Samenvatting

The simultaneous analysis of a broad range of polar ionogenic metabolites using capillary electrophoresis-mass spectrometry (CE-MS) can be challenging, as two different analytical methods are often required, that is, one for cations and one for anions. Even though CE-MS has shown to be an effective method for cationic metabolite profiling, the analysis of small anionic metabolites of ten results in relatively low sensitivity and poor repeatability. In this work, a novel derivatization strategy based on trimethyl-methaneaminophenacetyl bromide was developed to enable CE-MS analysis of carboxylicacid metabolites using normal CEpolarity (i.e.,cathode in the outlet) and detection by massspectrometry in positive ionization mode. Optimization of derivatization conditions was performed using a response surface methodology after which the optimized method (incubation time 50 min, temperature 90◦C, and pH10) was used for the analysis of carboxylicacidmetabolites in extracts from HepG2cells. For selected metabolites, detection limits were down to 8.2nM, and intraday relative standard deviation values for replicates (n=3) for peak areas were below 21.5%. Metabolites related to glycolysis, tricarboxylicacidcycle, and anaerobic respiration pathways were quantified in 250,000 cell lysates, and could still be detected in extracts from only 25,000 HepG2cell lysates (∼70 cell lysates injected).