Adsorptive stripping voltammetric determination of amitrole at a multi-wall carbon nanotubes paste electdrode

This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of amitrole down to the sub-mu M levels. The oxidation peak current is proportional to the amitrole concentration over the range from 0.8 to 7.0 mu M (5 min accumulation), with a detection limit of 0.6 mu M (48 mu gL(-1)) and a precision of 4.3%, n = 20. The proposed method was used for the determination of amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mu M.