Electron spin resonance identification of gamma irradiated 2,4′-dichlorodiphenyl dichloroethane and 6-mercaptopurine monohydrate in the solid state

The purpose of this study is to investigate the effects of ionizing radiation on two anticancer drugs, 2,4′-dichlorodiphenyl dichloroethane (DCP) and 6-mercaptopurine monohydrate (MPM), by using electron spin resonance (ESR) spectroscopy. For that purpose the intensity of ESR signals of the samples as a function of the microwave power was investigated in the range of 0.01-100 mW at room temperature. While unirradiated samples presented no ESR signal, irradiated samples exhibited significant ESR spectra. ESR measurements were performed at low and high temperatures to study the dosimetric features of free radicals induced by gamma irradiation. In order to obtain the dose-response curves, samples irradiated with gamma at 1, 5, 10, 15, 20, and 25 kGy dose values were used. Furthermore, the g values of the radicals and the hyperfine coupling constants were also determined. Additionally, the time dependency of the samples was analyzed to study the stability of the radicals.