Extinction coefficient

Determination of molar extinction coefficient for drug substance protein

Do you want to know the molar extinction coefficient of your drug substance protein?

The protein’s molar extinction coefficient depends on the actual protein sequence, the content of UV absorbing amino acids, and the buffer composition. We can help you determine it accurately.

The ICH Q6B Guidelines (Test Procedures and Acceptance Criteria for Biotechnological/Biological Products) requires the determination of the extinction coefficient. This blog post describes why it is important to determine it, regardless of whether you follow the ICH Q6B or not.

When the extinction coefficient of your drug substance protein is known, you can use spectrophotometry and UV-absorption to determine the protein concentration in laboratory samples.

Our procedure:

First we determine the exact quantity of protein by amino acid analysis. Then we prepare a dilution series of your protein and measure the UV absorbance at 280 nm at different protein concentrations. Finally, we calculate the molar extinction coefficient from the dilution series and the protein molecular weight.

You will receive:

  • Determination of the molar extinction coefficient.
  • Dilution series with UV absorbance at 280 nm as function of concentration.
  • Quantitative amino acid analysis of your protein stock solution.
  • Calculation of protein molecular weight from sequence.
  • Analysis result in 2-3 weeks.

You are welcome to send us a request if you have specific analysis needs.

Protein analysis by Alphalyse

Extinction coefficient of protein biologics

  • Molar extinction coefficient determination
  • UV absorbance 280nm of protein dilution series
  • Triplicate amino acid analysis for exact concentration in dilution series


World Class Service
Quality analysis, presented in easy-to-understand reports
Info / Order
Request quote
Order analysis now
Newsletter Subscribe to the Alphalyse Newsletter to get 3 tips
about protein analysis methods and applications
Private, secure, spam-free
© Copyright Alphalyse , Inc. 2002 - 2017. All rights reserved.