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Chemical analysis of heterocyclic amines : quantification in heat processed food

Protein-rich cooked food can be contaminated by heterocyclic amines (HAs) which are strongly suspected to be human carcinogens. Recent literature data reveals however that large discrepancies are still existing in the levels detected in commercial products like food grade beef extract.

The objectives of this SM&T project is to improve the procedures actually used in order to quantify as precisely as possible these genotoxic contaminants in a heat processed food matrix.

In a first phase, seven European laboratories (B-F-ES-S-CH-GR-UK) participated in an intercomparison on the analysis of a solution with an identity and content of HAs both unknown to participants. The results of this exercise, where the participants used different HPLC conditions with UV, fluorescence, mass spectrometry and electrochemical detection, revealed a good precision and accuracy of the end determination of 3 HAs (IQ, 4, 8-Di Me IQX and PhIP).

In a second intercomparison, a batch of commercial beef extract was prepared and spiked with known amounts of: IQ, MelQX and PhIP. The long-term stability study at -18ºC, +4ºC, +25ºC, +40ºC and +60ºC revealed a good stability of these HAs up to 6 months of storage at +25ºC. At +40ºC and +60ºC however a significant decrease was observed, more particularly for PhIP. It was thus decided to send out the sealed ampoules containing the beef extract in a refrigerated container, to the participants.

Different extraction and clean-up procedures were followed by the participants, before the analysis by HPLC. The comparison of the results revealed however large variations not only between but also within laboratories. During a meeting held on September 1996, the participants have agreed on minimum recovery levels. Different sources of variations in the extraction procedures were identified, which could be the subject of a next project for which most of the participants expressed their interest.

Reported by

Université - Catholique de Louvain Ecole de Pharmacie
73 Avenue E. Mounier
1200 Bruxelles
Belgium
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