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)
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>
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 UÂ(VI)-phosphates precipitation. The X-ray
diffraction analysis identified the phase of UÂ(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 UÂ(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 UÂ(VI) on <i>B. mucilaginosus</i> could be converted into UO<sub>2</sub> and KÂ(UO<sub>2</sub>)Â(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