分散液液微萃取-原子荧光光度法测定大米中的汞

硝酸-高氯酸(4∶1，V/V)混合酸消解样品。双硫腙为络合剂，乙醇为分散剂，四氯化碳为萃取剂，建立了分散液液微萃取-原子荧光光度法测定大米中的汞的方法。优化了原子荧光光度计工作参数和分散液液微萃取的最佳络合酸度、络合剂用量、萃取剂种类及用量等条件。实验表明，在最佳条件下，方法的线性范围为0.005～25 μg·L-1，相关系数为0.996 6，检出限为0.003 μg·L-1，相对标准偏差为3.84%，加标回收率为90%～120%。该方法灵敏度高，分析速度快，准确性高，能有效检测大米中的痕量汞。

Determination of Mercury in Rice with Dispersive Liquid-Liquid Microextraction and Atomic Fluorescence Spectrometry

Rice samples were digested by a mixture of nitric and perchloric acids (4 : 1,V/V ).Dithizone was used to chelate mercury ion in the sample solution,and the mercury complex was dispersed in ethanol before being extracted into carbon tetra-chloride.Thus,a method of determining mercury in rice by dispersion liquid micro extraction-atomic fluorescence spectrometry was established.The operating parameters of the instrument and optimal experimental conditions of dispersive liquid-liquid mi-croextraction were optimized,including the best complex acidity,the amount of complexing agent,extraction solvent type,the amount of dispersant dosage,and the extraction time.Experiments showed that under optimal conditions,the linear range was 0.005～25 μg·L-1 and the correlation coefficient was 0.9966 with the detection limit of 0.003 μg·L-1 ,the relative standard deviation (RSD)of 3.84％,and the recovery 95％～105％ .The method is proven to be a sensitive,rapid,and accurate,way which can detect effectively trace amounts of mercury in rice.