A NOVEL AND HIGHLY SENSITIVE CATALYTIC METHOD WITH OSCILLOPOLAROGRAPHIC DETECTION FOR THE DETERMINATION OF ULTRATRACE AMOUNTS OF IRIDIUM

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100-degrees, and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.