Palladium Ternary Complex with Chromeazurol S and Cetyltrimethylainmonium Bromide and Cetylpyridinium Bromide

Formation of green coloured ternary complexes between palladium, chromeazurol S and cetyltrimethylammonium bromide or cetylpyridinium bromide is described over the pH range 4.6 to 5.6. The compositions, Pd(CAS)CTA2 and Pd(CAS)CP2 for the ternary complexes have been established by Job's method of continuous variations and by the mole ratio method using absorbance data. Strict control of experimental conditions is essential for employing these methods for the determination of composition. The ternary systems obey Beer's law between 0.053 to 2.98 ppm of palladium. A high molar absorptivity (Pd-CAS-CTAB, 5.25 x 104 ; Pd-CAS-CPB, 6.16 X 104 mo1-1 cm-1) and Sandell's sensitivity (0.002 ~tg cm-2) have been obtained at 620 nm. A spectrophotometric method has been proposed using these ternary complexes for microdetermination of palladium. The method is sensitive, precise and selective. The effect of various cations and anions is studied. The mode of formation and structures of the ternary complexes are discussed.