A simple flow system with multiple pulse amperometric detection using a single working electrode is proposed for simultaneous determination of ascorbic (AA) and acetylsalicylic (AAS) acids in pharmaceutical formulations. The procedure is based on application of two potential pulses: 0.90 V/50 ms: oxidation and determination of AA without the interference of AAS; 1.35 V/50 ms: oxidation of both compounds and quantification of AAS by current subtraction using a correction factor. Sampling rate was estimated as 125 injections per hour and the limits of detection were 0.17 and 0.16 µmol L-1 for AA and AAS, respectively. Results for commercial samples agreed with those obtained using HPLC.
simultaneous determination; FIA; multiple pulse amperometry
