Enhanced elution of angiotensin converting enzyme inhibitors in ion chromatography: Application to their simultaneous quantitation in formulations and human plasma

In this paper, ion chromatography is utilized as a superior alternative to HPLC for analysis of angiotensin converting enzyme (ACE) inhibitors. A low-capacity weak cation exchanger functionalized with carboxylic acid groups (Dionex IonPac SCS1) is used in which the cation exchange separation mechanism predominates over the hydrophobic interactions that happen in most HPLC columns. This leads to much improvement of studied drugs peak profiles, which permits their analysis at normal temperature and ordinary pH with satisfactory accuracy and precision results. The developed procedure was applied for simultaneous analysis of the studied drugs in their tablets with recovery results ranging from 98 to103% with %RSD not exceeding 3.41 for all drugs. Water Oasis HLB sorbent cartridges were used for human plasma sample purification that permits satisfactory extraction recovery even for hydrophilic compounds like enalaprilat and lisinopril that have significant loss from regular RP cartridges. The recovery results lie in the range of 98-103 for all drugs with LOD equals to 10, 15, 10, and 20 ng mL− 1 for benazepril, enalapril, enalaprilat, and lisinopril, respectively. The method proved successful for drug routine analysis saving time, effort, and elaboration.