INDIRECT DETERMINATION OF IODIDE, AS AN HGXIY COMPLEX, BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A method for the indirect determination of trace amounts of iodide by electrothermal atomic absorption spectrometry through the measurement of the mercury signal generated when small amounts of iodide and mercury are heated in a graphite furnace is described. The measured absorbances are related to the values of the signals from an iodide-mercury complex. The pH required for the formation of the Hg(x)I(y) complex as well as other parameters involved in measurement of the signals are also determined. The limits of detection and quantification obtained were 3.0 and 10.1 mug l-1 of iodide, respectively, and the characteristic mass was 38.8 pg of iodide. The relative standard deviations obtained were from 5.1-8.9% (n=7), depending on concentration. In the range 5-20 mug l-1 recoveries were 94.8-104.4%. The method has been applied to a range of tap waters.