The flow rate dependence of the signal from an on-column laser fluorescence chromatography detector is modeled assuming that the fluorophore undergoes a first-order photobleaching reaction. The concentration distribution due to flow and reaction in the cylindrical detector cell is derived. At high flow rate or low laser power, no bleaching occurs, and the detector measures concentration, which is independent of flow rate. At low flow rate and high laser power, photobleaching is important, and the detector measures flux. The ability to operate in a concentration measuring or flux measuring mode allows use of the detector as a flow rate measuring device. Capillary flow experiments and static fluorescence decay experiments, performed with 250 ppb fluorescein dye at three laser powers, yield data which display behavior predicted by the flow/reaction model.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering