Fast and accurate absolute quantification of antibodies and antibody-drug conjugate using Isotope Dilution-Triple Quadrupole ICP-MS

Juliusz Bianga
Philippe De Raeve
Magali Perez
Arnaud Delobel

Traditional “absolute” methods of analysis for protein quantification include colorimetry, amino acid (AA) analysis and UV-Vis spectroscopy but each of these techniques has its limitations.

Clearly there is a requirement for a fast, generic method that provides accurate protein quantification without the need for a reference material, in this case a protein standard.

In this study, we evaluated an Agilent 8800 ICP-QQQ and isotope dilution analysis (ID-ICP-QQQ) of sulphur, for the quantification of proteins, including antibodies and ADCs.

The method, which requires only very common reagents and standards, was found to provide:

  • High sensitivity, so only requires a low concentration of the analyte protein

  • Good reproducibility: RSD < 1 %

  • Excellent accuracy: < 2 % bias

  • Matrix tolerance: results were consistent in the presence of various types and combination of formulation buffer

  • Wide applicability: the same method can be used for the analysis of any sulphur-containing protein or peptide and possibly any other small sulphurcontaining molecules

  • Fast: all results were obtained within half a day of lab work in routine use