3 research outputs found
Thermoluminescence analysis to detect irradiated fruit and vegetables - an intercomparison study A report in English and German
This report describes in detail an intercomparison study to detect the irradiation of fruit and vegetables with a dose upwards of approx. 1 kGy. The 12 participating laboratories determined the thermoluminescence (TL) of mineral contaminations isolated from coded samples. Papayas, mangos, strawberries and mushrooms, which were either non-irradiated or irradiated with doses of between 1.4 and 1.6 kGy were chosen for examination as well as potatoes, which were either nonirradiated or treated with 200 Gy (for prevention of germination). The results of this intercomparison study were largely identical with those of the thermoluminescence intercomparison study on spice products. Therefore, it was applied to publish the method in the official collection of methods under article 35 of the German Foods Act (LMBG). In this method the integration of glow curves in a certain temperature range is recommended. The threshold value for the TL signal to distinguish irradiated and non-irradiated samples is fixed at 0.6. Under these conditions, all the non-irradiated samples in this intercomparison study and approx. 66% of the samples irradiated with doses of 1.4 to 1.6 kGy would have been correctly identified. As expected, the potato samples treated with a 200 Gy dose were not recognized as irradiated after normalization of the TL intensity using a re-irradiation dose of 1 kGy. Nevertheless, much higher TL intensities were recorded for the irradiated samples than for the non-irradiated samples in the first TL reading. By using different re-irradiation doses for the same mineral sample or by determining the re-irradiation dose that is required to obtain a TL signal value of approx. 1, however, it is possible to detect samples given a dose of below 1 kGy. The doses used to irradiate these samples can probably also be determined. The report deals briefly with this modified normalization procedure. (orig./VHE)Available from TIB Hannover: RR 1068(1993,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Gas chromatographic analysis of volatile hydrocarbons to detect irradiated chicken, pork and beef - an intercomparison study A report in English and German
This report provides a detailed description of an inter-laboratory study to detect irradiation treatment of chicken carcasses, pork and beef using a method suitable for routine application. The 17 participating laboratories determined the quantity of four different radiation-induced hydrocarbons (1-tetradecene, pentadecane, 1,7-hexadecadiene, 8-heptadecene) in coded samples approx. 3 and 6 months after irradiation. The quantities detected were used to identify the samples as irradiated or non-irradiated. The samples of each type of meat to be examined had been supplied by two different producers. The dose range that was tested (approx. 0.6 to 7.5 kGy) included commercially used doses (approx. 1 to 5 kGy). The method employed enable 98.3% of a total of 864 samples to be correctly identified as irradiated or non-irradiated. This result is remarkable: Although the marker concentrations in the various samples showed a clear dose dependency, the variation was quite marked. The high rate of correct identifications could be achieved by defining a sample only as irradiated if certain quantities of at least 3 of the radiolytic products to be determined had been found. A similar identification rate was achieved if quantification of markers was omitted to identify a sample only as irradiated when all the expected radiolysis products could be clearly detected. For all three types of meat, no significant differences in marker yields could be shown for the products of the respective two producers. Also, in none of the types of meat, any significant difference could be revealed for the quantiatitive results achieved three and six months after irradiation. These results show that irradiation of chicken carcasses, pork and beef in the commerically used dose range can be clearly detected throughout the entire period in which products are normally stored and that the method described is suitable for routine analyses in food control laboratories. (orig.)Available from TIB Hannover: RR 1068(1993,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman