The experimental parameters affecting the fluorescence of N-methyl carbamates as their dansyl (1-dimethylaminophthalene-5-sulfonyl) derivatives were investigated. Exposure to ultraviolet light causes a degradation of the dansyl derivatives, resulting in slight shifts in fluorescence excitation and emission maxima as well as in a decrease in fluorescence intensity. Spraying the derivatives with triethanolamine in isopropanol improved the in situ quantitative analysis of the carbamates. Further increase in fluorescence is observed with sprays consisting of aqueous buffers, but the derivatives are less stable with time. Stabilization is possible, however, by covering the moist chromatoplate with a thin glass sheet. Only 2–3 % loss in sensitivity is observed under these conditions. Long-range storage, however, is not possible with the aqueous buffers. At a pH of less than one, the fluorescence of the derivatives is quenched reversibly.