Low-flow rate separation systems (e.g. nano liquid chromatography and capillary electrophoresis) can allow for enhanced sensitivity and/or resolution. Such systems can be used for detecting low-abundant lipids, performing lipidomics of very small amounts of sample, and for studying interactions between lipids and other compounds, e.g. drugs. Low-flow separation systems are highly compatible with mass spectrometry, on-line sample preparation, and multi-dimensional chromatography, for example.