NaOH Pretreated Molybdate-Carbon Paste Electrode for the Determination of Phosphate in Seawater by Square Wave Voltammetry with Impedimetric Evaluation

Phosphate (PO 4 3? ) is an important nutrient for phytoplankton growth and at high loadings can result in water quality deteriorations. Autonomous PO measurements are required monitoring purposes, best achieved using sensitive, portable low-cost techniques. Here we describe a new electrochemical sensor detection seawater. The quantification of typically depends on the reaction between molybdate under acidic conditions to form phosphomolybdic complex, which electrochemically active. In this work, prepared carbon paste electrode (CPE) modified with pretreated 0.1 M NaOH cyclic voltammetry (CV). CPE was employed determination artificial seawater (35 g l ?1 NaCl) acidified sulfuric acid pH 0.8. analytical conditions, including pH, waiting time complexation, square wave amplitude frequency, were optimized. An additional cleaning step (cyclic (CV)) 10 cycles ?0.5 0.5 V determinations dissolve complex formed surface working electrode. Electrochemical impedance spectroscopy (EIS) results confirmed that molybdate-modified (molybdate/CPE) exhibited low charge-transfer resistance (R ct toward , showed improved performance different concentrations . A calibration plot range 0.01–5 ? limit (LOD) 0.003 obtained. proposed demonstrated good precision (4.3% 5.8%) 5 0.2 M, respectively. method analyze samples research cruise North Sea, close agreement those obtained conventional colorimetric measurements.