Study And Application On The Detection Method Of N-Nitrosamines In Animal Source Food

N-nitrosamine(NAMS)is a kind of carcinogenic and important food contaminant which is produced by precursors of nitrates and nitrides.In this paper,a new method for the pretreatment of alkaline solution,liquid liquid extraction and alkaline solution-active carbon solid phase extraction is studied for animal source food,and a new method for the detection of N-nitrosamines is established in combination with high sensitivity and high selectivity of gas chromatography tandem mass spectrometry(GC-MS/MS).A sampling survey was carried out on commercially available animal source foods.The effects of four processing methods on the contents of N-nitrosodimethylamine in food were studied.1.A new method for the determination of NAMS in animal source foods by GC-MS/MS was established by steam distillation with alkali heat treatment instead of the national standard method.Taking NDMA-d6,NDPA-d14 and NPYR-d8 as internal standard,add 10 g sample,3 g barium hydroxide(8 water)to 50 mL centrifuge tube and add water to 50 mL scale line.After being treated in an oven at 90°C for 2 h,the centrifuge was removed.The supernatant was extracted with dichloromethane and concentrated to 1 mL by steaming nitrogen blow,separated by DB-WAXUI column and detected under multiple reaction monitoring(MRM)mode.The results show that this method can be used to detect 7 kinds of NAMS,NDMA,NMEA,NDEA,NDPA,NPIP,NMOR and NPYR.It has been verified that the linearity is good in the concentration range of 1 to 100 ng/mL,and the correlation coefficient is R~2?0.999.The limit of detection is 0.08 to 0.23?g/kg,and the limit of quantitative is 0.25to 0.76?g/kg.The NDMA addition level is 1,3 and 10?g/kg,the recovery rate is 71.6%to 138.8%,and the RSD is 2.04%to 19.1%,which realizes the effective simplification of the national standard method.2.A new method of one-step treatment-activated carbon column solid phase extraction-GC-MS/MS detection of NAMS in animal source food was established.The samples were extracted by barium hydroxide solution and then all the samples liquid flowed through Sep-Pak?Plus AC-2 small column,eluted with 5 mL dichloromethane,collected eluent,concentrated to 1 mL by nitrogen blow,and detected in GC-MS/MS.The results show that the method can satisfy 8 kinds of NAMS detection of NDMA,NMEA,NDEA,NDPA,NDBA,NPIP,NPYR and NMOR.The limit of detection is 0.03 to0.25?g/kg,and the limit of quantitative is 0.10?g/kg.The standard level of aquatic products was 3,10and 20?g/kg,the recovery rate was 71.3%to 119%and the relative standard deviation was 0.65%to15.4%.The concentration level of processed meat products was 0.3,3 and 10?g/kg,and the recovery rate was 61.1%to 125.3%,RSD was 2.13%to 18.4%.This method can reduce the interference of impurities,realize the rapid processing of samples,and can meet the requirements of batch sample detection.3.A total of 66 samples of processed meat products,canned food,dried shrimps,dried fish and dried shrimps in the market are tested.The detection rate of NDMA compound is 100%.The content of NDMA in processed meat products is 0.27 to 28.7?g/kg.The content of NDMA in canned food is 0.63to 25.7?g/kg;The content of NDMA in the skin of shrimp is 3.72 to 25.4?g/kg;The content of NDMA in dried fish is 0.69 to 80.04?g/kg;The content of NDMA in shrimps is 0.47 to 9.05?g/kg.The effects of four processing methods of steaming,boiling,baking and microwave treatment on the change of NDMA content in food were studied.The results showed that the NDMA content increased with the heating time increasing,but,boiling and microwave treatment can reduce the increase of NDMA content.