Batch Injection Coulometry Based Absolute Quantitative Analysis for Detecting Chlorine Dioxide

In this work, we describe the absolute quantitative analysis of a chlorine dioxide (ClO2) based on a batch injection coulometry. The oxidation/reduction waves between ClO2 and the chlorate ion (ClO3−) in the cyclic voltammogram could be observed by using a carbon felt electrode in an acidic medium. The electrochemical performance for the electrode oxidation of ClO2 has successfully been applied to the batch injection coulometric determinations of ClO2 in water. The typical current response vs. time curve was measured by the repetitive determination of ClO2, and the measurement of ClO2 was fully completed in a short time (∼20 s). The relative standard deviation (RSD) for fifteen successive measurements was found to be 2.98 %, indicating the good reproducibility of batch injection coulometric determinations. The oxidation current was actually increased as the sample solution volume increased. This fact indicates that the current response was generated by the electrode oxidation of ClO2. The electrical charge was proportional to the concentration range from 3 to 1000 ppm with a good linearity. The experimental value of the electrical charge for the electrode oxidation of ClO2 corresponding to the theoretical value of the electrical charge for the electrode oxidation of ClO2. Thus, the electrolysis efficiency for the ClO2 is expected to be nearly 100 % because extremely rapid determination is realized. Herein, our proposed batch injection coulometry is proven to be very promising for ClO2 measurements without calibration curves for sensor in practical applications.