Protein quantification or total protein content by colorimetric methods such as absorbance at 280, Bradford or BCA assays and quantitative amino acid analysis

Protein quantification is necessary to understand the total protein content in a sample or in a formulated product. Accurate protein quantification is important as a range of other critical assays require precise total protein content results in order to generate data. Careful selection of the protein quantification method is required to ensure accurate data. Colorimetric assays, for example, are dependent on the use of an external reference standard and the different absorbance properties between product and the reference standard may lead to inaccuracies. Quantitative amino acid analysis can also be used for protein content determination but an understanding of how different proteins hydrolyze under similar conditions and the stability of amino acids during hydrolysis is critical.

Our scientists are experts in the selection of protein quantification assays which is underpinned by a deep knowledge of the physicochemical properties of proteins and amino acids. We address any potential source of variability in the accuracy of measurement of total protein content, delivering precise and robust data every time.

We provide a range of total protein quantification methods, including European Pharmacopoeia (EP) and United States Pharmacopeia (USP) methods. Colorimetric assays such as the Bradford or bicinchoninic acid (BCA) assays measure UV-light absorbance and can be used to calculate protein concentration from the absorbance measurement, once the extinction coefficient (molar absorptivity) has been accurately established. Other assays include absorbance at 280nm, Lowry assay and the Biuret assay. We also provide quantitative amino acid analysis by High performance liquid chromatography (HPLC) or ion chromatography (IC).

Our experts are also adept at determining the extinction coefficient (molar absorptivity) for a protein by determining the absorbance using UV/visible spectrophotometry of a solution of known protein content as determined by quantitative amino acid analysis or total nitrogen determination.

Protein quantification can be offered from our cGMP compliant laboratories as a standalone test or as part of a biologic release testing package for commercial release or a biopharmaceutical stability study test.

As your outsourcing partner for biologics or protein product development, our expertise in protein content can accelerate development timelines through delivering accurate and robust analytical services. Bringing quality and safety to life, we offer Total Quality Assurance expertise to help you to meet and exceed quality, safety and regulatory standards. 

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