Fig 1: Scheme of the experiment. Blood plasma samples were uniformly prepared: we extracted low molecular weight compounds, then dried (I), methoxylated, and derivatized (II) the extracts. Our experiment implied three options for sample storage conditions before injection into the GCxGC-MS system (III): immediate loading or storage for 24 h (at ambient temperature and in a refrigerator at +4 °C). We washed the injection system with pyridine or methanol to evaluate the effect of the solvent used for syringe wash on the final signal on the chromatogram (IV) between injections. At the same stage (IV), we tested two schemes of sample loading into the chromatograph: we injected the sample from the same vial three times or used three intact vials. The resulting GCxGC-MS data were processed in a unified manner using the LECO ChromaTOF (V) software (v. 5.51) and statistically processed to develop final recommendations for sample storage and injection.