Development of a Cobalt Electrode for the Determination of Phosphate in Soil Extracts and Comparison with Standard Methods
- 14 December 2017
- journal article
- research article
- Published by Taylor & Francis Ltd in Analytical Letters
- Vol. 51 (6), 834-848
- https://doi.org/10.1080/00032719.2017.1360899
Abstract
A phosphate-sensitive cobalt electrode was evaluated in detecting orthophosphate ions in ammonium lactate-acetic acid soil extracts. The dependence of the mixed potential of a cobalt electrode on concentration was investigated through potentiometry. The mechanism of detection is based on the consumption of a surface cobalt (II) oxide layer to form (Co-3(PO4)(2)), which leads to a concentration-dependent shift of the mixed potential. Two reference electrodes were evaluated: Ag/AgCl (3M) KCl and a platinum (Pt) wire. A linear response was observed using both reference electrodes. However, application of a Pt wire quasireference electrode increased the linear dynamic response range of the detector from 10-10(3)mgL(-1) or 10(-4)-10(-1)M (Ag/AgCl (3M) KCl) to 0.1-10(5)mgL(-1) or 10(-6)-10(1)M. In addition, the response time using the Pt wire was less than 5min compared to a minimum of 10min using Ag/AgCl (3M) KCl. There was close agreement between the response of the phosphate-sensitive cobalt electrode with a standard colorimetric method. As dissolved organic substances can potentially interfere with electrochemical techniques, an investigation into the use of a nonpolar resin for decolorization and removal of organic matter in soil extracts was performed and successfully used. The phosphate-sensitive cobalt electrode was found to be a fast method for the analysis of soil extracts with high sensitivity and selectivity. It has the potential to be developed into a sensor for the in situ measurement of phosphate in various environmental matrices.Keywords
This publication has 19 references indexed in Scilit:
- Characteristics of a cobalt-based phosphate microelectrode for in situ monitoring of phosphate and its biological applicationSensors and Actuators B: Chemical, 2009
- Functional polyterthiophene-appended uranyl-salophen complex: Electropolymerization and ion-selective response for monohydrogen phosphateAnalytica Chimica Acta, 2008
- Platinum as a Reference Electrode in Electrochemical MeasurementsPlatinum Metals Review, 2008
- Investigation of amperometric detection of phosphate: Application in seawater and cyanobacterial biofilm samplesTalanta, 2004
- Flow injection potentiometric determination of phosphate in waste waters and fertilisers using a cobalt wire ion-selective electrodeThe Analyst, 1998
- Flow-injection Potentiometric Detection of Phosphates Using a Metallic Cobalt Wire Ion-selective ElectrodeAnalytical Communications, 1997
- Mixed Potential Response Mechanism of Cobalt Electrodes toward Inorganic PhosphateAnalytical Chemistry, 1996
- Flow-injection determination of phosphate species in detergents with a calciumion-selective electrodeAnalytica Chimica Acta, 1987
- Solid-state ion-selective electrodes for the potentiometric determination of phosphateTalanta, 1979
- A modified single solution method for the determination of phosphate in natural watersAnalytica Chimica Acta, 1962