Use beer\'s law to find the concentration of a solution of tpcp in methanol solution if a 1 cm cuvette of the solution has an absorption of 1.23 at 343 nm. the molar extinction coefficient for tpcp at 343 nm is 6460 m–1cm–1.

According to Beer-Lambert law the absorption of light by a solution is directly proportional to the concentration of that solution.
Mathmatically,
                                    A  =  ∈ C l          (1)
Where,
                                    A  =  Absorption = 1.23
                                    ∈  =  molar absorptivity coefficient =  6460 M⁻¹cm⁻¹
                                    C  =  Concentration = ?
                                    l    =  Path Length = 1 cm
Solving eq.1 for concentration,
                         
                                    C  =  A / ∈ l
Putting values,
                                    C  =  1.23 / (6460 M⁻¹cm⁻¹ × 1 cm)

                                    C  =  0.00019 mol/L