2 research outputs found

    Determination of Persistent Organic Pollutants (POPs) in Atmospheric Gases and Particles by Solid-Phase Extraction (SPE) and Gas Chromatography–Tandem Mass Spectrometry (GC–MS/MS)

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    Persistent organic pollutants (POPs) are harmful to the environment and human health. A simple method was developed for the determination of 58 POPs, including 16 polycyclic aromatic hydrocarbons (PAHs), 18 polychlorinated biphenyls (PCBs), and 24 organochlorine pesticides (OCPs), in atmospheric gaseous and particle-phase samples. Different extraction solvents, solid-phase extraction (SPE) cartridges and elution steps were used and compared to optimize the extraction efficiency. The POPs were isolated from the atmospheric samples by Soxhlet extraction using 1:1 acetone:n-hexane and separated using SPE cartridges. The fractions were collected by two-step elution with10 mL of n-hexane and 10 mL of 1:1 n-hexane:dichloromethane. The method validation showed that PAHs, PCBs and OCPs had good linearity, with the coefficients of determination higher than 0.995, from 2.5 to 800, 2.5 to 800, and 2.5 to 600 ng/mL, respectively. The average recoveries were 67–117%, 67–113%, and 73–114% for the PAHs, PCBs, and OCPs. The limits of detection for PAHs, PCBs, and OCPs were from 0.55 to 3.29, 0.09 to 2.00, and 0.57 to 4.86 pg/m3. The limits of quantification (LOQs) for PAHs, PCBs and OCPs were 1.80 to 10.48, 0.29 to 6.37, and 1.82 to 15.48 pg/m3. The applicability of the method was confirmed using an urban dust standard reference material. The method was employed for the analysis of atmospheric samples collected weekly for one-half year on the rooftop of a 14 m tall building in the downtown Mianyang, Sichuan, China. The developed method is demonstrated to accurately monitor persistent organic pollutants in the atmosphere.</p

    Microscopic and Spectroscopic Insights into Uranium Phosphate Mineral Precipitated by <i>Bacillus Mucilaginosus</i>

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    In this paper, we used spectroscopic and microscopic techniques to investigate the interaction mechanism between uranium and <i>Bacillus mucilaginosus</i>. According to scanning electron microscope couple with energy dispersive X-ray detector analysis, the lamellar uranium phosphate precipitation was only observed on the living <i>B. mucilaginosus</i> and the resting <i>B. mucilaginosus</i>. The Fourier transform infrared spectroscopy spectrum also indicated the important role of phosphate groups in forming U­(VI)-phosphates precipitation. The X-ray diffraction analysis identified the phase of U­(VI)-phosphate precipitation as H<sub>3</sub>OUO<sub>2</sub>PO<sub>4</sub>·3H<sub>2</sub>O. Batch experiment showed that biominerilization amount could be up to 195.84 mg/g when exposing living <i>B. mucilaginosus</i> to U­(VI) aqueous solution at pH 5.0 for 1 h. The precipitate was further evidenced by extended X-ray absorption fine structure spectra based on the presence of U–P shell, which demonstrated that hydrogen uranyl phosphate became the main products on the living <i>B. mucilaginosus</i> with prolonged reacting time. After ashing and hydrothermal process, the precipitated U­(VI) on <i>B. mucilaginosus</i> could be converted into UO<sub>2</sub> and K­(UO<sub>2</sub>)­(PO<sub>4</sub>)·3H<sub>2</sub>O. Our findings have significant implications in elucidating the potential role of bacteria in the migration of uranium in geological environment
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