Sulfur-containing compounds (VSCs) are a very important class of aroma compounds in alcoholic beverages, including Chinese baijiu. Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-pulsed flame photometric detection (GC-PFPD) or chemiluminescence detection (GC-SCD) is a used approach in the quantitation of VSCs due to its high selectivity and sensitivity. However, the competitive adsorption of volatile compounds on the SPME fiber is an unavoidable drawback. The volatile composition varies widely in different styles of baijiu, but the effects of volatile matrix on the analytical accuracy of VSC in baijiu has never been reported. This study investigated the analytical error of 18 VSCs in Chinese baijiu, using six internal standards commonly used in literature. The quantitation errors of VSCs were evaluated both on CAR/PDMS and DVB/CAR/PDMS fibers under different concentrations of the major volatile compounds in Chinese baijiu. The results showed that ethyl hexanoate and ethyl butanoate had the most influential impact on the quantification of VSCs in Chinese baijiu. It was essential to match the right internal standard-VSC pair to improve the quantification accuracy. In addition, it was found that baijiu's aroma types (strong, light, and soy sauce aroma) affected quantification accuracy regardless of the internal standard used for analysis. The larger the difference in the matrix composition, the more significant the quantitative deviation would be. The study proposed a new approach of employing an internal standard system and corresponding matrix for the quantification of VSCs in baijiu using HS-SPME-GC-SCD to achieve acceptable accuracy. This new approach could be adopted by the industry for quality control and new product development across different aroma types of baijiu and brands.

Quantitative errors and analytical method improvement of volatile sulfur-containing compounds in Chinese Baijiu

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