阳离子交换高效液相色谱法快速测定蔬菜中灭蝇胺的残留量

Rapid Determination of Cyromazine Residue in Vegetables by Cation Exchange High Performance Liquid Chromatography

取10 g蔬菜样品,加入20 mL体积比1∶99的乙酸-乙腈混合溶液,振荡提取20 min,加入6 g无水硫酸镁,振荡5 min,离心2 min,分取4 mL上清液,过活化好的氨基固相萃取柱,收集全部流出液。用2 mL体积比3∶1的乙腈-甲苯混合溶液洗脱柱子,收集洗脱液并合并至上述流出液中。所得溶液于40℃氮吹至近干,用1.0 mL体积比65∶35的含0.2%(体积分数)乙酸的20 mmol·L^(-1)乙酸钠溶液和乙腈的混合溶液(流动相)复溶,涡旋1 min,过0.22μm滤膜,滤液供高效液相色谱仪分析。在ZORBAX 300-SCX强阳离子交换色谱柱上以流动相等度洗脱分离滤液中的目标物,外标法定量。结果显示,灭蝇胺的质量浓度在0.02~2.00 mg·L^(-1)内和峰面积呈线性关系,检出限(3S/N)为0.006 mg·kg^(-1)。按照标准加入法进行回收试验,回收率为83.6%~90.5%,测定值的相对标准偏差(n=6)为1.5%~9.0%。方法用于43批蔬菜样品的分析,灭蝇胺的检出率为28%,有3批豇豆中灭蝇胺的残留量超过GB 2763—2021规定的限量。

A total of 10 g of vegetable sample was taken,and 20 mL of acetic acid-acetonitrile mixed solution at volume ratio of 1∶99 was added.The mixture was shaken for extraction for 20 min,and 6 g of anhydrous magnesium sulfate was added.The mixture was shaken for 5 min,and centrifuged for 2 min.An aliquot(4 mL)of the supernatant was taken and passed through an activated amino solid phase extraction column,and all the effluent was collected.The column was eluted by 2 mL of acetonitrile-toluene mixed solution at volume ratio of 3∶1,and the eluate was collected and combined with the above mentioned effluent.The obtained solution was blown to near dryness by nitrogen at 40℃,and re-dissolved in 1.0 mL of the mixed solution(mobile phase)of 20 mmol·L^(−1) sodium acetate solution containing 0.2%(volume fraction)acetic acid and acetonitrile at volume ratio of 65∶35 by vortex for 1 min.After passing through a 0.22μm filter membrane,the filtrate was analyzed by high performance liquid chromatograph.The mobile phase was used for isocratic elution separation of the target in the filtrate on the ZORBAX 300-SCX strong cation exchange chromatographic column,with the external standard method for quantitative analysis.It was shown that linear relationship between values of the mass concentration and peak area of cyromazine was kept in the range of 0.02-2.00 mg·L^(−1),with detection limit(3S/N)of 0.006 mg·kg^(−1).Test for recovery was made according to the standard addition method,giving recoveries in the range of 83.6%-90.5%,and RSDs(n=6)of the determined values ranged from 1.5%to 9.0%.The proposed method was applied to the analysis of 43 batches of vegetable samples,with the detection rate of 28%for cyromazine.The detection amounts of cyromazine in 3 batches of cowpeas exceeded the limit specified in GB 2763—2021.