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Janusz Pawliszyn - One of the best experts on this subject based on the ideXlab platform.
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needle trap extraction for gc analysis of formic and Acetic Acids in aqueous solution
Journal of Separation Science, 2012Co-Authors: Xinqing Lee, Daikuan Huang, Dawei Lou, Janusz PawliszynAbstract:Formic and Acetic Acids are ubiquitous in the environment, food, and most of the natural products. Extraction of the Acids from aqueous solution is required for their isotope analysis by the gas chromatography-isotope ratio mass spectrometry. To this objective, we have previously developed a purge-and-trap technique using the dynamic solid-phase microextraction technology, the NeedlEX. The extraction efficiency, however, remains unexamined. Here, we address this question using the flame ionization detector and isotope ratio mass spectrometer while comparing it with that of the CAR/PDMS fiber. The results show that the NeedlEX is applicable at a wide range of concentration through coordination of purge volume given the minimum amount 3.7 ng and 1.8 ng of formic and Acetic, respectively, is extracted. The efficiency of NeedlEX was 6-7 times lower than the fiber at 1000 μg/mL depending on the analyte. It is, however, superior to the latter at 10 μg/mL or less owing to its lower detection limit. The extraction efficiency of both Acids is equivalent in molar amount. This is, however, disguised by the different response of the flame ionization detector. The isotope ratio mass spectrometor overcomes this problem but is compromised by relatively large errors. These results are particularly useful for isotopic analysis of carboxylic Acids.
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extraction of formic and Acetic Acids from aqueous solution by dynamic headspace needle trap extraction temperature and ph optimization
Journal of Chromatography A, 2008Co-Authors: Janusz PawliszynAbstract:Abstract A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and Acetic Acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE) technique allows for the successful sampling of short chain fatty Acids under dynamic conditions while keeping the headspace (HS) volume constant. Two important parameters, including extraction temperature and effect of acidification, have been optimized and evaluated using the needle trap device. The method detection limits for the compounds estimated were 87.2 μg/L for Acetic acid and 234.8 μg/L for formic acid in spite of the low flame ionization detection response for formic acid and its low Henry's law constant in aqueous solution. Precision was determined based on the two real samples and ranged between 4.7 and 10.7%. The validated headspace-needle trap extraction method was also successfully applied to several environmental samples.
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extraction of formic and Acetic Acids from aqueous solution by dynamic headspace needle trap extraction temperature and ph optimization
Journal of Chromatography A, 2008Co-Authors: Janusz PawliszynAbstract:Abstract A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and Acetic Acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE) technique allows for the successful sampling of short chain fatty Acids under dynamic conditions while keeping the headspace (HS) volume constant. Two important parameters, including extraction temperature and effect of acidification, have been optimized and evaluated using the needle trap device. The method detection limits for the compounds estimated were 87.2 μg/L for Acetic acid and 234.8 μg/L for formic acid in spite of the low flame ionization detection response for formic acid and its low Henry's law constant in aqueous solution. Precision was determined based on the two real samples and ranged between 4.7 and 10.7%. The validated headspace-needle trap extraction method was also successfully applied to several environmental samples.
Xinqing Lee - One of the best experts on this subject based on the ideXlab platform.
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analysis of the stable carbon isotope composition of formic and Acetic Acids
Analytical Biochemistry, 2013Co-Authors: Xinqing Lee, Like Zhang, Daikuan Huang, Fang Yang, Wei Jiang, Bin FangAbstract:Abstract Formic and Acetic Acids are ubiquitous in the environment and in many biological processes. Analysis of the stable carbon isotope composition (δ13C) of formic and Acetic Acids is important to understanding their biogeochemical cycles. However, it has been faced with poor accuracy and high detection limits due to their low carbon number, high hydrophilicity, and semi-volatility. Here we developed an analytical technique by needle trap and gas chromatography–isotope ratio mass spectrometry (GC–IRMS). The organic Acids in aqueous solution were extracted using a NeedlEx needle through purge-and-trap and were analyzed by GC–IRMS for δ13C. The procedures incur no isotope fractionation. Defined as the point at which the mean δ13C is statistically the same as the given value and the analytical error starts rising, the method’s detection limits are 200 and 100 mg/L for formic and Acetic Acids, respectively, with an uncertainty of approximately 0.5‰ in direct extraction and analysis. They were lowered to 1 mg/L with precision of 0.9‰ after samples were subjected to preconcentration. The method was successfully applied to natural samples as diverse as precipitation, vinegars, ant plasma, and vehicle exhaust, which vary considerably in concentration and matrix of the organic Acids. It is applicable to the organic Acids in not only aqueous solution but also gaseous phase.
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needle trap extraction for gc analysis of formic and Acetic Acids in aqueous solution
Journal of Separation Science, 2012Co-Authors: Xinqing Lee, Daikuan Huang, Dawei Lou, Janusz PawliszynAbstract:Formic and Acetic Acids are ubiquitous in the environment, food, and most of the natural products. Extraction of the Acids from aqueous solution is required for their isotope analysis by the gas chromatography-isotope ratio mass spectrometry. To this objective, we have previously developed a purge-and-trap technique using the dynamic solid-phase microextraction technology, the NeedlEX. The extraction efficiency, however, remains unexamined. Here, we address this question using the flame ionization detector and isotope ratio mass spectrometer while comparing it with that of the CAR/PDMS fiber. The results show that the NeedlEX is applicable at a wide range of concentration through coordination of purge volume given the minimum amount 3.7 ng and 1.8 ng of formic and Acetic, respectively, is extracted. The efficiency of NeedlEX was 6-7 times lower than the fiber at 1000 μg/mL depending on the analyte. It is, however, superior to the latter at 10 μg/mL or less owing to its lower detection limit. The extraction efficiency of both Acids is equivalent in molar amount. This is, however, disguised by the different response of the flame ionization detector. The isotope ratio mass spectrometor overcomes this problem but is compromised by relatively large errors. These results are particularly useful for isotopic analysis of carboxylic Acids.
Fumio Nanbu - One of the best experts on this subject based on the ideXlab platform.
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Discovery of orally active prostaglandin D2 receptor antagonists.
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Kazuhiko Torisu, Yoshihiko Nakai, Takahiro Onoda, Toshihiko Nagase, Isamu Sugimoto, Yutaka Okada, Ryoji Matsumoto, Maki Iwahashi, Kaoru Kobayashi, Fumio NanbuAbstract:Abstract A series of N-(p-alkoxy)benzoyl-2-methylindole-4-Acetic Acids were synthesized and evaluated for prostaglandin D2 (DP) receptor affinity and antagonist activity. Some of them exhibited strong receptor binding and were potent in the cAMP formation assays. These antagonists also suppressed allergic inflammatory responses such as the PGD2-induced increase of microvascular permeability. Structure–activity relationship (SAR) data are presented.
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development of prostaglandin d2 receptor antagonist discovery of highly potent antagonists
Bioorganic & Medicinal Chemistry, 2004Co-Authors: Kazuhiko Torisu, Yoshihiko Nakai, Takahiro Onoda, Toshihiko Nagase, Isamu Sugimoto, Yutaka Okada, Ryoji Matsumoto, Maki Iwahashi, Kaoru Kobayashi, Fumio NanbuAbstract:The process of discovery for highly potent prostaglandin D(2) (PGD(2)) receptor antagonists is reported. A series of N-(p-alkoxy)benzoyl-2-methylindole-4-Acetic Acids were synthesized and identified as a new class of selective PGD(2) receptor antagonists. Most of them exhibited strong PGD(2) receptor antagonism in binding studies and the cAMP formation assay. The structure-activity relationships (SAR), including subtype selectivity of the synthesized compounds, are also discussed.
V. M. Odyntsova - One of the best experts on this subject based on the ideXlab platform.
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Synthesis, physical-chemical properties of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic acid esters
Zaporozhye State Medical University, 2017Co-Authors: V. M. OdyntsovaAbstract:The nitrogen-containing heterocyclic systems from the class of 1,2,4-triazole derivatives, which exhibit wide range of actions, occupy special place among the variety of heterocyclic compounds. Derived biologically active substances are actively introduced into practice as new original and effective drugs. We were interested in esters of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic Acids, which exhibit high biological activity and can be intermediates for the synthesis of amides, hydrazides, ylidenderivatives of corresponding Acids. The aim of this work is the synthesis of new esters of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic Acids and the establishment of their physical-chemical properties. Materials and methods. Melting point was determined by open capillary method on the device OptiMelt MPA100. The elemental composition of the synthesized compounds was determined on the universal analyzer ElementarVario ЕL cube (CHNS) (standard – sulfanilamide). 1H NMR spectra were recorded on spectrometer Varian Mercury VX-200 (1H, 200 MHz) in the solvent dimethyl sulfoxide-d6 (tetramethylsilane internal standard) and decoded using a program ADVASP(tm) Analyzer program (Umatek International Inc.). Chromato-mass-spectral studies were performed on hazarding chromatograph Agilent 1260 Infinity HPLC equipped with mass spectrometer Agilent 6120 (ionization electro-spray (ESI). The results and discussion. Synthesis of 11 new compounds, namely esters of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic Acids was carried out by two methods. According to the A method the alkylation of previously synthesized 3-(adamantan-1-yl)-1H-1,2,4-triazole-5-thiol was performed with the use of corresponding methyl ester of 2-chloroAcetic acid and the presence of equivalent amount of sodium hydroxide. The B method involves the etherification of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic acid with the use of methyl, ethyl, i-propyl, n-propyl and n-butyl alcohols in the presence of concentrated sulfuric acid. Compounds, which were obtained by different methods, do not give depression of the melting point. It should be noted that the practical yield of the reaction according to the A method is a little bit higher in comparison with the B method. Conclusions. The study of 11 new synthesized compounds, namely esters of 2-((5-(adamantan-1-yl)-4-R-4H-1,2,4-triazole-3-yl)thio)Acetic Acids has been performed. The structure of the synthesized compounds has been confirmed by modern instrumental methods of analysis (1H NMR spectroscopy, IR spectrophotometry, gas chromatography-mass spectrometry and elemental analysis)
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Acute toxicity of 2-(5-(adamantane-1-yl)-4R-1,2,4-triazole-3-ylthio) of the Acetic Acids and their salts’ derivatives
Zaporozhye State Medical University, 2015Co-Authors: V. M. Odyntsova, O. I. Panasenko, Ye. H. KnyshAbstract:Aim. To study the acute toxicity of 2-(5-(adamantane-1-yl)-4R-1,2,4-triazole-3-ylthio) Acetic Acids and their salts’ derivatives. Methods and results. According to the data the acute toxicity of investigated substances belongs to the 4th class of toxicity and they are low-toxic, their LD50 ranges from 306 to 1520 mg/kg. The most toxic compound among the investigated compounds is derived thioAcetic acid containing N4 nitrogen atom of the methyl substitute and its medium lethal dose (LD50) is 306 mg/kg. It is indicated that among the studied derived thioAcetic Acids and their salts’ derivatives the least toxic is also derived thioAcetic acid containing instead of N4 nitrogen atom phenyl radical, and its LD50 is 1520 mg/kg. After analyzing the data obtained by experimental studies of acute toxicity and chemical structure of the investigated compounds some patterns concerning the chemical structure and acute toxicity have been established. Conclusion. In the row of derived thioAcetic Acids from № 9 to № 1 and № 3 their toxicity increased in this case the loss of phenyl substitute of the acid 9 accompanied by a insignificant increase of toxicity, where the substitution of this phenyl substitute on the methyl leads to a significant toxicity’s increase on 1214 mg/kg and is 306 mg/kg unlike 1520 mg/kg
Maki Iwahashi - One of the best experts on this subject based on the ideXlab platform.
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discovery of selective indole based prostaglandin d2 receptor antagonist
Bioorganic & Medicinal Chemistry, 2011Co-Authors: Maki Iwahashi, Takahiro Onoda, Yutaka Okada, Ryoji Matsumoto, Hisao Nakai, Atsushi Shimabukuro, Yoko Matsunaga, Fumio Nambu, Masaaki TodaAbstract:Abstract A series of N -benzoyl-2-methylindole-3-Acetic Acids were synthesized and biologically evaluated as prostaglandin (PG) D 2 receptor antagonists. Some of the selected compounds significantly inhibited OVA-induced vascular permeability in guinea pig conjunctiva after oral dosing. Structure–activity relationship study is presented.
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Discovery of orally active prostaglandin D2 receptor antagonists.
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Kazuhiko Torisu, Yoshihiko Nakai, Takahiro Onoda, Toshihiko Nagase, Isamu Sugimoto, Yutaka Okada, Ryoji Matsumoto, Maki Iwahashi, Kaoru Kobayashi, Fumio NanbuAbstract:Abstract A series of N-(p-alkoxy)benzoyl-2-methylindole-4-Acetic Acids were synthesized and evaluated for prostaglandin D2 (DP) receptor affinity and antagonist activity. Some of them exhibited strong receptor binding and were potent in the cAMP formation assays. These antagonists also suppressed allergic inflammatory responses such as the PGD2-induced increase of microvascular permeability. Structure–activity relationship (SAR) data are presented.
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development of prostaglandin d2 receptor antagonist discovery of highly potent antagonists
Bioorganic & Medicinal Chemistry, 2004Co-Authors: Kazuhiko Torisu, Yoshihiko Nakai, Takahiro Onoda, Toshihiko Nagase, Isamu Sugimoto, Yutaka Okada, Ryoji Matsumoto, Maki Iwahashi, Kaoru Kobayashi, Fumio NanbuAbstract:The process of discovery for highly potent prostaglandin D(2) (PGD(2)) receptor antagonists is reported. A series of N-(p-alkoxy)benzoyl-2-methylindole-4-Acetic Acids were synthesized and identified as a new class of selective PGD(2) receptor antagonists. Most of them exhibited strong PGD(2) receptor antagonism in binding studies and the cAMP formation assay. The structure-activity relationships (SAR), including subtype selectivity of the synthesized compounds, are also discussed.