Quantitative mass spectrometry-based assay development and validation: From small molecules to proteins

Mass spectrometry (MS) has emerged as a powerful analytical tool for the identification, characterization and quantification of various biomolecules (small molecules, drug metabolites and proteins) in biological specimens. The use of mass spectrometers in the clinical diagnostic laboratories have gained popularity due to its ease of development of new assays, ability to measure multiple analytes in a single analytical run, low volume requirements and low reagent costs. Novel technological advancements in ionization sources, instrumentation and software have increased the popularity of these platforms. Consequently, a number of home-brew assays, utilizing the power of MS, are being developed and validated for clinical diagnostic use. In this review, we will discuss the two phases that precede method implementation: method development and validation for both small molecule analysis and protein quantification using liquid chromatography tandem mass spectrometry (LC–MS/MS). Some of the challenges facing protein quantification will be highlighted and an outlook for the future of laboratory medicine and MS will be provided.

► Home-brew assays utilizing MS are being developed in clinical laboratories.
► Two phases that precede method implementation are method development and validation.
► Protein quantification by MS has not fully penetrated into the clinical laboratories.
► Novel technological developments are constantly emerging from the research community.