Optimization of pretreatment conditions for determination of ethyl carbamate content in cheese by GC-MS/MS

Abstract

In this study, an external standard quantitative method for the determination of ethyl carbamate content in cheese by GC-MS/MS was established, the pretreatment conditions of the sample were optimized, and the methodology of the detection method was investigated. The results showed that the optimal pretreatment conditions were as follows: 2 ml of deionized water was added to the sample for mixing, 1 ml of acetonitrile was added for extraction, the sample was centrifuged at 0 ℃ and 6 000 r/min for 8 min, the supernatant was cleaned-up by an alkaline diatomaceous earth solid-phase extraction cartridge (2 g/10 ml), n-hexane drenching, eluted with 20 ml dichloromethane, nitrogen blown against the eluent to about 0.5 ml, and then the supernatant was set volume with methanol for GC-MS/MS detection and quantified by external standard method. The method was linear in the mass concentration range of 5-200 ng/ml with the correlation coefficient R2>0.99. The limit of quantification (LOQ) was 0.01 mg/kg, the limit of detection (LOD) was 0.005 mg/kg, the recovery rates ranged from 69.1% to 90.7% in the experinents of standard recovery rates of high, middle and low addition levels, and the relative standard deviations (RSDs) of the results of the precision tests ranged from 4.2% to 11.1%. The method was easy to operate, accurate and suitable for the determination of ethyl carbamate content in cheese.

Keywords

• cheese|ethyl carbamate|gc-ms/ms|pretreatment conditions optimization