ABSTRACT
A kinetic method for the detemination of trace rhodium based on the catalytic effect of Rh on the oxidative color reaction of diantipyry1-(p-dimethylamino)-phenylmethane (DAMAM) with potassium periodate in the H3PO4 medium and ot wateer bath was estabished. The optimum condition and kinetic parameters of this reaction were studied in detail. The linear range of the determination was 0～80μg/L, and the detection limit was 6.20×10-7g/L. The apparent activation energy og catalytic reaction was found to be 89.03kJ/mol, rate constant was 2.51×10-4/s. The system wasstable at least 6h. The method has been applid to determine trace rhodium in some catalyst samples with the relative standard deviation of 2.7%～3.2%(n=6) and recovery of 98.2%～103.2% (n=5).
ABSTRACT
The catalytic effect of ruthenium on the oxidation reacti on of methylene blue (MB) was investigated and applied for the determination of ruthenium(Ⅲ) by the kinetic spectrophotometry in the sulfuric acid medium at 90±0.5℃. The optimum reaction conditions, kinetic parameters and r eaction mechan ism were studied. The linear ranges for the determination of ruthenium (Ⅲ) were 0.0～1.2 and 1.2～5.6 μg/L with a detection limit of 0.05 μg/L . Almost no foreign ions more than 50-fold concentration of Ru(Ⅲ) I nterfered with the determination. The method, which was of high sensitivity, good selectivity and stability, was s uccessfully applied for the determination of trace ruthenium in some ores and m e tallurgical products, the RSD (n=8) was 1.3%～2．2％ and the recovery was between 99% and 105%.