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Molar Extinction Coefficient Equation:
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The 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 Beer-Lambert's Law.
The calculator uses the Beer-Lambert Law equation:
Where:
Explanation: The extinction coefficient represents the absorbance of a 1 M solution in a 1 cm path length cuvette at a specific wavelength.
Details: The extinction coefficient is crucial for determining concentrations of unknown samples, characterizing chemical compounds, and is widely used in biochemistry, analytical chemistry, and pharmaceutical sciences.
Tips: Enter absorbance (typically between 0.1-1.0 for accurate measurements), concentration in mol/L, and path length in cm. All values must be positive numbers.
Q1: What is a typical range for extinction coefficients?
A: Extinction coefficients vary widely by compound, ranging from 10 to over 100,000 M⁻¹·cm⁻¹ depending on the chromophore and wavelength.
Q2: How does wavelength affect extinction coefficient?
A: Extinction coefficient is wavelength-dependent and is typically reported at the absorption maximum (λmax) of the compound.
Q3: Can this calculator be used for proteins?
A: Yes, but protein extinction coefficients are often calculated differently using amino acid composition or measured experimentally.
Q4: What are common sources of error?
A: Instrument calibration, sample impurities, incorrect path length measurement, and deviations from Beer's Law at high concentrations.
Q5: How is extinction coefficient related to molar absorptivity?
A: They are the same physical quantity - extinction coefficient is synonymous with molar absorptivity in spectroscopy.