BACKGROUND: Metabolomics is a real challenge owing to the complexity and 
chemical heterogeneity of biological samples. In this study, a comparative 
analysis of metabolite profiling using ten metabolite extraction techniques were 
investigated on a pooled plasma sample followed by direct infusion ESI-MS 
analysis on both positive and negative modes. Methodology & Results: Metabolites 
from a pooled sample of 50 healthy volunteers were separated one- and 
two-dimensionally utilizing solvent precipitation, solid-phase extraction and 
molecular weight fractionation. Numbers of unique metabolites that are specific 
to a particular sample preparation approach were also identified by online 
available database, Metlin. The (1)H NMR study of different extraction 
procedures were also recorded to elaborate the comparative profiling of the 
various fractionation procedures.
CONCLUSION: The results of this study suggest that the metabolite extraction 
procedures based on 1- and 2-dimensions, followed by direct infusion ESI-MS 
analysis were able to detect endogenous metabolites belonging to different 
chemical classes.