Conductance based sensing and analysis of soluble phosphates in wastewater

Biosensors and Bioelectronics.  Volume 52, 15 February 2014, Pages 173–179. 

Christopher Warwick, Antonio Guerreiro, Alberto Gomez-Caballero, Elizabeth Wood, James Kitson, James Robinson, Ana Soares.
Cranfield Water Sciences Institute, School of Applied Sciences, Cranfield University, Cranfield MK43 0AL, UK &
Cranfield Biotechnology Centre, Cranfield Health, Cranfield University, Cranfield MK43 0AL, UK &
Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country, 01006 Vitoria-Gasteiz, Spain &
Yorkshire Water, Western House, Halifax Road, Bradford BD6 2SZ, UK.

Abstract

The current standard method used for measuring soluble phosphate in environmental water samples is based on a colourimetric approach, developed in the early 1960s. In order to provide an alternative, label free sensing solution, a molecularly imprinted polymer (MIP) was designed to function as a phosphate receptor. A combination of functional monomer (N-allylthiourea), cross-linker and monomer/template ratios were optimised in order to maximise the binding capacity for phosphate. When produced in membrane format, the MIP’s ability to produce a reversible change in conductance in the presence of phosphate was explored for fabrication of a sensor which was able to selectively detect the presence of phosphate compared to sulphate, nitrate and chloride. In wastewater samples the sensor had a limit of detection of 0.16 mg P/l, and a linear range between 0.66 and 8 mg P/l. This is below the minimum monitoring level (1 mg P/l) as required by current legislation for wastewater discharges, making the sensor as developed promising for direct quantification of phosphate in environmental monitoring applications.

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