Concentration from Absorbance Calculator

This calculator determines the concentration of a solution from its absorbance using Beer-Lambert Law.

Input Parameters

Calculation Results

Calculation Formula

C = A / (ε × l)

Where:
C = Concentration (mol/L)
A = Absorbance
ε = Molar Absorptivity (L mol⁻¹ cm⁻¹)
l = Path Length (cm)

Result

Concentration from Absorbance Calculator Usage Guide

Learn how to use the Concentration from Absorbance Calculator and its working principles

How to Use This Calculator

  1. Enter the absorbance (A) of your solution. This can be measured using a spectrophotometer.
  2. Enter the molar absorptivity (ε) of the substance at the specific wavelength of measurement. This value is substance-specific and can be found in scientific literature.
  3. Enter the path length (l) of the cuvette. The standard path length is 1 cm, but if you're using a different cuvette, adjust this value accordingly.
  4. Click the "Calculate" button to determine the concentration.

Beer-Lambert Law

This calculator uses Beer-Lambert Law, which states that the absorbance of a solution is directly proportional to the concentration of the solute and the path length of the light through the solution. The law is expressed as:

A = ε × l × C

Where:

  • A is the absorbance
  • ε is the molar absorptivity (or molar extinction coefficient)
  • l is the path length of the light through the solution
  • C is the concentration of the solute

Applications

This calculator is commonly used in analytical chemistry for determining the concentration of:

  • Chemical substances in solution
  • Biological molecules such as proteins and nucleic acids
  • Drugs in pharmaceutical analysis
  • Environmental samples

Important Notes

Accuracy Considerations: For accurate results, ensure that the absorbance reading falls within the linear range of the instrument (typically between 0.1 and 1.0). If the absorbance is too high, consider diluting the sample and recalculating the concentration.

Temperature Effects: Molar absorptivity can be temperature-dependent, so ensure your measurements are taken at consistent temperatures if high precision is required.