Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II)

Two sensitive, spectrophotometric and atomic absorption spectrometric proce dures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophoto metrically under the optimum condition, the ternary complexes showed an abs orption maximum at 535 nm, with apparent molar absorptivities of 6.55 and 4 .00 x 10(3) mol(-1)cm(-1) and Sandell's sensitivities of 5.80 x 10(-2) and 1.04 x 10(-1) mu g cm(-2) for perindopril and ramipril, respectively. The s olution of ternary complex obeyed Beer's law in concentration ranges 10-60 and 20-100 mu g ml(-1) for perindopril and ramipril, respectively. The prop osed method was applied to the determination of the two cited drugs in phar maceutical tablets. The atomic absorption spectrometric method, directly th rough the quantitative determination of copper content of the organic extra ct of the complex, was also investigated for the purpose of enhancing the s ensitivity of the determination. The spectrophotometric and atomic absorpti on spectrometric procedures hold their accuracy and precision well when app lied to the determination of ramipril and perindopril dosage forms. (C) 199 9 Elsevier Science B.V. All rights reserved.