Abstract
Nitrosamine is one of the three strong carcinogenic contaminants in food and widely present in pickled and heat-treated food. A new solid phase extraction (SPE)-HPLC method based on the HPLC-MS identification for the determination of nine nitrosamines has been established. The method could be used for the direct and fast detection of 9 nitrosamines in pickles. The conditions for chromatographic separation and detection have been optimized. Four SPE columns with single packing materials (Al2O3, C18, Silica, and Diatomite) and two SPE columns with mixed dual packing materials (Al2O3-C18, Al2O3-Silica) have also been investigated. As a result, the recoveries for determination of 9 nitrosamines by HPLC with SPE column of mixed Al2O3-C18 for cleanup were in the range of 75.7% to 116.0% and the limit of detection was 0.20-0.49 mg/L. On the basis of the above methods, the concentrations of nitrosamines in pickled vegetables of six varieties produced from different origins were investigated. The occurrence rate of N-nitrosodiethylamine (NDMA) and NDEA in all samples was 37.5% and 25.0%, relatively higher than that of other nitrosamines. The highest content of NDEA occurred especially in potherb mustard was up to 59.1 mg/L, and N-nitrosomorpholine (NMOR) has not been detected in all samples.