Studies on color reaction of ruthenium(II) with 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline

A new method for determination of ruthenium(Ⅱ) was investigated. Ruthenium can react with 5 Br PADMA and form a green blue complex at pH range of 4.25～6.20 in boiling water bath in the presence of NH 2OH·HCl. The apparent molar absorptivity was found to be 9.27×10 4 L·mol -1 ·cm -1 in 40% ethanol aqueous solution at the maximum absorption of 619 nm. Beer's law is obeyed in the range of 0～0.80 mg/L for Ru(Ⅱ).Using EDTA as a masking reagent, most of the common ions did not interfere the determination of Ru(Ⅱ). The proposed method was applied to the spectrophotometric determination of micro Ru in synthetic and catalyst samples with satisfactory results.