Capillary electrochromatography and capillary electrochromatography-electrospray mass spectrometry for the separation of non-steroidal anti-inflammatory drugs

In this study capillary electrochromatography (CEC) was utilized for the se paration of ten non-steroidal anti-inflammatory drugs (NSAIDs). Experiments were carried out in a commercially available CE instrument using a packed capillary with RP-18 silica particles where the stationary phase completely filled the capillary. The mobile phase consisted of a mixture of ammonium formate buffer pH 2.5 and acetonitrile. Selectivity and resolution were stu died changing the pH and the concentration of the buffer, the acetonitrile content mobile phase and the capillary temperature. The optimum experimenta l conditions for CEC separation of the studied drug mixture were found usin g 50 mM ammonium formate pH 2.5-acetonitrile (40:60) at 25 degreesC. The CE C capillary was coupled to an electrospray mass spectrometer for the charac terization of the NSAIDs. A mobile phase composed by the same buffer but wi th a higher concentration of acetonitrile (90%) was used in order to speed up the separation of analytes. (C) 2000 Elsevier Science B.V. All rights re served.