As with transcriptomics and proteomics, the analytical tools employed in metabolomics can yield massive data sets. The main obstacle in metabolomics studies is that the discovery phase is most commonly undertaken by mass spectrometry (MS) [5,6,7,8,9] or nuclear magnetic resonance (NMR) spectrometry [10,11]. MS and NMR are among the most important

emerging technologies in metabolomics, offering the shortest route toward metabolite identification and quantification [12]. NMR has demonstrated great potential, essentially due to the high measurement reproducibility and the high throughput of analysis [13,14]. However, one major problem in metabolomics studies by NMR is the Inhibitors,research,lifescience,medical relatively poor sensitivity of the technique. Furthermore, the number of MS researchers is much larger than that of NMR researchers trained to acquire metabolomics data [15]. In parallel, capillary electrophoresis (CE) [16], gas chromatography (GC) [17], and high performance Inhibitors,research,lifescience,medical liquid chromatography (HPLC) [18,19,20] separation techniques coupled to online MS detection can provide higher levels of sensitivity. Many important endogenous metabolites exist at very low concentrations in biological systems. Metabolomics could enable mapping of perturbations of early biochemical changes in diseases and hence provide an opportunity Inhibitors,research,lifescience,medical to develop predictive biomarkers that could result

in earlier intervention and provide valuable insights into the mechanisms of diseases. The primary goal of metabolomics analysis is the unbiased relative quantification of every metabolite in a biological Inhibitors,research,lifescience,medical system. Organic acids and amino acids represent metabolite classes of high significance because these metabolites are involved in a multitude of biochemical pathways and fluxes and are thus important for the diagnosis/evaluation of

a number of critical metabolic states. However, these metabolite classes can be difficult to separate from each other and matrix components because of their polar nature. In this review, we introduce various separation methods, such as CE, GC, and HPLC, for the determination Inhibitors,research,lifescience,medical of endogenous highly polar metabolites in biological samples. 2. Non-Target and Target Metabolomics Metabolomics is a promising Ketanserin approach aimed at facilitating our understanding of the dynamics of the biological composition in living systems. Metabolomics is classified into non-targeted or targeted metabolomics. Non-targeted metabolomics seeks to assign as many compounds as possible by either de novo analyte identification or ideally, utilizing reference standards to achieve the highest level of confidence. Changes in the metabolites can be mapped to specific pathways, thereby providing mechanistic information of the process under study. Targeted metabolomics measures RAD001 chemical structure analytes that have been selected a priori, on the basis of known biology and chemistry.