Strategies for improving sensitivity and selectivity for the quantitation of biotherapeutics in biological matrix using LC-MS/MS

In recent years, the applicability of using LC-MS/MS as a complementary technique to traditional ligand binding assays in the absolute quantitation of therapeutic proteins in biologic matrix has been demonstrated. Protein quantitation workflow via LC-MS/MS is primarily based on a enzymatic digestion model and recent works seek to improve selectivity and sensitivity. This review focuses on recent innovations in this field and discusses the following in detail: the applicability of two-dimensional liquid chromatography and its use to improve sensitivity and alleviate matrix ion suppression; the use of derivatization agents after digestion to improve extraction and MS ionization efficiency; techniques to reduce excess protein background and their positive effects on sensitivity, selectivity, and extraction consistency; the application of immunoaffinity extraction of proteins to enrich the analyte(s) of interest while improving selectivity and sensitivity.