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Biopharmaceutical development is booming and now an integral part of many pharmaceutical company pipelines. While these emerging biologics present exciting opportunities for the industry, their sophistication is challenging the limits of characterization at all stages of discovery and development.

The quantitation of proteins using the surrogate peptide approach can complicate nominal mass Triple Quadrupole MRM measurements due to co-extracted interference when using non-selective extraction techniques such as pellet digestion. High resolution coupled with accurate mass filtering can mitigate such interference, as reported previously for the determination of rituximab using the TripleTOF 6600 (Protein Quant Approaches). However, an additional level of selectivity can often be achieved on nominal mass systems using the orthogonal gas-phase separation approach offered by the SelexION+® Differential Mobility System technology (DMS). Interfaced between the sampling orifice and ion source, the DMS separates ions based upon differences in their migration rates under alternating low and high field waveform amplitudes (Figure 1). Ion clustering in low fields and declustering in high fields amplifies the distinction in mobility of an ion, resulting in improved resolution from interfering species of differing molecular cross-section.1-4

The number of protein based drugs coming onto the market is at an all-time high, particularly those produced with a host cell system. With host cells come their own proteins. These host cell proteins (HCPs) constitute a major part of process-related impurities and can adversely affect drug safety, so it is critical that they are identified and quantified accurately.