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 · 100 micron i.d. fused-silica capillary packed with 3 micron diameter octadecylsilane-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 (tR), retention factors (k), and resolution (RS) 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 (LOQ) were in the ranges 2–8 and 7–33 microg/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).