CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
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2022
·
IF 1.193
Yuzhe LI,Hui ZENG,Jin XU,Yan LI,Lishan ZHANG,Ying LIANG,Min ZHANG
A gas-phase absorption detector (GPAD) was developed using a surface-mount 235 nm light-emitting diode (LED) as the light source. Modules for housing the LED and photodiode were three-dimensional printed. A stainless-steel tube was used as the detection cell. To perform long path absorption detection, a fused silica full-ball lens (5 mm diameter) was employed to collimate the light produced by the UV-LED with a viewing angle of 120°. The light attenuation coefficient ( α b ) was measured to be 0.025±0.001 cm −1 . The optimum path length with the maximum signal-to-noise ratio was obtained at ca. 80 cm. This result agreed with the theoretical calculation for optimum path length, i.e., 2/ α b . The GPAD was coupled with an automated analysis system and applied to detect nitrite in water. The automated system added citric acid and ethanol into a water sample, and nitrite was converted to gaseous nitrous acid (HONO), which has a strong absorption at 235 nm. The produced HONO was purged with air, followed by water removal, and then detected with the GPAD. The method was used to detect nitrate and total dissolved nitrogen (TDN) in water as well. Nitrate was reduced to nitrite through a photo-induced reaction with a conversion efficiency of ca. 60%. TDN was converted to nitrate by using an alkaline persulfate digestion method, followed by photoreduction to nitrite, and detected by using the automated system. The limits of detection were 0.4 μM, 3.9 μM, and 6.7 μM (94 μg N/L) for nitrite, nitrate, and TDN, respectively.
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RAPID COMMUNICATIONS IN MASS SPECTROMETRY
·
2022
·Vol. 37
·期 4
·e9450
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IF 2.586
Yunning Cao,Hu Liu,Jing Hu,Zheng Wang,Mengshu Zhu,Xu Liu,Kaili Yang,Haijiao Gan,Weiguo Liu
Rationale Gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) is widely used for compound-specific carbon isotopic analysis. However, current isotopic analysis systems utilize the GC IsoLink combustion reactor, and independent reduction furnaces are not implemented. Therefore, whether this limitation in furnace use affects the precision of compound-specific carbon isotopic analysis needs to be evaluated. Methods We attempted to add a separate reduction furnace to the GC IsoLink interface and compared the δ 13 C values of n -alkanes (including C and H elements), fatty acid methyl ester (including C, H, and O elements), caffeine (USGS61 and USGS62, including C, H, O, and N elements), and 9-ethylcarbazole (including C, H, and N elements) before and after the addition of the reduction furnace using the GC IsoLink combustion reactor. Results For n -alkanes and fatty acid methyl esters, the δ 13 C differences between the measured values and their standard values were basically falling within 0.5‰ whether or not an independent reduction furnace was added. However, for the nitrogen-containing compounds (caffeine and 9-ethylcarbazole), the δ 13 C differences between the measured values and their standard values were much larger without an independent reduction furnace (1.0–3.71‰ for USGS61, 1.78–2.19‰ for USGS62, and 0.39–1.13‰ for 9-ethylcarbazole) than with a reduction furnace (−0.31–0.68‰ for USGS61, −0.44–0.06‰ for USGS62, and −0.04–0.25‰ for 9-ethylcarbazole). Conclusions The addition of an independent reduction furnace had no significant effect on the δ 13 C of n -alkanes and fatty acid methyl esters, but it had a significant effect on the δ 13 C of nitrogen-containing compounds. It is suggested that GC IsoLink needs an independent reduction furnace to effectively eliminate the interference of NO x on CO 2 isotopic determination to improve the accuracy of δ 13 C for nitrogen-containing compounds.
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RESEARCH ON CHEMICAL INTERMEDIATES
·
2022
·Vol. 49
·期 8
·3381-3393
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IF 3.134
Yang Haoguo,Guo Yijun,Han Shitong,Xi Hailing,Lin Huaxiang,Yuan Rusheng,Ding Zhengxin,Long Jinlin,Lin Qun
Mustard gas is a kind of erosive poison with great harm and used as a chemical weapon since World War. It has suggested that the photocatalytic technology is an effective method to eliminate it. Because the small difference in molecular structure between 2-CEES and Mustard gas, and the less toxic of 2-CEES, 2-CEES is often used as a simulator to evaluate the photocatalytic activity of catalysts. In this work, symbiotic mixture of Bi 2 WO 6 and Bi 6 O 6 (OH) 3 (NO 3 ) 3 ·1.5H 2 O nanosheets doped with Mo (Mo-B-B) have been synthesized by a facile hydrothermal treatment. The samples were characterized by XRD, DRS, XPS, SEM, TEM, Raman, and PL. The photocatalytic activity of the samples was evaluated by measuring the degradation of 2-CEES under visible light irradiation. The results showed that the doped Mo reduce the Eg of bare symbiotic mixture and improve the separation efficiency of photo-generated carriers that is beneficial to photocatalytic activity. The optimum amount of doped Mo is 5% that exhibits the best activity for degradation for 2-CEES.
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OPTICAL MATERIALS
·
2022
·
IF 3.754
Cheng Zuo,Xishi Tai,Qian Su
S-scheme heterojunction can accelerate the separation of photogenerated electron-hole pairs and retain strong redox ability, so it has outstanding advantages and application prospects in the field of photocatalysis . The Ce 3+ self-doping CeO 2-x @CuO nanowires arrays on copper mesh were synthesized with the strategy of surface hydrogenation and hydrothermal calcination method. The morphology, composition and properties of the catalysts were determined by SEM, TEM, EDS , UV-VIS, PL , CO 2 -TPD and other characterization methods. Ce 3+ self-doping introduces O vacancies on the surface of CeO 2 without introducing heteroatoms. The O vacancies of CeO 2-x could enhance the adsorption, activation and reduction of CO 2 . The existence of coaxial S-scheme heterojunctions could effectively enhance the light absorption range and the separation of photo-generated charges. The photocatalytic activity of the composite catalyst was much higher than that of pure CuO/copper mesh (CM) and CeO 2 , and the difference in activity of catalysts composed of different proportions was studied. When the Ce 3+ self-doping CeO 2-x loading was moderate, the methanol yield reached 6.73 μmol·g cat −1 after 4 h reaction under visible light , which is 5.26 times of CuO/CM and 9.35 times of CeO 2 . The reduction mechanism of the composite catalyst at the gas-liquid interface was studied. This work demonstrates a feasible strategy to create efficient S-scheme heterojunction photocatalysts with rich active surface O vacancies for photocatalytic CO 2 reduction.
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MICROCHEMICAL JOURNAL
·
2022
·
IF 5.304
Yuan Peng,Si-Yuan He,Fang-Huan Wang,Hao-Bo Zheng,Zhe Meng
In this work, a magnetic mesoporous molybdenum disulfide/graphite nanosheets (mm-MoS 2 /GN) was successfully synthesized and applied to magnetic solid phase extraction (MSPE) of 13 polycyclic aromatic hydrocarbons (PAHs) from edible oil samples. The prepared mm-MoS 2 /GN was characterized by FT-IR, XRD, VSM, BET, SEM and TEM. The influence of various parameters such as the adsorbent mass, adsorption/desorption time, and elution solvent through response surface methodology in MSPE was investigated. The porous and fluffy structure with rich active sites (π interactions, electrostatics, hydrogen bonds) and amphiphilicity properties of mm-MoS 2 /GN make it an ideal material for the separation and enrichment of trace PAHs in edible oils. Under optimal MSPE and GC-MS conditions, the linearity ranges of the proposed method were 1.0–100.0 μg·kg −1 with a satisfactory correlation coefficient above 0.9907. The limits of detection and quantification for 13 PAHs were 0.10–2.50 μg·kg −1 and 0.85–5.00 μg·kg −1 , respectively. The intra- and inter-day precisions were less than 3.0 % and 3.6 %, respectively. The recoveries for spiked edible oil samples ranged from 70.2 % to 112.6 % with RSDs of less than 5.8 %. In this work, a novel, rapid, economic and effective method was proposed, and successfully applied to detect polycyclic aromatic hydrocarbons in several oil samples from local market.
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CHROMATOGRAPHIA
·
2022
·Vol. 85
·期 8
·689-697
·
IF 2.213
Luo Xiaoqing,Weng Qianfeng,Li Jinxiang
A new composite of o-aminobenzene sulfonic acid self-doped polyaniline (SPAN) and multi-walled carbon nanotubes was prepared on a stainless steel wire by electrochemical method as a headspace solid-phase microextraction fiber for gas chromatography. Preparation conditions were investigated, and the resulting composite coating was characterized via scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis. Introduction of MWCNTs and o-aminobenzene sulfonic acid into the composite leads to formation of plenty of microglobules and mesopores and makes BET surface area and thermal decomposition temperature of the composite increase by ~ 340% and ~ 130 ℃, respectively, compared to common polyaniline coating. Extraction conditions were optimized, and chromatographic analysis of 2,4-dichlorophenol was conducted. Extraction efficiency of the new composite coated fiber increases by 320% compared to polyaniline-coated fiber. Relative standard deviations of peak areas are 4.3%, 6.3%, 7.1% ( n = 5) for identical fiber, fibers prepared in identical batch and different batches, respectively, exhibiting good repeatability and reproducibility. Detection limit is 1.30 ng L −1 (S/N = 3), and recoveries are in the ranges from 82.3 to 110.2%, from 91.5 to 109.4% and from 94.2 to 113.0% for three different water samples spiked at three levels of 500, 100 and 10 ng mL −1 , respectively.
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JOURNAL OF FOOD SCIENCE
·
2023
·Vol. 88
·期 7
·2870-2881
·
IF 3.9
Zhipeng Liu,Kangzhuo Yang,Zhanglan He,Dong Zhao,Jia Zheng,Michael C. Qian
Whisky, brandy, rum, and Chinese baijiu are popular distilled spirits globally, and the volatile components play an essential role in the aroma of these distilled liquors. Volatile compounds in whisky, brandy, rum, and three main aroma types of Chinese baijiu (strong, light, and sauce) were investigated using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC–TOFMS). Two significant variable detection approaches, the variable importance in the projection (VIP) and nonparametric test ( Mann–Whitney U test ), were compared to determine the volatile markers among these samples. It was found that the VIP model was more efficient in screening significant variants than the U test . A total of 117 common markers were selected by both the VIP and U test methods with potential aroma contributions. Esters and acids were the main aroma markers for baijiu, diethyl esters were the main aroma markers for brandy, whereras pyrazines, lactones, and furans were the main aroma markers for whisky. Based on the chosen markers, different unknown distilled liquors were successfully classified in the model validation. This study provided a feasible methodology for spirit sample speculation based on volatile composition obtained by GC×GC-TOFMS.
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Food Packaging and Shelf Life
·
2021
·
IF 6.429
Lijing Lu,Yingjie Su,Jing Xu,Haoyue Ning,Xueyu cheng,Lixin Lu
In order to inhibit the spoilage of the packaged food , a gas phase controlled-release low-density polyethylene (LDPE) film containing carvacrol loaded with halloysite nanotubes (HNTs) was prepared and studied in this work. HNTs were etched by 4 mol/L hydrochloric acid to obtain HNT-4M, which increased the carvacrol loading capacity. Then, it was characterized before and after loading with carvacrol by transmission electron microscopy , nitrogen adsorption isotherms, and thermogravimetric analysis . A new LDPE film containing carvacrol adsorbed on HNT-4M was prepared by extrusion, and the physical properties were studied. In addition, the release rate of carvacrol in the film was measured, and the antibacterial and antioxidant properties of the film were evaluated. The results showed that the carvacrol load of HNT increased from 6.7% to 24.2% after acid etching. The diffusion coefficient of carvacrol from the active film containing HNT-4 M/carvacrol was 9.546 × 10 -12 cm 2 ·s -1 , which was decreased by 57.3% compared with the films directly adding carvacrol. Moreover, according to the DPPH radical scavenging assay and micro-atmosphere diffusion antibacterial test, it was verified that carvacrol retained its antioxidant activity and antibacterial activity in the new film.
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EUROPEAN FOOD RESEARCH AND TECHNOLOGY
·
2021
·Vol. 248
·期 1
·45-56
·
IF 2.998
Ma Lijuan,Gao Manman,Hu Jiangnan,Tong Wenzhe,Du Liping,Yu Aiqun,Huang Jihong,Li Jianxun,He Ronglin
The aroma characteristics of Pu-erh tea were studied in this work. A total of 117 volatile compounds were identified by HS-SPME combined with GC–TOF/MS, of which 29 active aroma compounds were identified by olfactometry. The active aroma compounds of Pu-erh tea were analyzed by intensity aroma (IA), aroma extraction dilution (AEDA), sensory quantification value (MF), detection frequency (DFA) and odor activity value (OAV). 24, 21 and 23 active aroma components were identified by DFA, AEDA and OAV, while 20 by IA and MF. Recombination of the obtained active aroma components indicated that OAV method was best for determining the active aroma compounds as the aroma profile of OAV recombination model was the most similar to that of Pu-erh tea sample. Omission test of the OAV recombination model furtherly identified 19 characteristic active aroma compounds of Pu-erh tea, and linalool, 1,2,3-trimenthoxybenzebe, 1,2,4-trimethoxybenzene and ɑ-ionone were the key characteristic active aromatic compounds.
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2021
·Vol. 32
·期 24
·28891-28908
·
IF 2.478
Liu Guangdi,Cui Xiuxiu,Yao Lijia,Zhao Rongjun,Tian Xu,Li Diquan,Sun Chunyan,Wang Yude
This paper reports the synthesis of ZnO-SnO 2 nanocomposites modified by PdO nanoparticles named PdO-ZSO which are prepared by the one-step hydrothermal method at 160 °C for 12 h and gas sensing test to H 2 and C 4 H 10 inflammable gas. Meanwhile, PdO-ZSO nanoparticles are XRD, SEM, TEM, EDS, XPS and other characterization methods to further explain its morphological formation process. As the sensing materials, PdO-ZSO exhibits extraordinary gas sensing behaviors for hydrogen (H 2 ) and butane (C 4 H 10 ) and the response reaches 98 and 58 to H 2 and C 4 H 10 at operating temperature of 370 °C, respectively. And the response time and recovery time are both less than 2 s and 4 s respectively, with good repeatability and outstanding long-term stability. The existence of PdO is able to increase the resistance modulation range of heterostructure. And the enhanced gas sensing performances can be ascribed to the catalysis of noble metal doping and the formation of ternary heterostructure between PdO and ZnO-SnO 2 nanocomposites.
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MATERIALS RESEARCH BULLETIN
·
2023
·
IF 5.4
Zhen Zhao,Lei Zhang,Hongming Zhang,Wuhong Xin,Xiaowen Wang,Chunmiao Liu,Yang Guo,Yinghua Zhuang,Wanli Jiao
Investigating high-performance and low-energy consumption H 2 S sensors has become a hot research topic. This study adopted a one-step co-precipitation method to synthesize La-doped ZIF-8 deprotonating zinc acetate, lanthanum nitrate, and 2-Methylimidazole in an aqueous. La 2 O 3 /ZnO were synthesized with different La 3+ doping concentrations (0, 0.5, 1, and 1.5 at%). We found that La 3+ doping at a concentration of 1 at% showed the highest response value of 140 for 5 ppm H 2 S, at a low operating temperature of 100 °C, which is 2.4 times higher than that of pure ZnO. Additionally, La 3+ doping led to a lower detection limit of 1.9 ppb. The enhanced performance can be attributed to the widening of the difference in electron concentration, the increase in vacant oxygen content, and the spillover effect of H 2 S sensing. These factors were analyzed in detail by means of porosity, P-N heterojunctions, and the increased in adsorbed oxygen content caused by La 3+ doping.
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JOURNAL OF CHROMATOGRAPHY A
·
2021
·
IF 4.759
Ruijuan Duan,Meiling Qi
This work presents the investigation of using the amphiphilic triblock copolymer composed of poly(ethylene oxide)(PEO)-poly(propylene oxide) (PPO)-poly(ethylene oxide) (PEO) (denoted as EPE) as the stationary phase for gas chromatographic (GC) analyses . The EPE capillary column exhibited moderate polarity and column efficiency of 4348 plates/m determined by naphthalene at 120 °C ( k = 11.52) . Different from the PEG and polysiloxane homopolymers, it showed high-resolution performance towards a wide range of aliphatic and aromatic isomers in terms of polarity and acid-base properties. Particularly, the EPE column displayed distinct advantages for separating the critical isomers of alkanes, anilines and phenols and the components of the lemon essential oil over the commercial PEG and polysiloxane columns. In addition, the EPE column exhibited excellent separation repeatability and reproducibility with the relative standard deviation (RSD) values in the range of 0.03% – 0.08% for run-to-run, 0.14% – 0.61% for day-to-day and 3.1% – 4.0% for column-to-column, respectively. Moreover, the EPE column was investigated in terms of thermal stability, the minimum allowable operating temperature (MiAOT) and sample loadability. Its application to GC-MS analysis of the essential oil demonstrated its feasibility for practical analyses. This work demonstrates the promising future of triblock copolymers as a new class of selective stationary phases for GC analyses, which is barely reported up to date. The findings of this work is of important value for fundamental researches and practical applications.
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