Portable fiber-optic immunosensor for detection of methsulfuron methyl.

This fiber optic sensor, based on competitive immunoreactions between coating-haptens and free haptens in solutions with corresponding antibodies, was developed to determine the concentration of the free hapten, methsulfuron-methyl. The ovalbumin (OVA)-methsulfuron-methyl conjugate was immobilized on a microscope slide. Horseradish peroxidase (HRP) labeled goat anti-rabbit IgG was used to generate an optical signal. The portable optical device consisted of a 0.25-W tungsten-halogen light source and a photosensitive diode detector. A typical competitive-binding calibration curve was seen between 0.3 and 100 ng/ml of methsulfuron-methyl. The detection limit for methsulfuron-methyl was 0.1 ng/ml.