Novel method for fast determination of ultra trace amounts of timolol maleate by continuous cyclic voltammetry at Au microelectrode in flowing injection systems

A novel method for easy and fast detection of timolol maleate in flow-injection system has been introduced. It was used for analysis of timolol maleate in pure form as well as in its pharmaceutical formulations. The reported method is simple, precise, accurate, time saving and economic as compared to all previously reported methods. The best performance for measurement of timolol maleate was obtained at, pH 2.0, scans rate 300 V s−1, accumulation potential −500 mV and delay time 0.6 s. The advantages of the proposed detection method are, (1) the removal of oxygen from the test solution is not required any more, (2) the detection limit of the method is sub-micromolar, (3) this method is fast enough for determination of the drug compound, in a wide variety of chromatographic techniques. The potential waveform consists of potential steps for cleaning, accumulation and potential ramp that were continuously applied on an Au disk microelectrode (with a radius of 12.5 μm). The detection limit of the method for timolol maleate was 1.58 ng ml−1. The relative standard deviation of the method at 1.0 × 10−9 M was 2.3% for 20 runs.