Differential electrolytic potentiometric detector in flow injection analysis and in micro titration

Abstract

Differential Electrolytic Potentiometric detector system is used in Flow Injection Analysis for the determination of Cyanides, Residual Chlorine and different types of Acid-Base reactions. The method is rapid, simple, less costly and precise compared to other techniques. The technique of direct current differential electrolytic potentiometry (dc DEP) consists of polarizing two identical electrodes with a heavily stabilized current and measuring the potential difference (ΔE) between them during the course of the reaction. It is almost the first time that this type of detector is used in Flow Injection Analysis. Univariate method was applied for the optimization of necessary parameters including the current density, coil length and the flow rate. It was observed that when small current densities were employed, the polarized electrode exhibited a sluggish response, hence the resulting signal was relatively small. The height of this signal was improved on increasing the current density but there are some limitations which do not allow to increase the current densities above 20μA.cm−1. The residence time of the sample is found to be inversely related to the flow rate and the coil length upto certain limit. The calibration curve obtained on these optimized parameters having good correlation coefficient between 0.975 to 0.999. The main objective of this research is to develop an analytical technique, which is fast, accurate, having minimum interference with other substances, by using simple, portable and inexpensive apparatus, especially for the detection of those substances which are of some environmental interest like chlorine and cyanides and Alhamdolillah it has been achieved.