Fast Fourier Transform Continuous Cyclic Voltammetry Development as a Highly Sensitive Detection System for Ultra Trace Monitoring of Thiamine

Application of a continuous square-wave potential program for sub nano molar determination of ketotifen

An electroanalytical method has been developed for the determination of the ketotifen by continuous square wave adsorptive stripping voltammetry on a ultra-gold microelectrode (Au UME) in aqueous solution with phosphate buffer as supporting electrolyte. The best adsorption conditions were found to be pH 2.3, an accumulation potential of 300 mV (Au vs. Ag: AgCl-KCl 3 M) and an accumulation time of 400 ms. Variation of admittance in the detection process is created by inhibition of oxidation reaction of the electrode surface, by adsorption of ketotifen. Furthermore, signal-to-noise ratio was significantly increased by application of discrete fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as square-wave frequency, eluent pH, and accumulation time were optimized. Effects of square-wave frequency, step potential and pulse amplitude were examined for the optimization of instrumental conditions. The calibration curve is linear in the range 2.0x10(-7)---5.0x10(-12) M with a detection limit of 2.0x10(-12) M (ca. 0.7 pg/ml). The method maybe applied direct determination of the drug in pharmaceutical and biological samples. For a concentration of 5.0x10(-8) M a recovery value of 99.89% is obtained.

Development of fast Fourier transformation continuous cyclic voltammetry as a highly sensitive detection system for ultra trace monitoring of penicillin V

Fast continuous cyclic voltammetry was used as a detection method for penicillin V in a flow injection system. Additionally, a special computer-based numerical calculation method (using fast Fourier transformation) providing enhancement of the analyte signal and noise reduction is introduced here. During the measurements, the potential waveform (consisting of the potential steps of cleaning, stripping, and the potential ramp) was continuously applied to an Au disk microelectrode (12.5 microm in radius). In particular, the effects of accumulation potential, sweep rate, and delay time on the sensitivity and selectivity of the method were investigated. Eventually, the stripping time was found to be less than 300 ms, the detection limit of the method was 7.0x10(-12) M, and the associated relative standard deviation at 5.0x10(-6) M penicillin V was 2.3 for eight runs.