Evaluation of on-line preconcentration and flow-injection amperometry for phosphate determination in fresh and marine waters

• Main Authors: Y. Udnan, I. D. McKelvie, M. R. Grace, J. Jakmunee, K. Grudpan
• Format: Journal
• Published: 2018
• Subjects: Chemistry
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=17744362273&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/62149
• Institution: Chiang Mai University

Dissolved reactive phosphorus (DRP) was determined as orthophosphate (PO4-P) in fresh and saline water samples by flow-injection (FI) amperometry, without and with in-valve column preconcentration. Detection is based on reduction of the product formed from the reaction of DRP with acidic molybdate at a glassy carbon working electrode (GCE) at 220 mV versus the Ag/AgCl reference electrode. A 0.1 M potassium chloride solution was used as both supporting electrolyte and eluent in the preconcentration system. For the FI configuration without preconcentration, a detection limit of 3.4 μg P l-1and sample throughput of 70 samples h-1were achieved. The relative standard deviations for 50 and 500 μg P l-1orthophosphate standards were 5.2 and 5.9%, respectively. By incorporating an ion exchange preconcentration column, a detection limit of 0.18 μg P l-1was obtained for a 2-min preconcentration time (R.S.D.s for 0.1 and 1 μg P l-1standards were 22 and 1.0%, respectively). Potential interference from silicate, sulfide, organic phosphates and sodium chloride were investigated. Both the systems were applied to the analysis of certified reference materials and water samples. © 2005 Elsevier B.V. All rights reserved.