Absolute quantification of proteins by ICP-MS/MS

Since 2015, Quality Assistance proposes to its partners a method based on Sulphur specific ICP-MS/MS detection combined with an ³⁴S/³²S isotope dilution quantification.

Over the years, high precision and accuracy of this methodology gained recognition; however, the sample quantity required by the method was limiting its applicability, especially for early-stage projects. Thanks to the expertise gained over the application of the method, it was redesigned to decrease by ten-fold the sample uptake. This application note presents an overview of this optimised method together with a demonstration of its performance through a partial validation study. This may be considered as a state-of-the-art approach for absolute quantification of proteins, to be used for both biological reference standard qualification and for protein molecular extinction coefficient determination.