High pressure liquid chromatographic determination of melengestrol acetate in dry feed supplements.

A high pressure liquid chromatographic (HPLC) method is described for the quantitative determination of melengestrol acetate (MGA) in dry animal feed supplements containing 0.000027-0.000220% MGA (0.125-1.00 mg/lb). Ground feed is Soxhlet-extracted with hexane, and the extract is partitioned from hexane into aqueous methanol and then into methylene chloride, followed by mixed column chromatography. MGA is then quantitated by HPLC. Average recovery of standard MGA through the method at 1.00 ppm (0.454 mg/lb) was 94.8% with a 3.58% standard deviation. Average spike recovery of MGA in fortified feed at 0.100 ppm (0.0454 mg/lb) to 2.00 ppm (0.907 mg/lb) level was 97.8% with a standard deviation of 5.39%. In addition, the method includes a 2-dimensional thin layer chromatographic confirmatory test for MGA.