SPECTROPHOTOMETRIC INVESTIGATION ON COMPLEX-FORMATION OF CAPTOPRIL WITH PALLADIUM(II) AND ITS ANALYTICAL APPLICATION

The formation of the complex between captopril and palladium(II) Chloride in Britton-Robinson buffer solution was studied. It has been established that captopril reacts with palladium(II) chloride in the pH range 2.14-9.10 to form a yellow water - soluble 2:1 complex with maximum absorbance at 380 nm. By applying different spectrophotometric methods, the conditional stability constant of the complex at the optimum pH of 4.03 and ionic strength mu = 0.5 M was found to be 10(8.25). The molar absorptivity was 1.875 x 10(3) l mel(-1) cm(-1). Beer's law was obeyed in concentrations up to 5 x 10(-4) M captopril. The detection limit was 2.17 mu g ml(-1) and the relative standard deviation varied from 1.24 to 1.68%. The proposed method was found to be suitable for the accurate and reproducible analysis of captopril in water and in tablets.