Determination of 1,3-dichloropropanol in soy sauces by automated headspace gas chromatography-mass spectrometry.

There has been recent concern about the levels of carcinogenic chloropropanols in some soy sauces. We have devised and tested a new automated headspace GC-MS technique for the analysis of 1,3-dichloropropan-2-ol (1,3-DCP) in soy sauce and similar products. The method incorporates the use of cryogenic trapping and a deuterium-labelled internal standard. The limit of detection was 0.003 mg kg(-1). After in-house validation testing, the method was applied to soy sauce samples that had previously been analysed for the related contaminant 3-monochloropropanediol (3-MCPD). 1,3-DCP was detected in 10 of 40 sauces, all of which also contained 3-MCPD. The highest level was just >1 mg kg(-1). There was no correlation between the levels of 1,3-DCP and 3-MCPD.