Analysis of volatile fatty acids in rumen fluid by proton NMR spectroscopy

A study was conducted to quantify the volatile fatty acid (VFA) concentrations in aqueous and rumen fluid samples using a standard additions based quantitative proton nuclear magnetic resonance (NMR) spectroscopic method. Standard plots for acetic, propionic and butyric acids were all found to be linear (R2 > 0.99). Results obtained by NMR were compared with those obtained using the conventional gas chromatographic method. No significant differences were found between the means and precisions of the two techniques (P < 0.05). The method is well-suited for the routine quantification of these acids, requires no sample pretreatment and is more rapid than gas chromatography. Key words: Volatile fatty acid determination, rumen fluid, gas chromatography, nuclear magnetic resonance spectroscopy