Fatty Acids

Fatty acids with carboxyl groups are highly adsorptive and often analyzed by esterification. Ester derivatives of lower fatty acids are highly volatile and cannot be recovered in good yield, requiring direct analysis Unisole F-200 is the most suitable packing material for analysis of traces of lower fatty acids in water. Though there are few ghost peaks due to water, quantitative analyses can be performed at concentrations in the order of 10 ppm (Fig. 2). If a short column is used, lower fatty acids of up to around C14 can be analyzed. Sharp peaks can be obtained with the injection volume of 1 μL, at 200 °C of Inj.Temp. Formic acid and acetic acid are however eluted together. In order to separate them, the analysis must be carried out on a combination of PEG-6000 and Flusin P (Fig. 1). Unisole 400 or FFAP is used for analysis of higher free fatty acids (Fig. 3).To separate saturated from unstaturated fatty acids they must be esterified before analysis.