Many clinical laboratory analytes can be quantified using spectrophotometry. Spectrophotometry capitalizes on the concept that concentrations of some analytes in solution have a direct relationship with the amount of light that the solution absorbs. This direct relationship is described in an equation called Beer's Law.
- The Beer's law equation is A=elc
- A = absorbance
- e = molar absorptivity coefficient
- l = path length of the solution the light must travel through
- c = concentration
The molar absorptivity coefficient is intrinsic to each molecular analyte and the path length is held constant (i.e., a cuvette that is 1 cm in length). Therefore, as the concentration of the analyte in solution increases or decreases, the amount of light that the analyte in solution absorbs, increases or decreases proportionally.
- This is represented by the formula: A ∝ c
- A = absorbance
- ∝ = proportional
- c = concentration
