Multiple et extraction SPME et simultanée pour maximiser le potentiel d'un échantillon

peer reviewe

Simultaneous Multiple SPME Fibers Sampling for Multi-instrument Approaches

In omics research setting, access to sample is usually a key factor of the experimental design. In this study, we evaluate simultaneous multiple SPME fibers sampling. Using three fibers simultaneously, we generated three technical replicates from one biological sample. Each fiber was then analyzed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) in separated runs. The robustness of the procedure was tested on a 24-standards mixture, human whole stool matrix, and human whole stool samples from the National Institute of Standards and Technology (NIST). In addition, we studied three fiber storage conditions: storage at room temperature and at -20°C in HeadSpace (HS) vials, and storage in NMR tubes at -20°C. For the storage condition, the RSD mean value based on the area of 18 of the 24 standards is 38.4 % for the storage of fibers at room temperature and 19.8 % for the storage at -20°C, both in HS vials. The best RSD value is 10.0 % and it was obtain using the NMR vial at -20°C. The cold temperature storage and the decrease of the vial volume allow decreasing the RSD mean value by a factor of two. The mean area values for two targeted fecal biomarkers on the PegasusTM BT 4D are 100 times higher than the PegasusTM 4D HRT. The former detects more than 11 times more compounds than the later. However, the high resolution of the PegasusTM 4D HRT system offers stronger mass accuracy and enable a more robust compound identification

Simultaneous multiple SPME fibers sampling

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Elucidating Environmental Fingerprinting Mechanisms of Unconventional Gas Development through Hydrocarbon Analysis

Hydraulic fracturing is an increasingly common technique for the extraction of natural gas entrapped in shale formations. This technique has been highly criticized due to the possibility of environmental contamination, underscoring the need for method development to identify chemical factors that could be utilized in point-source identification of environmental contamination events. Here, we utilize comprehensive two-dimensional gas chromatography (GC × GC) coupled to high-resolution time-of-flight (HRT) mass spectrometry, which offers a unique instrumental combination allowing for petroleomics hydrocarbon fingerprinting. Four flowback fluids from Marcellus shale gas wells in geographic proximity were analyzed for differentiating factors that could be exploited in environmental forensics investigations of shale gas impacts. Kendrick mass defect (KMD) plots of these flowback fluids illustrated well-to-well differences in heteroatomic substituted hydrocarbons, while GC × GC separations showed variance in cyclic hydrocarbons and polyaromatic hydrocarbons among the four wells. Additionally, generating plots that combine GC × GC separation with KMD established a novel data-rich visualization technique that further differentiated the samples

Enhancing untargeted metabolomics using metadata-based source annotation

Human untargeted metabolomics studies annotate only ~10% of molecular features. We introduce reference-data-driven analysis to match metabolomics tandem mass spectrometry (MS/MS) data against metadata-annotated source data as a pseudo-MS/MS reference library. Applying this approach to food source data, we show that it increases MS/MS spectral usage 5.1-fold over conventional structural MS/MS library matches and allows empirical assessment of dietary patterns from untargeted data