Multidimensional gas chromatographic‒Mass spectrometric method for separation and identification of triacylglycerols in olive oil

A ‘heart-cut’ multidimensional gas chromatography‒mass spectrometry (H/C MDGC‒MS) method for separation and identification of triacylglycerols (TAGs) in extra virgin olive oil was developed. A GC configuration, comprising a non-polar first dimension (¹D) column (15 m length) and a mid-polarity second dimension (²D) column (9 m length), was employed. Standard TAGs were used to test and demonstrate the H/C MDGC method, for identification of TAG components and to validate the method. Various chromatographic conditions such as column flow and temperature program were evaluated. The ¹D separation resulted in overlap of some standard TAG peaks. These overlapped ¹D regions of the standard TAGs were H/C to ²D for further separation and resulted in clearly distinguished individual TAG component peaks. The ¹D separation of olive oil TAGs displayed three major peaks and four minor peaks. The application of the H/C MDGC method to olive oil TAGs resulted in the separation of each sampled ¹D region into two or more TAG peaks. TAG components in olive oil resolved on the ²D column were identified based on characteristic mass fragment ions such as [M–RCO₂]⁺, [RCO+128]⁺, [RCO+74]⁺ and RCO⁺ and comparison of their mass spectra with that of the standard TAGs. Sixteen olive oil TAGs were identified by MS after ²D separation. The repeatability of the H/C method was evaluated in terms of retention time shift and area response in the ²D and found to be <0.02% and <8% RSD respectively.