IDENTIFICATION OF IRRADIATED PULSES BY THERMOLUMINESCENCE OF THE CONTAMINATING MINERALS

Thermoluminescence (TL) response of contaminating minerals from six sa mples of pulses commonly consumed in Pakistan has been studied for ide ntification of irradiation treatment. The samples were irradiated by C o-60 gamma rays at 0.3, 0.5 and 1.0 kGy, or by 10 MeV electrons using an accelerator at 0.75 and 2.2 kGy. Generally, the TL intensity for mi nerals separated from irradiated samples was higher than for unirradia ted samples. To normalize the results, separated minerals deposited on stainless steel discs were re-irradiated by a normalizing dose and TL response was redetermined. The ratio of the area of the first glow cu rve to the second glow curve was more than 0.8 for all irradiated samp les and less than 0.03 for most of the unirradiated samples. For those unirradiated samples where the ratio of the glow curves was more then 0.03, the shapes of the glow curves were compared. Taking this criter ion into consideration, all 21 unirradiated and irradiated samples of pulses were identified correctly. Therefore, a normalization procedure by re-irradiation of minerals and analysis of TL glow curve shapes le ad to unequivocal identification of radiation treatment of pulses.