Analysis of ethyl carbamate in Korean soy sauce using high-performance liquid chromatography with fluorescence detection or tandem mass spectrometry and gas chromatography with mass spectrometry

A specific, sensitive procedure involving high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS) was developed and compared to other analytical methods for quantification of ethyl carbamate (EC) in Korean soy sauce products. HPLC with a fluorescence detector was not applicable for monitoring trace amounts of EC in soy sauce due to its low detection limit (20 ppb). The use of gas chromatography (GC) coupled to MS could be applied to soy sauce, but it was not as simple and fast as HPLC/MS/MS. The GC/MS procedure exhibited excellent linearity over the concentration range of 10–200 ppb with a 0.5 ppb limit of detection (LOD) and 82.7 ± 3.1% recovery. A procedure involving HPLC/MS/MS with multiple reaction monitoring was developed. The characteristic transitions of m/z 90 → 62 for EC as well as m/z 104 → 62 for propyl carbamate (PC) as the internal standard were monitored. Good linearity was obtained both in the range from 10 to 100 ppb and in the range from 0.1 to 20 ppb with a LOD of 0.05 ppb. The average recovery was 92.2 ± 1.7%. The applicability of the GC/MS and developed HPLC/MS/MS methods was demonstrated by detection of EC in 12 kinds of commercial Korean soy sauce products at levels of 0.5 and 0.1 ppb, respectively. The new HPLC/MS/MS method provided greater sensitivity with a simpler and shorter confirmatory analysis than the GC/MS method.