Spatial intensity distribution model of fluorescence emission considering the spatial attenuation effect of excitation light.

The fluorescence quantitative analysis method of a solution is widely applied in chemical analysis, clinical medicine testing, environmental monitoring, food safety detection, and so on. It is based on the linear relationship between the intensity of fluorescence emission and the concentration of the substance in solution. Without consideration of the spatial attenuation effect of excitation light, it is applied only to a dilute solution. In this research, a fluorescence emission model is established based on the interaction and propagation law between the excitation light and the fluorescent substances. The spatial attenuation effect of excitation light is analyzed by an element analysis method, and the spatial intensity distribution of fluorescence is revealed. Further, a high accuracy model between the received fluorescence intensity and concentration is obtained. Applications of this model and further design will allow for high throughput fluorescence analysis and the analysis of fluorescent substances with ultra-wide range concentration, such as on-line testing fluorescent dyes in the textile industry, monitoring protein plasma in biomedical field, and high-throughput DNA fluorescence analysis etc. As an example, based on this model, an ultra-wide concentration range (0.02 - 250 mg/L) detection of tryptophan with high accuracy (R = 0.9994, RRMSE = 0.0356) is realized.