Potential of polyE-323 coated capillaries for capillary electrophoresis of lipids

• Study of the resistance of polyamine-based capillary coating to organic solvents.
• Development of organic solution based BGE for lipid analysis in polyE-323 capillary.
• CE–MS analysis of cell membrane lipid extract.

In this note the feasibility of a polyamine-based capillary coating, polyE-323, for capillary electrophoresis (CE) of lipids is explored. PolyE-323 has previously been demonstrated to be suitable to suppress analyte-wall interaction of proteins in CE. However, the full applicability range of polyE-323 has not been exploited yet and it might be useful in the analysis of hydrophobic analytes, such as lipids. In this study, the stability of polyE-323 when using highly organic background electrolytes (BGEs), which are needed to solubilize the lipid analytes, was studied. For this, we used three different lipid samples: sphingomyelin, cardiolipin and a lipid extract from a cell culture. The highly organic BGEs that were used in this study consisted of 94.5% of organic solvents and 5.5% of an aqueous buffer. First, the influence of pure acetonitrile, methanol, propylene carbonate, isopropanol and chloroform on the polyE-323 coating was investigated. Then BGEs were developed and tested, using sphingomyelin and cardiolipin as test analytes in CE–UV experiments. After establishing the best BGEs (in terms of analysis time and repeatability) by CE–UV, sphingomyelin was used as a test analyte to demonstrate that method was also suitable for CE with mass-spectrometry detection (CE–MS). The LOD of sphingomyelin was estimated to be 100 nM and its migration time repeatability was 1.3%. The CE–MS analysis was further applied on a lipid extract obtained from human glioblastoma cells, which resulted in the separation and detection of a multitude of putative lipids.The results of our feasibility study indicate that CE systems based on polyE-323 coated capillaries and highly organic BGEs are promising for fast electromigration-based analysis of lipids.