在稀硫酸介质中,钯(Ⅱ)对高碘酸钾氧化甲基百里酚蓝褪色具有明显的催化作用,且褪色程度与钯(Ⅱ)的量在85 μg·L-1以内呈线性关系.在选定试验条件下,非催化反应体系与催化反应体系的最大吸收波长均为441 nm,据此建立了一种痕量钯的分光光度测定法.检出限为5.23×10-6g·L-1,催化反应的表观活化能为60.03 kJ·mol-1.该方法用于含钯催化剂中钯的测定,回收率为97.8%~100.8%,相对标准偏差为1.54%~2.01%.

It was found that the oxidative decoloration of methyl thymol blue (MTB) by potassium periodate was catalyzed by the presence of trace amounts of palladium(Ⅱ),and that a linear relationship between magnitude of decrease in absorbance of the reaction system and concentration of palladium was obtained in the range within 85 μg·L-1,with detection limit (S/N=3) of 5.23×10-6g·L-1.Base on these facts,a new catalytic spectrophotometric method for determination of Pd(Ⅱ) in trace amounts was proposed.Measurements of absorbance were made at the wavelength of 441 nm,which is the absorption maximum of methyl thymol blue under the selected reaction condition.Apparent activation energy of this catalytic reaction is found to be 60.03 kJ·mol-1.The proposed method has been applied to the determination of palladium in samples of palladium containing catalyt,giving values of RSD′s (n=5) and recovery in the ranges of 1.54%-2.01% and 97.8%-100.8% respectively.