Translocation of uranium from water to foodstuff while cooking

[Display omitted] •Rice can efficiently uptake uranium from water contaminated with uranyl nitrate hexahydrate (UO2(NO3) 2.6 H2O), while cooking.•Unusual uranium uptake to the extent of about 1000ppm is observed when rice is cooked in highly concentrated uranium contaminated water (1240ppm).•Nature of interaction of uranium with carbohydrates is probed using small monosaccharides like glucose and mannose.•Electrospray ionization mass spectrometry showed UO22+ to be the most stable species in water in such solutions which can form complexes with sugars.•The species (UO22+) is also observed in the case of water exposed to the common mineral, uranium oxide (UO2) and similar type of complexation is observed with sugars. The present work report the unusual uranium uptake by foodstuff, especially those rich in carbohydrates like rice when they are cooked in water, contaminated with uranium. The major staple diet in South Asia, rice, was chosen to study its interaction with UO22+, the active uranium species in water, using inductively coupled plasma mass spectrometry. Highest uptake limit was checked by cooking rice at very high uranium concentration and it was found to be good scavenger of uranium. To gain insight into the mechanism of uptake, direct interaction of UO22+ with monosaccharides was also studied, using electrospray ionization mass spectrometry taking mannose as a model. The studies have been done with dissolved uranium salt, uranyl nitrate hexahydrate (UO2(NO3)2·6H2O), as well as the leachate of a stable oxide of uranium, UO2(s), both of which exist as UO22+ in water. Among the eight different rice varieties investigated, Karnataka Ponni showed the maximum uranium uptake whereas unpolished Basmati rice showed the minimum. Interaction with other foodstuffs (potato, carrot, peas, kidney beans and lentils) with and without NaCl affected the extent of chemical interaction but was not consistent with the carbohydrate content. Uranium interaction with d-mannose monitored through ESI–MS, under optimized instrumental parameters, identified the peaks corresponding to uranyl adduct with mannose monomer, dimer and trimer and the species were confirmed by MS/MS studies. The product ion mass spectra showed peaks illustrating water loss from the parent ion as the collision energy was increased, an evidence for the strong interaction of uranium with mannose. This study would constitute the essential background for understanding interaction of uranium with various