How does photochemical decay affect fluorescence?
Many fluorescent molecules can be bleached or destroyed by light (fading of dyes in the sun). Ultraviolet light, especially, can cause certain molecules to break down. Fluorescence readings decrease as the molecules are destroyed. Rate of destruction varies depending upon environmental factors, temperature. Fluorescein, for example, is destroyed rapidly in sunlight. Rhodamine WT, however, is adequately stable for field studies. For chlorophyll measurements, samples and standards need to be kept in the dark until read. All flow measurements should employ opaque delivery hoses to minimize photochemical interference. ยท What are the advantages of fluorescence? Sensitivity: Limits of detection depend to a large extent on the properties of the sample being measured. Detectability to parts per billion or even parts per trillion is common for most analytes. Fluorometers achieve 1,000 to 500,000 times better limits of detection as compared to spectrophotometers. Specificity: Spectrophotometers
