Optimization of pretreatment conditions for determination of ethyl carbamate content in cheese by GC-MS/MS
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.
万方数据
维普
