Improved hydride generation-atomic fluorescence spectrometry for determination of trace lead: minimization of blank from potassium ferricyanide

Abstract

A new efficient method was described for the purification of K₃[Fe(CN)₆] for the purpose of minimization of the blank in the determination of trace lead by hydride generation-atomic fluorescence spectrometry using the HCl–K₃[Fe(CN)₆]–KBH₄ system. The lead impurity in K₃[Fe(CN)₆] solution was removed by reacting with KBH₄ to form PbH₄, which was efficiently separated from the solution by a nitrogen gas flow. The purified K₃[Fe(CN)₆] was obtained via Cl₂ oxidation and subsequent ethanol purification of its reduced compound. The optimum conditions for hydride generation of lead and purification of K₃[Fe(CN)₆] were carefully investigated. A limit of detection (LOD) of 0.05 μg L⁻¹ was obtained, 100-fold better than that achieved with unpurified K₃[Fe(CN)₆]. The accuracy of the proposed method was validated by analyzing a Certified Reference hair sample (GBW07610) and two ore samples (GBW07106 and GBW07112) with satisfactory analytical results.