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

Abstract

Nickel(II) of 0.04-1.4mmol dm^-3 and palladium(II) of 1-32μmol dm^-3 were extracted quantitatively into chloroform from the aqueous phases containing 0.2mol dm^-3 and 2mmol dm^-3O, O′-diethyldithiophosphate(dtp^-) at pH 1-7 and 1-13, and determined at 385nm (ε=8.4×10²mol^-1 dm³ cm^-1) and 298nm (ε=2.9×10⁴mol^-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 10mmol 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.