Separation of ^71,72As from alpha-particle induced reaction on gallium oxide target using naturally occurring alkaloid caffeine

Gallium oxide target was irradiated with 46 MeV alpha-particle beam, which produced As-71,As-72 and Ga-67 radioisotopes in the matrix. Separation of radio-arsenics from the bulk gallium target was carried out by caffeine, a nature-resourced reagent, extracted from black tea leaves. As-71,As-72 radionuclides were preferentially attached with caffeine and precipitated with caffeine in 2 M Na2SO4 solution as caffeine was insoluble in aqueous medium under this condition. With increase in weight of caffeine, extraction of As-71,As-72 and bulk gallium significantly increased. Bulk Ga along with Ga-67 remained in the supernatant. Geometry optimization of caffeine-metal complex was carried out by theoretical computational analysis. DFT calculation corroborated with the experimental findings where As3+ preferentially binds with caffeine in presence of gallium and arsenic. As evidenced by the short As-O and As-N distances, the high binding energies are a result of the metal ion's strong binding to the carbonyl and nitrogen centres, whereas no such result could be obtained in case of bulk gallium.