Extraction spectrophotometric determination of micro amounts of palladium(II) in catalysts

A new reagent, 4-(2'-furalideneimino)-3-methyl-5-mercapto-1,2,4-triazole, has been synthesized and used as a chromogenic reagent for palladium(II). Palladium(11) has been extracted as a yellow complex (lambda(max) 410 nm) from an aqueous solution at pH 5.4 with FIMMT in n-butanol. The molar extinction coefficient and Sandell's sensitivity are 1.4 x 10(3) L mol(-1) cm(-1) and 0.073 mu g cm(-2), respectively. The effects of pH, reagent concentration, solvent, shaking time and stability of the complex have been studied. The complex system confirms to Beer's law over the range 5-50 ppm of palladium(II) with optimum range 17-50 ppm of the metal as evaluated from Ringbom's plot. The tolerance limit for many metal ions has been determined. The method has been applied successfully for the determination of palladium(II) in synthetic mixtures corresponding to alloys and palladium(II) in various hydrogenation catalysts.