New developments in the absolute quantification of proteins 

9th July 2020

Absolute quantification of proteins (i.e. quantification without the need for a reference standard) is a key analysis for the qualification of reference standards or to determine the extinction coefficient of a protein. It is usually performed using amino acid analysis, but this technique shows limited accuracy and repeatability.

Unprecedented precision and accuracy can be obtained with Quality Assistance’s innovative method based on the quantification of sulphur by isotope dilution ICP-MS. This method was validated using a National Institute of Standards and Technology (NIST) certified bovine serum albumin (BSA) solution with precision <1% relative standard deviation (RSD) and accuracy <2% bias over the range of concentrations tested. As a conclusion of the validation study, we were able to prove that the method could provide excellent results for a wide range of biopharmaceutical samples, yielding a very precise and very accurate absolute quantification of proteins. Compared to the reference method (amino acid analysis), results are significantly improved. Even by performing a large number of replicates, amino acid analysis would not able to yield such accurate measurements.

New developments

In order to upstream the application of this approach from early stages of the development, this method was optimised and validated using smaller amounts of sample demonstrating the same levels of precision and accuracy.


In 2019, this method was nominated for the essenscia Innovation Award and included in the list of 5 high-potential innovations as it may contribute to improve the control on the manufacturing process. It enables biopharma companies to accelerate the development of their product, and eventually to speed up people’s access to new medicines.

innovation awards

More literature

Click here to access a webinar recording on the absolute quantification of mAbs and ADCs. Arnaud Delobel, R&D Director at Quality Assistance, outlined the steps we took to successfully develop this innovative analytical method, the results of the validation study, and the application of the method to monoclonal antibodies and antibody-drug conjugates.

webinar absolute quantification abs

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