Metabolite analysis of human fecal water by gas chromatography/mass spectrometry with ethyl chloroformate derivatization.
Fecal water is a complex mixture of various metabolites with a wide range of physicochemical properties and boiling points. The analytical method developed here provides a qualitative and quantitative gas chromatography/mass spectrometry (GC/MS) analysis, with high sensitivity and efficiency, coupled with derivatization of ethyl chloroformate in aqueous medium. The water/ethanol/pyridine ratio was optimized to 12:6:1, and a two-step derivatization with an initial pH regulation of 0.1M sodium bicarbonate was developed. The deionized water exhibited better extraction efficiency for fecal water compounds than did acidified and alkalized water. Furthermore, more amino acids were extracted from frozen fecal samples than from fresh samples based on multivariate statistical analysis and univariate statistical validation on GC/MS data. Method validation by 34 reference standards and fecal water samples showed a correlation coefficient higher than 0.99 for each of the standards, and the limit of detection (LOD) was from 10 to 500pg on-column for most of the standards. The analytical equipment exhibited excellent repeatability, with the relative standard deviation (RSD) lower than 4% for standards and lower than 7% for fecal water. The derivatization method also demonstrated good repeatability, with the RSD lower than 6.4% for standards (except 3,4-dihydroxyphenylacetic acid) and lower than 10% for fecal water (except dicarboxylic acids). The qualitative means by searching the electron impact (EI) mass spectral database, chemical ionization (CI) mass spectra validation, and reference standards comparison totally identified and structurally confirmed 73 compounds, and the fecal water compounds of healthy humans were also quantified. This protocol shows a promising application in metabolome analysis based on human fecal water samples.
Gao
Xianfu
X
Nutrition Humaine, Plate forme Exploration du Métabolisme, Institut National de la Recherche Agronomique, Clermont-Ferrand, France.
Pujos-Guillot
Estelle
E
Martin
Jean-François
JF
Galan
Pilar
P
Juste
Catherine
C
Jia
Wei
W
Sebedio
Jean-Louis
JL
D000477:Alkylating Agents; D053000:Analytic Sample Preparation Methods; D001834:Body Water / Q000737:chemistry*; D016208:Databases, Factual; D005243:Feces / Q000737:chemistry*; D005563:Formic Acid Esters; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D055442:Metabolome; D055432:Metabolomics / Q000379:methods*; D015999:Multivariate Analysis; D012015:Reference Standards; D015203:Reproducibility of Results; D012997:Solvents
D000477:Alkylating Agents; D005563:Formic Acid Esters; D007202:Indicators and Reagents; D012997:Solvents; C007658:ethyl chloroformate