DETERMINATION OF MORESTAN RESIDUES IN WATERS BY SOLID-PHASE SPECTROFLUOROMETRY

Morestan in solution in a neutral medium shows native fluorescence. A method for the determination of trace amounts of morestan in waters by solid-phase spectrofluorimetry is described. Morestan is fixed on C-1 8 silica-gel, packed in a 1-nun silica cell and measured directly with a solid-surface attachment giving fluorescence at lambda(em) = 392 nm for wavelength of excitation lambda(ex) = 370 nm. The applicable conc entration range is 1.0-7.0 ng ml-1 with a relative standard deviation of 1.9% and a detection limit of 0.15 ng ml-1. The influence of the pr esence of other pesticides and chemical species has also been studied. The method is found to be more sensitive and selective than other met hods proposed in the literature. It was applied to the determination o f morestan in natural waters. Recoveries were from 95 to 105%.