Microextraction of Aromatic Microbial Metabolites by Packed Sorbent (MEPS) from Model Solutions Followed by Gas Chromatography/Mass Spectrometry Analysis of Their Silyl Derivatives

The paper describes the results of extraction of aromatic microbial metabolites (phenylcarboxylic acids) from model aqueous solutions using microextraction by packed sorbent (MEPS), followed by the determination of their silyl derivatives by gas chromatography/mass spectrometry. The selected conditions of adsorption–desorption, derivatization, and gas chromatography determination enable the detection of a number of compounds, which are proved and prospective disease markers. This detection could be performed at the level of their concentration in blood of healthy donors (0.5 μmol L^–1) and patients of intensive care units, having an initial stage of sepsis (2–3 μmol L^–1) or other serious diseases caused by significant microbial load and led to the development of multiple organ failure. The recoveries of phenylcarboxylic acids using nonpolar sorbent (C18) reached 20–65% for hydroxylated acids (phenyllactic, 4-hydroxybenzoic, 4-hydroxyphenylacetic, 4-hydroxyphenylpropanoic, homovanillic, and 4-hydroxyphenyllactic acids) and 100% for more nonpolar acids (benzoic, phenylpropanoic, and cinnamic acids).