Fecha de publicación: -- Fuente: PubMed "essential oil" J Chromatogr A. 2026 Sep 25;1788:467496. doi: 10.1016/j.chroma.2026.467496. Online ahead of print.ABSTRACTAnalysis conditions commonly employed in gas chromatography (GC) using splitless injection methods often result in distorted or split peak shapes especially for early elution of very volatile organic compounds (VVOCs; B.P. < 50-100 °C), as they are not fully trapped or focussed at the head of the capillary column. Conversely, volatile organic compounds (VOCs; 50-100 °C to 240-260 °C) may produce sharp peaks for exactly the same introduction procedure. Consequently, these distorted peak shapes, poorer detection limits, and co-elutions with other solutes are frequently observed, which can lead to inaccurate identification and quantification of sample components. This study aimed to evaluate pulsed splitless injection combined with solid phase micro-extraction (SPME) and liquefied CO2 cryogenic focusing for the analysis of VVOCs and VOCs by GC-MS. Flowers of Swartzia simplex and Lavender (Lavandula angustifolia) essential oil, primarily composed of VVOCs and VOCs, respectively, were extracted by SPME and analysed by GC-MS under different pressure pulses (7-55 psi), with and without cryogenic focusing. In both samples, a two-fold increase in the number of peaks were observed when the cryogenic system was activated, and this was due to sharper (narrower), better resolved peaks. Furthermore, the sum of absolute peak areas for the flower samples was 10.75 times higher than that obtained via conventional injection (i.e., without pressure pulsing and cryogenic focusing) and 1.7 times higher for the Lavender oil. The results indicated that higher sample transfer rates were achieved with increasing injection pulsed-pressure operation, though this trend reversed at very high pressures; the opposite behaviour was observed for the system without cryogenic focusing. Finally, pulsed injection coupled with cryogenic trapping provided an enhanced method for SPME-GC-MS analysis of VOCs, ensuring greater sample transfer to the capillary column arising from fully trapped peaks, improved symmetry, and higher signal-to-noise ratios. This translates to superior mass spectrum quality. This approach also yielded chromatograms with increased peak capacity and resolution, enabling more accurate qualitative and quantitative analysis.PMID:42815110 | DOI:10.1016/j.chroma.2026.467496