Determination of benomyl residues in waters by solid-phase spectrofluorimetry

A sensitive spectrofluorimetric method for the determination of trace amounts of benomyl was developed, based on solid-phase spectrofluorimetry. The relative fluorescence intensity of the benomyl fixed on C18 silica gel was measured directly after packing the gel beads in a 1 mm silica cell, using a solid-phase attachment. The wavelengths of excitation and emission were 293 and 375 nm, respectively. The applicable concentration range was from 0.2 to 20.0 ng ml–1, with a relative standard deviation of 1.1% and a detection limit of 0.04 ng ml–1. The method was applied to the determination of benomyl residues in natural waters. Recoveries were 96–103%. The method is more sensitive and selective than other methods described in the literature.