Xing-Hong Li

Determination of triclosan, triclocarban and methyl-triclosan in aqueous samples by dispersive liquid–liquid microextraction combined with rapid liquid chromatography

In this study, dispersive liquid-liquid microextraction (DLLME) combined with ultra-high-pressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV), has been developed for pre-concentration and determination of triclosan (TCS), triclocarban (TCC) and methyl-triclosan (M-TCS) in aqueous samples. The key factors, including the kind and volume of extraction solvent and dispersive solvent, extraction time, salt effect and pH, which probably affect the extraction efficiencies were examined and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.0500-100 microg L(-1) for TCS, 0.0250-50.0 microg L(-1) for TCC, and 0.500-100 microgL(-1) for M-TCS, respectively, with correlation coefficients (r(2))>0.9945. The limits of detection (LODs) ranged from 45.1 to 236 ng L(-1). TCS in domestic waters was detected with the concentration of 2.08 microg L(-1). The spiked recoveries of three target compounds in river water, irrigating water, reclaimed water and domestic water samples were achieved in the range of 96.4-121%, 64.3-84.9%, 77.2-115% and 75.5-106%, respectively. As a result, this method can be successfully applied for the rapid and convenient determination of TCS, TCC and M-TCS in real water samples.

Structural stability of multiferroic BiFeO3

Multiferroic BiFeO3 was fabricated via a high pressure of 5 GPa at 900 °C. The crystal structure of the BiFeO3 ceramic was determined by X-ray diffraction (XRD) to be a rhombohedral perovskite with a space group of R3c. The temperature dependence of XRDs was collected down to 5 K under ambient pressure that showed no structure phase transition. The structural evolution of BiFeO3 under high pressures up to 56.6 GPa was studied at room temperature using a diamond anvil cell combined with synchrotron radiation XRD. A possible phase transition was proposed at around 10 GPa. The bulk modulus was estimated to be B 0=97.3(7) GPa in the low-pressure range.

Dechloranes in lichens from the southeast Tibetan Plateau: Evidence of long-range atmospheric transport.

Dechloranes (Decs) have been recently found to occur widely in the environment even in the remote polar regions. However, the understanding of their environmental fate is rather limited. The Tibetan Plateau (TP) may be an important indicator region to study the long-range atmospheric transport and their fates of these emerging contaminants since it has very limited local sources. In the present study, Dechlorane plus (DP), Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603) and Dechlorane 604 (Dec 604) were analyzed in lichen samples from the southeast TP. The results showed that only DP and Dec 602 were detected, with a detection frequency of 89% and 100%, respectively. The average concentrations (dry weight) of ΣDP and Dec 602 were 318 pg g(-1) (20-1132 pg g(-1)) and 167 pg g(-1) (27-843 pg g(-1)), respectively. The DP concentration in this study was much higher than those in moss from the remote Ny-Ålesund, Arctic. The concentrations of Dec 602 were found to generally increase with increasing altitude, while DP concentrations seemingly showed an opposite altitudinal trend along the mountain slopes. No stereoselective accumulation or transformation of anti-DP and syn-DP was observed in lichens and the altitudinal behavior of the two isomers was similar. This research documented that Decs are prone to undergo LRAT and cold-trapping by the mountains in the southeast TP.

Application of counter-current chromatography as a new pretreatment method for the determination of polycyclic aromatic hydrocarbons in environmental water.

Counter-current chromatography (CCC) was investigated as a new sample pretreatment method for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in water environmental samples. The experiment was performed with a non-aqueous binary two-phase solvent system composed of n-heptane and acetonitrile. The CCC column was first filled with the upper stationary phase, and then a large volume of water sample was pumped into the column while the CCC column was rotated at 1600 rpm. Finally, the trace amounts of PAHs extracted and enriched in the stationary phase were eluted out by the lower mobile phase and determined by gas chromatography-flame ionization detector (GC-FID) or gas chromatography-mass spectrometry (GC-MS). The enrichment and cleanup of PAHs can be fulfilled online by this method with high recoveries (84.1-103.2%) and good reproducibility (RSDs: 4.9-12.2%) for 16 EPA PAHs under the optimized CCC pretreatment conditions. This method has been successfully applied to determine PAHs in lake water where 8 PAHs were detected in the concentration of 40.9-89.9 ng/L. The present method is extremely suitable for the preparation of large volume of environmental water sample for the determination of trace amounts of organic pollutants including PAHs as studied in this paper.

SYNTHESIS AND STRUCTURAL STABILITY OF BiRhO3 AT HIGH PRESSURE

The bismuth rhodate BiRhO3, which crystallizes in a perovskite structure, was synthesized under high-pressure and high-temperature conditions, using a 6–8 double stage multi-anvil apparatus. The synchrotron powder X-ray diffraction data suggest that the crystal structure of the BiRhO3 perovskite is stable under pressures up to 34 GPa at room temperature with anisotropic compressibility. The equation of state for BiRhO3 compound was obtained. The results offer opportunities for further research into the BiRhO3 quantum compound with strong spin orbital coupling.

Synthesis and structure stability of Ba2CuO3+delta under high pressure

The Ba2CuO3.3 sample with the nominal composition was synthesized. Powder X-ray diffraction (XRD) experiments confirm that it crystallizes in an orthorhombic structure with space group Immm. The synchrotron powder XRD results suggest that the crystal structure of Ba2CuO3.3 keeps stable under pressure up to 34 GPa at room temperature with nearly isotropic compressibility. The equation of state for Ba2CuO3.3 was obtained. The results offer opportunities to further synthesize and research Ba2CuO3+delta superconductor with tetragonal K2NiF4 structure.