Efficient procedure for pre-column derivatization of fatty acids with emphasis on short-chain carboxylic acids

An original derivatization method for short-chain carboxylic acids (SCAs), including volatile fatty acids (VFAs), lactic and succinic acids, followed by revesed-phase (RP) HPLC with photodiode array detection has been described. Initially, all acids present in the samples were converted into sodium salts (RCOONa); then, derivatization of RCOONa was carried out with an excess of 2,4-dibromoacetophenone and triethylamme. Under such conditions, all acids were converted into derivatives with chromophoric groups. Their high molar absorptivity and absorbance maximum located close to 259 +/- 2 nm make them ideally suited for RP-HPLC analysis with UV detection. All derivatized acids were substantially retained on the C,,, column. The proposed procedure provides a simple and sensitive analytical tool for quantification of SCAs, especially VEAs, in biological samples. As acid derivatization is carried out at 45 +/- 2 degrees C for only 60 min, the proposed procedure can be used for determination of polyunsaturated fatty acids.