absorbanssin

Absorbanssi (Finnish for absorbance) is a dimensionless quantitative measure of the amount of light at a given wavelength removed from a beam as it passes through a sample. It is defined as A = -log10(T) = log10(I0/I), where I0 is incident light intensity and I is transmitted light intensity. In spectrophotometry, absorbanssi is commonly measured across wavelengths to characterize chemical species or to quantify concentration.

Beer's law relates absorbanssi to concentration, path length, and molar absorptivity: A = ε c l. Here ε is the molar extinction coefficient (M^-1 cm^-1), c is the sample concentration (mol/L), and l is the optical path length (cm). The law predicts a linear relationship between A and c for dilute solutions within a reliable range.

Applications include quantitative analysis in chemistry and biochemistry, such as determining concentrations with calibration curves, and monitoring reaction kinetics. Instruments used include UV–visible spectrophotometers and plate readers; cuvettes or microplates determine transmitted light across wavelengths, typically from about 190 to 1100 nm.

Limitations: Beer's law is an approximation. Deviations occur at high concentrations, with scattering, fluorescence, or significant refractive-index changes, or when solvent/background absorbance is not properly corrected. Background signals from the solvent, turbidity, or overlapping absorptions of interfering species must be accounted for by blank subtraction and appropriate wavelength selection.

In contexts beyond solutions, absorbance concepts extend to diffuse reflectance and other light-mample interactions, with related quantities such as optical density in microbiology. The term absorbanssi remains central to quantitative spectroscopy and analytical chemistry.