Development of an automated on-line electrochemical chlorite ion sensor

• Published in: Talanta (Oxford) Vol. 94; pp. 227 - 231
• Main Authors: Myers, John N., Steinecker, William H., Sandlin, Zechariah D., Cox, James A., Gordon, Gilbert, Pacey, Gilbert E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30.05.2012; Elsevier
• Subjects: Analytical chemistry; Anions; Automated; Automation, Laboratory; Calibration; Chemistry; Chlorides - analysis; Chlorite ion; Chlorites; Drinking Water - chemistry; Electrochemical methods; Electrochemical probe; Electrochemical Techniques; Electrolytic cells; Exact sciences and technology; Flow Injection Analysis; General, instrumentation; Halogenation; Humans; Limit of Detection; Liquids; Oxidation; Oxidation-Reduction; Perchlorates; Reproducibility of Results; Sensors; Voltammetry; Water Pollutants, Chemical - analysis; Electrochemical probe; Chlorite ion; Flow injection analysis; Water; On line; Electrochemical method; Nitrates; Time; Probe; Cyclic voltammetry; Signal; DBP; Detection limit; Amperometry; Standard curve; Oxidation; Coupling; Monitoring; Flow injection; Automation; Stability; Chlorates; Chemical sensor; Perchlorates; Electrochemical detector; Automatic processing; Resistance; Lifetime; Transfer; Regulation; Automatic analysis; Detection
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2012.03.026

► Selectivity for chlorite ion. ► Not affected by electrolyte concentration in the in-line flow system. ► The electrochemical probe is based on sol–gel chemistry. ► The sensor system compared well to the approved ion chromatography method. A sensor system for the automatic, in-line, determination of chlorite ion is reported. Electroanalytical measurements were performed in electrolyte-free liquids by using an electrochemical probe (EC), which enables in-line detection in high-resistance media such as disinfected water. Cyclic voltammetry scan rate studies suggest that the current arising from the oxidation of chlorite ion at an EC probe is mass-transfer limited. By coupling FIA with an EC probe amperometric cell, automated analysis was achieved. This sensor is intended to fulfill the daily monitoring requirements of the EPA DBP regulations for chlorite ion. Detection limits of 0.02–0.13mg/L were attained, which is about one order of magnitude below the MRDL. The sensor showed no faradaic signal for perchlorate, chlorate, or nitrate. The lifetime and stability of the sensor were investigated by measuring calibration curves over time under constant-flow conditions. Detection limits of <0.1mg/L were repeatedly achieved over a period of three weeks.