RESUMO
Objective To establish an isotope dilution gas chromatography-mass spectrometry(GC-MS)for the determination of chloropropanol esters in fried foods.Methods A total of 88 fried food samples were collected from supermarket,breakfast shop and street breakfast,stalls,the fried food sample with no chloropropanols esters detected was used as the blank sample. Samples were extracted using a solvent extraction method,followed by ester-bond cleavage reaction with sodium methylate-methanol and purification by diatomite solid-supported liquid-liquid extraction column. The derivatives in purified solution was detected by GC-MS after being derivatived with heptafluoro butyrylimidazole. The concentration of chloropropanols esters was quantified by using deuterium isotopes as internal standards. The accuracy of the method for evaluating recovery rate of blank samples was adopted,and the relative standard deviation(RSD)of the recovery rate represents the precision of the method.Results The 3-MCPD ester and 2-MCPD ester had good linear relationship in the concentration range of 25-1000 g/L(r>0.9995). The detection limits of 3-MCPD ester and 2-MCPD ester were 20μg/kg. The recovery rate of fat extracts from blank samples at 25,50,100,and 200μg/kg levels ranged from 89.7% to 103.7%,and RSD<8.4%. The detection rates of 3-MCPD ester and 2-MCPD ester in 88 samples were 81.82% and 70.45% respectively,and the content ranges from not-detected(ND) to 1.65mg/kg and to 0.93 mg/kg respectively.Conclusion The method is simple,accurate and reliable. It is suitable for the determination of chloropropanol esters in fried foods. There is a certain degree of contamination of chloropropanol esters in fried foods,and this comtamination is quite common.