Determination of 7 N-nitrosamines in Several Aquatic Products and Processed Meat Products by Gas Chromatography-tandem Mass Spectrometry with Barium Hydroxide Treatment Coupled Liquid-liquid Extraction

A new method for determination of 7 N-nitrosamines in several aquatic products and processed meat products was developed by gas chromatography-tandem mass spectrometry (GC-MS/MS) with barium hydroxide treatment combined with dichloromethane extraction. With N-nitrosodimethylamine-d6,N-nitrosadipropylamine-d14 and N-nitrosopyrrolidine-d8 as internal standards,total 10 g sample was treated with the barium hydroxide solution in a centrifuge tube of 50 mL and centrifuged,then the supernatant was extracted with dichloromethane one time and the extraction was concentrated to 5 mL with a rotary vacuum evaporator and was next concentrated to 1 mL by nitrogen gas blowing. The chromatographic separation was carried with a DB-WAXUI column (30 m×250 μm×0.25 μm) and the mass spectrometry detection was done with multiple reactions monitoring mode. The calibration curves showed good linearity (1~100 ng/mL) with R²>0.999;the detection limits were 0.08~0.23 μg/kg and the quantitative limits were 0.25~0.76 μg/kg;the recoveries were 71.6%~133.8% with the relative standard deviations of 2.04%~17.1%. The actual test of nine dried fish and shrimp meat and eight processed meat products showed that the content of N-nitrosodimethylamine was within the safe range.