Conductimetric sensor for atrazine detection based on molecularly imprinted polymer membranes

Abstract

Atrazine-sensitive conductimetric sensors were designed using molecularly imprinted polymer membranes. Membranes containing artificial recognition sites for atrazine were prepared by copolymerization of methacrylic acid and a cross-linker, tri(ethylene glycol) dimethacrylate, in the presence of atrazine as a template. In order to improve the flexibility and mechanical stability of the membranes, oligourethane acrylate was added to the mixture of monomers. The recognition sites complementary to atrazine were formed in the membranes after extraction of the template molecules with ethanol. Alternatively, reference polymer membranes were prepared with the same monomers but without the template. The responses of the membranes prepared with and without the template were monitored conductimetrically. The membranes prepared in the presence of atrazine showed significantly stronger responses to atrazine than to analogous compounds (triazine, simazine, prometryn). The response time was 6–15 min depending on the membrane thickness. The effect of the membrane composition and the porogen concentration on the magnitude of the conductimetric responses was also investigated. With the sensor designed here, the detection of the atrazine at concentrations down to 5 nmol dm^–3 was demonstrated. During a 6 month period, the sensitivity of the molecularly imprinted membranes to atrazine was found to remain constant.