No abstract

We describe within this paper a membrane based enzyme linked immunosorbent assay (MELISA) for the detection of a common herbicide, isoproturon. A heterogeneous competitive ELISA was the format chosen for isoproturon detection. An immunoassay system with a horseradish peroxidase (HRP) labeled polyclonal antibody preparation was developed and characterised before suitable sensitivity and selectivity for isoproturon was attained. After development as a microtitre plate immunoassay the system was transferred to an affinity membrane sorbent based ELISA where the isoproturon/ovalbumin conjugate was immobilised on commercial membranes. Different porosities and immobilisation conditions were utilised to optimise the MELISA, including sensitivity, selectivity and stability studies. This enabled detection of isoproturon in the range 0.5 ng ml-1-20 μg ml-1 , with an LLD90 of 0.5 ng ml-1. The use of acetonitrile extracts from soil samples was found to not overly impair the performance of the MELISA. Good correlation between ELISA and HPLC could be obtained for extracts from spiked soil samples.