Comparison of the quantification of a therapeutic protein using nominal and accurate mass MS/MS

Background: The quantification of proteins and peptides in in vivo samples is a critical part of supporting the drug development process for biotherapeutics. LC–MS/MS using tandem quadrupole mass spectrometers is well established as the technology of choice for the quantification of small-molecule drugs and their metabolites in biological fluid. The application of accurate mass MS for quantification in a DMPK environment has attracted considerable interest in recent years. Materials & Methods: In this article we describe and compare the application of LC–high-resolution MS and LC–selected reaction monitoring (SRM) for the quantification of a therapeutics proteins. Results: The accurate mass instrumentation showed acceptable linearity and sensitivity to quantify the protein therapeutic to the level of 10 ng/ml. The accurate mass instrument was operated in accurate mass SRM using high resolution (SRM-HR), the assay was demonstrated to be linear over three orders of magnitude. By narrowing the mass window fr...