This work describes the production and characterization of monoclonal antibodies (MAbs) to the organochlorine insecticide DDT and their incorporation into several ELISA configurations. A collection of DDT haptens was synthesized by introducing appropriate spacers at two sites of the analyte molecular structure. From mice immunized with hapten−protein conjugates, MAbs with I 50 values to p,p‘-DDT in the 2−11 nM range in homologous conjugate-coated assays were obtained. According to their cross-reactivity pattern with DDT isomers and metabolites, MAbs can be classified as class-specific or DDT-specific antibodies. Both types of MAbs were obtained from mice immunized with the same hapten−protein conjugate simply by applying a different selection criterion in the screening of fusion supernatants. These immunoassays are potentially very valuable analytical tools for the rapid and sensitive determination of DDT and congeners in food and the environment and for monitoring human exposure to these ubiquitous and toxic compounds. Keywords: ELISA; insecticide; organochlorine pesticide; monoclonal antibodies; DDT; DDE; DDD; hapten design; hapten heterology; ELISA format

An experimental ((1)H NMR) and theoretical (DFT) study of the ring-chain-ring isomerization of 3-(2-pyridyl)-[1,2,3]triazolo[1,5-a]pyrid-7-yl derivatives (A) into 6-{[1,2,3]triazolo[1,5-a]pyrid-3-yl}-2-pyridyl derivatives (B) has been carried out. Based on the calculations, a mechanism of several steps will be proposed. The experimental results as well as the calculations lead to the conclusion that the A-B ratio depends on the electronic properties of the substituents.

Organochlorine pesticides still generate public health concerns because of their unresolved health impact and their persistence in living beings, which is demanding appropriate analytical techniques for their monitoring. In this study, an enzyme-linked immunosorbent assay based on monoclonal antibodies (MAbs) for the detection of an important group of organochlorine pesticides, the cyclodiene group, has been developed. With this aim, several hapten-protein conjugates, characterized by exposure of the common hexachlorinated bicyclic (norbornene) moiety and differing in the linking structure to the carrier protein, were prepared. From mice immunized with these conjugates, several MAbs with the ability to sensitively bind the majority of cyclodienes were obtained. Among them CCD2.2 MAb displaying the broadest recognition to cyclodiene compounds (endosulfan, dieldrin, endrin, chlordane, heptachlor, aldrin, toxaphene: I(50) values in the 6-25 nM range) was selected for the assay. Interestingly, this MAb showed certain stereospecificity toward other polychlorinated cycloalkanes because the gamma-isomer of hexachlorocyclohexane (lindane) was also very well recognized (I(50) value of 22 nM). This immunoassay is potentially a very valuable analytical tool for the rapid and sensitive determination of cyclodiene insecticides and related compounds, which in turn may contribute to the understanding of the biological activities and of the overall environmental impact of these persistent organic pollutants.