DIFFERENTIAL-PULSE POLAROGRAPHIC-DETERMINATION OF RHODIUM(III) AND RUTHENIUM(III) IN SYNTHETIC SAMPLES AFTER PRECONCENTRATION OF THEIR QUINOLIN-8-OLATE COMPLEXES ONTO MICROCRYSTALLINE NAPHTHALENE

Rhodium(III) and ruthenium(III) form water-insoluble quinolin-8-olate complexes that are quantitatively retained on microcrystalline naphtha lene in the pH ranges 5.1-6.8 and 4.0-6.5, respectively. The metal com plex is desorbed with 10 ml of 2 M HCl and determined using a differen tial pulse polarograph. The detection limits are 0.06 ppm for rhodium and 1.0 ppm for ruthenium. Linearity is maintained in the concentratio n ranges 0.25-7.50 ppm for rhodium and 2.0-60.0 ppm for ruthenium, wit h correlation factors of 0.9997 and 0.9994 and relative standard devia tions of 0.79 and 0.81%, respectively. The effects of various paramete rs such as pH, volume of aqueous phase, reagent and naphthalene concen trations, and interference of a large number of metal ions and anions on the determination of these metals were studied in detail to optimiz e the conditions for their trace determination in various synthetic sa mples corresponding to real samples. The method is found to be highly selective, fairly sensitive, simple, rapid, and economical and may be safely applied to their determination in different complex materials s uch as environmental samples and ores. (C) 1998 Academic Press.