Fluorescence detector solvent effects

Fluorescence detectors can also be used and while their sensitivity may be greater, they are less widely applicable owing to the smaller number of fluorescent compounds. Differential refractometers will detect changes in the refractive index of the solvent due to the presence of solutes and, while they are less sensitive than the other detectors and often cannot be used effectively with gradient elution techniques, they are capable of detecting the presence of any solute. 

There are several ways to check or calibrate the time scale of a TCSPC insfru-ment. The most commonly used one is to measure the fluorescence decay of a dye of known lifetime and compare the result to lifetimes given in the literature [308]. However, the lifetime of an organic dye is actually the poorest calibration standard possible. The measured lifetime may depend on the solvent, the temperature, and the excitation wavelength. It may also be changed by fluorescence quenching by impurities or oxygen, and by reabsorption effects. Moreover, detector background and improper data analysis can easily introduce an uncertainty on the level of several percent. 

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