Fully automated liquid–liquid extraction for the determination of a novel insulin sensitizer in human plasma by heated nebulizer and turbo ionspray liquid chromatography-tandem mass spectrometry

I, 2-{[5,7-dipropyl-3-(trifluoromethyl)-1,2-benzisoxazol-6-yl]oxy}-2-methyl propionic acid is an α peroxisome proliferator-activated receptor (PPAR) agonist with some γ activity being investigated for potential use in the treatment of Type II diabetes mellitus and dyslipidemia. Two automated liquid–liquid extraction methods were developed and validated for the determination of I in human plasma. Concentrations of I were determined over a wide range of clinical doses. For Method A, plasma was acidified and extracted with ethyl acetate using a fully automated procedure. Analysis was performed by LC-MS/MS with a turbo ionspray source in negative ion mode. For Method B, a larger volume of plasma was extracted and a heated nebulizer source was used on the mass spectrometer. Method A was linear from 0.05 to 50 ng/mL and Method B from 0.2 to 1000 ng/mL. Validation procedures showed that both methods were robust, specific and reproducible.