[Fluorometric determination of trace Shachongdan with calcein-Pd2+]

A fluorometric determination of trace Shachongdan (SCD) [(CH3)2NHCH (CH2S2O3- )CH2S2O3Na x H2O] is described. The method is based on the calcein display fluorescence in pH6-7 phosphate buffer solution, it react with Pd2+ to the fluorescence disappeared. The complex of SCD-Pd2+ is more stability than the complex of calcein-Pd2+, when SCD react with calcein -PdZ+, the calcein can be freed and its fluorescence appears once again. The fluorescence excitation and emission wavelenghts are 494 and 514nm. The linear range is 2 x 10(-7) mol/L-3 x 10(-6)mol/L and the detection limit is 6 x 10(-8)mol/L.