Metabolomics targeted metabolite analysis

The first two approaches, target metabolomics and metabolite profiling, focus on the detection and quatification of biomarkers. Biomarkers are specific metabolites used to distinguish a normal biological state from a pathogenic process. Analytical methods have been developed to monitor selected biomarkers by well-calibrated methods of analyses. If a patient is already sick, target or profile metabolomics are capable of fast diagnostics since patient symptoms can narrow the analysis to the most affected metabolite(s). 

Targeted analysis refers to metabolome analysis that targets one, or a few metabolites, and typically uses an internal standard for quantitation. The most common method is isotope dilution mass spectrometry (IDMS) [34], which relies on the use of stable isotope internal standards to enable the absolute quantitation of metabolites. This method has proven highly effective and has been successfully used in numerous studies. 

In metabolomic studies, there are three commonly used research strategies, namely, targeted metabolomics, metabolite profiling, and analysis of metabolic fingerprints [12]. 

Markuszewski, M.J., Szczykowska, M., Siluk, D., Kaliszan, R. Human red blood cells targeted metabolome analysis of glycolysis cycle metabolites by capillary electrophoresis using an indirect photometric detection method. J. Pharm. Biomed. Anal. 39, 636-642 (2005)... 

Metabolic profiling and metabolite target analysis (and metabolomics)... 

Quantitative metabolomics, on the other hand, can be described as a targeted approach focused on the analysis of specific metabolite species. In this method, multivariate statistical analysis follows metabolite identification and quantitation. Because of the reliable peak identification and measurement of metabolite integrals, quantitative metabolomics promises greater insights into the dynamics and fluxes of metabolites, as well as robust statistical models for distinguishing classes with better classification accuracy. A major requirement for quantitative metabolomics is good-quality spectral analysis to provide reliable peak assignments and metabolite identification. 

It was then necessary to validate that NP-1 targeted the same enzyme in higher plants. A metabolomic analysis showed that metabolites in the target pathway that... 

The last section of the chapter includes a discussion about how the application of different analytical techniques could allow enhancing the coverage of the fruit metabolome, being it impossible for any single platform to obtain information about all the metabolites present in a sample. The mentioned section illustrates the different levels of information obtained for the analysis of avocado fruit by CE-UV, CE-MS, HPLC-MS, UHPLC-MS, and GC-MS (using targeted and/or nontargeted approaches). 

In this chapter, we will focus on the potential of metabolomics to detect these unintended effects. This method enables the analysis of the overall metabolite composition employing some of the traditional analytical techniques used for the targeted approach. These include GC and... 

Target metabolomics Analysis restricted to specific metabolites (e.g., determining glucose levels in blood). 

For forensic analysis, target metabolomics is focused on the quantitative and qualitative analysis of specific metabolites such as drugs in blood, urine, tissue, or hair. In a recent study using IM-MS, metabolites in hair samples were analyzed. Four of the nine hair samples were positive for caffeine and nicotine and one sample tested positive for methamphetamine in the mass spectrum. However, when mobility data was considered the caffeine and nicotine were found to be true positives while the methamphetamine was determined to be a false positive. The mobility values for the unknown with the mass of methamphetamine did not match that of the methamphetamine standard. This is an excellent example of utility of isomeric/isobaric separation in mobility space. 

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