Time-resolved fluorescence analysis

Abstract

The choice of fluorescence as an analytical tool is often based on its intrinsic sensitivity. Compounds can be identified on the basis of their steady-state excitation and emission spectra. Resolution and information can be enhanced by the parameters obtained from time-resolved fluorescence. This includes both the intensity decay (lifetimes) and anisotropy decay parameters. For example, often substances have overlapping steady-state excitation and emission spectra. Thus, they can be difficult to resolve. However, these same compounds will often have different fluorescence lifetimes. This allows resolution by excited-state decay kinetics. By testing various associations of the intensity decay parameters with the excitation and emission parameters, as well as with other experimental variables such as pH, temperature, pressure, viscosity, or interaction with other solutes (such as collisional quenchers), one can obtain substantial information about the physical and chemical nature of the sample. In this way, one may 'finger print' complex mixtures, assess compound purity, and characterize a fluorescent compound.