Optimization Of Pretreatment Method And Chromatographic Conditions Of N-nitrosamines In Meat Products

N-nitrosamines are recogn ized as a class of compounds that have strong toxic and harmful,widely exist in cured meat products and heat processed foods.Some volatile N-nitrosamines can induce cell canceration,which is an important latent danger to human diet.The matrix of meat products is very complex,and the content of N-nitrosamines is extremely low,so it is very important for the extraction and enrichment of N-nitrosamines in the sample before the detection of N-nitrosamines.The pretreatment method of national standard method adopt steam distillation,that needs lots of samples,long time and more organic reagents,so it is necessary to establish a pretreatment and detection method can detect quickly and accurately for N-nitrosamines.The GB method adopt the GC-MS as the detection method,it is expensive,if it can use the common GC or HPLC for detection,there will make the detect method for N-nitrosamines much more convenient.In this paper,we make the 9 kinds of common N-nitrosamines(NDMA,NMEA,NDEA,NPYR,NMOR,NDPA,NPIP,NDBA,NDPhA)in meat products as the research object,Focus on studying two pretreatment method(Solid-phase microextraction,SPME,ultrasonic extraction with SPE)and two chromatographic method(GC-NPD,HPLC),finally,comparing the result of samples,we choose to use the established method with the GB method.1.Determination of Nine Volatile N-Nitrosamines in Meat Products by Solid-Phase microextraction(SPME)with GC-NPD.The best extraction conditions of the nine N-nitrosamines(N-nitrosodimethylamine,N-nitrosodiethylamine,N-nitrosopyrrolidine,N-nitrosodipropylamine,N-nitrosodibutylamine,N-nitrosopiperidine,N-nitrosomethy lethylamine,N-nitrosomorpholine,and N-nitrosodiphenylamine)were determined by optimization of equilibration time,extraction time,extraction temperature,NaCl concentration,stirring speed and analysis time.The results showed that the best extraction effect can be obtained when the extraction fiber used PDMS/DVB/CAR,the equilibrium time was 10 min,the extraction temperature was 40 ?,the extraction time was 30 min,the stirring speed was 400 r/min,the salt concentration was 0.36 g/mL and the analytical time was 3 min.The linear correlation coefficients of the 9 kinds of N-nitrosamines were determined by SPME with GC-NPD in the range of 0.9964 to 0.9996,the detection limit was 0.01?10 ng/mL and the limit of quantification was 0.03?33 ng/mL,the recoverie was in the range of 66.76?90.4%,the RSD was 3.27?7.62%.2.Adopting high performance liquid chromatography(HPLC)with UV detector to separat and detect the 9 N-nitrosamines.Through optimizing the mobile phase type,ratio of mobile phase,the mobile phase pH and sample solvent to determine the optimum separation conditions of 9 kinds of N-nitrosoamines.The results show that adopting the HPLC-UV,external standard method to quantitate,between 0.1?4 ?g/mL,the linear correlation coefficient is above 0.9995,the HPLC-UV of the detection limit is 0.01?0.085 ?g/mL instrument 9 N-nitrosamines,the limit of quantification was 0.033?0.283?g/mL,the parallel test of relative standard deviation(RSD)was 0.03%?0.29%,and the method does not require derivatization,strong operability,high sensitivity,good reproducibility,it is suitable for separation and detection of 9 kinds of N-nitrosoamines.3.A solid phase extraction and liquid chromatography with ultraviolet detection(SPE-HPLC-UV)for simultaneous determination in meat products of NDMA,NMEA,NDEA,NDPA,NDBA,NPIP,NPYR,NMOR and NDpheA methods 9 N-nitrosoamines.Using dichloromethane as extraction reagent to investigate the effect of extraction consisting of extraction time,solvent amount and extraction power,compared the purification effect of C18,neutral alumina and activated carbon for ultrasonic extraction of sample.The results showed that using 40 mL dichloromethane,400 W,extract 20 min,the peak area of N-nitrosamines reached the maximum.And finally through the recovery experiment selected activated carbon solid-phase extraction as sample purification.The recovery of the method was 86%?99%,and the precision was 1.19?3.42%,the method is simple and rapid,with good sensitivity,repeatability,and can be applied to simultaneous determination of content in meat products of 9 kinds of N-nitrosamines compounds.4.Through the comparison of SPME-GC-NPD,SPE-GC-NPD and SPE-HPLC-UV and the national standard method in the determination of N-nitrosamines in samples shows that SPME-GC-NPD can detect N-nitrosoamines type less,more suitable for rapid determination of NDMA,NMEA and NDEA in meat products.The LOD of UE-SPE-GC-NPD was lower compared with UE-SPE-HPLC-UV methods,so it was more suitable to detect the lower content of N-nitrosamines in meat.For the same sample,the N-nitrosamines content of three methods optimised was higher lightly compared with GB method,but the species of N-nitrosamines was less to the GB method,so we choice the method to detect the N-nitrosamines should base the specific circumstance.