Calculadora da Lei de Beer-Lambert
Calcule absorbância, concentração ou caminho óptico usando a Lei de Beer-Lambert.
Absorbance (A)
3.1100
Absorbance (A) vs Molar Absorptivity (epsilon)
Formula
## Beer-Lambert Law The Beer-Lambert law relates the absorbance of a solution to the concentration of the absorbing species, the path length, and the molar absorptivity. ### Formula **A = epsilon × l × c** where A is absorbance (dimensionless), epsilon is the molar absorptivity (L/(mol·cm)), l is the optical path length (cm), and c is the molar concentration (mol/L). Transmittance: T = 10^(-A).
Exemplo Resolvido
NADH in a 1 cm cuvette at 0.5 mM concentration (epsilon = 6220 at 340 nm).
- 01A = 6220 × 1 × 0.0005 = 3.110
- 02%T = 10^(-3.110) × 100 = 0.0776 × 100 = 7.76%
Perguntas Frequentes
When does Beer-Lambert law fail?
At high concentrations (typically A > 2), intermolecular interactions cause deviations. Chemical changes (aggregation, pH-dependent equilibria), stray light, and fluorescence can also cause non-linearity.
What is a typical molar absorptivity?
Weak absorbers: 1-100 L/(mol·cm). Moderate: 100-10,000. Strong chromophores: 10,000-100,000+. Molar absorptivity is an intrinsic property of the molecule at a specific wavelength.
What is the ideal absorbance range?
For accurate measurements, keep A between 0.1 and 1.0 (10-80% transmittance). Below 0.1, noise dominates. Above 1.0, very little light reaches the detector, increasing measurement error.
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