Determination of short-chain fatty acids in feces by capillary electrophoresis with indirect UV-VIS detection

Fermentation of undigested carbohydrates and amino acids in the large intestine leads to the production of short-chain fatty acids (SCFAs). Increasing attention has been recently paid to investigating the effect of the presence of SCFAs in the mammalian large intestine on the colon health. Thus, clinical practice requires analytical methods capable of fast, reliable and inexpensive quantification of SCFAs. Capillary electrophoresis meets such requirements, and hence a capillary electrophoresis method was developed to quantify acetate, propionate, butyrate and isobutyrate in human and canine feces. Benzoic acid in the background electrolyte was selected as a suitable indirect probe for indirect UV-VIS detection. A considerable advantage of the proposed method is the determination of butyric acid as well as isobutyric acid in one analytical run. The separation of these isomers was achieved through addition of α-cyclodextrin to the background electrolyte. The optimized method offers quantification of acetate at concentrations above 10 μM, and propionate, butyrate and isobutyrate at concentrations above 8 μM with acceptable precision, accuracy and with no significant matrix effects.