Query: gas chromatography

title: Diagnosis of COVID 19 by analysis of breath with gas chromatography ion mobility spectrometry a feasibility study
abstract: There is an urgent need to rapidly distinguish COVID 19 from other respiratory conditions, including influenza, at first presentation. Point of care tests not requiring laboratory support will speed diagnosis and protect health care staff. We studied the feasibility of using breath analysis to distinguish these conditions with near patient gas chromatography ion mobility spectrometry (GC IMS) Methods Independent observational prevalence studies at Edinburgh, UK, and Dortmund, Germany, recruited adult patients with possible COVID 19 at hospital presentation. Participants gave a single breath sample for VOC analysis by GC IMS. COVID 19 infection was identified by transcription polymerase chain reaction (RT qPCR) of oral/nasal swabs together with clinical review. Following correction for environmental contaminants, potential COVID 19 breath biomarkers were identified by multi variate analysis and comparison to GC IMS databases. A COVID 19 breath score based on the relative abundance of a panel of volatile organic compounds was proposed and tested against the cohort data.  Ninety eight patients were recruited, of whom 21/33 (63.6% and 10/65 (15.4% had COVID 19 in Edinburgh and Dortmund, respectively. Other diagnoses included asthma, COPD, bacterial pneumonia, and cardiac conditions. Multivariate analysis identified aldehydes (ethanal, octanal) ketones (acetone, butanone) and methanol that discriminated COVID 19 from other conditions. An unidentified feature with significant predictive power for severity/death was isolated in Edinburgh, while heptanal was identified in Dortmund. Differentiation of patients with definite diagnosis (25 and 65) of COVID 19 from non COVID 19 was possible with 80% and 81.5% accuracy in Edinburgh and Dortmund respectively (sensitivity/specificity 82.4%/75% area under the receiver operator characteristic [AUROC] 0.87 95% CI 0.67 to 1) and Dortmund (sensitivity specificity 90%/80% AUROC 0.91 95% CI 0.87 to 1) Interpretation These two studies independently indicate that patients with COVID 19 can be rapidly distinguished from patients with other conditions at first healthcare contact. The identity of the marker compounds is consistent with COVID 19 derangement of breath biochemistry by ketosis, gastrointestinal effects, and inflammatory processes. Development and validation of this approach may allow rapid diagnosis of COVID 19 in the coming endemic flu seasons. Funding MR was supported by an NHS Research Scotland Career Researcher Clinician award. DMR was supported by the University of Edinburgh ref COV_29.

title: Quantitative analysis of selected plastics in high commercial value Australian seafood by Pyrolysis Gas Chromatography Mass Spectrometry.
abstract: Microplastic contamination of the marine environment is widespread, but the extent to which the marine food web is contaminated is not yet known. The aims of this study were to go beyond visual identification techniques and develop and apply a simple seafood sample clean up, extraction and analysis method using Pyrolysis Gas Chromatography Mass Spectrometry to improve the detection of plastic contamination. The method allows the identification and quantification of polystyrene, polyethylene, polyvinyl chloride, polypropylene and poly (methyl methacrylate) in the edible portion of five different seafood organisms: oysters, prawns, squid, crabs and sardines. Polyvinyl chloride was detected in all samples and polyethylene at the highest total concentration of between 0.04 2.4 mg g 1 of tissue. Sardines contained the highest total plastic mass concentration (0.3 mg g 1 tissue) and squid the lowest (0.04 mg g 1 tissue) Our findings show that the total concentration of plastic is highly variable among species and that microplastic concentration differs between organisms of the same species. The sources of microplastic exposure, such as packaging and handling with consequent transference and adherence to the tissues are discussed. This method is a major development in the standardization of plastic quantification techniques in seafood.

title: Auto deconvolution and molecular networking of gas chromatography mass spectrometry data
abstract: We engineered a machine learning approach, MSHub, to enable auto deconvolution of gas chromatography mass spectrometry (GC MS) data. We then designed workflows to enable the community to store, process, share, annotate, compare and perform molecular networking of GC MS data within the Global Natural Product Social (GNPS) Molecular Networking analysis platform. MSHub/GNPS performs auto deconvolution of compound fragmentation patterns via unsupervised non negative matrix factorization and quantifies the reproducibility of fragmentation patterns across samples. A machine learning workflow enables auto deconvolution of gas chromatography mass spectrometry data.

title: Solid phase microextraction techniques used for gas chromatography: a review
abstract: In the last decade, the development and adoption of greener and sustainable microextraction techniques have been proved to be an effective alternative to classical sample preparation procedures. In.

title: Aromatic Characterization of Mangoes (Mangifera indica L. Using Solid Phase Extraction Coupled with Gas Chromatography Mass Spectrometry and Olfactometry and Sensory Analyses
abstract: Mangoes (Mangifera indica L. are wildly cultivated in China with different commercial varieties; however, characterization of their aromatic profiles is limited. To better understand the aromatic compounds in different mango fruits, the characteristic aromatic components of five Chinese mango varieties were investigated using headspace solid phase microextraction (HS SPME) coupled with gas chromatography mass spectrometry gas chromatography olfactometry (GC MS O) techniques. Five major types of substances, including alcohols, terpenes, esters, aldehydes, and ketones were detected. GC O (frequency detection (FD)/order specific magnitude estimation (OSME) analysis identified 23, 20, 20, 24, and 24 kinds of aromatic components in Jinmang, Qingmang, Guifei, Hongyu, and Tainong, respectively. Moreover, 11, 9, 9, 8, and 17 substances with odor activity values (OAVs) =1 were observed in Jinmang, Qingmang, Guifei, Hongyu, and Tainong, respectively. Further sensory analysis revealed that the OAV and GC O (FD/OSME) methods were coincided with the main sensory aromatic profiles (fruit, sweet, flower, and rosin aromas) of the five mango pulps. Approximately 29 (FD 6, OSME 2, OAV 1) aroma active compounds were identified in the pulps of five mango varieties, namely, g terpinene, 1 hexanol, hexanal, terpinolene trans 2 heptenal, and p cymene, which were responsible for their special flavor. Aldehydes and terpenes play a vital role in the special flavor of mango, and those in Tainong were significantly higher than in the other four varieties.

title: Gas chromatography mass spectrometry analysis, phytochemical screening and antiprotozoal effects of the methanolic Viola tricolor and acetonic Laurus nobilis extracts
abstract: 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 mg/mL, and 86.6 8.2, 33.3 5.1, 62.2 3.3, 34.5 7.5 and 82.2 9.3 mg/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) of 930 29.9, 1260 18.9 mg/mL, and 573.7 12.4, 831 19.9 mg/mL, respectively, while human foreskin fibroblasts (HFF) cell viability was not influenced even at 1500 mg/mL. The in vivo experiment revealed that the oral administration of MEVT and AELN prohibited B. microti multiplication in mice by 35.1 and 56.1% respectively. These analyses indicate the prospects of MEVT and AELN as good candidates for isolating new anti protozoal compounds which could assist in the development of new drug molecules with new drug targets.

title: Comparison of pyrolysis gas chromatography/mass spectrometry and hyperspectral FTIR imaging spectroscopy for the analysis of microplastics
abstract: Analysis of microplastics (MP) in environmental samples is an emerging field, which is performed with various methods and instruments based either on spectroscopy or thermoanalytical methods. In general, both approaches result in two different types of data sets that are either mass or particle number related. Depending on detection limits of the respective method and instrumentation the derived polymer composition trends may vary. In this study, we compare the results of hyperspectral Fourier transform infrared (FTIR) imaging analysis and pyrolysis gas chromatography mass spectrometry (Py GC/MS) analysis performed on a set of environmental samples that differ in complexity and degree of microplastic contamination. The measurements were conducted consecutively, and on exactly the same sample. First, the samples were investigated with FTIR using aluminum oxide filters; subsequently, these were crushed, transferred to glass fiber filters, in pyrolysis cups, and measured via Py GC/MS. After a general data harmonization step, the trends in MP contamination were thoroughly investigated with regard to the respective sample set and the derived polymer compositions. While the overall trends in MP contamination were very similar, differences were observed in the polymer compositions. Furthermore, polymer masses were empirically calculated from FTIR data and compared with the Py GC/MS results. Here, a most plausible shape related overestimation of the calculated polymer masses was observed in samples with larger particles and increased particle numbers. Taking into account the different measurement principles of both methods, all results were examined and discussed, and future needs for harmonization of intermethodological results were identified and highlighted.

title: Climate and Processing Effects on Tea (Camellia sinensis L. Kuntze) Metabolome: Accurate Profiling and Fingerprinting by Comprehensive Two Dimensional Gas Chromatography/Time of Flight Mass Spectrometry
abstract: This study applied an untargeted targeted (UT) fingerprinting approach, based on comprehensive two dimensional gas chromatography time of flight mass spectrometry (GCxGC TOF MS) to assess the effects of rainfall and temperature (both seasonal and elevational) on the tea metabolome. By this strategy, the same compound found in multiple samples need only to be identified once, since chromatograms and mass spectral features are aligned in the data analysis process. Primary and specialized metabolites of leaves from two Chinese provinces, Yunnan (pu'erh) and Fujian (oolong) and a farm in South Carolina (USA, black tea) were studied. UT fingerprinting provided insight into plant metabolism activation/inhibition, taste and trigeminal sensations, and antioxidant properties, not easily attained by other analytical approaches. For example, pu'erh and oolong contained higher relative amounts of amino acids, organic acids, and sugars. Conversely, black tea contained less of all targeted compounds except fructose and glucose, which were more similar to oolong tea. Findings revealed compounds statistically different between spring (pre monsoon) and summer (monsoon) in pu'erh and oolong teas as well as compounds that exhibited the greatest variability due to seasonal and elevational differences. The UT fingerprinting approach offered unique insights into how differences in growing conditions and commercial processing affect the nutritional benefits and sensory characteristics of tea beverages.

title: Selective C2H2 detection with high sensitivity using SnO2 nanorod based gas sensors integrated with a gas chromatography
abstract: We report on the sensitive and selective sensing properties of SnO2 nanorods (NRs) based gas sensors coupled with a miniature gas chromatography (mini GC) system for the detection of acetylene. The SnO2 NRs were fabricated by a glancing angle deposition (GLAD) method and their average height and diameter were ~200 nm and ~30 nm, respectively. In order to overcome a selectivity issue of metal oxide semiconductor gas sensors, we integrated our SnO2 NRs based sensors with a packed column. The device accurately and selectively detected acetylene within 2 min ~120 s) We found that loading a thin layer (5 nm) of metal catalysts such as Au, Pt or Pd increases the sensing abilities of the SnO2 NRs sensors. Among the tested sensors, the Pd coated SnO2 NRs sensor (Pd SnO2 NRs) exhibited the best sensing performance for the detection of 10 ppm of acetylene and the lower detection limit of 0.01 ppm. The superior sensing properties of Pd SnO2 NRs are due to the large amount of oxygen deficiencies on the surface of Pd SnO2 NRs, which acts as reactive sites. More importantly, the mini GC device can be used to selectively detect 10 ppm of acetylene from other gases such as H2. Our findings demonstrate that Pd SnO2 NRs integrated with a mini GC device can be utilized to monitor the dissolved acetylene gas in transformer oil in real time.

title: Discrimination of Adzuki Bean (Vigna angularis) Geographical Origin by Targeted and Non Targeted Metabolite Profiling with Gas Chromatography Time of Flight Mass Spectrometry
abstract: As international food trade increases, consumers are becoming increasingly interested in food safety and authenticity, which are linked to geographical origin. Adzuki beans (Vigna angularis) are cultivated worldwide, but there are no tools for accurately discriminating their geographical origin. Thus, our study aims to develop a method for discriminating the geographical origin of adzuki beans through targeted and non targeted metabolite profiling with gas chromatography time of flight mass spectrometry combined with multivariate analysis. Orthogonal partial least squares discriminant analysis showed clear discrimination between adzuki beans cultivated in Korea and China. Non targeted metabolite profiling showed better separation than targeted profiling. Furthermore, citric acid and malic acid were the most notable metabolites for discriminating adzuki beans cultivated in Korea and China. The geographical discrimination method combining non targeted metabolite profiling and pareto scaling showed excellent predictability (Q2 0.812) Therefore, it is a suitable prediction tool for the discrimination of geographical origin and is expected to be applicable to the geographical authentication of adzuki beans.