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Stray-light effects

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  397

2026-11-07

101

Stray-light effects

Stray light is radiation at wavelengths different from those desired. It may arise from light scattering or other defects within the instrument, or it may be caused by external radiation. In the absence of stray light, the observed absorbance tends to a constant value as the concentration of a sample is increased because all light is absorbed and no light reaches the detector. However, if stray light is present and reaches the detector, this will give rise to a negative deviation from the Beer–Lambert law. Stray-light errors are more likely to be observed near the wavelength limits of an instrument, at which the radiation intensity of the source and the efficiency of the optical system are reduced, especially below 220 nm and at the crossover point between the UV and the visible lamps (about 320–400 nm). Errors may become serious if the solvent absorbs strongly or if a strongly absorbing sample is measured by difference spectrophotometry.