Trace 1310 gas chromatography

A Thermo Scientific TRACE 1310 Gas Chromatography coupled with TSQ 8000 Evo Triple Quadrupole Detector and AI 1310 Auto Sampler was used with Thermo Xcalibur 2.2 mass spectrometry data system (Software). For the chromatographic separation, a Thermo Scientific™ Trace GOLD™ TG-5SilMS 30 m × 0.25 mm I.D. × 0.25 µm film capillary column was used. The flow rate was maintained at constant flow 1.2 mL/min (He, inert carrier gas). The GC oven program was initially set at 70 °C (2 min), then increased 25 °C/min to 180 °C, 5 °C/min to 200 °C, and 10 °C/min to 280 °C, kept constant 5 min. The MS was operated with electrospray ionization (ESI+). The optimized parameters included transfer line (280 °C), electron energy(eV) 70, acquisition mode (SRM), and ion source temperature (320 °C). The Thermo ScientificTM TraceFinderTM software was used for method setup and data processing. For all pesticide compounds two SRM transitions were chosen for the overall MRM acquisition method. The first transition was used for quantitation, the second transition for confirmation. Table 5 and Figure 9, lists the SRM parameters for the compounds analyzed in this method.

50 µL serum specimen was blended in 200 µL methyl alcohol involving 1,2-¹³C-myristic acid and afterwards vortexed and centrifuged. Then 100 µL of supernatant was moved to another tube and subjected to evaporation. Samples were reconstituted in 30 µL of 10 mg/ml methoxyamine pyridine and oscillated for 1.5 h with the speed of 300 rpm at 30°C. 30 µL of BSTFA was supplemented and oscillated for 0.5 h at 37°C. After derivation and centrifugation, 50 µL of supernate was prepared for GC-MS analyses. Metabonomic analyses were conducted via Trace 1,310 gas chromatography and TSQ 8000 triple-quadrupole mass spectrometry detector (Thermo Fisher Scientific, USA) under the same conditions described before (Zhang H. R. et al., 2019 (link)). NIST Database (https://www.nist.gov/) and MS-DIAL (v.4.10) software were used to convert format, process and analyze data. The significantly differential metabolites were identified based on the threshold of fold change (FC) > 1.2 (or <0.83) and p < 0.05. The quantity of selected metabolites in each of these two groups was reflected via a venn graph. In addition, partial least squares discriminant analysis (PLS-DA) and enrichment analyses were conducted in MetaboAnalyst5.0 (http://www.metaboanalyst.ca/).