Tandem mass spectrometry (GC-MS/MS) is an alternative to GC-HRMS

The Revision of EU Regulation laying down methods of sampling and analysis for the control of levels of dioxins (PCDD/Fs), dioxin-like and non-dioxin-like PCBs in foodstuffs allows GC-MS/MS in addition to GC-HRMS as confirmatory method since 23rd June 2014.

Technical progress and development has shown, that gas chromatography / tandem mass spectrometry (GC-MS/MS) can also be used as a confirmatory method in addition to gas chromatography / high resolution mass spectrometry (GC-HRMS) for checking compliance with maximum levels. We confirmed this by way of extensive comparative tests over a period of several months.

By enhancing their technical performance tandem mass spectrometers (MS/MS) show now analytical characteristics being comparable with the GC-HRMS. Current EU law demands particular requirements concerning three analytical parameters for confirmatory methods in dioxin analysis: accuracy, precision and quantification limit. Within Eurofins extensive studies on the comparability of GC-MS/MS and GC-HRMS were carried out. It could be shown that all three characteristics (in addition to some others) are in the same order for GC-MS/MS as for GC-HRMS. In addition, it could be shown for a large number of samples of various matrices that both MS techniques provide comparable results. For the control of dioxin and PCB levels and their compliance with maximum levels GC-MS/MS is therefore as fit as the GC-HRMS.

Accordingly, the current EU Regulation laying down methods of sampling and analysis for the control of levels of dioxins, dioxin-like PCBs and non-dioxin-like PCBs in certain foodstuffs has been adjusted with effect from 23rd June 2014 and has not only been recognized as quantitative methods for dioxin analysis, but also has been authorized as confirmatory method in addition to the "classic" GC-HRMS at European level (Commission Regulation (EU) No 589/2014).

In special cases (e.g. determination of low background levels in food monitoring, following of time trends or exposure assessment of the population), GC-HRMS is exclusively used in the future. It is estimated that these cases of application will play a minor role only in the practice of the food business.

Screening methods (such as Calux) compare the analytical result with a tolerance value, providing a yes/no-decision over possible exceedance of the maximum or action level. Confirmatory methods allow the unequivocal identification and quantification of dioxins, dioxin-like PCBs resp. non-dioxin-like PCBs being present in a sample. Therefore, these methods allow the control of maximum and action levels, including the confirmation of results obtained by screening methods. The information on individual dioxin- and / or PCB-congeners, provided by confirmatory methods, allows compiling the pattern of these compounds. The recognition of such patterns and its interpretation are of invaluable value when looking for potential sources of elevated contamination levels of dioxins and / or PCB.

The experience shows that above all, besides mastering the measuring technique, a long-lasting experience concerning appropriate extraction and clean-up-procedures of the extracts will lead to correct analytical results. Numerous participations within national and international laboratory proficiency tests demonstrate the efficiency of the analytical methods using both the GC-HRMS and the GC-MS/MS-technique.

Source: Eurofins Scientific