Coprecipitation with tin(IV) hydroxide followed by removal of tin carrier for the determination of trace heavy metals by graphite-furnace atomic absorption spectrometry

Nanogram amounts of trace heavy metals are quantitatively coprecipitated with tin(IV) hydroxide at pH 5–6. After centrifugation, the precipitate is dissolved in nitric acid and the solution is allowed to stand overnight to form stannic acid. More than 90% of tin is precipitated, leaving trace heavy metals in the solution. The formation of stannic acid is highly accelerated by heating at 50 °C. The trace heavy metals are successfully determined by graphite-furnace atomic absorption spectrometry without any interference from tin. The proposed method has been applied to the analysis of high-purity magnesium metal and river water.