铑(Ⅲ)与5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯配合物催化氢波研究及其应用

Studies on the Catalytic Hydrogen Wave of Rhodium(Ⅲ) with 5-(5-Iodine-2-pyridylazo)-2, 4-diaminotoluene Complex and Its Application

建立了催化极谱法测定超痕量铑(Ⅲ)的新方法,在0.1mol.L-1 HAc-NaAc底液(pH=4.8)中,铑(Ⅲ)与5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)反应形成稳定配合物,并在适量HClO4底液中于-1.02V(vs.SCE)处产生灵敏极谱催化波。该催化波一阶导数峰电流i′p与铑(Ⅲ)浓度在9.7×10-12～3.9×10-9 mol.L-1范围内成良好线性关系,检出限达3.0×10-12 mol.L-1。研究证明该波为铑(Ⅲ)-5-I-PADAT配合物的催化氢波,其电极过程为不可逆过程。方法用于铑炭催化剂中铑的测定,结果较好。

A new sensitive analysis method for determining rhodium by catalytic polarography was established. The stable complex of rhodium with 5-（5-iodine-2-pyridylazo）-2, 4-diaminotoluene （5-I- PADAT） can produce a sensitive polarographic catalytic wave in 0. 1 moloL-1 HAc-NaAc（pH=4.8） buffer solution which was acidized with perchloric acid at -1.02 V（vs. SCE ）. The first-order derivative peak current was linear in the range of 9.7 × 10^-12-3.9 × 10^-9 molo L -1 for Rh（ III） and the detection limit was 3. 1 × 10 ^-13 g · mL- 1. The common metal ions did not interfere with the determination of rhodium. The method could tolerate Au （ III ） in 1 000 times, Ag （I）, Os （III ） and Pd （II） in 400 times, Ir （III） and Pt（IV） in 200 times, and Ru（II） in 10 times of Rh（III）. The properties and the reaction mechanism of the catalytic wave were studied. It was proved that the wave was a catalytic hydrogen wave of the complex of rhodium with 5-I-PADAT, and the electrode process was an irreversible reduction reaction and one electron was transferred in the process. The method was used successfully to determine trace rhodium in Rhodium-Carbon catalyst and GBW07198.