Luminescence detection and dose assessment of irradiated Yerba Mate (Ilex paraguariensis) tea leaves

Abstract

Imported commercial samples of Yerba Mate (Ilex paraguariensis) tea leaves were characterized by thermoluminescence (TL) and photoluminescence (PSL) physical methods. Samples of Yerba Mate were irradiated between 0.5?50 Gy and 20 Gy?5 kGy gamma doses by using two different dose rates from 60Co irradiators. The Electron Dispersive Analysis (EDS) shows that the inorganic fraction is mainly composed by quartz and Ca-feldspars minerals. These polyminerals show a good sensitivity to gamma radiation and to UV light (530 nm). Linear dose?response curves were obtained between 0.5 and 12 Gy at low dose-rate, and with 20 to 500 Gy at high dose-rate of gamma radiation. At higher doses (600 Gy) an apparent slow saturation effect was observed. Low fading of the TL signal was found. The detection limits of TL and PSL are 6 Gy and 300 Gy, respectively. Results show that luminescence emission (TL and PSL) is a reliable method for detection of irradiation Yerba Mate.