【摘要】 本文报道了在乙醇存在下,以2-(5-溴-2-噻唑偶氮)-5-二甲氨基苯甲酸(简称5-Br-TAMB)作为显色剂同时测定Pd(Ⅱ)Rh(Ⅲ)的新体系。试验表明,在40%乙醇-水溶液中,于pH 3.0～4.1范围内,Pd(Ⅱ)与显色剂形成1:1螯合物。其最大吸收峰位于685nm,表观摩尔吸光系数为5.6×10~4。Rh(Ⅲ)在pH 3.8～7.0范围内与显色剂形成1:2螯合物,其最大吸收峰位于678nm,表观摩尔吸光系数为1.1×10~5。由于在室温下仅Pd(Ⅱ)与试剂反应,而Rh(Ⅲ)则需在加热情况下才能反应,基于这一差异,建立了一个同时测定痕量Pd(Ⅱ)、Rh(Ⅲ)的新方法。更多还原

【Abstract】 A new photometric method for simultaneous determination of palladium （Ⅱ） and rhodium（Ⅲ） has been developed using 2-（5-bromo-2-thiazolyazo）-5-dimethylaminobenzoic acid （5-Br-TAMB） as chromogenic reagent in 40%C₂H₅OH solution. In a medium of pH 4.0, palladium （Ⅱ） reacts with 5-Br-TAMB after 30 min at room temperature to form a 1:1 complex, and rhodium （Ⅲ） reacts with it by heating in boiling water bath for 5 min to form a 1:2 complex. The complex of palladium has a maximum absorption at 685nm. Its apparent molar absorptivity is 5.6×10⁴. Beer’s law is obeyed for Pd 0～25μg/25ml, while Rh-5-Br-TAMB has a maximum absorption at 678nm with apparent molar absorptivity of 1.1×10⁵, and adheres to a linearity of Rh 0～12μg/25ml. Using NaF and EDTA as masking agents common ions and other platinum elements do not interfere. The method has been applied to the simultaneous determination of traces of Pd and Rh in some samples with satisfactory results.更多还原