Facile analysis of short-chain fatty acids as 4-nitrophenyl esters in complex anaerobic fermentation samples by high performance liquid chromatography

Short-chain fatty acids are crucial intermediates in the conversion of biomass to methane. Due to the complexity of raw biomass, volatile fatty acids (including n- and branched-chain compounds) as well as arylacetic and arylpropionic acids arise from digestion of carbohydrates, proteins and lipids. The development of a simple extraction procedure in combination with internal standardization and facile 4-nitrophenyl-labelling via oxalylchloride-generated acylchlorides enabled robust separation and quantification of the target compounds in crude biological samples like raw cattle manure and biogas fermenter contents. Detection limits of