A comparative study of the reversed-phase HPLC retention behaviour of S-adenosyl-L-methionine and its related metabolites on Hypersil ODS and Supelcosil LC-ABZ stationary phases.

S-Adenosyl-L-methionine (SAM) and its metabolites S-adenosyl-L-homocysteine (SAH) and methyl-thioadenosine (MTA) are endogenous compounds that are heavily involved in a variety of biochemical processes, and have therefore been the target for several assays in body fluids and tissues. Reversed-phase chromatographic behaviour of SAM and its metabolites has been studied by using Supelcosil LC-ABZ column, specially designed for analysis of acidic, basic, zwitterionic and neutral compounds, and on a Hypersil ODS column as a function of mobile phase pH. The retentions of the compounds, expressed by the capacity ratio (k'), are measured on both column with mobile phases comprised of 10% acetonitrile and 10 mM ammonium formate buffer with pH values ranging from 2 to 9. Higher selectivity is observed on Supelcosil LC-ABZ within pH range 4-6. Different retention properties are observed at very low pH and seemed as if the Supelcosil LC-ABZ column reduced the effect of the mobile phase pH by about 1 pH unit. Whilst the Supelcosil column can be recommended for the routine analysis of SAM and its related metabolites in biological fluids by using mobile phase pH 5, the Hypersil ODS column may be suggested for use with mobile phase pH values of 3-4.

Simultaneous high-performance liquid chromatographic determination of propoxyphene and acetaminophen in pharmaceutical preparations.

A normal-phase high-performance liquid chromatographic method, using a 3.3 cm x 4.6 mm silica column (3 microns packing) and an ammonium hydroxide-methanol-dichloromethane mobile phase, has been developed to separate propoxyphene and acetaminophen in less than 5 min. Quantitative recovery of both compounds from various pharmaceutical preparations was achieved, following a single dilution scheme. The method is stable, reproducible, and selective.