Beer-Lambert Law
Beer-Lambert Law — The principle that absorbance is proportional to concentration and path length, the mathematical basis for determining peptide concentration by UV spectrophotometry.
What Is the Beer-Lambert Law?
The Beer-Lambert law (A = εlc) relates the absorbance (A) of a solution to the molar extinction coefficient (ε), path length (l, in cm), and molar concentration (c). It is the mathematical basis for all spectrophotometric peptide concentration measurements, enabling rapid, non-destructive quantification from a simple UV absorbance reading.
Application to Peptides
- A280 method: c = A280 / (ε280 x l). Works for peptides containing Trp or Tyr
- ε280 calculation: ε280 = 5500(nTrp) + 1490(nTyr) + 125(nCys-SS) M⁻¹cm⁻¹
- A205 method: Universal for all peptides via peptide bond absorbance, but less specific
- Linearity range: Valid for A = 0.1-1.0. Dilute concentrated samples to stay within linear range
Frequently Asked Questions
What is Beer-Lambert Law?
The principle that absorbance is proportional to concentration and path length, the mathematical basis for determining peptide concentration by UV spectrophotometry.
Why is Beer-Lambert Law important in peptide research?
Beer-Lambert Law is a fundamental concept in analytical as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.
Authority Sources
- Beer-Lambert Law on Wikipedia
- Search Beer-Lambert Law on PubChem (NIH)
- Research articles on ScienceDirect