Electron Capture Determination of Melengestrol Acetate in Bovine Tissue

Abstract

Abstract An electron capture GLC method has been developed for the determination of melengestrol acetate (MGA) in frozen bovine tissue, which removes, through extraction, solvent partition, and chromatographic cleanup, most of the interfering materials before injection of the sample onto the column for detection. MGA is extracted from lean tissue with acetonitrile and partitioned against hexane to remove nonpolar impurities. MGA in fatty tissues is first extracted with hexane and then transferred into acetonitrile. The residue from either extract, after evaporation of the solvent, is chromatographed on an alumina column with hexane and a mixture of hexane-acetone to remove the interfering lipids. The MGA is then eluted with hexane-chloroform (1+1). The residue, after rotary evaporation, is dissolved in the appropriate volume of hexanemethanol (94+6) and injected onto a 2′ 1% OV-17 column in an all-glass system. MGA can be detected at 25 ppb (2–3 mm peak) with no interference from tissue or reagents. The observed recovery of MGA at 25 ppb in muscle, liver, fat, kidney, and bone marrow was 93 ±7%.