Highly sensitive immunoassay based on a monoclonal antibody specific for [4-arginine]microcystins Original Research Article

The production and characterization of a monoclonal antibody (clone (MC10E7)) with extraordinary sensitivity and high selectivity for [4-arginine]microcystins is described. The immunogen used for the production of the antibody was synthesized using a novel coupling chemistry to bind microcystin-LR(MC–LR) via dehydroalanine to the carrier protein. With a direct competitive enzyme-linked immunosorbent assay (ELISA) using MC10E7, IC50 values for MC–LR of 0.06 μg l−1 have been achieved. The detection limit for MC–LR was 6 ng l−1. The provisional guideline value proposed by the World Health Organization (WHO) is 1 μg l−1 for drinking water. All [4-arginine]microcystins show similar IC50 values and detection limits, whereas other MCs such as MC–LA, are not recognized. The affinity constant for MC10E7 was determined to be at least 7×1010 l mol−1. The antibody was tested for its robustness against interference of humic acids, pH, salt content, surfactants or organic solvents and was found to be very stable. MC–LR spiked water samples in the concentration range between 0.01 and 0.1 μg l−1 were measured and a mean recovery of 99.9±16.4% was found. The antibody is well suited for sensitive analysis for MCs in drinking as well as surface water.