Determination of underivated fatty acids by HPLC

Inclusion of high-quality vegetable oils is of great importance for a scientifically balanced diet. Hence, there is a need for analytical techniques that can be used in the control of the purity and authenticity of such oils. Therefore, three reversed-phase HPLC methods were devised for the qualitative and quantitative measurement of fatty acids. These methods were applied to various vegetable oils and are an alternative to often-used gas chromatographic techniques. In the first step, the vegetable oil is hydrolysed, then the free fatty acids obtained are analysed by HPLC without any further derivatization. Omission of the hydrolysis step allows the determination of the amount of free fatty acids in the oils with the proposed methods. The iodine value and the acid number can be calculated from the chromatographic data.