采用反相高效液相色谱(RP-HPLC)与质谱(MS)联用技术对固相法化学合成七肽(H2N-PFNSLAI-COOH,M r 760.9)时出现的消旋产物进行了分析。根据弱疏水性合成七肽粗品特性,提出了充分利用吸附和分配双重保留机制的“早期吸附”概念,以此优化...采用反相高效液相色谱(RP-HPLC)与质谱(MS)联用技术对固相法化学合成七肽(H2N-PFNSLAI-COOH,M r 760.9)时出现的消旋产物进行了分析。根据弱疏水性合成七肽粗品特性,提出了充分利用吸附和分配双重保留机制的“早期吸附”概念,以此优化色谱条件得到4个峰形良好的色谱峰;质谱分析表明:4谱峰具有相同的m/z761.5[M+H]+值,对每一消旋产物进行在线多肽测序,并利用串联质谱(MSn)谱图叠加的方法,得到b轴和y轴两套片段信息,成功确定了合成七肽的4个消旋产物。展开更多
This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqh...This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqhusainii. CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCI2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100-110 ℃. The overall reactivity order of the catalysts was found to be CaO 〉 MgO 〉 Pb02 〉 ZnC12 〉 TIC14 〉 PbO 〉 HgC12 〉 ZnO 〉 AIC13 〉 SnCI2 〉 TiO2 whereas, CaCI2, MgCI2, A1203, HgO, PbCI2, MnO2, MnC12, Fe203 and FeCI3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether ： chloroform ： toluene （7：2：1 ） is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chroma- tography （TLC） examination ofbiodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials （ASTM）,展开更多
Recently microwave-induced chemical synthesis of curcumin-metformin adduct to enhance the efficacy of metformin in preventing the formation of Advanced Glycation End Products （AGEs） has been reported from authors＇ ...Recently microwave-induced chemical synthesis of curcumin-metformin adduct to enhance the efficacy of metformin in preventing the formation of Advanced Glycation End Products （AGEs） has been reported from authors＇ laboratory. The present studies describe microwave-induced chemical synthesis and mass spectral characterization of curcumin-phenformin adducts using LC-MS/MS. The mechanism of formation and its analytical data via Thin-Layer Chromatography （TLC） combined with MS/MS fragmentation revealed a major six membered ring adduct and a minor eight membered ring isomer. A facile chemical synthesis and identification of major and minor isomers presented in this study may offer novel therapeutic strategies for inhibiting AGEs as well as anti-cancer treatments.展开更多
Gas chromatography/mass spectrometry (GC MS) of the essential oil from the aerial parts of Rabdosia lophanthoides resulted in the identification of 108 compounds representing 78.120% of the oil. Hydro distillati...Gas chromatography/mass spectrometry (GC MS) of the essential oil from the aerial parts of Rabdosia lophanthoides resulted in the identification of 108 compounds representing 78.120% of the oil. Hydro distillation of Rabdosia lophanthoides yielded a pale yellow oil. The compounds identified and their relative proportions are listed in Table 1 according to their order of elution on an HP 5MS capillary column. .展开更多
The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H...The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H NMR, and MS spectroscopy. These dyestuffs gave satisfactory results when applied as disperse dyes to polyester fabric. The dyeing properties such as light fasmess, washing fastness and exhaustion studies have been investigated.展开更多
The distillation range analysis and elemental analysis of fractioned direct liquefied oil were conducted. Each fraction of liquefied oil contains some nitrogen compounds. Using the acid extraction method and gas chrom...The distillation range analysis and elemental analysis of fractioned direct liquefied oil were conducted. Each fraction of liquefied oil contains some nitrogen compounds. Using the acid extraction method and gas chromatography/mass spectrometry （GC-MS）, the basic nitrogen compounds have been separated and identified. Compared with the nitrogen content of the liquefied oil before and after separation, the basic nitrogen compounds account for more than half of all nitrogen compounds. The basic nitrogen compounds in the light liquefied oil are easily separated, and contain more types of basic nitrogen compounds. The results also show that there are many basic nitrogen compounds in liquefied oil, such as pyrrole, aniline, pyridine, quinoline and so on. However, there are fewer other types of basic nitrogen compounds.展开更多
In order to reveal difference of phenolic substances and the content in the different varieties of pomegranate fruit and different mature period. The article uses 3 different fruit color phenotype （white, red, green...In order to reveal difference of phenolic substances and the content in the different varieties of pomegranate fruit and different mature period. The article uses 3 different fruit color phenotype （white, red, green） pomegranate cultivars as materials, the peel were determined by high performance liquid chromatography respectively （composition and content of phenolic compounds in the seeds and juice）. Results shows that the varieties of pomegranate peel and seeds were detected in 13 kinds of phenols, juice was detected in 12 type, and which did not detect epicatechin. At the same time, there was a significant difference in different parts of different varieties of pomegranate phenolic content.展开更多
Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it ...Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it is a challenge to obtain a baseline separation of ASPM components.Meanwhile,in some cases it was found that the results obtained by different brands of C_（18） columns were significantly different,indicating the necessity of a rational column selection for the separation of ASPM components.In this paper,we attempted to facilitate column selection for the analysis of ASPM using the database of the column characterization system established by Leuven University.With the CAPCELL PAK MG C_（18）（250 mm×4.6 mm,5μm） as the reference column,three groups of columns（F2 group：similar selectivity;2F6：intermediate ranked group;F6 group： different selectivity,compared to the reference column） were selected,and their performances in the separation of ASPM components were evaluated under the chromatographic conditions described in Chinese Pharmacopoeia monograph.A good relationship was demonstrated between the ranking of columns and their selectivity in the separation of ASPM components,indicating the column classification system established by Leuven University was a helpful tool in the selection of suitable columns for the analysis of ASPM,a complex mixture of basic compounds.展开更多
Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Har...Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.展开更多
文摘采用反相高效液相色谱(RP-HPLC)与质谱(MS)联用技术对固相法化学合成七肽(H2N-PFNSLAI-COOH,M r 760.9)时出现的消旋产物进行了分析。根据弱疏水性合成七肽粗品特性,提出了充分利用吸附和分配双重保留机制的“早期吸附”概念,以此优化色谱条件得到4个峰形良好的色谱峰;质谱分析表明:4谱峰具有相同的m/z761.5[M+H]+值,对每一消旋产物进行在线多肽测序,并利用串联质谱(MSn)谱图叠加的方法,得到b轴和y轴两套片段信息,成功确定了合成七肽的4个消旋产物。
基金the Higher Education Commission of Pakistan for providing the Ph.D.scholarship(117-3083-PS7-208,50018488)to Noureen Fatima under Indigenous Ph.D.5000 Fellowship Program
文摘This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqhusainii. CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCI2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100-110 ℃. The overall reactivity order of the catalysts was found to be CaO 〉 MgO 〉 Pb02 〉 ZnC12 〉 TIC14 〉 PbO 〉 HgC12 〉 ZnO 〉 AIC13 〉 SnCI2 〉 TiO2 whereas, CaCI2, MgCI2, A1203, HgO, PbCI2, MnO2, MnC12, Fe203 and FeCI3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether ： chloroform ： toluene （7：2：1 ） is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chroma- tography （TLC） examination ofbiodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials （ASTM）,
文摘Recently microwave-induced chemical synthesis of curcumin-metformin adduct to enhance the efficacy of metformin in preventing the formation of Advanced Glycation End Products （AGEs） has been reported from authors＇ laboratory. The present studies describe microwave-induced chemical synthesis and mass spectral characterization of curcumin-phenformin adducts using LC-MS/MS. The mechanism of formation and its analytical data via Thin-Layer Chromatography （TLC） combined with MS/MS fragmentation revealed a major six membered ring adduct and a minor eight membered ring isomer. A facile chemical synthesis and identification of major and minor isomers presented in this study may offer novel therapeutic strategies for inhibiting AGEs as well as anti-cancer treatments.
文摘Gas chromatography/mass spectrometry (GC MS) of the essential oil from the aerial parts of Rabdosia lophanthoides resulted in the identification of 108 compounds representing 78.120% of the oil. Hydro distillation of Rabdosia lophanthoides yielded a pale yellow oil. The compounds identified and their relative proportions are listed in Table 1 according to their order of elution on an HP 5MS capillary column. .
文摘The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H NMR, and MS spectroscopy. These dyestuffs gave satisfactory results when applied as disperse dyes to polyester fabric. The dyeing properties such as light fasmess, washing fastness and exhaustion studies have been investigated.
文摘The distillation range analysis and elemental analysis of fractioned direct liquefied oil were conducted. Each fraction of liquefied oil contains some nitrogen compounds. Using the acid extraction method and gas chromatography/mass spectrometry （GC-MS）, the basic nitrogen compounds have been separated and identified. Compared with the nitrogen content of the liquefied oil before and after separation, the basic nitrogen compounds account for more than half of all nitrogen compounds. The basic nitrogen compounds in the light liquefied oil are easily separated, and contain more types of basic nitrogen compounds. The results also show that there are many basic nitrogen compounds in liquefied oil, such as pyrrole, aniline, pyridine, quinoline and so on. However, there are fewer other types of basic nitrogen compounds.
文摘In order to reveal difference of phenolic substances and the content in the different varieties of pomegranate fruit and different mature period. The article uses 3 different fruit color phenotype （white, red, green） pomegranate cultivars as materials, the peel were determined by high performance liquid chromatography respectively （composition and content of phenolic compounds in the seeds and juice）. Results shows that the varieties of pomegranate peel and seeds were detected in 13 kinds of phenols, juice was detected in 12 type, and which did not detect epicatechin. At the same time, there was a significant difference in different parts of different varieties of pomegranate phenolic content.
文摘Acetylspiramycin（ASPM）,a 16-membered basic macrolide antibiotic,is the acetylated derivative of spiramycin.In addition to the four main components,more than seventy minor components could be present in ASPM.Thus,it is a challenge to obtain a baseline separation of ASPM components.Meanwhile,in some cases it was found that the results obtained by different brands of C_（18） columns were significantly different,indicating the necessity of a rational column selection for the separation of ASPM components.In this paper,we attempted to facilitate column selection for the analysis of ASPM using the database of the column characterization system established by Leuven University.With the CAPCELL PAK MG C_（18）（250 mm×4.6 mm,5μm） as the reference column,three groups of columns（F2 group：similar selectivity;2F6：intermediate ranked group;F6 group： different selectivity,compared to the reference column） were selected,and their performances in the separation of ASPM components were evaluated under the chromatographic conditions described in Chinese Pharmacopoeia monograph.A good relationship was demonstrated between the ranking of columns and their selectivity in the separation of ASPM components,indicating the column classification system established by Leuven University was a helpful tool in the selection of suitable columns for the analysis of ASPM,a complex mixture of basic compounds.
基金supported by the Fonds der Chemischen Industrie and Deutsche Forschungsgemeinschaft (Mu 1088/9-1)
文摘Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.
