Simultaneous generation of hydrides of bismuth, lead and tin in the presence of ferricyanide and application to determination in biominerals by ICP-AES

Abstract

Performance of potassium ferricyanide, K₃(Fe(CN)₆, for simultaneous generation of hydrides of Bi, Pb and Sn in dilute HCl is investigated for determination by ICP-AES. On-line addition of K₃Fe(CN)₆ to sample solution was essential to achieve optimum signals and stability in generation of BiH₃ and SnH₄. Off-line addition caused instability for Bi(III) and Sn(IV) that resulted in substantial loss in hydride generation efficiency within 24 h. Lead hydride (PbH₄) generation, however, was not influenced from on-line or off-line addition of [Fe(CN)₆]³⁻, nor did it show any instability under the same conditions indicating that [Fe(CN)₆]³⁻ affects generation of PbH₄ differently from those of BiH₃ and SnH₄. The effects of transition metals and hydride forming elements were not significant, except Cr(VI) and Cu(II) that suppressed the signals of Bi and Sn, and Pb, respectively, at and above 1.0 μg mL⁻¹. The detection limits (3s, n = 11) were 0.20, 0.13 and 0.10 μg L⁻¹ for Bi, Pb and Sn, respectively. The method was applied to the analysis of calcium-rich biominerals - fish otoliths and NIST bone ash certified reference material (SRM 1400).