3-Chloropropane-1,2-diol (alpha-chlorohydrin; 3-monochloropropanediol; 3-MCPD) is a toxic contaminant that has been found in soy sauce and other food products that use acid-hydrolysed vegetable protein (acid-HVP). Gas chromatography is usually the analytical method of choice for the quantitative determination of 3-MCPD. Brereton et al. recently published a validated method capable of measuring 3-MCPD ? 0.01 mg/kg, based on gas chromatography with mass spectrometric detection [Brereton et al., 2001]. This method is based on extraction of 3-MCPD followed by its derivatisation using N-heptafluorobutyrylimidazole (HFBI) to give compound (1).