Determination of Glycidol in Soy Sauce Using p-Dimethylaminophenol Derivatization Coupled with Liquid Chromatography-Tandem Mass Spectrometry.

Glycidol, a probable human carcinogen, remains an under-investigated process contaminant in soy sauce. This study developed a sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for its determination in this complex condiment. The approach combined chemical derivatization with p-Dimethylaminophenol hydrochloride for analyte stabilization with an optimized sample pretreatment using a custom-packed activated carbon solid-phase extraction (SPE) cartridge effectively removed matrix interferences, and performing the derivatization at pH 6.5 prevented conversion of 2- and 3-monochloropropanediol (2-MCPD and 3-MCPD) into glycidol, ensuring high specificity and accuracy. This approach shows broad linearity from 1 to at least 100 ng/mL (R2 = 0.9993), and demonstrates excellent performance, with a limit of detection and quantification of 0.5 ng/mL and 1.0 ng/mL, respectively. Application to commercial samples (n = 11) confirmed the presence of glycidol, highlighting the need for its monitoring. This work provides a robust analytical tool essential for supporting food safety surveillance of this contaminant in fermented foods.