Flow injection analysis using carbon film resistor electrodes for amperometric determination of ambroxol

Flow injection analysis (FIA) using a carbon film sensor for amperometric detection was explored for ambroxol analysis in pharmaceutical formulations. The specially designed flow cell designed in the lab generated sharp and reproducible current peaks, with a wide linear dynamic range from 5 × 10−7 to 3.5 × 10−4 mol L−1, in 0.1 mol L−1 sulfuric acid electrolyte, as well as high sensitivity, 0.110 A mol−1 L cm−2 at the optimized flow rate. A detection limit of 7.6 × 10−8 mol L−1 and a sampling frequency of 50 determinations per hour were achieved, employing injected volumes of 100 μL and a flow rate of 2.0 mL min−1. The repeatability, expressed as R.S.D. for successive and alternated injections of 6.0 × 10−6 and 6.0 × 10−5 mol L−1 ambroxol solutions, was 3.0 and 1.5%, respectively, without any noticeable memory effect between injections. The proposed method was applied to the analysis of ambroxol in pharmaceutical samples and the results obtained were compared with UV spectrophotometric and acid–base titrimetric methods. Good agreement between the results utilizing the three methods and the labeled values was achieved, corroborating the good performance of the proposed electrochemical methodology for ambroxol analysis.