Abstract
A pressurized, gradient capillary electrochromatography (pCEC) instrument has been designed and built. This versatile instrument can be operated in three separation modes, namely, pCEC, micro high performance liquid chromatography (ΞΌHPLC) and capillary electrophoresis (CE). In pCEC mode, both an electric field and a pressure can be applied across a packed capillary column, allowing fine tuning of the selectivity without changing the composition of the mobile phase. This technique also facilitates the use of gradient elution, making it more powerful for separation of complex mixtures. The technique was evaluated and compared with ΞΌHPLC by separating a mixture of organic acids and neutral pyridazinone derivatives. Experiments in pCEC were carried out with a fusedβsilica capillary column packed with 3βΞΌm octadecyl silica (ODS) particles. A separation with baseline resolution was achieved for ten pyridazinone derivatives at optimum conditions. Compared with the separation results by ΞΌHPLC method, pCEC is more powerful than ΞΌHPLC for the separation of both neutral and charged compounds. The influence of the supplementary pressure, the flow rate of pumps and applied voltage on the separation was also investigated.βΒ© 2001 John Wiley & Sons, Inc.βJ Micro Sep 13: 191β196, 2001