The main objective of a metabolomics experiment is to determine the composition of the set of small molecules in one or more biological samples, both with respect to quantity and chemical characteristics. Two detection platforms are most commonly used in metabolomics: mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Since biological samples often consist of very complex matrices, containing several hundred to thousands of metabolites, these techniques are often coupled to different chromatographic separation techniques. In this chapter, we will treat the basic principles of the most commonly used chromatographic techniques and the very foundations of MS and NMR as major detection techniques in metabolomics. Numerous chromatographic techniques exist, but here we focus on three that are commonly used in metabolomics: gas chromatography, liquid chromatography and capillary electrophoresis. The focus is on concepts that are of particular importance for subsequent analysis and interpretation of the data. Less common detection methods based on vibrational and UV-Vis spectroscopy are treated briefly at the end of the chapter.