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

A 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 <i style="">N</i>-hydroxy-<i style="">N,N</i>’-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 6.0x10⁴dm³/mol/cm. The repeatability of the method was checked by finding relative standard deviation (RSD, n=10) value for solutions each containing 1.5 <img src='/image/spc_char/micro.gif'> 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.