FGC-E-Nose and HS-SPME/GC–MS Comparative Analysis of Headspace Volatiles: Hibiscus Leaves Application

This study addresses the reliability of dual-flash gas chromatography electronic nose (FGC-E-Nose) technology for the analysis of volatile organic compounds (VOCs) in conjunction with headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC–MS). The edible leaves of Hibiscus cannabinus L.,Hibiscus radiatus Cav., and Hibiscus sabdariffa L., at 60 days after sowing (DAS), were analyzed for VOCs in fresh and shade-dried leaves. (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, 1-hexanol, hexanal, heptanal, 6-methylhept-5-en-2-one, and Benzeneacetaldehyde were the major VOCs detected by both methods. The Bland–Altman analysis demonstrated good agreement between the FGC-E-Nose and HS-SPME/GC–MS methods, indicating that the FGC-E-Nose is a reliable tool for detecting targeted VOCs. To the best of our knowledge, this is the first study to directly correlate semiquantitative FGC-E-Nose results with confirmatory HS-SPME/GC–MS analysis. The FGC-E-nose showed greater discriminatory capability, detecting significant differences (p < 0.05) in 6 volatile compounds compared with only 1 compound identified by HS-SPME/GC–MS among the 11 matching VOCs. Benzeneacetaldehyde was the predominant compound in both methods, ranging from 6.85–9.47 μg/g in HS-SPME/GC–MS and 3.92–4.16 μg/g in FGC-E-nose analysis, followed by nonanal, 6-methyl-hept-5-en-2-one, and heptanal as major volatiles. Chemometric analyses, such as PCA (>92% variance) and PLS-DA (p < 0.001), revealed significant differences between species and between leaf conditions (fresh vs dried), and both methods explained these differences. The FGC-E-Nose shows strong potential for rapid detection of volatiles, complementing HS-SPME/GC–MS.