A new method for quantification of short chain C1-C6 carboxylic acids in vegetable oils and fats by
employing Liquid Chromatography Mass Spectrometry (LC-MS) has been developed. The method
requires minor sample preparation and applies non-conventional Electrospray Ionization (ESI) liquid
phase chemistry. Samples are first dissolved in chloroform and then extracted using water that has been
spiked with stable isotope labeled internal standards that are used for signal normalization and absolut
quantification of selected acids. The analytes are separated using Ion Exclusion Chromatography (IEC)
and detected with Electrospray Ionization Mass Spectrometry (ESI-MS) as deprotonated molecules. Prior
to ionization the eluent that contains hydrochloric acid is modified post-column to ensure good
ionization efficiency of the analytes. The averaged within run precision and between run precision were
generally lower than 8 %. The accuracy was between 85 and 115 % for most of the analytes. The Lower
Limit of Quantification (LLOQ) ranged from 0.006 to 7 mg/kg. It is shown that this method offers good
selectivity in cases where UV detection fails to produce reliable results