Thus, plasma samples were extracted using the solvent method recommended by the manufacturer
Briefly, equal volumes of 40:60 butanol:diisopropyl ether were added to samples prior to centrifugation at RT for 5 min at 8000×g The top organic layer was
discarded and the aqueous solution transferred to a new mircocentrifuge tube. A 2:1 volume of ice cold acetone was then added toallsamplesprior tocentrifugationat
4◦C for 20 min at 12,000×g