Rapid Purification and Quantification of Intestinal and Fecal Short-Chain Fatty Acids by Solid-Phase Extraction Using Bond Elut Plexa

Short-chain fatty acids (SCFAs) in feces are inextricably linked to intestinal homeostasis and can be used as potential markers for metabolic diseases. In this study, an efficient and simple method was developed for the purification of SCFAs without the need for derivatization of the samples. The SCFAs (acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acid) were extracted from a small amount (50 mg) of fecal and intestinal samples using acetone combined with solid phase extraction column (Bond Elut Plexa) enrichment. Quantitative analysis was performed using gas chromatography with a flame ionization detector. The developed method has shown very good limits of detection (LOD, 0.11–0.36 μM) and limits of quantification (LOQ, 0.38–1.21 μM) with excellent linearity (R2 ≥ 0.9998), good recovery (98.34–137.83%), and high reproducibility (RSD ≤ 1.30). The applicability of this method was also demonstrated by testing the fecal and cecum contents of different species from mammals (mice, pigs) to insects (honeybees). The technique is highly suitable for analyzing complex, small amounts of intestinal and fecal SCFAs.