Development of a highly sensitive inhibition immunoassay for microcystin-LR

The development of a rapid one-step antigen-immobilized inhibition ELISA for microcystin-LR is described. For microplate coating a microcystin–biotin conjugate was synthesized. Using the commercially available monoclonal antibody MC10E7 in our newly established assay, IC50 values of 0.045 (mu)g l^-1 have been achieved. The detection limit for microcystin-LR was 4 ng l^-1. Considering the guidelines proposed by the world health organization (WHO) for microcystin-LR in drinking water (1 (mu)g l^-1) the sensitivity of our test is more than sufficient. The period of assay processing could successfully be shortened to about 3 h without any loss in sensitivity. The suitability of the newly developed assay was evaluated with microcystin-LR spiked environmental water samples. Recovery rates for microcystin-LR between 60 and 165% were obtained in the linear range of the test format. The antigen-immobilized test format provides a highly reproducible, easy, and fast to perform detection system for microcystin allowing an internal retrospective quality control of the assay.