Fast and Simple Electrochemical Analysis Kit for Quality Control of Narrow Therapeutic Index Drugs

The use of multiple-pulse amperometry (MPA) for the determination of narrow therapeutic index (NTI) drugs using batch injection analysis (BIA) with carbon screen-printed electrodes (SPE) is proposed, seeking to develop a practical and low-cost analysis kit for application in routine quality control of these drugs. The electrochemical behaviors of aminophylline, carbamazepine, clindamycin, colchicine, minoxidil, prazosin, procainamide, theophylline, warfarin and verapamil were evaluated in different electrolytes, but just one, the 0.1molL(-1) phosphate buffer, pH7.0, was chosen for determination of all the analytes. The amperometric detection was optimized as a function of the best oxidation potential for carbon SPE for each analyte, which was in a range from 0.7 to 1.1V. The injection conditions were determined as a function of the velocity and the volume injected by the BIA system, which were 92.5Ls(-1) and 100L, respectively. Under these conditions, a good repeatability (RSD<3%), high analytical frequency (>215 determinations per hour), large linear ranges and low LOD (<0.42molL(-1)) for all the NTI drugs were obtained. Furthermore, the proposed method provided an easy qualitative analysis of the investigated analytes using MPA detection. The addition-recovery studies in pharmaceutical samples containing NTI drugs and the comparison with official methods showed that the proposed analysis Kit is a very fast, simple and efficient alternative for quantification of these analytes.