Bioanalysis of therapeutic monoclonal antibody by peptide adsorption-controlled LC-MS.

We aimed to develop an easy, low-cost and versatile mass spectrometric method for the bioanalysis of a therapeutic monoclonal antibody (mAb) in human serum that employs peptide adsorption-controlled (PAC)-LC/MS using selected reaction monitoring mode (LC-MS/MS-SRM). Rituximab was used as a model mAb. To apply the method to human serum samples, a peptide of the complementarity-determining region was selected as the surrogate peptide. The usefulness of PAC-LC-MS/MS-SRM was evaluated by a collaborative study. The calibration curve ranged from 0.5 (or 1.0) to 1000.0 μg/ml. The selectivity, linearity, accuracy and precision met the predefined acceptance criteria. Our method could be a useful bioanalytical method for the quantification of mAbs in clinical samples.