Extraction-Spectrophotometric Determination of Nickel(II) and Palladium(II) with O,O′-Diethyldithiophosphate1

Abstract

Nickel(II) of 0.04–1,4 mmol dm^-3 and palladium(II) of 1–32 μmol dm^-3 were extracted quantitatively into chloroform from the aqueous phases containing 0.2 mol dm^-3 and 2 mmol dm^-3 O,O’-diethyldithiophosphate(dtp^-) at pH 1–7 and 1–13, and determined at 385 nm(ε=8.4×102 mol^-1 dm³ cm^-1) and 298 nm(e=2.9×104 mol^-1 dm³ cm^-1), respectively. The determination of nickel was affected with many diverse ions, but that of palladium was hardly affected with them except copper(II), tin(II), antimony(III), silver(I), mercury(II), gold(III), osmium(VIII), and nitrite ion by using 10 mmol dm^-3 EDTA as a masking agent. The extracted species of nickel(II) and palladium(II) were [Ni(dtp)₂] and [Pd(dtp)₂], respectively. The stability and distribution constants for the nickel(II) complex were determined as 1.3×10 (mol dm^-3)^-2 and 1.0×103, respectively. The palladium(II) complex was, however, too stable to determine the constants.