Ambient mass spectrometry has been increasingly applied for sensitive detection of trace organic compounds present in complex matrixes. In the real world, detection of trace amounts of inorganic species, particularly with speciation information, is of great significances. Herein a method based on extractive electrospray ionization (EESI) tandem mass spectrometry (MS/MS) has been established for rapid detection of radioactive inorganic species in natural water samples. Negatively charged uranyl acetate undergoes characteristic fragmentation in the gas phase, providing the fundamental chemistry for specific detection of uranyl species in complex matrixes without sample pretreatment. Under the optimized experimental conditions, uranyl species in various natural water samples were rapidly detected using multiple-stage EESI mass spectrometry. The mean time for each sample analysis was about 10 s. The limit of detection was about a few 10(-3) ng/L of uranium by utilizing the characteristic fragments obtained in the EESI-MS(3) experiments. The typical relative standard deviation (RSD) of this method was 6.9-8.1% for 8 measurements (S/N = 3). The dynamic response range was 10(-1)-10(3) ng/L for uranium in water samples. The isotope ratio of uranyl species was quantitatively detected using EESI-MS experiments. The results show that EESI-MS, a typical method initially developed for organic compound analysis, has promising perspectives for real time, online monitoring of inorganic species such as uranyl species in natural water samples.

Novel graft copolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with N-vinylpyrrolidone (NVP) were designed and synthesized by the free radical copolymerization of DMAEMA with precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP). The ability of the PVP-grafted copolymers to bind and condense DNA was confirmed by ethidium bromide displacement assay, agarose gel electrophoresis and transmission electron microscopy. The presence of PVP in the copolymers had a favorable effect on the biophysical properties of polymer/DNA complexes. Colloidal stable complexes obtained from the copolymer systems, were shown to be separate, uniformly spherical nanoparticles by transmission electron microscopy. The approximate diameter of the complexes was 150 -200 nm, as determined by dynamic light scattering studies. These results confirm an important role played by the PVP grafts in producing compact stable DNA complexes. The ζ-potential measurements revealed that the incorporation of the PVP grafts reduced the positive surface charge of polymer/DNA complexes. The cytotoxicity of the copolymers decreased with an increasing fraction of PVP. Furthermore, in vitro transfection experiments with these copolymers showed improved ability of transfection in cell culture, demonstrating an important role for PVP grafts in enhancement of the transfection efficiency.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Summary Seeking highly efficient and low‐cost sorbents to removal uranium contaminants is of great concern in demand. In present work, a graphene oxide sponge (GOS) was successfully assembled by a facile Ethylenediaminetetraacetic acid (EDTA)‐assisted hydrothermal method from graphene oxide (GO) sheets. The prepared GOS was characterized, and the influencing factors on uranium sorption were optimized. Results indicate that the GOS shows a spongy porous structure and significantly enhances the U(VI) removal compared with the pristine GO. Langmuir model well describes the equilibrium sorption data. Under experimental conditions, the maximal uranium sorption calculated from Langmuir model was found to be 212.77 mg · L−1. Sorption kinetics data are matched with pseudo‐second‐order model. Reusability experiments indicate that the prepared GOS can be regenerated using dilute acid treatment and be used repeatedly. The simple and low‐cost preparation of GOS predicts the potential applications of spongy GO as an effective sorbent for U(VI) capture and also expands the possibility of using graphene‐based sorbent in the disposal of liquid radioactive waste. Copyright © 2016 John Wiley & Sons, Ltd.