Fading kinetic spectrophotometric determination of trace ruthenium(III) based on catalytical action of ruthenium on reaction of bromophenol blue and potassium periodate

Ruthenium(Ⅲ) had significant catalytic effect on the fading reaction of bromophenol blue oxidized by potassium periodate in the medium of diluted sulfuric acid and sodium tetraborate at 85 ℃ water bath.On the basis of this fact,a novel method for determination of ruthenium(Ⅲ) was proposed by catalytic kinetic spectrophotometry.The experiment results indicated that the absorbency difference ΔA remained a good linear relationship with the mass concentration of ruthenium(Ⅲ) in the range of 9.6×10-4-4.4×10-2 μg/mL.Detection limit of this method was 1.506 × 10-10 g/mL.The catalytic reaction was a first order reaction for ruthenium(Ⅲ)) while the whole reaction was pseudo-first order reaction under the experiment condition with apparent rate constant of 4.137×10-3 /s and apparent activation energy of 56.45 kJ/mol.The determination was conducted on 1.0 μg of ruthenium(Ⅲ) in 25 mL of solution and the relative standard deviation was 1.3%(n=11).This method was applied to determine ruthenium(Ⅲ) in molecular sieve and activated carbon samples with the relative standard deviations(n=6) of 4.7% and 1.1% respectively and the recoveries of 98% and 102%.