A method for long chain fatty acids (LCFA) extraction, identification and further
quantification by capillary gas chromatography was developed and its application to liquid and
solid samples demonstrated. Linear calibration curves (r² between 0.997 and 1.000) were
constructed for C12 to C18 LCFA, in the range from 25 to 1270 mg/L. All the acids were
quantified in a single run using pentadecanoic acid (C15:0) as internal standard with response
factors ranging from 0.79 to 1.09. Relative standard deviation values lower than 15% and mean
LCFA recoveries above 90% were obtained. After validation, the usefulness of this method was
demonstrated in a cow manure digester receiving pulses of an industrial effluent containing high
lipid content. The knowledge obtained with the application of this method can contribute to a
better understanding of LCFA adsorption and degradation processes that occur during the
anaerobic digestion of lipids
