Determination of micromolar concentrations of iodide by electrothermal atomic absorption spectrometry

When a solution (at pH 3.4–4.8) containing iodide and mercury(II) nitrate in a graphite tube is heated by increasing the temperature at a uniform rate, two mercury absorption peaks appear because the decomposition temperature of mercury(II) iodide is higher than that of mercury(II) nitrate. Measurement of the second peak allows 1 × 10^-6–5 × 10^-5 M iodide to be determined with good reproducibility. Equimolar concentrations of cyanide, sulfide and thiosulfate interfered, but these anions could be destroyed with hydrogen peroxide. Interfering cations were removed by extraction of 8-quinolinol complexes.