onion powders at 5% and 10 % levels or their essential oils at 0.01% and 0.02% levels. The progress of oxidation was assessed in terms of acid value, peroxide value, and oxidative stability determined by Rancimat. The yield and Gas Chromatography-Mass Spectrometry analysis of the garlic and onion essential oils were determined. These results suggested that garlic or onion could be used as a natural flavoring material for improving oxidative stability of sunflower oil ...
Deoxynivalenol (DON) is the most frequently detected mycotoxin in cereal and cereal-based products, and a continuous monitoring of this toxin in foodstuffs is highly desirable. In this sense,a QuEChERS based extraction and gas chromatography-tandem mass spectrometry detection is proposed to determine DON in an appetizer largely consumed, the wheat-based snacks. In this study, a total of 40 samples were analyzed. The samples were divided into two groups based on the composition. Extraction was carried out with acetonitrile followed by a dispersive solid phase extraction and analyzed for DON content by gas chromatography-tandem mass spectrometry (GC-QqQ-MS/MS) method. The overall occurrence of samples with DON was 67.5%, with maximum content of 61μg/kg. In spite of its high incidence, DON concentrations found in samples were much lower than the maximum limit established in the current European legislation (500 μg/kg) for the foodstuff evaluated. Data obtained indicated a low exposure to DON ...
Solid phase microextraction (SPME) is a solventless extraction technique that combines sample preparation and sample introduction into a gas chromatograph into a single step. For the past 20 years, solid-phase micro-extraction (SPME) has been used in numerous fields such as: food analysis, including juices, alcohols fruits and vegetables for volatiles, aroma, caffeine, fatty esters, environmental applications including volatile organic contaminants, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phenols, pesticides, steroids, herbicides, acid/neutral/base compounds, and organometallic compounds from water, air, soil, sludge, and sediment samples and in biomedical analysis. This work demonstrates the extension of the limitations of SPME with respect to extraction and analysis of a) extension of headspace SPME to larger polycyclic aromatic hydrocarbons from fish oil b) less volatility analytes, combination of SPME-Gas Chromatograph -Mass Spectrometer -Mass Spectrometer (SPME-GC-MS-MS) to
Examples of application of pyrolysis-gas chromatography-mass spectrometry technique for identification of different polymeric materials are demonstrated.
Examples of application of pyrolysis-gas chromatography-mass spectrometry technique for identification of different polymeric materials are demonstrated.
Mitochondrial dysfunction plays a role in a wide range of diseases resulting in an enormous public health burden. The goal of this thesis is to identify metabolic pathways that are disrupted in response to mitochondrial insults. A large proportion of this work is based on the generation of stable isotope labelled metabolites to allow for the rigorous quantification of intracellular metabolites by liquid chromatography-mass spectrometry. Once developed, this methodology was employed in cell culture models initially to characterize an unidentified acyl-CoA thioester induced by propionate metabolism. This novel pathway was identified as the direct formation of 2-methyl-2-pentenoyl-CoA, and using isotopic labeling by metabolic precursors served as a critical component to this pathway elucidation. These same techniques were then applied to studying rotenone, a mitochondrial complex I inhibitor associated with Parkinsonâ??s disease. Previous work by our group has shown that rotenone inhibits components of
TY - JOUR. T1 - Determination of active hydrogen in organic compounds by electron‐impact mass spectrometry. AU - Dinya, Z.. AU - Lipták, Miklós. AU - Szabó, Pál. AU - Sztaricskai, F.. AU - Vékey, K.. PY - 1992. Y1 - 1992. N2 - We report here detailed studies of Bose et al.s (J. Org. Chem. 47, 4008 (1982)) simple method for obtaining electron‐impact (EI) mass spectra from non‐volatile and/or thermolabile organic compounds by using ammonium salts. Good quality mass spectra can be obtained by mixing the analyte with different ammonium salts (mainly with NH4Cl) in a given ratio, the mixture being introduced through a conventonal direct probe. A wide variety of ammonium salts has been used to study the effect of the anion and to determine the optimum analyte:NH4X ratio and the other experimental parameters (i.e., electron energy, source temperature etc). A very simple and cheap means of determination of active hydrogen in hydroxyl, carboxyl, sulfhydryl, amino and amido etc groups by EI ...
Abstract: Medicinal plant can be considered as a great source of new antimicrobial agents due to their enormous therapeutic potential and limited side effects. Nettle (Urtica dioica L.) is a widespread and common medicinal plant widely used in traditional medicine. The present study investigates the antimicrobial potency of alcoholic and aqueous extracts of Urtica dioica on some gram positive and negative bacteria and also a particular type of fungi and analyzes the extracts to find the active ingredients by gas chromatography-mass spectroscopy (GC-MS) method. Results from disc diffusion assay indicated that water extract of root, leaf and stalk had the highest antimicrobial activity respectively and caused significant inhibition zones in P. vulgaris, L. monocytogenes and K. pneumoniae cultures. Antimicrobial efficacy of ethanol extracts was higher in root extract which caused high growth inhibition zones in P. vulgaris, K. pneumoniae and S. aureus cultures. MBC and MIC experiments of the ...
An analytical method has been established for the quantitative determination of 48 gaseous volatile organic compounds (VOCs) that were detected in the outdoor environment in Western Singapore by Thermal Desorption Gas Chromatography Mass Spectrometry (TD-GCMS). Tenax/Carbopack X multi-sorbent tubes were evaluated for active sampling performance and the method was validated using VOC standard solutions. The procedure exhibited repeatability with relative standard deviation (%RSD) values ≤ 10%, linearity with R2 values ≥ 0.99 for concentrations from 0.02 to 500 ng, VOC standards breakthrough ≤ 5% , tube desorption efficiencies ~100% and the majority of recoveries were between 61% to 120%. 30 mL/min flow rate coupled with sampling volumes of 1 L and 5 L gave the best results for sampling breakthrough and reproducibility during air sampling. Most of the target analytes exhibited acceptable breakthrough ≤ 5%, reproducibility ≤ 20% and method detection limits below 0.5 ppbv. The analyte ...
Background and objectives: Ferula assa-foetida (asafoetida) is a native Iranian species which grows in different regions and climates in Iran. The plant is well known in Iranian Traditional Medicine as well as folk medicine for treatment of diseases. Several studies have been carried out on the essential oil of this species collected from different areas of Iran. This study is the first report about the essential oil of the plant collected from Neishabour mountains that is a potent area for growing this valuable plant species. Methods: Essential oil of the aerial part of Ferula assa-foetidawhich wascollected from Neishabour, Iran, was analyzed by gas chromatography-mass spectroscopy (GC/MS). The minimum inhibitory concentrations of the essential oil was investigated against both Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia) bacteria using microdilution method. Results: Twenty three
The quality-control lab is equipped with a wide array of instrumentation, including gas chromatograph / mass spectrometers (GC/MS) and a high-field NMRs. Chemistry laboratories are equipped with apparatus for both large-scale (50+ liters) and microscale chemistry, which includes equipment for high-pressure gas reactions, pH and temperature-controlled enzyme chemistry, high-resolution distillation processes, and catalytic reduction with both hydrogen and deuterium . The production laboratories are also equipped with analytical equipment for in-process testing. All of these resources allow us to consistently produce products with high chemical and isotopic purity. All our production is evaluated before and after packaging.. Our experience and skill allow us to obtain a chemical purity of NMR deuterated solvents higher or equal to 99,9 ...
Determination of 1,8 Cineole in Fresh Rosemary and Sage Leaves by Solid-phase Microextraction and Gas Chromatography/Mass Spectrometry
TY - JOUR. T1 - Branched chain amino acids as a major source of alanine nitrogen in man. AU - Haymond, M. W.. AU - Miles, J. M.. PY - 1982. Y1 - 1982. N2 - In vitro perfusion and incubation studies and recent investigations in dogs suggest that branched chain amino acids (BCAA)may be a major source of alanine nitrogen. To determine the contribution of BCAA nitrogen to the formation of alanine in man, seven postabsorptive adults received prime-dose constant infusions of 15N-leucine, L-[6,6,6-2H3] leucine, and L-[2,3,3,3-2H4] alanine; isotopic enrichment was determined in arterialized venous plasma samples by gas chromatography-mass spectroscopy. At substrate and isotope steady state, alanine flux and the rate of 15N alanine appearance were 5.4 ± 0.3 μmol/kg.min and 32 ± 2 nmol/kg.min, respectively. Leucine nitrogen flux was significantly greater than that of leucine carbon flux (2.54 ± 0.25 vs. 1.90 ± 0.10 μmol/kg.min, respectively; P , 0.001). Greater flux of leucine nitrogen when compared ...
The distinction between autochthonous, and oil-like origin of organic matter in geological sediments can be performed on the basis of n-alkane abundance and distribution patterns, determined by gas chromatography, or on the basis of the carbon-isotope ratio (delta (CPDB)-P-13) patterns of dominant n-alkanes, determined by gas chromatography-mass spectroscopy. Here we present solutions for automatic classification of organic matter origin in geological sediments, based on artificial neural networks ...
The non-invasive nature of volatile organic compound (VOC) sampling from skin makes this a priority in the development of new screening and diagnostic assays. Evaluation of recent literature highlights the tension between the analytical utility of ambient ionisation approaches for skin profiling and the practicality of undertaking larger campaigns (higher statistical power), or undertaking research in remote locations. This study describes how VOC may be sampled from skin and recovered from a polydimethylsilicone sampling coupon and analysed by thermal desorption (TD) interfaced to secondary electrospray ionisation (SESI) time-of-flight mass spectrometry (MS) for the high throughput screening of volatile fatty acids (VFAs) from human skin. Analysis times were reduced by 79% compared to gas chromatography-mass spectrometry methods (GC-MS) and limits of detection in the range 300 to 900 pg cm−2 for VFA skin concentrations were obtained. Using body odour as a surrogate model for clinical testing ...
Drug use histories were collected from 100 subjects recruited from the dance scene in and around Glasgow. In addition, each subject donated a hair sample that was analyzed by gas chromatography/mass spectrometry (GC/MS) for amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethylamphetamine (MDEA). The hair samples were analyzed in two 6 cm segments or in full, ranging from 1.5 to 12 cm, depending on the length of the hair. Approximately 10 mg of hair was ground to a fine powder before treatment with B-glucuronidase/aryl sulfatase. A solid-phase extraction procedure was conducted, followed by derivatization with pentafluoropropionic anhydride (PFPA). All extracts were analyzed by GC/MS. Of the 139 segments analyzed, 77 (52.5 percent) were positive for at least one of the five amphetamines. The drug concentrations found in the hair were compared with the self-reported drug histories. A concordance of greater than 50 percent was found between the ...
This review deals with overview of methods of multidimensional gas chromatography (MDGC), the classical meaning- conventional heart-cut MDGC, and the comprehensive two-dimensional gas chromatography (GC×GC). MDGC is widely used because it increases required separation efficiency, which cannot be achieved by one-dimensional gas chromatography. Selected applications in food quality and safety, monitoring of environment, food authentication are summarized. This review summarizes the advances and applications of MDGC that have been published over last 10 years. ...
The composition of detectable small organic compounds in the ethanol extract of Achillea micrantha was defined by means of gas chromatography-mass spectrometric analysis. There we..
PCB signatures can be used for source identification, exposure studies, age dating and bio-monitoring. This study uses comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS) to produce a PCB signature comprised of over 80 PCBs for individual Leachs storm petrels (Oceanodroma leucorhoa). The Leachs storm petrel is a relatively small, elusive, understudied pelagic bird, which only returns to remote islands under darkness during the breeding season. Samples were obtained from 25 Leachs storm petrels found dead in Canada and the UK following storm events in 2006 and 2009. Tissue samples were extracted and analysed by GCxGC-ToFMS and results showed that 83 PCB congeners were present in ,60% of samples. An assessment of the PCB signature in four different tissue types showed that it did not vary greatly in samples obtained from the gut, heart, liver and stomach. Multivariate statistical analysis identified a distinctive PCB signature in birds from ...
A method for the determination of cocaine (COC), benzoylecgonine (BE), ecgonine methyl ester (EME), and ecgonine (ECG) in plasma by liquid chromatography-mass spectrometry (LC-MS-MS) was developed. The analytes were isolated from human plasma by subsequent solid-phase extraction and were separated on a Zorbax Eclipse XDB-C8 narrow-bore column using an ammonium acetate buffer/acetonitrile/methanol gradient. A Turbolonspray® source was used for ionization. The analytes were characterized by their particular molecular ion and several fragments. Multiple reaction monitoring (MRM) was used for isolation and quantitation. The assay was rapid, highly sensitive, and reliable. The method was applied to monitor the in vitro degradation of cocaine in plasma. Fresh unpreserved and preserved (0.25 % KF) plasma samples were spiked with 1000 ng cocaine/mL. Aliquots of both series were stored at 4°C and 20°C and were analyzed at selected storage times of up to 15 days. In all samples, degradation of cocaine ...
To better understand the coalification process, we have conducted numerous studies of the chemical structural composition of xylem tissue from gymosperm wood and related woods that has been coalified to varying degrees. The studies presented here, examine the chemical nature of buried and coalified xylem tissue at the molecular level. To achieve this, we employed pyrolysis/gas chromatography (py/gc) and pyrolysis/gas chromotography/mass spectrometry (py/gc/ms). Pyrolysis techniques have been used to examine peat, coal, coalified wood, and related substances. However, the technique has not been previously applied to a systematic and histologically-related series of coalified woods. It is particularly useful to compare the results from pyrolytic studies with the data obtained from solid-state **1**3C NMR....
Gas chromatography-mass spectrometry (GC-MS) and liquid chromatographymass spectrometry (LC-MS) are powerful analytical techniques that combine the separation power in a stationary phase with the detection power of mass spectrometry. GCMS and LC-MS have gained dominant positions in identifying and quantifying different analyte species due to their high selectivity, high sensitivity, and high reproducibility. My research utilizes the analytical power of LC-MS and GC-MS to address two environmental issues: 1) Identification of biodegradation products of the ionic liquid 1- butyl-3-methylimidazolium chloride (BMIMCl) by an activated sludge microbial community using LC-MS and 2) identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in the Kalamazoo River oil spill using GC-MS. Three major metabolites from BMIMCl biodegradation were identified, and their structures were confirmed using MS/MS and 1H-NMR techniques. Many PAHs were identified, and their concentrations were quantified in
As a commercial laboratory specializing in organic & inorganic analysis of hazardous waste, waste water, soil, and petroleum product samples, our continued existence depends upon quality of service and timely turnaround. We provide very competitive pricing along with technical services under price schedule and contract arrangements. Analytical methodology employed meets the requirements of the USEPA and the National Environmental Laboratory Accreditation Conference (NELAC). Quality Control   Instrumentation Laboratory instruments play a vital role in reporting timely and accurate results. With the needs of our clients in mind, NAS keeps up-to-date by investing in the latest analytical instrumentation which include, but are not limited to:   Gas Chromatograph-Mass Spectroscopy (GC-MS) Gas Chromatograph (GC) Systems Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) Ion-Chromatography (IC) High Pressure Liquid Chromatography (HPLC)
Applications of the developed procedure based on pyrolysis-gas chromatography (Py-GC) and principal component analysis (PCA) for the characterization of plastic bonded explosives (PBXs) are described. Due to difficulties with the commonly used normalization method a new normalization method was developed and applied in this investigation. The patterns in the score plots obtained after PCA of the Py-GC results appeared much clearer using this new method. PBX samples were examined on homogeneity, influence of the amount of antioxidant (Flexzone) and the crosslink density. It appears that PBXs were inhomogeneous despite a thorough mixing of the constituents during the preparation. Aging experiments were performed on samples which differed in the amount of Flexzone and in the crosslink density. As more Flexzone was added the change in the pattern of the GC-peaks became less. No relation could be found between the stability of PBXs and the crosslink density. Finally, a comparison was made between Dutch