Diaminopyridine fluorescence

After ca. 30 min, when the chloroform had evaporated, fluorescent chromatogram zones appeared on a dark background on excitation with long-wavelength UV light (X = 365 run) 2,3-diaminonaphthalene (h/ f 70-75), red and 2,3-diaminopyridine (h/Jf 55-60), blue. The detection limits were 3 ng substance per chromatogram zone. 

Fig. 1 Fluorescence scans of a chromatogram track with 60 ng each of 2,3-diaminopyridine (Ijl and 2,3-diaminonaphthalene (2) per chromatogram zone ...

Fluorescence of the diaminopyridine group allows detection of conjugates down to the pico-mole range, with excitation and emission maxima at 345 and 400 nm, respectively. For detection of BAP and its conjugates, the optimal buffer environment is less than pH 5, because its fluorescent properties are pH dependent. A preferred buffer is sodium acetate at pH 4. 

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