科研之友
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摘要
In chronoamprometric methods, the current is usually measured at relatively long times, where the contribution of charging current is assumed to be negligible. Previously, we used a chemometric method to resolve numerically the total current which is composed of three pure currents namely net faradaic current, induced charging current and step charging current. In this work, we investigated the effect of analyte concentration on each current component to derive calibration curves for quantitative analyses. In potential step chronoamperometric method, a current data matrix is obtained for each concentration of the analyte. Simultaneous analysis of the data matrices obtained at different concentrations of the analyte by multivariate curve resolution-alternative least squares (MCR-ALS) analysis, produced the net contribution of three types of currents for each concentration of the analyte. Then, the calibration curves based on the faradaic and induced charging current contributions below five cell time constants were compared with the traditional calibration curve, which was based on the total current. In this manner, the linear range, limit of detection and analytical sensitivity of all kinds of calibration curves were compared with each other. The calibration curves obtained based on net faradaic current represented better analytical appraisals compared to those obtained by total current In addition, we found that at low analyte concentrations, the induced charging currents have insignificant contribution in total current, whereas it represented very significant contribution (even larger than net faradaic current) at high analyte concentrations. Also, the obtained calibration curves were used for prediction of unknown concentrations.
- 出版日期2015-10-15
