赶酸对微波消解-氢化物发生-原子荧光法测定谷物中砷元素的影响

在利用氢化物发生-原子荧光分测定谷物类样品中砷元素时，硫脲-抗坏血酸的还原效果会受到硝酸含量的影响，试液中硝酸含量过高，会与硫脲-抗坏血酸溶液发生氧化还原反应，降低其还原效率。本研究通过对赶酸时间和赶酸温度进行试验，获得最佳的赶酸条件，结合微波消解技术，利用氢化物发生-原子荧光光谱法测定谷物中的微量砷，结果表明，谷物中砷浓度与荧光强度呈线性关系，线性方程为 y=0.0028x-0.1728，线性相关系数R2=0.9993，检出限为1.72ng/g。 通过对9份样品进行检测，其相对标准偏差RSD在4.32-7.59%之间，其准确度相对误差RE均小于±6.50%。经多次检测证实该方法较稳定，可用于谷物类样品中砷元素的快速测定。

Effect of acid catching on determination of As in grain by microwave digestion-hydride generation-atomic fluorescence

The reduction effect of thiourea-ascorbic acid was affected by the content of nitric acid in the determination of arsenic in grain samples by hydride generation-atomic fluorescence spectrometry. The content of nitric acid in the test solution is too high, and the redox reaction with thiourea-ascorbic acid solution will reduce its reduction efficiency. In this study, the best acid catching condition was obtained in the determination of As in grain by the method of Hydride Formation-Atomic Fluorescence Spectrometry with digestion by microwave through testing the acid catching time and the acid catching temperature. The result showed that the concentration of As in grain is linearly related to the fluorescence intensity, which is in accordance with the equation of y = 0.0028x - 0.1728 (R2= 0.9993). The detection limit is 1.72 ng/g. The relative standard deviation RSD of the 9 samples is in the range of 4.32% to7.59 %, and the relative error(RE) is less than ± 6.50 %. The method is stable in numerous tests and can be used for the rapid determination of arsenic in grain samples.