Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with a reagent to form a fluorescent product or measuring the decrease in fluorescence upon adding the analyte to a solution containing a fluorescent molecule.

Inorganic ions, with a few exceptions like UO₂⁺, are generally not sufficiently fluorescent for direct analysis. These ions can be analyzed with an organic ligand to form a fluorescent or phosphorescent metal-ligand complex. Organic compounds containing aromatic rings are typically fluorescent, while aromatic heterocycles tend to be phosphorescent. If the organic analyte is not naturally fluorescent or phosphorescent, it can sometimes be incorporated into a chemical reaction to produce a fluorescent or phosphorescent product. For instance, the enzyme creatine phosphokinase can be determined by catalyzing the formation of creatine from phosphocreatine, which then reacts with ninhydrin to yield a fluorescent product of unknown structure.

Phosphorescence and fluorescence methods are complementary as strongly fluorescing compounds exhibit weak phosphorescence and vice versa. Phosphorimetry has been used to determine a variety of organic and biochemical species. However, it is not as widespread as fluorometry, possibly due to the need for low temperatures and the generally poorer precision of phosphorescence measurements. In recent years, considerable effort has been put into developing phosphorimetric methods that can be carried out at room temperature. These include methods where the analyte is bound to a solid support, such as filter paper or silica gel, or incorporated into the core of micelles or cyclodextrin molecules. In most room-temperature experiments, heavy atoms, such as Tl(I), Pb(II), Ag(I), and halide ions, are used to promote intersystem crossing.