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Fluorescent labels

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  385

2026-11-05

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Fluorescent labels

Fluorescent end-points for heterogeneous immunoassays are based on a fluorescent label or fluorophore. The principle of fluorescence relies on the ‘Stokes’ shift’ or movement of wave length from that used to excite the fluorophore to the detection wavelength at which light is emitted from the fluorophore. The labels can be used in an immunoassay in the same way as a radioactive label or by using an enzyme label to generate a fluorescent molecule.

An example of this type of signal system utilises an alkaline phosphatase enzyme label and 4-methylumbelliferyl phosphate substrate. The substrate is converted into the fluorescent 4-methylumbelliferone, which can be detected by a suitable fluorimeter. When using the assay procedure described for the heterogeneous EIA above, the fluorescence obtained is inversely proportional to the amount of drug in the sample.

The use of fluorescent labels in toxicology testing has not gained wide popularity because of the interference from endogenous sample components.