Separation of phosphatidylinositol 4-phosphate from a mixture with phosphatidylserine and phosphatidylinositol by Sep-Pak C-18 cartridge

A simple and efficient method for the separation of phosphatidylinositol 4- phosphate (PI 4-P) from phosphatidylinositol (PI) and phosphatidylserine (P S) is described, A mixture of PI, PI 4-P and PS was injected onto a Sep-Pak C-18 cartridge. PI and PS were flushed through the cartridge with solvent 1 [methanol-chloroform (3 : 1)] while PI 4-P remained in it. Then the cartr idge was inverted, and PI 4-P was eluted backward with solvent 2 [chlorofor m-methanol-0.5 M aqueous ammonium hydroxide (9 : 7 : 2)].