HPLC on Chiralcel OJ-R for enantiomer separation and analysis of ketoprofen, from horse plasma, as the 9-aminophenanthrene derivative.

Racemic ketoprofen is a non-steroidal anti-inflammatory drug used to treat musculoskeletal and colic conditions in horses. The enantioselective chiral inversion of ketoprofen administered to horses has been studied by use of cellulose tris(4-methylbenzoate), also known as Chiralcel OJ-R, as chiral stationary phase; acetonitrile - 0.02 M perchlorate buffer (pH 2.0)-methanol, 60:15:25 (v/v/v) was used as mobile phase. Before chromatography, to effect adequate chiral interaction with the chiral stationary phase ketoprofen was derivatized with 9-aminophenanthrene, under acid conditions, after solid-phase (C18) extraction and then liquid-liquid extraction, to ensure effective removal of endogenous plasma materials. The 9-aminophenanthrene derivative of S-ibuprofen was used as internal standard. The enantiomers of ketoprofen were separated to baseline (Rs = 6.44, alpha = 1.76) within a short analysis time. The results indicate that the bio-inversion of R-ketoprofen to the S isomer is significant in equine species. However, considerable differences in pharmacokinetic parameters were observed, indicating large inter-animal variation.

Survey of the hormones used in cattle fattening based on the analysis of Belgian injection sites.

Although the illegal use of orally administered compounds in cattle fattening has gained popularity, injection sites are still frequently found during control experiments on the carcasses in the slaughterhouses. The high concentrations of hormones in injection sites enable screening for the presence of 39 different hormones by a simple extraction followed by a fast and simple high-performance thin-layer chromatography analysis. Analysis of injection-site tissue is particularly successful for determining the hormones that are illegally injected. This data can not be obtained by analysis of other biological matrices like faeces, kidney fat or urine, owing to metabolization and selective excretion and/or deposition of these compounds. Since 1989, over 2000 injection sites have been analysed in our laboratory, which yielded a good survey of the hormones that were illegally injected. Over this period, the natural hormones estradiol and testosterone (mostly present as their esters) have obviously been used extensively. It is clear that since 1990 clostebol acetate has remained the most abused exogenous hormone. Additionally, some distinct trends were noticed, e.g., a tendency towards a highly decreased use of nandrolone, an increased use of progesterone and an increased occurrence of certain androgens like stanozolol and fluoxymesterone.

Separation of 2-arylpropionic acids on a cellulose based chiral stationary phase by RP-HPLC.

The enantiomers of eight 2-arylpropionic acids, a group of chiral non steroidal antiinflammatory drugs, were resolved as their benzylamide derivatives on a high-performance liquid chromatographic chiral stationary phase consisting of a covalently bound tris (4-methylbenzoate) cellulose layer on silica gel. The column was used under reversed-phase conditions using methanol as the main mobile phase component, with a perchlorate buffer pH 2.0. A compromise for derivatization with a water soluble carbodiimide and 1-hydroxybenzotriazole of a group of eight analytes was obtained. The derivatives were identified by IR- and MS-spectroscopy.

Enantiomeric separation of amide derivatives of some 2-arylpropionic acids by HPLC on a cellulose-based chiral stationary phase.

A reversed phase high-performance liquid chromatographic method has been developed for the determination of the R- and S-enantiomers of ibuprofen, flurbiprofen, ketoprofen and tiaprofenic acid. Separation has been achieved using a tris(4-methylbenzoate)cellulose phase after derivatization into their amides. Flurbiprofen could also be partially resolved into its enantiomers without prior derivatization.