Metabolite Profiling of Natural Volatiles and Extracts

Keywords metabolomics phenotype genotype SPME GC-MS GC-MS/MS AMDIS deconvolution biomarker identification library search MRM quantitation 

Analyses focusing on a group of metabolites or watching as many metabolites as possible at specified environmental or developmental stages is called metabolite profiling . The analysis of metabolites is very complex due to the chemical diversity of these small biological molecules. On the other hand metabolite target analyses may be restricted to specific metabolites of interest, which can be selectively monitored and quantified (Weckwerth, Wenzel and Fiehn, 2004). 

The deconvolution step is greatly facilitated by using the AMDIS program and the NIST mass spectral library search program (Mallard and Reed, 1997). Unique compound mass spectra are extracted by the analysis of all the transient ion signals allocating ion masses and relative intensities for each of the eluting compounds. 

The identification of metabolites is based on the characteristic El fragmentation patterns as well as on retention time (RT). The mass spectrum identification is facilitated by searching large data bases with NIST, Wiley or dedicated collections of mass spectra like the Fiehn metabolite spectrum library, or already available in-house metabolite databases, which are linked seamlessly into the search procedure. 

For the targeted quantitation phase suitable MS/MS transitions for each compound are applied using the identical chromatography setup and the retention 

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Section 4.23 Metabolite Profiling of Natural Volatiles and Extracts... 

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