Determination of Al, Cr, Fe, Zn, Cd, Pb and Bi in Crude Drugs by Inductively Coupled Plasma Atomic Emission Spectrometry after Coprecipitation with Yttrium Phosphate

摘要

A novel method that combines inductively coupled plasma atomic emission spectrometry (ICP-AES) with a coprecipitation technique to determine trace and sub-trace elements in crude drugs is described herein. Yttrium phosphate quantitatively coprecipitated seven elements (Al, Cr, Fe, Zn, Cd, Pb and Bi) at pH 6 in a solution prepared from microwave-digested samples of crude drugs. Some matrix elements such as Na, K, Mg and Ca were effectively removed by this process. The thus coprecipitated elements were then determined by ICP-AES with yttrium as an internal standard element. The detection limits (3sigma, n = 10) were 0.17 mg/kg for Al, 0.004 mg/kg for Cr, 0.03 mg/kg for Fe, 0.13 mg/kg for Zn, 0.004 mg/kg for Cd, 0.19 mg/kg for Pb and 0.06 mg/kg for Bi. The proposed method was successfully utilized to determine the concentration of the above-mentioned seven elements in standard reference materials [National Institute of Standards Technology (NIST) SRM1515, SRM1547 and SRM1575a] and seven kinds of crude drugs.