1. What is the Extinction Coefficient?

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.

2. How Does the Calculator Work?

The calculator uses the Beer-Lambert law equation:

Where:

• \( \varepsilon \) — Molar extinction coefficient (L/mol·cm)
• \( A \) — Absorbance (unitless)
• \( c \) — Concentration (mol/L)
• \( l \) — Path length (cm)

Explanation: The extinction coefficient represents the absorbance of a 1 M solution in a 1 cm path length cuvette at a specific wavelength.

3. Importance of Extinction Coefficient

Details: The extinction coefficient is crucial for determining protein concentrations, studying enzyme kinetics, monitoring chemical reactions, and in various analytical chemistry applications. It is particularly important in biochemistry for quantifying biomolecules.

4. Using the Calculator

Tips: Enter absorbance (typically measured at specific wavelengths like 280nm for proteins), concentration in mol/L, and path length in cm. Ensure all values are positive and measured under consistent conditions.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical range for extinction coefficients?
A: Extinction coefficients vary widely depending on the compound. Small molecules typically range from 1,000-50,000 L/mol·cm, while proteins can range from thousands to hundreds of thousands.

Q2: Why is the extinction coefficient wavelength-dependent?
A: Different compounds absorb light most strongly at specific wavelengths due to their unique electronic structures and chromophores.

Q3: How is extinction coefficient used in protein quantification?
A: For proteins, extinction coefficients at 280nm are used with the Beer-Lambert law to determine concentration based on absorbance measurements.

Q4: What factors affect extinction coefficient measurements?
A: Temperature, pH, solvent composition, and the presence of interfering substances can all affect extinction coefficient values.

Q5: Can this calculator be used for any wavelength?
A: Yes, but remember that extinction coefficients are wavelength-specific. The calculated value applies only to the wavelength at which absorbance was measured.