Spectrophotometric determination of micro ruthenium(III) using 5-(5-chloro-2-pyridylazo)-2,4-diaminotoluene

The color reaction of ruthenium(Ⅲ) with 5 (5 chloro 2 pyridylazo) 2,4 diaminotoluene(5 Cl PADAT) was studies .The results showed that Ru(Ⅲ) reacted with 5 Cl PADAT to form a stable complex in the HAc NaAc medium at pH 4.0～6.5 in boiling water. By addition of mineral acid (HCl, HClO 4, H 2SO 4, H 3PO 4), its apparent molar absorptivity is 8.5×10 4 L·mol -1 ·cm -1 at 505 nm. The complex was stable for at least 24 h. The molar ratio of Ru(Ⅲ) to 5 Cl PADAT was found to be 1∶2. Beer′s law is obeyed in the rang of 0～6 μg/10 mL for Ru(Ⅲ).The proposed method was used for the determination of ruthenium in the synthesized samples with satisfactory results.