Colour reaction of platinum(II) with 5-(4-nitrophenylazo)-8-(p-toluenesulphonamido)-quinoline and its analytical applications

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of platinum. 5-(4-Nitrophenylazo)-8-(p-toluenesulphonamido)quinoline (NPTSQ) reacts with platinum(II) almost instantaneously in alkaline solution to form a violet-red 1:2 complex with an absorption maximum at 640 nm. Beer's law is obeyed over the concentration range 0-1 mug/ml platinum. The molar absorptivity is 1.37 x 10(5) 1.mole(-1).cm(-1). The method has been used for the determination of microamounts of platinum in catalysts and anode slime.