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

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.