Herbal materials used in dietary supplements: Comparison of luminescence methods for detection of irradiation

Abstract

In EU the treatment with ionising radiation is allowed for dried aromatic herbs, spices and seasonings, but not for herbal supplements and their ingredients. Nevertheless, controls carried out in EU at the product marketing stage, showed a large number of irradiated herbal supplements and herbal ingredients. Due to low sensitivity to radiation of this kind of products, the aim of this work was to test the efficacy of the luminescence-based methods in identifying irradiated herbal supplements. To this end, photo-stimulated luminescence (PSL) and thermo-luminescence (TL) measurements were performed on 24 products, including 8 herbal raw materials (plants or parts of plants) and 16 herbal extracts. The PSL technique, provided intermediate results, with a low number of total counts near to the upper negative limit, for all irradiated herbal extracts, showing possible limits in the detection of these products, specially in view of their use in mixtures with non-irradiated components. The TL method, was successfully applied to all herbal materials; in the case of herbal extracts, however, particular attention at the mineral separation step was necessary.