期刊文献+
共找到752,467篇文章
< 1 2 250 >
每页显示 20 50 100
Controllable synthesis of CuAlO_(2) via solid-phase method and its catalytic performance for methanol steam reforming to hydrogen
1
作者 QING Shaojun SUN Xun +3 位作者 LI Xinglong WANG Lei WU Zhiwei WANG Jianguo 《燃料化学学报(中英文)》 EI CAS CSCD 北大核心 2024年第11期1641-1651,共11页
This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investi... This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investigation in methanol steam reforming(MSR).Various catalysts were prepared under different conditions,such as calcination temperature,calcination atmosphere,and heating rate.Characterization techniques including BET,XRD,XPS,SEM and H2-TPR were employed to analyze the samples.The results revealed significant effects of calcination temperature on the phase compositions,specific surface area,reduction performance,and surface properties of the CA-T catalysts.Based on the findings,a synthesis route of CuAlO_(2) via the solid-phase method was proposed,highlighting the importance of high calcination temperature,nitrogen atmosphere,and low heating rate for CuAlO_(2) formation.Catalytic evaluation data demonstrated that CuAlO_(2) could catalyze MSR without pre-reduction,with the catalytic performance of CA-T catalysts being notably influenced by calcination temperature.Among the prepared catalysts,the CA-1100 catalyst exhibited the highest catalytic activity and stability.The findings of this study might be useful for the further study of the catalytic material for sustained release catalysis,including the synthesis of catalytic materials and the regulation of sustained release catalytic performance. 展开更多
关键词 CuAlO_(2) solid-phase method methanol steam reforming sustained release catalysis calcination temperature
下载PDF
Solid-phase extraction of trace Au(Ⅲ) with SDG and determination by the catalytic spectrophotometric method 被引量:2
2
作者 LI Huizhi ZHAI Yubo 《Rare Metals》 SCIE EI CAS CSCD 2008年第6期560-565,共6页
The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ... The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triacetic acid as an activator in microemulsion and H2SO4 medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10^-5 μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(Ⅲ) ions. The method has been applied to the determination of trace gold with satisfactory results. 展开更多
关键词 analytical chemistry catalytic kinetic spectrophotometric method solid-phase extraction gold(Ⅲ)
下载PDF
Multiresidue Method for Determination of 67 Pesticides in Water Samples Using Solid-Phase Extraction with Centrifugation and Gas Chromatography-Mass Spectrometry 被引量:3
3
作者 Abir Kouzayha Abdul Rahman Rabaa +3 位作者 Mohamad Al Iskandarani Daniel Beh Hélène Budzinski Farouk Jaber 《American Journal of Analytical Chemistry》 2012年第3期257-265,共9页
A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 a... A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 and Oasis HLB. Parameters that influence the extraction efficiency such as the eluent volume, the sample loading volume, the addition of organic solvent to water sample, sorbent drying and elute concentration were optimized. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 2 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under the optimized conditions, this method showed good recoveries higher than 65% - 68% for the 67 analyzed pesticides using the C18 and HLB cartridges with relative standard deviations lower than 9.7% - 12.3%. Limits of quantification were between 2 and 20 ng.L–1. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples. 展开更多
关键词 MULTI-RESIDUE PESTICIDES solid-phase Extraction CENTRIFUGATION Gas Chromatography-Mass SPECTROMETRY
下载PDF
Solid-phase microextraction of endogenous metabolites from intact tissue validated using a Biocrates standard reference method kit 被引量:1
4
作者 Runshan Will Jiang Karol Jaroch Janusz Pawliszyn 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2023年第1期55-62,共8页
Improved analytical methods for the metabolomic profiling of tissue samples are constantly needed.Currently,conventional sample preparation methods often involve tissue biopsy and/or homogenization,which disrupts the ... Improved analytical methods for the metabolomic profiling of tissue samples are constantly needed.Currently,conventional sample preparation methods often involve tissue biopsy and/or homogenization,which disrupts the endogenous metabolome.In this study,solid-phase microextraction(SPME)fibers were used to monitor changes in endogenous compounds in homogenized and intact ovine lung tissue.Following SPME,a Biocrates AbsoluteIDQ assay was applied to make a downstream targeted metabolomics analysis and confirm the advantages of in vivo SPME metabolomics.The AbsoluteIDQ kit enabled the targeted analysis of over 100 metabolites via solid-liquid extraction and SPME.Statistical analysis revealed significant differences between conventional liquid extractions from homogenized tissue and SPME results for both homogenized and intact tissue samples.In addition,principal component analysis revealed separated clustering among all the three sample groups,indicating changes in the metabolome due to tissue homogenization and the chosen sample preparation method.Furthermore,clear differences in free metabolites were observed when extractions were performed on the intact and homogenized tissue using identical SPME procedures.Specifically,a direct comparison showed that 47 statistically distinct metabolites were detected between the homogenized and intact lung tissue samples(P<0.05)using mixed-mode SPME fibers.These changes were probably due to the disruptive homogenization of the tissue.This study's findings highlight both the importance of sample preparation in tissue-based metabolomics studies and SPME's unique ability to perform minimally invasive extractions without tissue biopsy or homogenization while providing broad metabolite coverage. 展开更多
关键词 solid-phase microextraction Solvent extraction Metabolomics Sample preparation In vivo sampling
下载PDF
An optimized numerical method to pre-researching the performance of solid-phase oxygen control in a non-isothermal lead–bismuth eutectic loop 被引量:1
5
作者 Xiao-Bo Li Rui-Xian Liang +6 位作者 Yi-Feng Wang Hui-Ping Zhu Fang Liu Yang Liu Cong Li Hao Wu Feng-Lei Niu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第3期77-88,共12页
In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was p... In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was proposed.It incorporates the dissolution process of PbO particles and the oxygen mass transfer process,and an optimized method was used for finding out the optimized oxygen mass transfer coefficient.In numerical terms,three mass transfer models were simultaneously applied,and comparisons of calculated and experimental results from the CRAFT loop indicated that the optimized calculation method and these new oxygen mass transfer models were correct and applicable to other LBE loops.Through this calculation method,we aimed to optimize prediction of the distribution of oxygen and iron concentrations,time taken to establish the steady state of oxygen,and maximum dissolution/precipitation rates of corrosion products and corrosion depth across the entire LBE loop.We hope that this work will provide a potential reference for designing a more intelligent oxygen control system in the future. 展开更多
关键词 LBE solid-phase oxygen control Operating domain Operating model Corrosion depth Dissolution/precipitation
下载PDF
Grafting Maleic Anhydride onto Carbon Fiber via a Solid-phase Grafting Method
6
作者 林国良 郑玉婴 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2015年第9期1458-1464,共7页
By combining the strong and light carbon fibers (CFs) with polymers, composite materials with extraordinary mechanical properties are achieved. However, the mechanical properties of the as-prepared CF-reinforced pol... By combining the strong and light carbon fibers (CFs) with polymers, composite materials with extraordinary mechanical properties are achieved. However, the mechanical properties of the as-prepared CF-reinforced polymer composites can not satisfy the applications in certain fields, especially for the poor interactions between CFs and the polymers. To enhance the mechanical properties of composite materials, a solid phase grafting method has been developed to improve the adhesion forces between CFs and the polymer, by modifying the surfaces of CFs. The effects of the reaction temperature, reaction time, as well as the dosage of the initiator and maleic anhydride (MAH) on the grafting efficiency have been investigated systematically. The structure and the surface chemistry of functionalized CFs have been characterized by Fourier Transform Infrared (FT-IR), Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric (TG), and contact angle test. All of these results demonstrate that MAH is grafted onto the surface of CFs successfully by the solid phase grafting method. The MAH grafted CFs significantly improve its wettability, which further improves the interfacial adhesion between CFs and the polymeric matrix. The optimal reaction conditions are determined, such as the MAH/CF molar ratio, the dosage of initiator, the reaction temperature and the reaction time to be 3/1, 2%, 90℃ and 4 h, respectively. These attractive interracial characteristics of modified CFs suggest that the method proposed herein is a novel and efficient approach to develop CF-reinforced polymer composites with outstanding mechanical properties for cutting-edge industrial applications. 展开更多
关键词 carbon fiber maleic anhydride fuctionalized solid-phase grafting
下载PDF
Optimization of the Solid-phase Fermentation Medium of Metarhizium flavoviride by Response Surface Method
7
作者 Li Maoye Lin Huafeng +4 位作者 Li Shiguang Pan Jing Xu Amei Chen Dexin Yin Jianli 《Plant Diseases and Pests》 CAS 2015年第1期35-40,共6页
Rice flour, puparium of yellow mealworm, peanut shell and sunflower seed shell are made into the culture medium, and the optimal solid-phase fermen- tation formula for M. flavoviride is figured out. In the solid-phase... Rice flour, puparium of yellow mealworm, peanut shell and sunflower seed shell are made into the culture medium, and the optimal solid-phase fermen- tation formula for M. flavoviride is figured out. In the solid-phase fermentation, Design-Expert is applied to analyze the significance of all components on the sporu- lotion, and response surface method used to optimize the fermentation medium of M. flavoviride. The results show that puparlum of yellow mealworm is the most sig- nificant component for the sporulation; and the optimal medium formula for the fermentation of M. flavoviride: 0.25-g rice flour, 0. 14-g yellow mealworm pupari- urn, 1.00-g peanut shell, and 0.25-g sunflower seedshell. In this optimal medium, the sporulation achieves 100. 013 × 10^8 spores/mL fungal liquid, 31.7% higher than that of the initial design. Application of the optimal formula will reduce the production cost, obtain higher yield of spores, produce no pollution, and offer tech- nical support for the future large-scale production. 展开更多
关键词 Metarhizium flavoviride solid-phase fermentation Response surface
下载PDF
Low temperature solid-phase sintering of sintered metal fibrous media with high specific surface area 被引量:4
8
作者 唐彪 汤勇 +3 位作者 周蕤 陆龙生 刘彬 屈修明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第8期1755-1760,共6页
A procedure of low temperature solid-phase sintering(LTSS) was carried out to fabricate sintered metal fibrous media(SMFM) with high specific surface area.Stainless steel fibers which were produced by cutting proc... A procedure of low temperature solid-phase sintering(LTSS) was carried out to fabricate sintered metal fibrous media(SMFM) with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area(0.2 m2/g) can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C. 展开更多
关键词 sintered metal fibrous media low temperature solid-phase sintering electroless copper plating surface morphology specific surface area
下载PDF
Solid-phase sintering process and forced convective heat transfer performance of porous-structured micro-channels 被引量:2
9
作者 白鹏飞 易子川 +1 位作者 唐彪 周国富 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第3期900-906,共7页
A solid-phase sintering process for the low-cost fabrication of composite micro-channels was developed. Three kinds of composite micro-channels with metallic porous structures were designed. The sintering process was ... A solid-phase sintering process for the low-cost fabrication of composite micro-channels was developed. Three kinds of composite micro-channels with metallic porous structures were designed. The sintering process was studied and optimized to obtain porous-structured micro-channels with high porosity. The flow resistance and heat transfer performance in the composite micro-channels were investigated. The composite micro-channels show acceptable flow resistance, significant enhancement of heat transfer and dramatic improvement of flow boiling stability, which indicates a promising prospect for the application in forced convective heat transfer. 展开更多
关键词 solid-phase sintering composite micro-channels porous structure flow resistance convective heat transfer
下载PDF
Determination of phthalate esters in fat-containing foods by packed nanofiber solid-phase extraction column and gas chromatography 被引量:2
10
作者 邱金丽 王羽 +1 位作者 周小玲 康学军 《Journal of Southeast University(English Edition)》 EI CAS 2016年第3期322-326,共5页
A new method for simultaneous determination of four phthalate esters ( PAEs) in commercial fat-containing foods was developed by the combination of a packed nanofibers column based on solid-phase extraction with gas... A new method for simultaneous determination of four phthalate esters ( PAEs) in commercial fat-containing foods was developed by the combination of a packed nanofibers column based on solid-phase extraction with gas chromatography-flame ionization detector ( GC-FID ). Conditions for obtaining optimum extraction efficiency such as extraction solvents, morphologies of adsorbent, ion strength and pH were investigated and optimized in detail. Under the optimized conditions, the limits of detection (LODs) found for dibutyl phthalate (DBP) , butyl benzyl phthalate (BBP), diethyl hexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP) were 50, 25, 50 and 25 ng/g, respectively. Good linearity of four PAEs was achieved in the range of 50 to 4 000 ng/g. The proposed method was applied for analyzing different kinds of fat-containing samples. PAEs in commercial fat-containing samples can be highly extracted by a packed solid-phase extraction column of 5 mg polystyrene ( PS) nanofibers. The satisfactory average recoveries were obtained in the range of 96. 7% to 102. 3% , and the relative standard deviations (RSDs) below 5% were achieved. The proposed method reduces the organic solvent consumption, the complex and tedious procedures for sample pretreatment, and achieves high sensitivity and reproducibility for the investigated PAEs. 展开更多
关键词 phthalate esters (PAEs nanofibers solid-phase extraction gas chromatography fat-containing foods
下载PDF
Chemiluminescence Determination of Benzoic Acid Using A Solid-Phase Verdigris Reactor 被引量:1
11
作者 王晓妮 张洁 《Chinese Chemical Letters》 SCIE CAS CSCD 2003年第3期283-286,共4页
A new chemiluminescence flow system has been developed for sequential determina-tion of benzoic acid based on the reaction of the compound with copper carbonate entrapped in a solid-phase reactor. It was found that t... A new chemiluminescence flow system has been developed for sequential determina-tion of benzoic acid based on the reaction of the compound with copper carbonate entrapped in a solid-phase reactor. It was found that the unsaturated complex of Cu(II) and benzoic acid (1:1) has strong catalytic effect on the luminol-H2O2 chemiluminescence reaction. The calibration graph is linear over the range of 0.025 ~ 60 g/mL of benzoic acid, with a relative standard deviation of less than 3.0 %, and the detection limit is 0.01礸穖L-1. The proposed method was applied to the determination of benzoic acid content in different pharmaceutical formulations. 展开更多
关键词 Benzoic acid CHEMILUMINESCENCE solid-phase reactor pharmaceutical formulations.
下载PDF
HPLC Determination of Captopril in Human Plasma with Pre-column Derivation and Solid-phase Extraction and Studies on Its Pharmacokinetic and Relative Bioavailability
12
作者 丁劲松 张毕奎 +2 位作者 李焕德 刘义钊 邓航 《Journal of Chinese Pharmaceutical Sciences》 CAS 2001年第3期152-156,共5页
A new pre-column derivation HPLC method with solid-phase extraction to determine captopril in human plasma was established. Derivation products were extracted by a solid-phase extraction method after the reagent, p-a-... A new pre-column derivation HPLC method with solid-phase extraction to determine captopril in human plasma was established. Derivation products were extracted by a solid-phase extraction method after the reagent, p-a-dibromoacetophenone(p-BPB), was added in the plasma samples. The samples were analyzed in a VP-ODS column with UV-detector. The calibration curve of captopril was linear within the range of 5~1000 ngmL-1 with r=0.9987, the recovery of this method was 98.652.04%, within day and between day RSD were no more than 3.4% and 8.4% respectively. To study the pharmacokinetics and the relative bioavailability of captopril tablets, two formulations of captopril tablets were given to 18 healthy male volunteers according to a randomized 2-way cross-over design with a 1-week washout period. The respective AUC0~6 , Cmax and Tmax values of the two formulations were 424.5125.7 and 439.4113.3 mghL-1; 505.9244.6 and 504.8172.2 mgL-1; 0.6620.181 and 0.5280.176 h. Results from statistics analysis showed that there were no significant difference between the AUC0~6 , Cmax and Tmax values of the two formulations, The relative bioavailability of tablets I with respect to II was 96.114.6% from AUC0~6 measurement. Bioequivalance was observed between the two tablets. 展开更多
关键词 CAPTOPRIL solid-phase Extraction HPLC PHARMACOKINETICS BIOAVAILABILITY
下载PDF
Solid-Phase Preparation and Characterization of Chitosan
13
作者 GaoLe-ping DuYu-min +3 位作者 ZhangDao-bin ShiXiao-wen ZhanHuai-yu SongWen-hua 《Wuhan University Journal of Natural Sciences》 CAS 2003年第04A期1156-1160,共5页
Chitosan was prepared with stressing method by blending chitin and solid alkali in a single-screw extruder at given temperature and characterized by potentiometric titration, gel permeation chromatography (GPC), infra... Chitosan was prepared with stressing method by blending chitin and solid alkali in a single-screw extruder at given temperature and characterized by potentiometric titration, gel permeation chromatography (GPC), infrared spectrum (IR) and carbon-13 magnetic resonance sperctroscopy ( 13 C NMR) . Chitosan with a deacetylation degree (DD) of 76.1% was obtained at a mass ratio 0.2∶1∶1 for H_ 2 O/chitin/NaOH at 160 ℃ for 12 min. Compared to conventional solution method(usually 1∶10 for chitin/NaOH), the alkali assumption greatly decreased. Molecular weight of chitosan obtained by solid-phase method(S3,M_w1.54×10 5 ) was lower than that obtained by suspension method(Y2,M_w3.34×10 5 ). During deacetylation, molecular weight decreased with high reaction temperature and long reaction time but remained same at different initial ratios of NaOH/chitin. It might be concluded that degradation of chitosan was caused by breakout of the main chain of the oxidized chitosan catalyzed by alkali during the deactylation. IR and 13 C NMR showed that structures of chitosans prepared by solid-phase method were not changed. 展开更多
关键词 solid-phase method CHITOSAN DEACETYLATION molecular weight
下载PDF
Comparison of Headspace Solid-Phase Microextraction with Simultaneous Steam Distillation Extraction for the Analysis of the Volatile Constituents in Chinese Apricot 被引量:20
14
作者 CHEN Mei-xia CHEN Xue-sen +4 位作者 WANG Xin-guo CI Zhi-juan LIU Xiao-li HE Tian-ming ZHANG Li-jie 《Agricultural Sciences in China》 CAS CSCD 2006年第11期879-884,共6页
Volatile constituents in fully mature fruits of apricot (Prunus armeniaca L.) cultivar Xinshiji were extracted using headspace solid-phase microextraction (HS-SPME) and simultaneous steam distillation extraction ... Volatile constituents in fully mature fruits of apricot (Prunus armeniaca L.) cultivar Xinshiji were extracted using headspace solid-phase microextraction (HS-SPME) and simultaneous steam distillation extraction (SSDE) and then analyzed using capillary gas chromatography and gas chromatography-mass spectrometry. A total of 70 components were identified by HSSPME, including 20 esters, 19 hydrocarbons, 5 alcohols, 5 ketones, 4 acids, 4 lactones, 3 aldehydes, and 10 miscellaneous components, with the esters being the dominant constituent. On the basis of the odor unit values, it is believed that the following compounds probably contributed to the fresh apricot odor: hexyl acetate, β-ionone, butyl acetate, (E)-2-hexenal, linalool, limonene, γ-decalactone, and hexanal. A total of 49 components were also detected by SSDE, including 13 hydrocarbons, 9 alcohols, 7 aldehydes, 9 esters, 4 ketones, 4 lactones, 2 acids, and 1 miscellaneous component, of which the monoterpene alcohols were the dominant constituents. It could be judged from the odor unit values that the following compounds were the major contributors to boiled apricot aroma: β-ionone, linalool, hexyl acetate, γ-dodecalactone, γ- decalactone, (E)-2-hexenal, hexanal, γ-octalactone, phenylacetaldehyde, butyl acetate, limonene, α-terpineol, and δ-decalactone. The results show that HS-SPME is a simple, rapid, and solvent-free method, which is an alternative to the classical SSDE. 展开更多
关键词 AROMA volatile constituents APRICOT solid-phase microextraction simultaneous distillation-extraction
下载PDF
Use of packed-fiber solid-phase extraction for sample clean-up and preconcentration of vitamin B_(12) before determination 被引量:5
15
作者 Fang Fang Xue Jun Kang Zhi Yong Liu Yu Qin Ma Zhong Ze GU 《Chinese Chemical Letters》 SCIE CAS CSCD 2009年第12期1491-1494,共4页
A rapid and simple preconcentration step applying packed-fiber solid-phase extraction columns has been investigated to vitamin B12. The extraction performance of the new method was investigated preliminarily on vitami... A rapid and simple preconcentration step applying packed-fiber solid-phase extraction columns has been investigated to vitamin B12. The extraction performance of the new method was investigated preliminarily on vitamin functional drink. The analysis used a reversed-phase C18 column, with a photo-diode array detector at 220 nm. The samples were preconcentrated with packed-fiber solid-phase extraction columns. Good linearity was observed in vitamin functional drink. The repeatability of extraction performance, expressed as relative standard deviations, was from 3.5% to 4.3%. The limit of detection (LOD) is 5 ng mL^-1 (S/N = 3). Finally, the method had been applied for the determination of vitamin B12 in vitamin functional drink. 展开更多
关键词 Vitamin B12 NANOFIBERS Packed-fiber solid-phase extraction PRECONCENTRATION
下载PDF
Comparison of simultaneous distillation extraction and solid-phase micro-extraction for determination of volatile constituents in tobacco flavor 被引量:8
16
作者 钟科军 魏万之 +1 位作者 郭方遒 黄兰芳 《Journal of Central South University of Technology》 EI 2005年第5期546-551,共6页
The volatile and semi-volatile components in tobacco flavor additives were extracted by both simultaneous distillation extraction and solid-phase micro-extraction. Extraction conditions for solid-phase micro-extractio... The volatile and semi-volatile components in tobacco flavor additives were extracted by both simultaneous distillation extraction and solid-phase micro-extraction. Extraction conditions for solid-phase micro-extraction were optimized with information theory. Then, detection were accomplished by gas chromatography-mass spectrometry. Characteristic of each method was compared. Qualitative analysis and quantitative analysis of 6# tobacco flavor sample were accomplished through both simultaneous distillation extraction and solid-phase micro-extraction. The experimental results show that solid-phase micro-extraction method is the first choice for qualitative analysis and simultaneous distillation extraction is another good selection for quantitative analysis. By means of simultaneous distillation extraction, 20 components are identified, accounting for 92.77% of the total peak areas. Through solid-phase micro-extraction, there are 17 components identified accounting for 91.49% of the total peak areas. The main aromatic components in 6# tobacco flavor sample are propanoic acid, 2-hydroxy-, ethyl ester, menthol and menthyl acetate. The presented method has been successfully used for quality control of tobacco flavor. 展开更多
关键词 simultaneous distillation extraction solid-phase micro-extraction gas chromatography-mass spectrometry tobacco flavor
下载PDF
Synthesis of a highly hydrophobic cyclic decapeptide by solid-phase synthesis of linear peptide and cyclization in solution 被引量:5
17
作者 Chen, Jian Zhang, Bei +2 位作者 Xie, Cao Lu, Yi Wu, Wei 《Chinese Chemical Letters》 SCIE CAS CSCD 2010年第4期391-394,共4页
A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The l... A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility. In subsequent purification by semi-preparative HPLC,50%(v/v) DMF/H_2O was employed as the solvent to overcome the difficulty of solubilization... 展开更多
关键词 Cyclic peptide Decapeptide cyclo[LWLWLWLWLQ] solid-phase synthesis CYCLIZATION PURIFICATION
下载PDF
Fast determination of multi-mycotoxins in corn by dispersive solid-phase extraction coupled with ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry 被引量:3
18
作者 WANG Yan DONG Yan-jie +5 位作者 LI Zeng-mei DENG Li-gang GUO Chang-ying ZHANG Shu-qiu LI Da-peng ZHAO Shan-cang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2016年第7期1656-1666,共11页
A fast analytical method for the simultaneous determination of 9 mycotoxins, including alfatoxins (B1, B2, G1, and G2), fumonisins (B1, B2 and B3), zearalenone, and deoxynivalenol in corn using dispersive solid-ph... A fast analytical method for the simultaneous determination of 9 mycotoxins, including alfatoxins (B1, B2, G1, and G2), fumonisins (B1, B2 and B3), zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-lfight mass spectrometry (UPLC-Q-TOF-MS) was developed and validated. Samples were extracted with acetonitrile-water (84:16, v:v, containing 1% acetic acid) using ultrasonic extraction. The extracts were puriifed with a dispersive SPE method using C18 as a cleaning agent. The ifnal clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water (5:5, v:v). The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation (RSD) ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg?1, and limits of quantiifcation ranged from 0.1 to 200 μg kg?1, which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, alfatoxins B1 and fumonisins B1, B2 and B3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×104, 0–6.94×103 and 0–3.05×103 μg kg–1, respectively. 展开更多
关键词 C18 CORN mycotoxins dispersive solid-phase extraction
下载PDF
Solid-phase synthesis of Cu2MoS4 nanoparticles for degradation of methyl blue under a halogen-tungsten lamp 被引量:4
19
作者 Shi-na Li Rui-xin Ma Cheng-yan Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2018年第3期310-314,共5页
The Cu_2MoS_4 nanoparticles were prepared using a relatively simple and convenient solid-phase process, which was applied for the first time. The crystalline structure, morphology, and optical properties of Cu_2MoS_4 ... The Cu_2MoS_4 nanoparticles were prepared using a relatively simple and convenient solid-phase process, which was applied for the first time. The crystalline structure, morphology, and optical properties of Cu_2MoS_4 nanoparticles were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and UV-vis spectrophotometry. Cu_2MoS_4 nanoparticles having a band gap of 1.66 eV exhibits good photocatalytic activity in the degradation of methylene blue, which indicates that this simple process may be critical to facilitate the cheap production of photocatalysts. 展开更多
关键词 Cu2MoS4 NANOPARTICLES solid-phase synthesis DEGRADATION PHOTOCATALYST METHYL blue
下载PDF
Organic acids and inorganic anions in Bayer liquors by ion chromatography after solid-phase extraction 被引量:3
20
作者 钟付金 陈晓青 +1 位作者 张树朝 李跃平 《Journal of Central South University of Technology》 EI 2007年第2期191-195,共5页
A method for the simultaneous separation and determination of organic acids and inorganic anions in Bayer liquors was developed by gradient ion chromatography with suppressed conductivity detection. Formate, acetate, ... A method for the simultaneous separation and determination of organic acids and inorganic anions in Bayer liquors was developed by gradient ion chromatography with suppressed conductivity detection. Formate, acetate, propionate, oxalate, succinate, glutarate, fluoride, chloride and sulfate were separated and determined in 33 min. The samples were pretreated with solid-phase extraction, which has high selectivity for removing a large number of metallic ions in the Bayer liquors, and filtered with a 0.45 μm filter membrane before being injected into the ion chromatographic system. The separation of six organic acids and three inorganic anions was achieved on an IonPac AS11-HC column with KOH as the eluent, and the detection was performed by a conductivity detection mode. No interference is found in the presence of fluorate, chlorate and sulphate when organic acids are determined. The calibration graphs of peak area for all the analytes are linear over a wide range. The relative standard derivation of the peak area of analytes is less than 2.14%. Under optimum conditions the detection ranges from 0.2 to 100.0 mg/L. The average recoveries of the added standards are between 94.3% and 102.8%. 展开更多
关键词 Bayer liquors organic acid inorganic anion ion chromatography solid-phase extraction
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部