IODOMETRIC DETERMINATION OF GOLD AND PLATINUM BY 168-FOLD AND 126-FOLD CHEMICAL AMPLIFICATION REACTIONS

A simple, low cost method is described for the determination of gold(I ) and platinum(II) at the mu g level with 8- and 6-fold amplification, respectively. The method is based on oxidation in a solution (pH 2.4- 4.3) of gold(I) or platinum(II) with aqueous potassium periodate, mask ing the unreacted periodate with molybdate and iodometric determinatio n of the produced iodate and gold(III) or platinum(IV). The sensitivit y of the proposed method can be enhanced by separation of the liberate d iodine on a polyurethane foam column, and oxidizing the collected io dine with an excess of periodate. The iodate produced in the effluent and washing solution is then titrated iodometrically after masking the excess periodate. This procedure offers a 168- and 126-fold amplifica tion for gold(I) and platinum(II), respectively. Analysis of the binar y mixtures of gold(I) and (III) or platinum(II) and (IV) in aqueous so lution has been carried out successfully.