Re: How to convert a concentration of an IFN ã of µg to units/ml?

Hi Rias,

You are not alone. Many researchers have faced this conundrum. This is a question that must be resolved in your laboratory. The reason is because biological activities are subject to loss of bioavailability due to stresses of purification, freezing, transport and re-thawing.

An international unit (IU)/mL is usually an indication of bioactivity in a very specific assay. For IFN-gamma, the assay is generally a cell protection assay for a specific cell against a specific antagonist. These assays are rather complex, requiring scrupulous care in making of buffers and cell nutrient media.

A ug quantity is a unit of mass, some of which, although pure, may not be 100% active. Some bioactivity may be lost through the purification process. This is quite common.

There is also the issue of conversion of IU/mL to ug. IU/mL is an activity concentration, ug is a mass. The best conversion one could hope for would be IU/mL to ug/mL or IU/ug.

Therefore, a concrete answer to a conversion of IU/mL to ug/mL in ground- breaking research is simply not yet feasible or workable in this biological system(s).

It may be suggested to contact the manufacturer, request the specifics of their Quality Assurance assay for the specific lot number of IFN you purchased. Perform the assay yourself and then calculate the activity to mass conversion for that lot number. In our hands, the manufacturer is more than willing to cooperate, provide the information and will even allow you to speak with the person who conducts the assay.

I hope this helps. Thanks for your question!

Peter, Mad Scientist

http://www.ncbi.nlm.nih.gov/pubmed/20721576
http://www.ebioscience.com/ebioscience/specs/antibody_14/14-8319.htm
http://www.interferonsource.com/New_InterferonSource/Protocols/PDF/41500-1_v.1.4.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC162563/