GRAVIMETRIC AND SPECTROPHOTOMETRIC DETERMINATION OF PALLADIUM, RHODIUM AND RUTHENIUM WITH THIOSALICYLAMIDE

Thiosalicylamide is proposed for the gravimetric and spectrophotometric determination of palladium, rhodium and ruthenium. The precipitates formed with palladium, rhodium and ruthenium can be dried at 110°-120° for direct weighing and correspond to Pd(C7H7ONS)4Cl2, Rh(C7H6ONS) 3 and Ru(C7H6ONS)2 respectively. Palladium can be separated from rhodium or ruthenium in highly acidic solution ; under suitable conditions, Co, Ni, Mn, Fe, Zn, Mo(VI), W(VI), Al, Ga, In, V(V), Ir, etc., do not interfere. The metal-thiosalicylamide complexes form coloured solutions in common organic solvents, so that spectrophotometric determinations are possible. The Pd complex is dissolved in 50% ethanol whereas the rhodium or ruthenium complex is extracted with a mixture of isobutyl methyl ketone and ethanol. Maximum absorbance is obtained at 350, 380 and 390 nm, and the molar absorptivities are 39,300, 7000 and 6330 for the Pd, Rh and Ru complexes, respectively. Few ions interfere. © 1969.