Optimization and validation for identification of volatile organic com-pounds released from Trogoderma variabile Ballion using headspace solid-phase microextraction and GC-FID/MS

Volatile organic compounds (VOC) emitted by Trogoderma variabile at different life stages (larvae, female and male) can help us to understand the chemical signals that are released by the beetle which can serve as biomarkers for diagnostic purpose. There are several factors that effect on the optimization of VOC extraction including, temperature, jar size, number of insects, duration of extraction, and gas chromatography (GC) conditions. This study used headspace solid phase microextraction (HS-SPME) fibre coupled with flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) to determine the optimal method for accurate, rapid and cost-effective extraction and identification of VOC from different life stages of T. variabile. The HS-SPME technique and the analytical conditions with GC and GCMS were optimized and validated for the determination of VOCs released from T. variabile. Selection of the number of insects was based on the height and the number of peaks. Results showed that 15 and 20 larvae and adults respectively gave the best number of peaks. Sixteen hours were optimized as the best extraction time for larvae and adults to get maximum number of emitted VOCs. The number of compound released from T.variabile different stages was 7, 9 and 11 for male, female and larvae respectively. Furthermore, some compounds were identified in all stages such as oxime-, methoxy-phenyl, 2(3H)-furanone, 5-ethyldihydro- and nonanal. Also, most of the compounds were significantly different in peak area between different life stages.