Ultra-high Throughput Mass Spectrometry Based Analysis by Direct Injection (Echo^® MS) for Plasma Protein Binding Assay

Plasma protein binding(PPB) assays are routinely performed during drug discovery.In our lab，a fully automated PPB assay was developed using an equilibrium dialysis device and Hamilton Microlab STAR workstation.Therefore，an ultra-high throughput mass spectrometry(MS) analysis platform needs to be developed to keep up with automated PPB assay.

In this study，a simple and reliable ADE-OPI-MS/MS(Echo^®MS) platform was established by optimizing MS detection conditions in terms of matrix effect and linearity.Here we take the positive control warfarin as an example.Thirty-eight compounds were tested in parallel by Echo^®MS and traditional LC-MS/MS in human，dog，rat，monkey，and mouse plasma using matrix-matched buffer in the PPB assay.Data showed that direct analysis on Echo^®MS， screening at a speed as fast as 3 seconds/injection，provided similar results with traditional LC-MS/MS method，with high data quality and good reproducibility even without internal standard.