Spectrophotometric and Derivative Spectrophotometric Study of the Reaction of Palladium(II) and Rhodium (III) with 5-(3,4-Methoxyhydroxybenzylidene)rhodanine and Cationic Surfactants

摘要

Spectrophotometric and derivative spectrophotometric methods for the determination of Pd(II) and Rh(III) are proposed. Pd(II) forms with 5-(3,4-methoxyhydroxybenzylidene)rhodanine [3,4-MHBR], in the absence and presence of cetylpyridinium bromide [CPB], 1:4 binary and 1:3:4 ternary complexes having molar absorptivities of 5.77 x 104 and 7.46 x 104 M~ l cm"x at 525 and 530nm, respectively. Rh(III) forms a 1:4 complex with 3,4-MHBR in the presence of cetyltrimethylammomum bromide [CTAB], which gives a maximum absorbance at 445 nm with a molar absorptivity of 5.13 x 104M~1cm~1. Derivative spectrophotometric methods are employed for the determination of Pd(II) and Rh(III) at ng ml"1 levels utilizing these complexes. Under the optimum conditions the calibration lines for Pd(II) and Rh(III) determination fit the equations d^A/dl4 = 1.10 x 106 [Pd] - 0.018 (r = 0.9967) and d4A/dX4 = 2.25 x 106 [Rh] + 0.03 (r= 1.0426) and have detection limits of 5.6 and 1.2ngmr respectively. The influences of experimental variables and foreign ions are studied. The methods are free of interference from most common metal ions and anions. The results of the analysis of some synthetic mixtures of Pd(II) and Rh(III) are reported.