Extraction of chloroplatinate(II)– 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol-(TX-100)-<i style="">N</i>-hydroxy-<i style="">N,N’</i>- diphenylbenzamidine complex

Abstract

138-143A sensitive and selective spectrophotometric method, developed for the determination of trace amounts of platinum, is based on the formation of platinum as a mixed complex with 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol (5-Br-PADAP) and TX-100 or triton X-100 (Polyethylene-di-isobutyl-glycol-ether) from 0.1M SnCl2 in to HCl and extraction with N-hydroxy-N,N’-diphenylbenzamidine (HDPBA) in dichloromethane. The violet coloured Pt(II)- 5-Br-PADAP-(TX-100)–HDPBA complex in dichloromethane shows maximum absorbance at 575 nm with molar absorptivity value of 6.0x104 dm3/mol/cm. The repeatability of the method was checked by finding relative standard deviation (RSD, n=10) value for solutions each containing 1.5 g/cm2 Pt(II) and the RSD value of the method was found to be 1.5%. The system obeyed Beer’s law up to 2.1 mg/cm2 of platinum and the detection limit of the method is 20 ng/cm2 on a three times the standard deviation of the blank absorbance basis. High concentration of foreign ions, with the exception of palladium, does not interfere with the determination of platinum. The proposed method has been applied for determination of platinum in automobile exhaust sample, soil and vegetation samples