Gas Chromatography-mass Spectrometry Technology Research Articles

Development and Applications of Portable Gas Chromatography-Mass Spectrometry for Emergency Responders, the Military, and Law-Enforcement Organizations.

Portable gas chromatography-mass spectrometry (GC-MS) systems are being deployed for field use, and are designed with this goal in mind. Performance characteristics of instruments that are successful in the field are different from those of equivalent technologies that are successful in a laboratory setting. These field-portable systems are extending the capabilities of the field user, providing investigative leads and confirmatory identifications in real time. Many different types of users benefit from the availability of this technology including emergency responders, the military, and law-enforcement organizations. This manuscript describes performance characteristics that are important for field-portable instruments, especially field-portable GC-MS systems, and demonstrates the value of this equipment to the disciplines of explosives investigations, fire investigations, and counterfeit-drug detection. This paper describes the current state of portable GC-MS technology, including a review of the development of portable GC-MS, as well as a demonstration of the value of this capability using different examples.

Integrated intracellular metabolic profiling and pathway analysis approaches reveal complex metabolic regulation by Clostridium acetobutylicum.

BackgroundClostridium acetobutylicum is one of the most important butanol producing strains. However, environmental stress in the fermentation process usually leads to a lower yield, seriously hampering its industrialization. In order to systematically investigate the key intracellular metabolites that influence the strain growth and butanol production, and find out the critical regulation nodes, an integrated analysis approach has been carried out in this study. ResultsBased on the gas chromatography-mass spectrometry technology, the partial least square discriminant analysis and the pathway analysis, 40 metabolic pathways linked with 43 key metabolic nodes were identified. In-depth analysis showed that lots of amino acids metabolism promoted cell growth but exerted slight influence on butanol production, while sugar metabolism was favorable for cell growth but unfavorable for butanol synthesis. Besides, both lysine and succinic acid metabolism generated a complex effect on the whole metabolic network. Dicarboxylate metabolism exerted an indispensable role on cell growth and butanol production. Subsequently, rational feeding strategies were proposed to verify these conclusions and facilitate the butanol biosynthesis. Feeding amino acids, especially glycine and serine, could obviously improve cell growth while yeast extract, citric acid and ethylene glycol could significantly enhance both growth and butanol production.ConclusionsThe feeding experiment confirmed that metabolic profiling combined with pathway analysis provided an accurate, reasonable and practical approach to explore the cellular metabolic activity and supplied a basis for improving butanol production. These strategies can also be extended for the production of other important bio-chemical compounds.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0436-4) contains supplementary material, which is available to authorized users.

Metabolic Profiling and Physiological Analysis of a Novel Rice Introgression Line with Broad Leaf Size.

A rice introgression line, NIL-SS1, and its recurrent parent, Teqing, were used to investigate the influence of the introgression segment on plant growth. The current research showed NIL-SS1 had an increased flag leaf width, total leaf area, spikelet number per panicle and grain yield, but a decreased photosynthetic rate. The metabolite differences in NIL-SS1 and Teqing at different developmental stages were assessed using gas chromatography—mass spectrometry technology. Significant metabolite differences were observed across the different stages. NIL-SS1 increased the plant leaf nitrogen content, and the greatest differences between NIL-SS1 and Teqing occurred at the booting stage. Compared to Teqing, the metabolic phenotype of NIL-SS1 at the booting stage has closer association with those at the flowering stage. The introgression segment induced more active competition for sugars and organic acids (OAs) from leaves to the growing young spikes, which resulted in more spikelet number per plant (SNP). The results indicated the introgression segment could improve rice grain yield by increasing the SNP and total leaf area per plant, which resulted from the higher plant nitrogen content across growth stages and stronger competition for sugars and OAs of young spikes at the booting stage.

AMPK Activation Affects Glutamate Metabolism in Astrocytes

Mammalian AMP-activated protein kinase (AMPK) functions as a metabolic switch. It is composed of 3 different subunits and its activation depends on phosphorylation of a threonine residue (Thr172) in the α-subunit. This phosphorylation can be brought about by 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) which in the cells is converted to a monophosphorylated nucleotide mimicking the effect of AMP. We show that the preparation of cultured astrocytes used for metabolic studies expresses AMPK, which could be phosphorylated by exposure of the cells to AICAR. The effect of AMPK activation on glutamate metabolism in astrocytes was studied using primary cultures of these cells from mouse cerebral cortex during incubation in media containing 2.5mM glucose and 100µM [U-(13)C]glutamate. The metabolism of glutamate including a detailed analysis of its metabolic pathways involving the tricarboxylic acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon skeleton into the TCA cycle was reduced. On the other hand, glutamate uptake into the astrocytes as well as its conversion to glutamine catalyzed by glutamine synthetase was not affected by AMPK activation. Interestingly, synthesis and release of citrate, which are hallmarks of astrocytic function, were affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK activation. Accordingly, the effects of AMPK activation appeared to be specific for certain key processes involved in glutamate metabolism.

Quantitative Approach to Melamine Detection in Egg White with Surface-Enhanced Raman Spectroscopy

Due to the harmfulness of melamine to human, the quantitative detection of melamine in egg is very necessary. In the present study, the surface enhanced Raman spectra technology combined with chemometric analysis method was used to conduct melamine quantitative detection in egg white. Firstly, the melamine egg sample could be got by the method of artificial feeding hens usingdifferent feeding formulation. Then the surface enhanced Raman spectra of egg white was determined using portable Raman spectroscopy (Opto Trace RamTracer-200) and Raman enhancement reagents, and the melamine content within the white eggs was measured with gas chromatography mass spectrometry technology. The software of Raman Analyzer was used for baseline correction of Raman spectra. The correlation coefficient method was used to choose 320 spectral variables from the surface enhanced Raman spectroscopy as input variables to establish partial least squares quantitative calibration model . And the peaks-decomposition method was used to establish peaks-decomposition quantitative calibration model. Both models selected 90 and 44 samples respectively as calibration sets and validation sets during model establishment, and both models achieved good prediction effect. The determination coefficient between predicted values of partial least squares quantitative calibration model and measured values of gas chromatography mass spectrometry was 0.856, and root mean square error of prediction was 1.547. The determination coefficient was 0.947 and RMSEP was 0.893 for the peaks-decomposition quantitative calibration model. This study demonstrated that the method can effectively quantitatively detect melamine in eggs. Testing a sample only takes 15 minutes, which can provide a new way for the melamine egg detection.

Urinary metabonomics research based on mass spectrometry in preterm and term infants

Objective Using gas chromatography-mass spectrometry and metabonomics technique to analyze the difference of urinary metabolites in preterm and term infants, looking for specific biomarkers in the urine of preterm infants. Methods Urine liquid specimens of 30 preterm infants and 20 term children were collected from the sixth Affiliated Hospital of Sun Yat-sen University, using gas chromatography-mass spectrometry technology to determine glucose, lactose, lactic acid, glycerol, palmitic acid, stearic acid, valsartan ammonia acid, light ammonia acid, different light ammonia acid, Gan ammonia acid, c ammonia acid, su ammonia acid, Arab sugar alcohol, wood sugar, and acetyl aspartate ammonia acid and other urine metabolism product content, and using main components analysis(PCA) and partial minimum II discriminant analysis(PLS) to look for differences and biomarkers between the 2 groups. Results 1.There was significant difference between preterm infants urine metabolism product and term children, using PCA and PLA discriminant analysis on the 2 groups for discrimination; 2.Main components analysis detected preterm infants and term children of special heterosexual metabolism product(biological signs property) for stearic acid, and lactic acid; 3.Preterm infants and term children were significantly different in metabolic pathways of major metabolites of amino acids(valsartan ammonia acid, light ammonia acid, different light ammonia acid, Su ammonia acid, c ammonia acid and Gan ammonia acid), and fat(glycerol, palmitic acid, and stearic acid) and sugar(lactose, and lactic acid). Conclusions Metabolite has an obvious difference in preterm and term infants, and determination of urine metabolites by gas chromatography-mass spectrometry with metabonomics analysis can be used as important tools to evaluate neonatal metabolic conditions, and is of importance in correcting metabolic disorders in premature infants, and supplying reasonable nutrient substance. Key words: Gas chromatography-mass spectrometry; Preterm infants; Metabonomics; Metabolites

Study on Pit Mud Lixivium from Different Years Pits by Gas Chromatography Mass Spectrometry

This thesis analyzed pit mud lixivium of 20 years, 100 years, 200 years, and 300 years pit age by gas chromatography-mass spectrometry technology. Through analyzing experimental results, 20 kinds of substances were obtained, and 10 kinds of substances were mutual in all pit mud samples. After carefully analyzing many substances in every pit age, the conclusion was obtained that the longer the pit mud had been stored, the more substances it had, the more complicated components were in pit mud, the higher metabolize diversity microorganism had, and the better quality the liquor had.

Researching the Influence of Repeated Using to the Migration of Residue Bisphenol a from Polycarbonate with GC-MS Technology

Content of residue bisphenol A from polycarbonate (PC) was measured used the technology of gas chromatography-mass spectrometry (GC-MS). Dichloromethane was used as solvent and methanol was used as precipitating agent. The solution was rotary evaporation after the polymer was filtered. The simple, rapid, sensitive and accurate method of external standard which linear range is 0.05-200.0mg/L, standard addition recoveries is 90.8% ~94.2% and RSD is 3.2% -4.5% was used to quantitative analysis. The influence of repeated using to the migration of bisphenol A was also studied in this experiment. The results show that with the reusing times increased, the migration content of bisphenol A was gradually reduced which reduced to 0.75mg/L at the sixth time from 2.4mg/L at the first time.

A global proteome study of Mycobacterium gilvum PYR-GCK grown on pyrene and glucose reveals the activation of glyoxylate, shikimate and gluconeogenetic pathways through the central carbon metabolism highway

Various hydrocarbons have been released into the environment as a result of industrialization. An effective way of removing these materials without further environmental contamination is microbial bioremediation. Mycobacterium gilvum PYR-GCK, a bacteria isolated from a PAH polluted estuary, was studied using comparative shotgun proteomics to gain insight on its molecular activity while using pyrene and glucose as sole carbon and energy sources. Based on annotated genomic information, a confirmation analysis was first performed to confirm its pyrene degradation activity, using gas chromatography-mass spectrometry technology. One dimensional gel electrophoresis and liquid chromatography-mass spectrometry technologies employed in the proteomics analysis revealed the expression of pyrene degrading gene products along with upregulated expression of proteins functioning in the glyoxylate and shikimate pathways, in the pyrene-induced cells. The study also revealed the pathway of pyrene degraded intermediates, via partial gluconeogenesis, into the pentose phosphate pathway to produce precursors for nucleotides and amino acids biosynthesis.

Using Gas Chromatography-Mass Spectrometry to Analysis Distribution of Gasoline Compositions

The using of Gas Chromatography-Mass Spectrometry (GC-MS) to the analysis of gasoline components is studied in this article. The results show that sample of fresh gasoline contains 27 kinds of compositions, Groups of characteristic compounds and distribution of components were clearly observed in the gasoline. As a result, Applying GC-MS technology to analysis distribution of gasoline compositions was practicable.

A Material Prediction Approach for Improving Indoor Air Quality

RATIONALE: Volatile Organic Compounds (VOCs) are known to increase acute asthmatic events. The prediction of their source will provide a process for improving home air quality.METHODS: Diagnostic tests to determine home VOCs levels have been nonexistent or expensive and difficult to deploy. Technological advances now allow for low cost VOC monitoring, VOC source prediction and hidden mold detection (MVOCs) in a home with a single test. This thermal desorption tube gas chromatography-mass spectrometry technology followed by a multivariate prediction has the ability to determine VOC levels and then provide the information necessary to reduce these levels and potentially reduce chemically induced asthmatic episodes.RESULTS: The median Total VOC (TVOC) level in homes tested with this new air testing technology is 1,200 ng/L. The U.S. Green Building Council (USGBC) recommends that homes are below 500 ng/L. Only 17.5% of homes tested with this technology have been below this level, with some well above 10,000 ng/L. While at home, one asthmatic client was having daily asthma exacerbations. His home TVOC level was determined to be 1,800 ng/L, not an extreme level. The report predicted the VOC source correctly (kerosene), the source was removed and the TVOC level on subsequent testing was reduced to 800 ng/L. His acute asthma episodes decreased from daily to weekly.CONCLUSION: Low cost home air testing technologies that can predict chemical sources could assist physicians and patients in developing a simple plan to improve their air quality and potentially improve their quality of life. RATIONALE: Volatile Organic Compounds (VOCs) are known to increase acute asthmatic events. The prediction of their source will provide a process for improving home air quality. METHODS: Diagnostic tests to determine home VOCs levels have been nonexistent or expensive and difficult to deploy. Technological advances now allow for low cost VOC monitoring, VOC source prediction and hidden mold detection (MVOCs) in a home with a single test. This thermal desorption tube gas chromatography-mass spectrometry technology followed by a multivariate prediction has the ability to determine VOC levels and then provide the information necessary to reduce these levels and potentially reduce chemically induced asthmatic episodes. RESULTS: The median Total VOC (TVOC) level in homes tested with this new air testing technology is 1,200 ng/L. The U.S. Green Building Council (USGBC) recommends that homes are below 500 ng/L. Only 17.5% of homes tested with this technology have been below this level, with some well above 10,000 ng/L. While at home, one asthmatic client was having daily asthma exacerbations. His home TVOC level was determined to be 1,800 ng/L, not an extreme level. The report predicted the VOC source correctly (kerosene), the source was removed and the TVOC level on subsequent testing was reduced to 800 ng/L. His acute asthma episodes decreased from daily to weekly. CONCLUSION: Low cost home air testing technologies that can predict chemical sources could assist physicians and patients in developing a simple plan to improve their air quality and potentially improve their quality of life.

Current challenges and developments in GC–MS based metabolite profiling technology

Gas chromatography-mass spectrometry (GC-MS) based metabolite profiling of biological samples is one of the key technologies for metabolite profiling and substantially contributes to our understanding of the metabolome. While the technology is in increasing use it is challenged with novel demands. Increasing the number of metabolite identifications within existing profiling platforms is prerequisite for a substantially improved scope of profiling studies. Clear, reproducible strategies for metabolite identification and exchange of identifications between laboratories will facilitate further developments, such as the extension of profiling technologies towards metabolic signals and other technically demanding trace compound analysis. Using GC-MS technology as an example the concept of mass spectral tags (MSTs) is presented. A mass spectral tag is defined by the chemometric properties, molecular mass to charge ratio, chromatographic retention index and an induced mass fragmentation pattern such as an electron impact mass spectrum (EI-MS) or secondary fragmentation (MS(2)). These properties if properly documented will allow identification of hitherto non-identified MSTs by standard addition experiments of authenticated reference substances even years after first MST description. Strategies are discussed for MST identification and enhanced MST characterization utilizing experimental schemes such as in vivo stable isotope labelling of whole organisms and open access information distribution, for example the GMG internet platform initiated in 2004 (GMD, http://www.csbdb.mpimp-golm.mpg.de/gmd.html).

Simultaneous analysis of amino and nonamino organic acids as methyl chloroformate derivatives using gas chromatography–mass spectrometry

There are numerous amino and nonamino organic acids that are intermediates in cellular metabolism. In the study of metabolic pathways, information about the concentration of these metabolites inside the cells is of crucial interest. Furthermore, many microorganisms overproduce a variety of amino and organic acids and secrete them to the extracellular medium, and this is explored for the production of many different chemicals in the biotechnology industry [1,2]. Several chromatographic methods, including liquid chromatography (LC), gas chromatography (GC), and gas chromatography–mass spectrometry (GC-MS), have been employed to analyze metabolites levels in biological samples [3–5, and others]. Few methods, however, enable simultaneous analysis of amino and nonamino organic acids in a single run [6,7], and to our knowledge none of these achieves analysis of a large number of diand tricarboxylic acids such as intermediates from the trichloroacetic acid cycle. GC-MS technology allows simultaneous detection of different classes of metabolites within a single analysis [8]. The determination of amino and nonamino organic acids by GC-MS methods requires the conversion of these compounds to volatile derivatives. The most popular derivatization approach is based on silylation of organic compounds, which are converted to their alkyl–silyl derivatives (i.e., by reacting with hexamethyldisilazane and obtaining trimethylsilyl derivatives) [3,7,9,10, and others]. Some disadvantages with this derivatization technique are silylation under anhydrous conditions, heating of the sample for a given period,

Radiogas chromatography mass spectrometry in the selected ion monitoring mode.

The value of selected ion monitoring in analyzing biological radio isotope incorporation experiments by radiogas chromatography mass spectrometry is illustrated with reference to the biosynthesis of the mycotoxin mycophenolic acid and the mode of action of the anticholesterolemic drug 20,25-diazacholesterol. It is shown that the increased sensitivity and specificity of the selected ion monitoring mode detector permits straightforward detection and identification of the relatively small cellular pools associated with metabolic intermediates. The computer program RADSIM is described. Problems that still exist in using radiogas gas chromatography mass spectrometry technology to analyse isotope incorporation experiments are discussed.