Sub-second adsorption for sub-nanomolar monitoring of metoclopramide by fast stripping continuous cyclic voltammetry

In this work a novel indirect method for the determination of metoclopramide (MET) in flow-injection systems by fast stripping continuous cyclic voltammetry (FSCCV) has been developed. The proposed method was used for the fast determination of metoclopramide in its pharmaceutical formulations. The developed technique is very simple, precise, accurate and time saving, compared to all of the previously reported methods. The effects of various parameters on the sensitivity of the method were investigated. The best performance was obtained within the pH value of 2.0 and sweep rate value of 20 V/s, accumulation potential of −700 mV and accumulation time of 0.1 s. The proposed method has some advantages, the greatest of which are: (1) removing of oxygen from the test solution is not necessary; (2) very low detection limit; and (3) it is fast enough for the determination of any such compound, in a wide variety of chromatographic methods. The potential waveform, consisting of the potential steps for cleaning, accumulation and potential ramp of analyte, was applied on an Au disk microelectrode (with a radius of 12.5 μm) in a continuous way. The detection limit of the method for metoclopramide was 1.0 × 10−11 M (3 pg/ml). The relative standard deviation of the method at 1.0 × 10−10 M was 2.0% for 8 runs.