Determination of 4 Chloropropanols in Liquid Condiments by Gas Chromatography-Tandem Mass Spectrometry with Dispersive Solid Phase Extraction

A method for the determination of chloropropanols including 3-chloro-1,2-propanediol (3-MCPD), 2-chloro-1,3-propanediol (2-MCPD), 1,3-dichloro-2-propanol (1,3-DCP) and 2,3-dichloro-1-propanol (2,3-DCP) in liquid condiments by gas chromatography-tandem mass spectrometry with dispersive solid phase extraction was proposed. The sample (2.0 g) was taken, and a certain amount of isotope internal standard mixed solution was added. After mixing well, 2 mL of methanol, 1 g of anhydrous sodium sulfate, 100 mg of C₁₈ and 100 mg of N-propyl ethylenediamine were added, and the mixture was swirled and centrifuged. Methanol (2 mL) was added into the obtained precipitation for repeated extraction, and the supernatants were combined, and made its volume up to 5 mL with methanol. The solution was filtered through 0.22 μm organic needle filter, and the filtrate was determined according to the operating conditions of the instrument. Four chloropropanols and their internal standards were separated on DB-WAX column by column heating program, ionized by electron impact ion source, detected by multi-reaction monitoring mode, and quantified by internal standard method. It was shown that the linear ranges of standard curves for 4 chloropropanols were 1-1 000 μg·L^-1, with detection limits (3S/N) in the range of 0.002-0.005 mg·kg^-1. Test for recovery was made on blank sample by standard addition method at 3 concentration levels, giving results in the range of 66.6%-102%, and RSDs (n=6) of the determined values ranged from 0.72% to 8.8%. This method was applied to the analysis of 70 liquid condiments including soy sauce, oyster sauce, fish sauce, balsamic vinegar and bean paste. It was shown that 1,3-DCP and 2,3-DCP were not detected, and detected amounts of 2-MCPD and 3-MCPD were in the ranges of 0.005-0.138 mg·kg^-1 and 0.005-0.954 mg·kg^-1, with detection rates of 41.4% and 100%, respectively. The detected amount of 3-MCPD in some samples exceeded the limit requirements stipulated in GB 2762-2017.