Time resolved fluoroimmunoassay of 7-methyl-2'-deoxyguanosine imidazole (ring open).

A solid-phase competitive time-resolved fluoroimmunoassay for 7-methyl-2'-deoxyguanosine imidazole (ring open) is described, based on highly specific hemocyanin carrier rabbit antibodies, modified with europium chelates. Eu3+ photoluminescence was detected in a novel micellar solution. The assay was validated both by comparing it with an ELISA and by analysing DNA samples, alkylated either 'in vitro' or 'in vivo' by dimethyl sulfate. The proposed assay proved to be sensitive, simple and reliable. It should be of value, together with other immunoassays for methylated DNA bases, in assessing human environmental exposure to alkylating agents such as nitrosamines, thereby providing a powerful tool in epidemiological investigations.