BROADENING THE ANTIBODY SPECIFICITY BY HAPTEN DESIGN FOR AN ENZYME-LINKED IMMUNOASSAY AS AN IMPROVED SCREENING METHOD FOR THE DETERMINATIONOF NITROAROMATIC RESIDUES IN SOILS

The development of a group-specific immunochemical test as a new appro ach to screening is reported. The broadening of antibody specificity w as achieved by design of the hapten part of the immunogen. We used mol ecular modelling to investigate the structure of the hapten and the in fluence of the spacer on its conformation and electronic nature as com pared with the analyte thereby allowing a selection of suitable primar y molecules for immunization. This offers the possibility of directing the cross-reactivity of the antibodies against structurally related c ompounds to a lower or a higher value. The analysis of 2,4,6-trinitrot oluene (TNT), its precursors and degradation products as residues in s oils was performed in an enzyme-linked immunosorbent assay (ELISA). A polyclonal anti-dinitrotolyl antiserum (AB1) was compared with a polyc lonal anti-trinitrophenyl antiserum (AB2). Both sera were found to be similar in relation to the detection limit (2 mu g/l) and sensitivity but differ in their affinities to structurally related compounds. AB2 is selective to TNT. AB1 is able to recognize important structurally r elated compounds even at low concentrations. AB1 would be chosen to de velop an immunochemical screening method. Real soil samples were inves tigated by ELISA and micellar electrokinetic capillary chromatography using the same extract solution. This combination could offer the poss ibility of rapid, cost efficient screening and determination of TNT an d its degradation products.