Square wave voltammetric determination of the angiotensin-converting enzyme inhibitors cilazapril, quinapril and ramipril in pharmaceutical formulations.Farmaco. 2003 May; 58(5):343-50.F
The angiotensin-converting enzyme inhibitors cilazapril, quinapril and ramipril are reduced at a hanging mercury drop electrode in the pH range 3.5-13 using Britton-Robinson buffers as supporting electrolyte and KCl as ionic medium. Square wave voltammetry has proved to be the most suitable electroanalytical technique for the quantitative voltammetric determination of these antihypertensive drugs. Optimisation of the chemical and instrumental variables was carried out. Analyses were performed in 0.02 M borate buffer at pH 9.5 and 0.5 M KCl as ionic medium, using a pulse amplitude of 50 mV and a frequency of 150 Hz. A linear relationship between peak current and concentration was found in the interval 0.5-8 microg/ml for cilazapril and up to 6 microg/ml for quinapril and ramipril, allowing the direct determination of their pharmaceutical formulations alone or mixed with hydrochlorothiazide. Good accuracy and repeatativity were obtained.