稀酸微波消解-氢化物发生原子荧光光谱法测定蔬菜中总汞

Determination of Total Mercury in Vegetables by Hydride Generation Atomic Fluorescence Spectrometry with Diluted Nitric Acid-Microwave-assisted Digestion

为践行食品检测工作“环保”的理念,以菠菜粉质控样品为研究对象,通过考察硝酸浓度、微波消解温度、赶酸条件以及其他检测条件对总汞测定的影响,建立稀酸微波消解-氢化物发生原子荧光光谱法测定蔬菜中总汞的方法,并对方法进行评价,对九江市售蔬菜中汞含量进行测定。结果表明,最佳消解液组成为5 mL硝酸(20%)+1.0 mL过氧化氢、微波消解最高温度为160℃、载流为HNO_(3)(5%)、负高压280 V、KBH_(4)浓度0.5%。新建立的方法检出限为0.000 1 mg/kg,汞在0~2.0μg/L线性关系良好,加标回收率为92.0%~106%,相对标准偏差RSD为2.5%~5.5%。方法操作简便,大幅度减少了前处理过程硝酸使用量,无需赶酸,精密度、重现性好,灵敏度、准确度高,推广应用前景广阔。

For practicing the concept of “greening” in the food inspection,a microwave-assisted digestion method using diluted nitric acid-hydride generation atomic fluorescence spectrometry was established to determine total mercury content in vegetables.The effects of nitric acid concentration,microwave digesting temperature,acid-driving and other conditions on the determination of total mercury were investigated.A method for determining total mercury in vegetables using dilute acid microwave digestion hydride generation atomic fluorescence spectrometry,and evaluate the method to determine the mercury content in vegetables sold in Jiujiang city.Results showed that the optimal composition of the digestion solution consist was 5 mL of 20% nitric acid and 1.0 mL of hydrogen peroxide,the maximum microwave digestion temperature was 160 ℃,the carrier current was 5% HNO_3,the negative high voltage was 280 V,and the KBH_(4) concentration was 0.5%.The detection limit of the newly established method was 0.000 1 mg/kg,the linear range of mercury was good at 0—2.0 μg/L,the recovery ranged from 92.0% to 106%,and the relative standard deviation(RSD) was from 2.5% to 5.5%.The method is easy to operate,reduces the amount of nitric acid used in the pre-treatment steps significantly,free of acid driving,good precision and reproducibility,high sensitivity and accuracy,and has broad prospects for promotion and application.