DIRECT POTENTIOMETRIC IMMUNOELECTRODES .3. A GRAPHITE BASED ATRAZINE IMMUNOELECTRODE

TK pencil fine mines type Faber Castell Super polymer from Staedtler are used as graphite based material for an atrazine-sensitive immunoelectrode. Eighteen procedures are tested to immobilize antibodies against atrazine but only one turned out to be useful for the preparation of a graphite based immunoelectrode. It incorporates binding of glutardialdehyde to active sites of the graphite surface and subsequent cross-linking of the antibodies with glutardialdehyde. The method has been carefully optimized with respect to selectivity and the cross-sensitivity is determined for such an electrode based on atrazine-rabbit and atrazine-sheep antibodies as well. Due to the structural difference of the used immunogens, the sign of the potential response and the cross-sensitivities are different. The application of such an electrode to a natural water sample is demonstrated and shows that the useful concentration range in a final solution is between 20 and 250 ng/l. Of course, interference from ions must be excluded in future analytical applications.