Comparison of Protein Precipitation,Turbulent Flow and Automated On-Line Solid Phase Extraction,as Plasma Sample Preparation Techniques for the Determination of Compound I by LC-MS-MS

Compound I is a novel subtype-selective 5-HT₁ receptor antagonist currently under pre-clinical investigation. A theoretical increase in sensitivity of about 4 times over the plasma protein precipitation method by the two on-line extraction systems tested should be expected due to the introduction of 100% of the analyte onto the column with both the on-line systems. The comparison of these three methods showed that the real gain in sensitivity was 4 times with Prospekt2? and 2 times with TurboFlow?. This might be explained by the different mobile phases used combined with different recoveries. Due to the improved chromatography, the higher sensitivity and lower carry-over observed for this compound, the Prospekt2? system was chosen in order to validate an analytical procedure for the quantitation of I in rat plasma followed by LC-MS-MS.