Determination of marker substances by high-pressure liquid chromatography

4 Determination of marker substances by high-pressure liquid chromatography 

As described above, 2-alkylcyclobutanones are the only cyclic irradiation products produced under food irradiation conditions. Le Tellier and Nawar (1972a) reported the formation of 2-alkylcyclobutanones. It was shown that a series of homologous 2-alkylcyclobutanone is formed in simple triglycerides (fatty acids with 6-18 carbon atoms). The number of carbon atoms is identical to the number of carbon atoms in the precursor acid. In 1991 Boyd and Stevenson published a method for the determination of 2-dodecylcyclo-butanone. It should be re-emphasized that 2-alkylcyclobutanones have never been detected in non-irradiated samples. Two general conclusions can be drawn from these results irradiated foods can be detected, and these marker substances are the first that have not been detected in thermally treated foodstuffs. 

HPLC for hydrocarbon analysis is of no practical interest because of the detection problems no sensitive light absorption, no electrochemical detectability. There have been some successful attempts with light-scattering detection but in total the detection limit is too insensitive for direct determination in irradiated samples. Thus, at present, only HPLC methods are available for the detection of 2-alkylcyclobutanones. 

The determination of o-tyrosine (formed from proteins during irradiation) can be done with HPLC as well as with GC. There are no satisfactory methods because of the bad resolution in the chromatograms, interfering sample constituents and missing reference materials. This area of irradiation analysis will be of further interest in the future because of identification problems with low-fat-containing protein-rich foodstuffs. 

Dauphin, C. and Saint-Lebe, C. (1977) in Radiation Chemistry of Carbohydrates, 275, Elsevier, Amsterdam. 

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