Sample preparation is a pivotal part of the integral LCMS bioanalysis, which has been heavily employed in the determination of drugs, drug metabolites, biomarkers, and other molecules of interest in various biological matrices (e.g. fluids or tissues) for decades. It has been playing an important role in a variety of human healthcare studies, ranging from drug discovery and development, therapeutic drug monitoring, to biomarker analysis. While highly sophisticated LC‐MS systems with better sensitivity and higher bioanalytical throughput have been continuously introduced, challenges that remain unchanged are the sample preparation prior to LC‐MS quantitation, for which data quality has direct impact on study conclusion.
The purpose of sample preparation is not only to make the analyte(s) of interest available in sample extracts at an appropriate concentration for MS detection but also to remove interfering matrix elements (e.g. phospholipids and salts) that, if not addressed properly, can alter MS response (e.g. signal suppression). In quantitative LCMS bioanalysis, clean sample extracts means: (i) better chromatography, (ii) lower limit of quantification, (iii) decreased assay variability (due to reduced matrix effects), (iv) less chance of false‐positive/negative results, (v) longer column lifetime, (vi) less instrument downtime, and (vii) minimized costs in manpower and equipment maintenance, etc. In practice, the best sample preparation strategies should always be considered, evaluated, and implemented whenever possible in developing a robust quantitative LC‐MS bioanalytical method