An optimized procedure for metabonomic analysis of rat liver tissue using gas chromatography/time-of-flight mass spectrometry

In this paper, we present a tissue metabonomic method with an optimized extraction procedure followed by instrumental analysis with gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) and spectral data analysis with multivariate statistics. Metabolite extractions were carried out using three solvents: chloroform, methanol, and water, with design of experiment (DOE) theory and multivariate statistical analysis. A two-step metabolite extraction procedure was optimized using a mixed solvent of chloroform–methanol–water (1:2:1, v/v/v) and then followed by methanol alone. This approach was subsequently validated using standard compounds and liver tissues. Calibration curves were obtained in the range of 0.50–125.0 μg/mL for standards and 0.02–0.25 g/mL acceptable for liver tissue samples. For most of the metabolites investigated, relative standard deviations (RSD) were below 10% within a day (reproducibility) and below 15% within a week (stability). Rat liver tissues of carbon tetrachloride-induced acute liver injury models (n = 10) and healthy control rats (n = 10) were analyzed which demonstrated the applicability of the developed procedure for the tissue metabonomic study.