Biosensor based on atemoya peroxidase immobilised on modified nanoclay for glyphosate biomonitoring

A biosensor based on atemoya peroxidase immobilised on modified nanoclay was developed for the determination of glyphosate by the enzyme inhibition method. The inhibitor effect of the biocide results in a decrease in the current response of the hydroquinone that was used as a phenolic substrate to obtain the base signal. The biosensor was constructed using graphite powder, multiwalled carbon nanotubes, peroxidase immobilised on nanoclay and mineral oil. Square-wave voltammetry was utilised for the optimisation and application of the biosensor, and several parameters were investigated to determine the optimum experimental conditions. The best performance was obtained using a 0.1molL−1 phosphate buffer solution (pH 7.0), 1.9×10−4molL−1 hydrogen peroxide, a frequency of 30Hz, a pulse amplitude of 50mV and a scan increment of 4mV. The glyphosate concentration response was linear between 0.10 and 4.55mgL−1 with a detection limit of 30μgL−1. The average recovery of glyphosate from spiked water samples ranged from 94.9 to 108.9%. The biosensor remained stable for a period of eight weeks. ► A novel atemoya biosensor for glyphosate determination was developed. ► The biosensor was based on the inhibitor effect of the pesticide on enzymatic activity. ► The peroxidase enzyme was immobilised on nanoclay based on montmorillonite modified. ► Multi-walled carbon nanotubes were incorporated into a carbon paste electrode. ► Square-wave voltammetry was used for the optimisation and application of the biosensor.