Determinação de anião nitrato em águas por FIA usando um detector potenciométrico tubular

In this work, a flow injection system for the potentiometric determination of nitrate content in waters, is described. A tubular nitrate ion-selective electrode without inner reference solution and an ion-exchanger system composed of (4,7-diphenylphenanthroline) nickelII nitrate in o-nitrophenil octyl ether was used as indicator electrode. These units were evaluated in two ionic strength adjuster solutions and their operational characteristics compared with those of conventionally shaped electrodes with the more sensor systems. The developed methodology allows the determination at nitrate anion in waters without a high sample pretreatment and with a high sampling rate (ranging from 60 to 120 determinations per hour) and precision (relative standard deviations interior to 2%). Results are in good agreement with the reference procedure and the lower limit of linear response is 14.9 mg L1.