Titrimetric microdetermination of inorganic or organic mercury by amplification reactions

A simple titrimetric method for estimation of 0.05-7 mg of Hg(II) is presented. The acidic sample solution is treated with a measured and excessive amount of iodide, then mercuric iodide is extracted at ph 2-3.5, and the unreacted iodide is determined iodometrically after 6- or 36-fold amplification by use of bromine water for oxidation of iodide to iodate. Periodate oxidation of excess of iodide gives 24-fold amplification. The coefficient of variation does not usually exceed 1% for above 1 mg of mercury but increases to 4% at the 0.05-mg level. The 6-fold amplification method is used for microdetermination of organically bound mercury following oxygen-flask combustion. The average absolute error for 10 determinations (3 compounds) amounted to +/-0.6%; one determination takes less than one hour.