A membrane-based immunosensor for the analysis of the herbicide isoproturon

A membrane based heterogeneous competitive enzyme-linked immunosorbent assay (ELISA) was used in this work to develop an immunosensor for the detection of a common herbicide, isoproturon. A screen-printed carbon working electrode with carbon counter and silver–silver chloride pseudo-reference electrode was utilized incorporating a membrane fixed into intimate contact with the working electrode to facilitate signal transduction. The membrane containing an immobilized isoproturon–ovalbumin conjugate was laminated onto the carbon working electrode and horseradish peroxidase (HRP) labeled polyclonal antibody was then applied for the competitive assay. Two different amperometric systems, hydroquinone and o-phenylenediamine (OPD) mediation reduction were utilised and the properties of the resultant sensors were compared. A flow injection apparatus was also developed utilising the immunosensor. Limits of detection for isoproturon (LLD₉₀) were found to be as low as 0.84 ng mL⁻¹. The senor was also validated using spiked extracted soil samples and also isoproturon contaminated samples.