Detailed elucidation of hydrocarbon contamination in food products by using solid-phase extraction and comprehensive gas chromatography with dual detection

• Analysis of mineral oil (both MOSH and MOAH fractions) in food products.
• Use of a comprehensive gas chromatographic system (GC × GC), with dual detection (FID and MS).
• Silver nitrate silica gel solid-phase extraction (SPE) cartridge was exploited for sample preparation.
• Comparison of quantitative results obtained via GC × GC, off-line GC-FID, and on-line liquid–gas chromatography (LC–GC).

The present work is focused on the development/optimization of a comprehensive two-dimensional gas chromatography method, with dual detection [flame ionization (FID) and mass spectrometric], for the simultaneous identification and quantification of mineral-oil contaminants in a variety of food products. The two main classes of contaminants, namely saturated and aromatic hydrocarbons, were previously fractionated on a manually-packed silver silica solid-phase extraction (SPE) cartridge. The quantitative results were compared with those obtained by performing a large volume injection, in a GC-FID system, after the same SPE process and by an on-line liquid–gas chromatography method, with very similar results observed. The presence of a series of unknown compounds, that appeared when using the off-line methods, was investigated using the mass spectrometric data, and were tentatively-identified as esterified fatty acids, most probably derived from vegetable oil based ink.

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