Determination of palladium by solid phase extraction and spectrophotometry with p-rhodanineazobenzoic acid

Based on the color reaction of p-rhodanineazo benzoic acid(RABA) with palladium(Ⅱ) and the solid phase extraction of its colored complex with C18 cartridge,a new method for the determination of palladium was studied.In the presence of CTMAB and HCl-KHP buffer solution(pH 2.0～4.0) medium.RABA reacts with palladium(Ⅱ) to form a stable 1∶1 complex.The colored complex was extracted by C18 cartridge and the retained chelate was eluted from cartridge with ethanol,then can be determined by spectrophotometry at 500 nm.Beer′s law is obeyed in range of 0.1～1.0 μg/mL and e is 1.36×105 L·mol-1·cm-1.The method was applied to determination of the trace palladium in the Pt/Pd catalysts with a satisfactory result.