Analytical optimization of liquid-liquid extractive spectrophotometric assessment protocol for tetravalent platinum: Analysis of environmental samples and cisplatin.

An easy and reliable method is optimized for extractive spectrophotometric assessment of platinum(IV) with 4-(4'-nitrobenzylideneimino)-3-methyl-5-mercapto-1,2,4-triazole as an extractant. The basis of this method is the formation of red platinum(IV) complex with the above reagent in acetate buffer medium (pH 5.0) and extraction in chloroform. Good linearity with regression equation as y = 1.011 × 104 ×  + 0.002 having correlation coefficient (R2) of 0.998 over concentration up to 17.5 µg mL-1 of platinum(IV) was achieved with apparent molar absorptivity of 1.011 × 104 L mol-1 cm-1. The limit of detection (0.22 µg mL-1), limit of quantification (0.73 µg mL-1) and Sandell's sensitivity (0.0193 µg cm-2) were also estimated. The interference of various cations was removed by using proper masking agents and consequently by using EDTA and citrate to mask certain transition metals, the method becomes highly specific for platinum(IV), including the effects of platinum group metals. The method is effectively used for determination of platinum(IV) from environmental and real samples such as alloys, catalysts, thermocouple wire and pharmaceutical sample.