Spectrofluorimetric determination of paraquat by manual and flow injection methods

The reaction involving the formation of a fluorescent charge-transfer complex between paraquat and benzaldehyde was studied in ethanol-water medium. In the presence of a large excess of.benzaldehyde, the fluorescence intensity is linearly related to paraquat concentration from 0.13 to 7.4 mu g ml(-1). The method can be easily adapted to a flow system using a two-channel manifold, the peak height being proportional to the paraquat concentration over the range 1.6-22.3 mu g ml(-1) Manual and flow-injection procedures were satisfactorily applied to the determination of paraquat in commercial herbicides, waters, soils and potatoes.