[Determination of six bisphenols in human urine by ultra-high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop and validate a solid phase extraction-ultra-high performance liquid chromatography-tandem mass spectrometry method for the determination of six bisphenols(bisphenol S, bisphenol F, bisphenol A, 2, 2'-methylenediphenol, bisphenol AF, bisphenol AP) in urine. METHODS: After enzymolysis of urine sample, the target substances were quickly purified and extracted by WAX solid phase extraction column. On ACQUITY BEH C_(18) column(2.1 mm×100 mm, 1.7 µm), the mobile phase of water and methanol was used to separate. Finally, multi-reaction detection was carried out under electrospray negative ion scanning, and quantification was carried out by internal standard method. RESULTS: The correlation coefficients(r) of the target compounds were all more than 0.998 in the range of 0.1-50.0 ng/mL, the linearity was good, and the detection limits were all lower than 0.1 ng/mL. The recoveries of the three standard concentrations(0.5, 5.0 and 50.0 ng/mL) were all between 80% and 120%, and the relative standard deviation was less than 20%(n=5). The standard reference material was detected and the concentration was within the reference range. CONCLUSION: This method can be used to detect six bisphenols in urine quickly and accurately, is suitable for the trace analysis of bisphenol compounds in human urine.

Pore Classification and Structural Characteristics of Oligocene-Pliocene Shale Reservoirs in the Western Qaidam Depression.

Oligocene-Pliocene shale reservoirs in the Western Qaidam Depression represent typical mixed shale deposits characterized by moderate organic matter (OM) abundance and sufficient OM maturity, indicating substantial shale-oil resource potential. Here, a comprehensive study was conducted to analyze the reservoir characteristics of different shale types, including the Upper Xiaganchaigou (late Oligocene), Shangganchaigou (Miocene), and Xiayoushashan (early Pliocene) Formations in the Western Qaidam Depression. Our analysis focused on the pore structural characteristics of shale reservoirs, employing X-ray diffraction, casting thin sections, scanning electron microscopy, low-temperature nitrogen adsorption, and nuclear magnetic resonance (NMR) as investigative techniques. Our results show that (1) the study area comprises five typical shale types: lime shale, argillaceous shale, limestone, argillaceous limestone, and mudstone. The best hydrocarbon source rock conditions are found in the lime shale and argillaceous shale. (2) Inorganic pores, including dissolution pores, intergranular pores, bedding fractures, structural fractures, and intraparticle pores in clay minerals, are the main pore types found in the studied samples and constitute the primary reservoir space for shale oil. On the basis of fractal dimensions obtained through NMR, the pores can be classified as micropores (<100 nm), mesopores (100-1000 nm), or macropores (>1000 nm). Mesopores are the main contributors to porosity. (3) The development of micropores is positively correlated with clay mineral content. The development of mesopores and macropores is influenced by the quartz, feldspar, dolomite, and calcite contents. Calcite content exhibits a negative correlation with porosity, suggesting that later-stage pore cementation hinders shale reservoir development. (4) The five typical shale reservoirs in the study area can be categorized into three types. Type I reservoir lithologies include lime shale and argillaceous shale; type II reservoir lithologies include limestone and argillaceous limestone; and type III reservoirs comprise mudstone. Type I and II reservoirs are of better quality than type III.

Polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in human milk from national human breast milk monitoring in 2016-2019 in China.

Human breast milk monitoring programs were recommended to be carried out to assess human body burden to persistent organic pollutants and their temporal trends. Thus, we conducted a national survey during the period of 2016-2019 to determine PCDD/Fs and dl-PCBs in human breast milk from China. The total TEQ amounts in the upper bound (UB) was in the range of 1.97 to 15.1 pg TEQ g-1 fat with a geometric mean (GM) of 4.50 pg TEQ g-1 fat. 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD, and PCB-126 were more predominant contributors with the percentage contribution of 34.2 %, 17.9 %, and 17.4 %, respectively. By comparison with our previous monitoring results, the total TEQ in breast milk sample of the present study is statistically lower than that in 2011 with a reduction of 16.9 % in the average (p < 0.05), and comparable to that in 2007. The estimated GM of dietary intake of total TEQ for the breastfed was 25.4 pg TEQ kg-1 body weight day-1 that was higher than that of the adult. It is therefore worthy to make more efforts to reduce amounts of PCDD/Fs and dl-PCBs in breast milk and to continue monitoring to further observe if the amount of these chemicals continue to decrease.

Exposure to Polybrominated Diphenyl Ethers in the Sixth Total Diet Study - China, 2016-2019.

What is already known about this topic?: Polybrominated diphenyl ethers (PBDEs) were widely used in many industrial and commercial materials as flame retardants, and its related exposure threatens human health. What is added by this report?: The Sixth Total Diet Study (TDS) indicated that the dietary intake of PBDEs was unlikely to pose significant health risks for the general Chinese people using the margin of exposure (MOE) approach recommended by the European Food Safety Authority (EFSA). What are the implications for public health practice?: This study highlights the necessity of continuous national monitoring of the dietary intake and strict legislation of PBDEs in China.

Role of Metal Electronegativity in the Dehydrogenation Thermodynamics and Kinetics of Composite Metal Borohydride-LiNH2 Hydrogen Storage Materials.

The composites of M(BH4) n-LiNH2 (1/2 n molar ratio, n = 1 or 2, M = Ca, Mg, Li) were synthesized by liquid ball milling. Samples were characterized by X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy (TG-DTA-MS), and kinetic models (Achar differential/Coats-Redfern integral method). The higher-electronegativity metal M in M(BH4) n-4LiNH2 (M = Ca, Mg) samples not only enables [BH4]- group to release easily, so as to facilitate the interaction of [BH4]- and [NH2]- groups, but also restrains the NH3 release and slightly decreases the onset dehydrogenation temperature concluded by TG-MS. Moreover, in stage 1 (200-350 °C), the kinetics performances of M(BH4) n-4LiNH2 (M = Ca, Mg) samples are distinctly improved, that is, the activation energies of them are reduced by ca. 30% compared to those of sample LiBH4-2LiNH2. The outstanding contribution of the replacement of M(BH4) n with high-electronegativity metal ion is to both improve the kinetics performance by changing the kinetics mechanism and decrease the temperature range of the initial dehydrogenation region.

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4 Hydrogen Storage Composite.

The lightweight compound material NaNH2-NaBH4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH2-NaBH4 (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H2, NH3, B2H6, and N2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B6H12 also exists. The TG/DTA analyses show that the composite NaNH2-NaBH4 (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na3(NH2)2BH4 hydride decomposes into Na3BN2 and H2 (200-350 °C); (2) remaining Na3(NH2)2BH4 reacts with NaBH4 and Na3BN2, generating Na, BN, NH3, N2, and H2 (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.