Biosensor for enantioselective analysis of S-cilazapril, S-trandolapril, and S-pentopril

The purpose of this research was to construct an amperometric biosensor on L-amino acid oxidase (L-AAOD) supported on a carbon paste for the enantioselective analysis of S-cilazapril (I), S-trandolapril (II), and S-pentopril (III). A chemically modified carbon paste was constructed with L-AAOD. The proposed amperometric biosensor proved reliable for the purity of I, II, and III. The linear working ranges obtained for drug assay were 0.001-100 mumol/l (I), 0.02-10 mumol/l (II), 0.08-50 mumol/l (III) over the pH ranges 7.0-7.4 (I), 6.8-7.4 (II), and 7.0-7.4 (III). The low limits of detection obtained were 5 pmol/l (I), 15 mumol/l (II), and 5 mumol/l (III), respectively. The selectivity of the biosensors was checked by both mixed and separate solution methods. Polyvinylpyrolidone and D-proline did not interfere with the assay of the studied drugs, whereas L-proline presented a potent interfering species. The relative standard deviation values (< 0.2%) make the biosensors suitable for direct amperometric assay of these angiotensin-converting enzyme (ACE) inhibitors. The proposed amperometric biosensor that was based on L-AAOD proved reliable in the analysis of the above-mentioned ACE inhibitors and can be used for the quality control of these drugs.