Abstract: A rapid method was developed for the determination of 5 common ethyl esters, ethyl acetate, ethyl butyrate, ethyl lactate, ethyl valerate and ethyl caproate, in liquor without any sample pretreatment using on-line mass spectrometry. Reasonable linearity was achieved for all the analytes over the range of 0.5–20 mg/L with correlation coefficients (R2) greater than 0.99. The recoveries for five ethyl esters at two spiked levels were in the range from 81.1% to 99.7% with relative standard deviations (RSDs) of 4.7%-9.4%. The limits of detection (LODs) of the method ranged from 24 to 312 μg/L. Under optimized conditions, four kinds of distilled spirits marketed in China were analyzed, such as Chinese liquor, brandy, Dry Gin and whiskies. The main ester components and their contents in the same kind of distilled spirit were basically the same while ethyl esters were determined at different levels in Chinese liquor, brandy and whiskies. Meanwhile, the four kinds of distilled spirits could be distinguished accurately using principal component analysis.

Key words: on-line mass spectrometry, time-of-flight mass spectrometry, liquor, distilled spirits, ethyl ester, principle component analysis