Optimization of capillary electrophoresis coupled to negative mode electrospray ionization-mass spectrometry using polyvinyl alcohol coated capillaries. Application to a study on non-small cell lung cancer

Despite recent developments in separation techniques, the analysis of relatively small highly polar negatively charged analytes (e.g. small organic acids, phosphorylated sugars, and underivatized amino acids) remains challenging. Capillary electrophoresis coupled to mass spectrometry (CE−MS) has been included in the untargeted metabolomics toolbox, although mostly in positive polarity. The aim of this study was to assess the use of CE−MS to analyze highly polar and negatively charged metabolites at physiological levels without the need for derivatization.