Separation of aryl propionic acids by capillary liquid chromatography

Capillary liquid chromatography (CLC) has been used to separate several aryl propionic acids (APA). Experiments were performed with a 23, cm x 100 mum W. fused-silica capillary packed with 3-mum diameter octadecylsilone-bonded silica gel. Detection, at 205 nm, was performed on-line. Carprofen, cicloprofen, fenoprofen, flurbiprofen, ibuprofen, indoprofen, ketoprofen, naproxen, suprofen, and tiaprofen were separated by use of ammonium formate, pH 2.5-methanol-acetonitrile-water as mobile phase. Retention times (t(R)), retention factors (k), and resolution (R-s) of the analytes were strongly affected by the amount of organic modifier in the mobile phase. Good repeatability was achieved for retention times (RSD% 0.8-1.5). Limits of detection (LOD) and quantitation (LOO) were in the ranges 2-8 and 7-33 ug mL(-1), respectively The usefulness of the optimized CLC method was demonstrated analyzing a pharmaceutical formulation containing ibuprofen; the analysis revealed the presence of ibuprofen only (96.8 +/- 2.3% of the declared APA content).