Direct screening of olive oil samples for residual benzene hydrocarbon compounds by headspacemass spectrometry

The applicability of the direct coupling of headspace-mass spectrometry for the expeditious and reliable screening of olive oil samples for selected volatile organic compounds (viz. benzene, toluene, ethylbenzene, xylene isomers and styrene) has been evaluated. Samples were classified as recommendable or non-recommendable for human consumption taking into account the average concentration of the target analytes in virgin olive oil. The cut-off level was fixed at a global concentration of BTEXS of 0.2 (mu)g ml^-1, and several pattern recognition techniques were used in the data treatment. The reliability of the proposed screening method was evaluated in terms of the percentage of false positives and false negatives. No false negatives were obtained, while the percentage of false positives were 5% when using CA and PCA techniques. However, SIMCA yielded the best percentage of prediction as neither false negatives nor positives were obtained. Finally, a total of 50 commercial virgin olive oil samples were analyzed and only four samples gave a BTEXS concentration over the cut-off.