Determination of total arsenic in traditional chinese medicines by flow injection hydride generation atomic fluorescence spectrometry

摘要

The samples were digested with a mixture of nitric acid and perchloric acid. Suitable amount of thiourea was added to reduce As(V) to As(III), and to minimize the interference from transition metal ions. Total arsenic was determined after transformation to arseine by the reaction with KBH_4 solution. The interferences from Cu(II), Fe(III), Hg(II) and Se(IV) were studied and the mechanisms of interference were also discussed. In the flow injection mode the relative detection limit was 0.114 ng mL~(-1), which corresponds to an absolute detection limit of 0.034 ng. Quantification was investigated with both standard additions technique and a simple calibration curve method. The recoveries for the spiked 4 ng mL~(-1) As inthe studied medicines ranged from 95 to 105%. The precision for eleven replicate measurements was 0.68% (RSD) at the 5 ng mL~(-1) level. The developed method was successfully applied to the determination of total arsenic in a number of traditional Chinese medicines.