Cold vapor atomic absorption spectrometric determination of mercury using sodium tetrahydroborate reduction and collection on gold

Summary

Sodium tetrahydroborate(III) is equivalent to or better than tin(II) chloride as a reducing agent for mercury in cold vapor atomic absorption spectrometry using collection on gold. Concentrations of copper, silver, nickel, iodide, antimony, arsenic, bismuth and selenium typically found in water or waste water do not interfere. Prerequirements for satisfactory performance are that the gold is at a temperature below 100‡C during collection of mercury and that the gas from the reaction flask is washed with sodium hydroxide and dried with magnesium perchlorate. All determinations were carried out in 5 mol l⁻¹ hydrochloric acid and in the presence of 200 mg l⁻¹ iron(III). Detection limits (3σ) of 0.15 ng absolute, and of 15 ng l⁻¹ or 3 ng l⁻¹, using 10 ml or 50 ml solution, respectively, are obtained. The analytical curve is linear to 40 ng, and the relative standard deviation in the optimum working range is better than 2%.