Measurement of short-chain fatty acids in human faeces using high-performance liquid chromatography: specimen stability

Background: Short-chain fatty acids such as lactic acid produced by the intestinal bacterial flora have various physiological actions involved in health, and it is important to determine the concentrations of faecal short-chain fatty acids and evaluate their relationship with large intestinal diseases. In this study, we evaluated the highly selective and sensitive simultaneous measurement of both volatile and non-volatile short-chain fatty acid hydrazides using high-performance liquid chromatography (HPLC). Materials and methods: Faeces treated with ethanol were used as analytic samples. Short-chain fatty acids were measured as fatty acid hydrazides by HPLC. Results: For 12 types of short-chain fatty acid, the results regarding linearity, recovery tests and reproducibility were favourable. Faeces treated with ethanol could be stored at room temperature. Discussion: The stability of short-chain fatty acids in faeces at room temperature was statistically analysed. Faeces stored without treatment with ethanol showed increases/decreases in the concentrations of short-chain fatty acids, which may be clue to assimilation by intestinal bacteria. However, specimen in 70% ethanol and stored in room temperature exhibited no substantial changes in concentrations of short-chain fatty acids up to seven days.