Analytical application of a new pyrazolditiocarboxylic acid reagent for determination of Pd(II) and Rh(III)

Spectrophotometric methods were described for the determination of Pd(II) a nd Rh(III) based on the formation of colored complexes with pyrazoldithioca rboxylic acid (PDT). The Pd(II)- and Rh(III)- PDT complexes were formed in the pH ranges 8.4 - 9.8 and 5.0 - 5.8 with molar absorptivities 6.28 x 10(4 ) and 5.45 x 10(4) 1 mol(-1) cm(-1) at 428 and 414 nm, respectively. The ca libration graphs were rectilinear in the ranges 0.1 - 1.7 and 0.09 - 1.9 mu g mL(-1) with detection limits of 0.077 and 0.08 mu g mL(-1) of Pd(II) and Rh(lII), respectively. The r.s.d (n=10) for the determination of 0.38 and 0.88 mu g mL(-1) were 0.18 and 1.1% respectively. The ionization constants of the reagent and the stability constants of the complexes were evaluated, The methods were practically free from interferences of common metal ions and anions. The methods were utilized to determine Pd and Rh in phosphate r ocks and Pd in activated charcoal and.