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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.

Services/Products
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

$2,200.00

World Class Service
Quality analysis, presented in easy-to-understand reports
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When the concentration of a given protein is known, the concentration and molecular weight can be used to determine the molar extinction coefficient.

The extinction coefficient is determined using the Beer-Lambert law: A = ε ∙ L ∙ c.
A is the absorbance at 280 nm, L is the light path (cm), c is protein concentration (g/L) and ε is the extinction coefficient (L g-1cm-1).

When the light path L = 1cm, ε = A/c. ε value corresponds to the slope of the line plotted between absorbance and concentration. The molar extinction coefficient am (L mol-1cm-1) is calculated using the formula am = ε∙ MW, where MW is the molecular weight of the protein.

 

What we need from you to perform this analysis:

  • 1-3 mg purified protein
  • The protein amino acid sequence
  • The buffer to be used for measurement
  • Concentration range to cover

If you do not provide the buffer with the sample we will use PBS as a standard buffer system.

Ship your protein samples by a courier company of your own choice

Place your samples into micro tubes and pack in a suitable transport box.

  • Contact a courier company of your choice (FedEx, UPS, DHL, TNT, World Courier etc.). Use the following sentence to describe the content: “Protein material – Non-toxic, non-hazardous, for research purpose only“.
  • Use cool packs or cooling units if your samples should be stored below 5°C/40°F
  • Ship the samples to the office closest to you (Canadian customers, please ship to Europe):
Customers in the USA
Alphalyse, Inc.
200 Page Mill Road, Suite 100
Palo Alto, CA, 94306
USA
Att: Jette Williams
Tel: (650) 543-3193
Customers outside of USA
Alphalyse A/S
Unsbjergvej 4 D
DK-5220, Odense
DENMARK
Att: Anette Rasmussen
Tel: +45 6310 6500
Order a prepaid FedEx Air Waybill < 1 lb./ 500g

A prepaid FedEx Air Waybill can be used for fast and easy shipment of samples in packages up to 1 lb./ 500g.
We will generate a prepaid Air Waybill, prefilled with the correct information, and send it to you by e-mail (PDF-format) within 24 hours.
Then follow these simple instructions:

  • Place your samples into micro tubes. Pack in suitable transport box.
  • Print the PDF document and stick it on the transport box or just hand it to your FedEx officer upon pickup.
  • Call to request a pickup from your local FedEx office.

If you plan to send your samples stored at room temperature, this option is usually the right choice. If you fill your box with cooling packs, the weight will most often exceed 1 lb./500g.

Order a prepaid FedEx Air Waybill < 10 lb./5kg (e.g. for packages with cooling packs)

This prepaid FedEx Air Waybill can be used for shipment of samples in packages up to 10 lb./ 5kg, with or without cooling packs (do not use dry ice!).
We will generate a prepaid Air Waybill, prefilled with the correct information, and send it to you by e-mail (PDF-format) within 24 hours.
Then follow these simple instructions:

  • Place your samples into micro tubes. Pack them in a suitable transport box. Fill with cooling units/cold packs (do not use dry ice!).
  • Print the PDF and stick it on the transport box or just hand it to your FedEx officer upon pickup.
  • Call to request a pickup from your local FedEx office.

If you plan to fill your transportation box with cooling packs, select this shipping option. If you plan to use dry ice, you cannot use this Waybill!

Get a quote for shipment by World Courier

The World Courier service can be used for shipment of samples of all types. If you select this option, we will contact you to provide a quotation based on location and shipping conditions. You will receive a prepaid Air Waybill which will be invoiced together with your analysis results. This is usually a good option if FedEx does not service your location.
With the prepaid World Courier service you get:

  • GxP compliant processes to ensure maximal security and traceability
  • Door-to-door solution on a dedicated vehicle
  • Possibility of providing qualified packaging, temperature monitoring and dry ice
  • Shortest possible transit-time through “next flight out”-procedure
  • Customs clearance and help with paperwork

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