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Beer-Lambert Law:
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The Beer-Lambert Law (also known as Beer's Law) relates the absorption of light to the properties of the material through which the light is traveling. It states that the concentration of a solute in solution is directly proportional to the absorbance of the solution.
The calculator uses the Beer-Lambert Law equation:
Where:
Explanation: The law shows that absorbance is directly proportional to both the concentration of the absorbing species and the path length through which the light travels.
Details: Calculating concentration from absorbance is fundamental in analytical chemistry, biochemistry, and molecular biology. It's used to determine concentrations of DNA, proteins, and other biomolecules, as well as in quality control and pharmaceutical analysis.
Tips: Enter absorbance (typically between 0.1-1.0 for most accurate results), molar extinction coefficient (specific to your compound and wavelength), and path length (usually 1 cm for standard cuvettes). All values must be positive numbers.
Q1: What is the ideal absorbance range for accurate measurements?
A: The most accurate measurements are typically obtained between 0.1 and 1.0 absorbance units. Below 0.1 may have too much noise, above 1.0 may deviate from linearity.
Q2: Where can I find the molar extinction coefficient?
A: Extinction coefficients are compound-specific and wavelength-dependent. They can be found in literature, chemical databases, or sometimes on the product specification sheet.
Q3: Does this work for any wavelength?
A: Yes, but you must use the extinction coefficient that corresponds to the wavelength at which you measured the absorbance.
Q4: What if my solution is too concentrated?
A: For absorbance >1.0, dilute your sample and multiply the calculated concentration by the dilution factor.
Q5: What are common sources of error?
A: Common errors include: using wrong extinction coefficient, dirty cuvettes, air bubbles in solution, incorrect wavelength setting, or stray light.