SPECTROPHOTOMETRIC DETERMINATION OF PALLADIUM(II) AND RHODIUM(III) USING N,N'-DIPYRIDYLTHIOUREA AS A NEW SENSITIVE AND SELECTIVE COMPLEXINGAGENT

N,N'-Dipyridylthiourea (DPyT) reacts with Pd-II and Rh-II to form stab le coloured complexes having lambda(max) at 330 and 335 nm respectivel y. The complexes obey Beer's law over the concentration range of 0.24- 2.88 mu g ml(-1) for Pd and 0.60-3.56 mu g ml(-1) for Rh. In the prese nce of moderate excess of diverse ions both Pd-II and Rh-III can be de termined successfully with DPyT. The molar extinction coefficient and Sandell sensitivity values for the palladium complex are respectively 2.36 x 10(4) dm(3) mol(-1) cm(-1), 0.0065 mu g ml(-1) and those for rh odium 1.5 x 10(4) dm(3) mol(-1) cm(-1), and 0.0065 mu g ml(-1).