用氢化物原子荧光光谱法测定蔬菜中的微量砷

研究了还原剂用量、酸介质及其酸度、载气及屏蔽气流量、原子化器温度和观测高度对原子荧光强度的影响。探讨了共存离子对砷测定的干扰及消除方法，提出以硫脲－ 抗坏血酸－ 柠檬酸作为预还原抗干扰剂，可有效消除金属离子对砷测定的干扰，并对有关机理作了初步探讨，成功地测定了某些蔬菜样品中的砷，方法检出限（３σ）为１．２６ ｎｇ／ｇ，回收率为９７．５％ ～１０４．５％ ，相对标准偏差为０．７９％ ～１．４３％ 。

Determination of Trace Arsenic in the Vegetables by Hydride Generation-Atomic Fluorescence Spectrometry

The effects of concentration of NaBH4 and HCl, flow rate of the carrier gas and the shield gas, the atomizer temperature and the observation height were studied in the determination of arsenic by hydride generation-atomic fluorescence spectrometry (HGAFS). The interference from foreign ions on arsenic was eliminated by adding ascorbic acid-thiourea-citric acid and the relevant mechanism wasbriefly discussed. The present method was applied to the determination of arsenic in vegetable samples with a recovery of 97.5%～104.5% and a RSD of 0.79%～1.43%. The detection limit(3σ) of arsenic is 1.26 ng/g for 5 g of sample.