Determination of compound potency using the PhABit displacement assay could be achieved using concentration-response studies. However, advancement from single concentration screening to concentration-response measurements (pIC50) was limited by the throughput of LC-MS analysis (7.7 min per sample). The protocol was therefore transferred to RapidFire TM MS, which uses a desalting cartridge rather than liquid chromatography, enabling analysis at a rate of just 12 seconds per sample. This acceleration in throughput significantly improved the scope of the screening approach.