Simultaneous determination of caffeine, paracetamol, and ibuprofen in pharmaceutical formulations by high-performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection

Paracetamol, caffeine and ibuprofen are found in over-the-counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high-performance liquid chromatography with diode-array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high-performance liquid chromatography with diode-array detection was achieved on a C-18 column (250x4.6 mm(2), 5 m) with a gradient mobile phase comprising 20-100% acetonitrile in 40 mmol L-1 phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused-silica capillary (40 cm length, 50 m i.d.) using 10 mmol L-1 3,4-dimethoxycinnamate and 10 mmol L-1 -alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 mol L-1 by liquid chromatography and 39, 32, and 49 mol L-1 by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92-107% for both proposed methods.