Online Mass Spectrometric Detection of Volatile Food Contaminants
Andrea Buettner,
Professor,
Fraunhofer IVV
The contamination of foods with undesired chemical molecules – sometimes odorous in nature – can arise from varying sources via diverse routes. Mineral oil residues in processing machinery or in packaging materials, for example, may lead to unwanted contaminants such as mineral oil hydrocarbons (MOH) in foods. In many cases the detection of the presence of such contaminants would be ideally achieved using on-line analytical screening tools. When sensorially-active by-products or contaminants are present – originating from packaging materials, pigments or additives and leading to sensory defects – these might not be detectable by conventional means when they are present at ultra-trace concentrations yet have high odour potency. Identification of these physiologically or sensorially critical substances currently requires an arsenal of often complex and costly analytical tools such as gas chromatography-mass spectrometry (GC-MS), or two-dimensional high-resolution GC-MS, coupled with olfactometry, which must be operated by expert sniffers for directly targeting the odorous contaminants.There is thus an increasing demand for fast analytical tools that allow high-throughput monitoring of food and packaging to screen for unwanted substances. Chemical ionisation mass spectrometry-based techniques, including proton-transfer-reaction mass spectrometry, offer a potential solution, enabling real-time detection of gas-phase volatile organic compounds (VOCs) down to sub-pptv concentrations. The recent use of a time-of-flight mass spectrometer (PTR-TOFMS) has improved the spectral resolution by three orders of magnitude whilst maintaining instrumental sensitivity and detection limits. Further, PTR-TOFMS offers the ability to scan an entire mass spectrum at several Hertz frequency, thereby providing the key parameters required for a real-time screening tool. Nevertheless, an enrichment of the target compounds may still remain a challenging factor; accordingly, potentials and limit
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