How to calculate concentration using the Beer-Lambert Law?

To calculate concentration using the Beer-Lambert Law, the formula c = A / (εl) is used, where A is the absorbance measured at the chosen wavelength, ε is the molar absorptivity of the analyte, and l is the path length of the sample. First, measure the absorbance (A) of the sample using a spectrophotometer. Next, determine the molar absorptivity (ε) either from literature or by experimental means for the specific analyte at the wavelength of interest. Finally, measure or confirm the path length (l) of the cuvette used in the spectrophotometer. Rearranging the equation and dividing absorbance by the product of molar absorptivity and path length gives the concentration of the analyte in the sample.