Development of thin-layer chromatography for selective analysis of volatile compounds using gas chromatography mass spectrometry

Abstract

In this study, simple and selective solid phase extraction approach for a range of volatile compounds in perfume was developed prior to analysis with headspace solid phase micro extraction (HS-SPME) and gas chromatography hyphenated with mass spectrometry (GC-MS). The technique relies on use of thin layer chromatography (TLC) for separation of compound along the silica gel plate followed by selective cuts of the regions of interest, desorption, HS-SPME and GC-MS analysis. The TLC separation of standard compounds using hexane and ethyl acetate (6:1 volume ratio) as the mobile phase was initially performed. The compounds was then desorbed from the TLC plate and extracted with SPME at 80 °C for 15 min resulting in insignificant bleeding signals (siloxane derivatives) of the plate with good linearity of the calibration curves (R2>0.98) and acceptable recovery range (65-81 %) of the volatiles after the TLC separation. The selectivity of this approach was demonstrated by cutting the plate after separation into 4 or 7 smaller parts. The SPME/GC-MS analysis of each part revealed different compound profile and the correlation between log P vs the position along the TLC plate of the standard compounds (R2=0.65). The developed 4-piece TLC based approach was further applied to analyze the perfume spiked into the synthetic agarwood sample with the strong matrix interference. Whilst, the SPME/GC-MS analysis of this sample solution revealed only 62 identified compounds (with 35 compounds from the perfume), the 4-piece approach could identify 109 compounds (including 62 perfume compounds). 15 compounds were not recovered from the TLC approach. In addition, the capability to analyze 2-phenylethanol in this complex sample was demonstrated by using the developed TLC approach. The established techniques allow simple and selective sample preparation for improved volatile compound analysis