“…A GO nanosheet (size ~600 nm, 4 mg mL −1 , dispersed in H 2 O, Merck & Co., Inc., Rahway, NJ, USA) was used to adsorb uranium. Similarly to our previous studies [ 17 , 22 , 23 , 24 ], the multielement standard XSTC-1407 (Spex CertiPrep Inc., Metuchen, NJ, USA), containing 10 μg mL −1 of each element (Co, Cs, Cu, Th, and U), was employed to adjust the uranium concentration in the standard sample. To obtain the fitting parameter for the Br Kβ peak, a 0.05 mol L −1 bromine solution (FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan) was used.…”