DETERMINATION OF KETOPROFEN ENANTIOMERS IN PLASMA BY SOLID-PHASE EXTRACTION AND COLUMN SWITCHING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Protein-coated cyanopropyl silica gel packed in a precolumn was successfully used as an adsorbent for ketoprofen in blood plasma. After column switching, ketoprofen collected in the precolumn was transferred into an ovomucoid column, and the chiral separation was carried out by a mobile phase of 0.1 M phosphate solution (pH 3.2) containing 20% methanol. The separation factor was 1.32, and the resolution was 1.30. The recovery by direct injection of plasma samples was approximately 100%, with a relative standard deviation of about 5% between days (n = 6). The calibration graph of each enantiomer was a straight line up to 1 nmol; each detection limit was 5 pmol (S/N = 5).