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Beer-Lambert Law:
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The molar extinction coefficient (ε) is a measure of how strongly a chemical species absorbs light at a particular wavelength. It is a fundamental parameter in spectroscopy and is used to quantify the concentration of substances in solution using the Beer-Lambert law.
The calculator uses the Beer-Lambert law:
Where:
Explanation: The equation describes how the absorption of light by a solution depends on the concentration of the absorbing species and the path length through which light travels.
Details: The molar extinction coefficient is crucial for quantitative analysis in spectroscopy, determining unknown concentrations, characterizing compounds, and in various applications including biochemistry, environmental science, and pharmaceutical analysis.
Tips: Enter absorbance (typically between 0.1-1.0 for best accuracy), concentration in mol/L, and path length in cm (usually 1 cm for standard cuvettes). All values must be positive numbers.
Q1: What is the typical range for molar extinction coefficients?
A: Values range from near zero for weak absorbers to over 100,000 L mol⁻¹ cm⁻¹ for strong chromophores like certain dyes and metal complexes.
Q2: Does extinction coefficient depend on wavelength?
A: Yes, ε is wavelength-dependent and is usually reported at the wavelength of maximum absorption (λmax).
Q3: What are common units for extinction coefficient?
A: The standard unit is L mol⁻¹ cm⁻¹, though M⁻¹ cm⁻¹ is also commonly used (where M represents mol/L).
Q4: How does temperature affect extinction coefficient?
A: Temperature can affect ε, particularly for compounds that undergo temperature-dependent conformational changes or aggregation.
Q5: Can this calculator be used for proteins and nucleic acids?
A: Yes, though proteins and nucleic acids often have characteristic extinction coefficients that are used for concentration determination.