Studies On The Novel Methods For The Determination Of Nitrosamines Carcinogens In Food By HPLC Based On Online UV Photolysis

Nitrosamines are a class of compounds with strong effects of mutagenesis,carcinogenesis and teratogenesis that exist widely in human living environments.Studies have shown that no animal can resist the carcinogenic effect of NAs so far.Therefore,it is of great significance to study and establish the analysis methods of NAs in the environment and food related to human health for safeguarding and maintaining the health and safety of all mankind.In this experiment,common NAs in daily life were taken as the research object,and two new methods for simultaneous detection of multiple NAs were established by combining online ultraviolet photolysis technology.The research mainly included the following contents:（1）A novel method based on terbium-doped carbon dots（Tb-CDs）by high performance liquid chromatography-online ultraviolet photolysis-fluorescence detector（HPLC-UV-FLD）was proposed for the detection of NAs.The carbon quantum dots（CDs）were characterized by transmission electron microscopy and infrared spectroscopy,and the intermediates produced by ultraviolet degradation of NAs were studied by ion chromatography.Experimental studies have shown that NAs can be degraded under 254 nm UV light and produce NO₂^-,which can quench the fluorescence produced by Tb-CDs rapidly and specifically.On this basis,we used HPLC to isolate five NAs in 8 min,which are N-nitrosodimethylamine（NDMA）,N-nitrosomorpholine（NMor）,N-nitrosopyrrolidine（NPYR）,N-nitrosodiethylamine（NDEA）and N-nitrosopiperidine（NPIP）.These five kinds of NAs showed a good linear relationship in the range of 10–2000μg/L,and the limit of detection was as low as 2.25μg/L.The relative standard deviation is in the range of 1.71～3.64%.The method has been successfully applied to the determination of sweet potato,lotus root,potato,water chestnut,tomato and cucumber.The recoveries of the samples were 77.35～119.30%.（2）Based on the linear change of conductivity caused by various intermediates produced by ultraviolet photolysis of NAs,a new method combining high performance liquid chromatography with online ultraviolet photolysis and conductivity detector（HPLC-UV-CD）was proposed.The concentration of NAs intermediates after UV photolysis was studied by ion chromatography.On the basis of single factor experiment optimization,BBD surface response method was used to optimize the experiment at three levels and three factors,so as to achieve the best experimental conditions.Under the optimal experimental conditions,the separation and analysis of seven NAs,named N-nitrosodimethylamine（NDMA）,N-nitrosomorpholine（NMor）,N-nitrosopyrrolidine（NPYR）,N-nitrosodiethylamine（NDEA）,N-nitrosopiperidine（NPIP）,N-nitrosodropylamine（NDPA）and N-nitrosodibutylamine（NDBA）,were successfully completed within 10 minutes.Theses seven kinds of NAs showed a good linear relationship in the range of 10-1000μg/L,and the detection limit was as low as3.97μg/L.The relative standard deviation is in the range of 0.44～0.97%.The method was successfully applied to the detection of meat floss,dried cuttlefish,dried shrimp,ham sausage,dried yellow croaker and beef in sauce.The recoveries of added standard were between 75.00～118.00%.In conclusion,two new methods for simultaneous detection of multiple NAs were established by analyzing the intermediate products of NAs online UV photolysis process with the help of high separation efficiency of HPLC in this study,which are HPLC-UV-FLD and HPLC-UV-CD.The two new methods were successfully applied to the detection of vegetable and meat products respectively.