碱液处理-活性炭柱固相萃取结合GC-MS/MS法检测鱼干、虾皮和虾仁中8种N-亚硝胺

摘要

建立了碱液处理-活性炭柱固相萃取结合气相色谱-串联质谱联用(GC-MS/MS)技术检测鱼干、虾皮和虾仁中N-亚硝基二甲胺(NDMA)、N-亚硝基甲乙胺(NMEA)、N-亚硝基二乙胺(NDEA)、N-亚硝基二正丙胺(NDPA)、N-亚硝基哌啶(NPIP)、N-亚硝基吡咯烷(NPYR)、N-亚硝基吗啉(NMOR)和N-亚硝基二正丁胺(NDBA)等有害物质.以 NDMA-d6、NDPA-d14和 NPYR-d8为内标,用 Ba(OH)2溶液于80 ℃处理样品1 h,离心上清液,经 Sep-Pak?plus AC-2活性炭小柱富集净化,DB-WAXUI(30 m× 250 μm×0.25 μm)色谱柱分离,质谱多反应监测(MRM)模式检测.结果表明,在1~200 μg/L 浓度范围内,8种N-亚硝胺的线性关系良好,R2>0.998;检出限为0.03~0.25 μg/kg,定量限为0.10~0.85 μg/kg,添加回收率为71.3%~119.0%(除NDBA在高添加水平时略低,为52.1%~69.0%),相对标准偏差为0.65%~15.4%.将该方法用于23种实际样品检测,在所有样品中均检出 NDMA,且含量相对较高,其他N-亚硝胺仅部分检出,含量相对较低.该方法操作简单、便于高通量分析、环境友好、定性定量可靠,可为水产品中N-亚硝胺类物质的检测提供参考.%N-nitrosodimethylamine (NDMA),N-nitroxymethylamine (NMEA),N-nitrosodiethylamine (NDEA),N-nitrosodipropylamine (NDPA),N-nitrosopiperidine (NPIP),N-nitrosopyrrolidine (NPYR),N-nitrosomorpholine (NMOR)and N-nitrosodibutylamine (NDBA)in dried fish,dried small shrimps and shrimp meat were determined by gas chromatography-tandem mass spectrometry(GC-MS/MS)with alkali solution treating and active carbon solid phase extraction.10 g of sample was placed into a 50 mL screw-cap plastic centrifugation tube,and 50 μL of internal standards solution including NDMA-d6,NDPA-d1 4 and NPYR-d8 with each concentration of 1 mg/L, 1.0 g of Ba(OH)2·8H2O and distilled water with volumn to the 50 mL scale line were added.Then the tube was heated at 80 ℃ for 1 h in an oven and centrifuged at 10 000 r/min for 10 min.All the supernatant was passed through a Sep-Pak?Plus AC-2 car-tridge which had been conditioned with 6 mL of dichloromethane,6 mL of methanol and 6 mL of water in turns,and the anlytes were eluted with 5 mL of dichloromethane from the cartridges after aspiration to dryness by a vacuum pump.The eluent was concentrat-ed further to 1 mL under nitrogen flow at 40 ℃ and was then passed through a 0.22 μm pore filter for inj ection.The chromatographic separation was carried on a DB WAXUI column (30 m×250 μm×0.25 μm)and detected with tandem mass spectrometry at multiple reactions monitoring mode.The calibration curves show good linearity in the range of 1-200 μg/L with the correlation coefficients (R2)greater than 0.998.The lim-its of detection and quantification are in the ranges of 0.03-0.25 μg/kg and 0.10-0.85 μg/kg,respectively.The recoveries of N-nitrosamines are 71.3%-119.0%,except that NDBA is slightly lower at high addition levels,and the relative standard deviations (RSD)is 0.65%-15.4%.23 samples from local supermarket including 8 ready-to-eat dried fish,5 fresh dried fish,4 dried small shrimp and 6 shrimp meat were detected. The results indicate that NDMA is the major N-nitrosamines and is detected in all samples with the highest level among of the analytes,and the other N-nitrosamines are detected in partial samples with relative lower levels even blow the LOQ.The samples with the highest levels of NDMA are dried fishes and the levels of ready-to-eat dried fishes are much higher than that of the fresh dried fishes,the samples with medium and the lowest levels of NDMA are dried small shrimps and shrimp meats,respectively. NDBA should be paid more attention during the relative food safety control.This meth-od is simple,environment-friendly,easy for high-throughput detection and reliable for both qualitative and quantitative analysis.