Influence of pressure upon coupling pressurized capillary electrochromatography with nuclear magnetic resonance spectroscopy

In this work, the influence of supplementary pressure:on the separation eff iciency of pressurized capillary electro-chromatography (pCEC) was examined . At low pressures of up to 30 bar, which is more than sufficient to preven t bubble formation, no significant loss in separation efficiency is observe d. Even at 100 bar, the efficiency of pCEC is still significantly better th an without application of an electric field. In addition, analysis times ar e drastically reduced compared to both capillary electrochromatography (CEC ) and capillary HPLC. On the basis of these results, an improved interface for capillary NMR coupling is described and used for the separation and ide ntification of a mixture of unsaturated fatty acid methyl esters. Under the se conditions, the analysis time could be shortened by up to a factor of 10 when pCEC is coupled to NMR spectroscopy.