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

Abstract

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-1 and sample throughput of 70 samples h-1 were achieved. The relative standard deviations for 50 and 500 μ..