In-situ assessment of olive oil adulteration with soybean oil based on thermogravimetric-gas chromatography/mass spectrometry combined with chemometrics

The feasibility of thermogravimetric-gas chromatography/mass spectrometry (TGA-GC/MS) combined with chemometrics for qualitative and quantitative determination of adulteration of olive oil with soybean oil was described. Discriminative separation between the two groups of oil samples could be seen from the principal component analysis (PCA). For quantitative evaluation, olive oils and mixtures with soybean oil at levels of 25%, 50% and 75% were analyzed. The least squares exponential fitting was conducted on the ratio of peak area of typical characteristic volatile oxidation products of olive oil to that of soybean oil. Satisfactory results (R2 > 0.99) were obtained with 1-heptene/1-octen-3-ol, 1-octene/1-octen-3-ol, trans-2-decenal/1-octen-3-ol and 2-undecenal/1-octen-3-ol. To the best of our knowledge, this is the first report on the application of TGA-GC/MS for olive oil adulteration study. It has to be highlighted that the new proposed analytical method is non-destructive and avoids the use of organic solvent.