Synergistic extraction and spectrophotometric determination of palladium(II), iron(III), and tellurium(IV) at trace level by newly synthesized p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene

A spectrophotometric method for the determination of palladium, iron and tellurium from nitric acid media after extraction of their p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene [DMIAPAC] complexes has been developed and possible synergistic effects have been investigated. Chloroform, carbon tetrachloride, cyclohexane, 1,2-dichloroethane, toluene and xylene were used as the diluents. The maximum enhancement was obtained in the presence of 30% 1,2-dichloroethane. The trace amounts of metals were determined spectrophotometrically. Beer's law obeyed in the concentration range of 5.0-95.0 mu g, 8.0-120.0 mu g and 10.0-140.0 mu g/10 mL of the final solution of palladium, iron and tellurium, respectively. The molar absorptivities (l mol(-1)cm(-1)) and Sandell's sensitivities (mu g cm(-1)) were calculated: Pd(II) = 1.73 x 10(4) and 0.0061; Fe(III) = 1.08 x 10(4) and 0.0052; Te(IV) = 1.67 x 10(4) and 0.0077. Ten replicate analyses containing 20 mu g of Pd(II), 12.5 mu g of Fe(III) and 32 mu g of Te(IV) gave mean absorbance of 0.326, 0.242 and 0.418 with relative standard deviation of 0.36, 0.65 and 0.82% for Pd(II), Fe(III) and Te(IV), respectively. The interference of various ions was studied and optimum conditions were developed for the determination of these metals in certain alloys and synthetic mixtures.