Automated Potentiometric Techniques for the On-Site Monitoring of Anion Concentrations in Water

摘要

Characteristics of several of the new non-glass ion-selective electrodes and of several reference electrodes were studied in detail with particular emphasis upon the nitrate ion-selective electrode. A new high accuracy standard addition technique for the potentiometric determination of nitrate ion in a cell without liquid junction using the fluoride electrode as a reference was developed. This method eliminates the liquid junction and dilution and activity coefficient changes cancel. The method is applicable to all monovalent anions for which an electrode is available and enables the determination of anion concentrations to within 1% relative accuracy. Low temperature potentiometric titrations of perchlorate and tetrafluoroborate ions with tetraphenylarsonium chloride and ion-selective electrodes were investigated and found to give high accuracy and reasonably good sensitivity for these ions. The nitrate electrode was used to follow nitrate ion concentration in microbial cultures. It was found to be useful for following nitrate ion reduction in situ. (Author)