Silver-modified mobile phase for normal-phase liquid chromatographic determination of prostaglandins and their 5,6-trans isomers in prostaglandin bulk drugs and triacetin solutions.

A silver-modified, normal-phase, high-performance liquid chromatographic system has been developed for prostaglanding bulk drugs and triacetin solutions. Silver nitrate present in the mobile phase results in high selectivity for cis/trans isomers with conventional silica columns. Prostaglandins were esterified with alpha-bromo-2'-acetonaphthone prior to chromatography to provide high detectability at 254 nm. For dilute triacetin solutions, a sample preparation scheme based on gravity-flow chromatography with silica columns was developed to isolate the prostaglandin from triacetin prior to derivatization. The analytical technique was applied to triacetin solutions containing as little as 10 micrograms/ml arbaprostil [15-(R)-methyl-PGE2].