ABSTRACT
The success of drug discovery assays, using plate-based technologies, relies heavily on the quality of the substrates being tested. Sample purity, identity and concentration must be assured for a screening hit to be validated. Most major pharmaceutical companies maintain large liquid screening files with often in excess of one million stock solutions, typically dissolved in DMSO. However, due to the inherent inaccuracies of high-throughput gravimetric analysis and automated dilution, stock solution concentrations can vary significantly from the assumed nominal value. Here, we present a rapid and effective method for measuring purity, identity and concentration of these stock solutions using four high-performance liquid chromatography (HPLC) columns with parallel ultraviolet spectrophotometry (UV), electrospray ionisation mass spectrometry (ESI-MS) and evaporative light scattering detection (ELSD) with a throughput of 1 min per sample.