The use of electron spin resonance spectroscopy for the detection of irradiated mackerel

Free radicals produced in Spanish mackerel fish bone by 60Co γ-rays were measured using electron spin resonance spectroscopy. The ESR spectra of the irradiated fish were found to have an asymmetric absorption characterized by a major resonance at g1 = 2.0020 and a minor resonance at g2 = 1.9980. The intensity of the radiation-induced ESR signal was found to increase with the absorbed dose. The results obtained after irradiation in the dose range 0.5–5.7 kGy gave a nonlinear relationship between the radiation dose and ESR signal height. The radiation-induced ESR signal of Spanish mackerel decayed most significantly in the first 15 days after irradiation, but could still be detected even after 60 days.