Study of Solid Phase Extraction Prior to Spectrophotometric Determination of Platinum with N-(3,5-Dimethylphenyl)-N'-(4-Aminobenzenesulfonate)-Thiourea

摘要

A highly sensitive,selective and rapid method for the determination of platinum based on the rapid reaction of platinum(IV) with N-(3,5-dimethylphenyl)-N'-(4-aminobenzenesulfonate)-thiourea (DMMPT) and the solid phase extraction of the Pt(IV)-DMMPT complex with C_(18) membrane disks was developed.In the presence of pH = 3.8 buffer solution and cetyl trimethylammonium bromide (CTMAB) medium,DMMPT reacts with platinum to form a violet complex of a molar ratio of 1:3 (platinum to DMMPT).This complex was enriched by solid phase extraction with C_(18) membrane disks,and an enrichment factor of 200 was obtained.The molar absorptivity of the complex is 9.51 x 10~4 L centre dot mol~(-1) centre dot cm~(-1) at 755 nm,and Beer's law is obeyed in the range of 0.01-3.0 mu g mL~(-1) in the measured solution.The relative standard deviation for eleven replicate samples of 0.01 mu g mL~(-1) level is 1.79%.The detection limit reaches 0.02 mu g L~(-1) in the original samples.This method was applied to the determination of platinum in water and soil samples.The relative standard deviations are 2.9-3.4%.The recoveries are 94-105%.The values of determination obtained agree with those of the ICP-MS method.The results are satisfactory.