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1.
In order to separate the potential arsenite metabolites methylarsonous acid and dimethylarsinous acid from arsenite, arsenate, methylarsonic acid and dimethylarsinic acid, the pH‐dependent retention behaviour of all six arsenic compounds was studied on a Hamilton PRP‐X100 anion‐exchange column with 30 mM phosphate buffers (pH 5, 6, 7, 8 and 9) containing 20% (v/v) methanol as mobile phase and employing an inductively coupled plasma atomic emission spectrometer (ICP–AES) as the arsenic‐specific detector. Baseline separation of dimethylarsinic acid, methylarsonous acid, methylarsonic acid, arsenate and dimethylarsinous acid was achieved with a 30 mmol dm−3 phosphate buffer (pH 5)–methanol mixture (80:20, v/v) in 25 min. Arsenite is not baseline‐separated from dimethylarsinic acid under these conditions. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
2.
Howard H. Weetall 《Applied biochemistry and biotechnology》1985,11(1):25-28
Esters of gallic acid were synthesized by enzymatic means using tannase fromAspergillus niger. Alcohols ranging from C1 through C12 and diols from C3 through C6 were tested and found to form esters in the presence of the enzyme. 相似文献
3.
M. Kalinowska L. Mazur E. Regulska A. Korczak G. Świderski W. Lewandowski 《Journal of Coordination Chemistry》2016,69(16):2415-2421
The synthesis, crystal structure, and spectral characteristics (IR, Raman, and 1H and 13C NMR) of a monomeric hexa(aqua)calcium compound, viz. [Ca(C7H5O4)2(H2O)6]·H2O (C7H5O4 = 2,5-dihydroxybenzoate), are reported. The central Ca(II) located on a twofold axis is eight coordinate in an approximate square antiprismatic environment, bonded to two monodentate 2,5-dihydroxybenzoate ligands via the carboxylate oxygen, and six waters. The adjacent monomeric units are linked with the aid of several O–H?O hydrogen bonds. 相似文献
4.
Determination of baicalin, chlorogenic acid and caffeic acid in traditional chinese medicinal preparations by capillary zone electrophoresis 总被引:3,自引:0,他引:3
Summary A capillary zone electrophoresis (CZE) method was developed for the simultaneous assay of three bioactive components—baicalin,
chlorogenic acid and caffeic acid—in seven traditional Chinese medicinal preparations. The analytes were separated successfully
within 3.5 min using 10 mM borate buffer (pH8.6). Regression equations revealed linear relationships (correlation coefficients
0.9942–0.9996) between the peak area and concentration of the three analytes. The relative standard deviations of the migration
times and the peak areas of the three constituents were 1.12–2.68% and 1.62–5.73%, respectively. Recovery of the three constituents
ranged from 89 to 107%. The extraction efficiencies of different extraction solutions are also discussed. The contents of
the three components in seven different Chinese medicinal preparations containing Honeysuckle flower and/orScutellariae radix were determined by the CZE method with satisfactory results. 相似文献
5.
Donald M. Kirschenbaumt 《Applied biochemistry and biotechnology》1982,7(5):343-384
The amino acid analyses of 183 proteins, as residues per 1000 residues, are given. In addition the carbohydrate content and
the content of any noncommon amino acids are also given. The sources of all proteins are presented. 相似文献
6.
<正>α-Aminonitriles were synthesized via a one-pot three-component condensation of aldehydes,amines,and trimethylsilyl cyanide using silica-bonded N-propylpiperazine sulfamic acid(SBPPSA) as a recyclable solid acid at room temperature.SBPPSA showed much the same efficiency when used in consecutive reaction runs. 相似文献
7.
A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes,chloroacetonitrile,benzenesulfinic acid sodium salt in the presence of l-butyl-3-methyl imidazolium hydroxide([bmim]OH) in EtOH under reflux.The ionic liquid was recovered and recycled for subsequent reactions.The advantages of this protocol were non-toxic,easy work-up and good yields. 相似文献
8.
桦木酸是一种羽扇豆烷型的五环三萜类化合物,因具有显著的抗肿瘤和抗HIV病毒特性而受到人们关注。桦木酸存在于多种植物中,可以用提取法得到,但由于桦木酸在植物中含量低,其主要来源是由合成法得到。许多桦木酸衍生物也具有抗肿瘤活性。本文介绍了桦木酸的提取与合成等制备方法,以及几种桦木酸衍生物的合成路线,并对桦木酸及其衍生物的抗肿瘤途径和机理进行了概述。 相似文献
9.
Davood Nematollahi Adel Ghorbani Amene Amani Hamid Salehzadeh Hadi Beiginejad 《中国化学快报》2013,24(3):205-207
The electrochemical oxidation of 2,5-dihydroxybenzoic acid (1) has been studied in the presence of 1,3-cyclopentadiene (2) as a diene in water/ethanol (40/60, v/v) mixture using cyclic voltammetry and controlled-potential coulometry. A plausible mechanism for the oxidation of 1 in the presence of 2 is presented. Compound 1 was converted into bis-adduct 5 via electrooxidation, Diels-Alder reaction of 2 to anodically generated 3,6-dioxocyclohexa-1,4-dienecarboxylic acid (1ox), decarboxylation reaction, electrooxidation and Diels-Alder reaction. The electrochemical synthesis of 5 was performed in a onepot reaction, without toxic reagents, at a carbon electrode in a simple cell using an environmentally friendly method. 相似文献
10.
Anthranilates of Tb-Lu prepared in the reaction of the rare earth hydroxides withortho-aminobenzoic acid (anthranilic acid) have the general formulaLn(C6H4NH2COO)3·2H2O whereLn=Tb, Dy, Ho, Er, Tm, Yb, Lu. The water molecules in the hydrated compounds are in the outer coordination sphere. On heating in air at 493K dehydration occurs and the anhydrous anthranilatesLn(C6H4NH2COO)3 are formed. On the basis of the IR spectra it was found that the metal in dihydrated anthranilates was simultaneously coordinated through amino and carboxyl groups whereas in anhydrous anthranilates only through the bidentate carboxyl group. From X-ray analysis it was stated that the anthranilatesLn(C6H4NH2COO)3·2H2O are isostructural, whereas the anhydrous compoundsLn(C6H4NH2COO)3 are isostructural in the two groups Tb-Er and Tm-Lu.
Die Komplexe der schweren Selteneerdmetalle mit Orthoaminobenzoesäure
Zusammenfassung Zur Darstellung der Verbindungen des TypsLn(C6H4NH2COO)3·2H2O (mitLn=Tb bis Lu) wurde die berechnete Menge vonLn(OH)3 und C6H4NH2COOH-Lösung gemischt und bei 363K schnell zur Kristallisation gebracht. Die Produkte werden schnell abfiltriert, mit Wasser gewaschen und bis zur Gewichtskonstanz getrocknet. Die VerbindungenLn(C6H4NH2COO)3·2H2O sind isostrukturell mit der Dichte ungefähr 1.6g·cm–1 und geringer Löslichkeit in Wasser bei Raumtemperatur. Beim Erhitzen folgt zunächst Entwässerung bei 493 K, später Zersetzung zu Tb4O7 undLn 2O3. Die wasserfreien VerbindungenLn(C6H4NH2COO)3 sind isostrukturell in 2 Strukturtypen: Tb-Er and Tm-Lu. Die Infrarotspektren von wasserfreien Verbindungen und Doppelhydraten wurden registriert. Es wurde festgestellt, daß die Koordinierung der Seltenerdmetalle mit Liganden in den Dihydraten sowohl durch die Amino- als auch durch Carboxylgruppen erfolgt. In den wasserfreien Komplexen tritt die Koordinierung nur durch Carboxylgruppen auf.相似文献
11.
L. G. Stolyarova O. G. Kesarev A. I. Chernyshev L. V. Gol'tsova L. D. Smirnov 《Russian Chemical Bulletin》1996,45(6):1483-1484
AnO,N-dialkylation product, 1-methyl-5-metlioxy-6-oxo-1,6-diliydropyridine-3 carboxylic acid, is formed in the reaction of 5,6-dihydroxynicotinic acid with dimethylsulfate.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1554–1555, June, 1996. 相似文献
12.
The Todd-Atherton reaction of dialkyl thiophosphonates orO-alkyl piperididothiophosphonates with monoethanolamine vinyl ether afforded the corresponding amidoesters of thiophosphoric
acid.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1876–1877, September, 1998. 相似文献
13.
R. Ahluwalia R. K. Wanchoo S. K. Sharma J. L. Vashisht 《Journal of solution chemistry》1996,25(9):905-917
Density, viscosity, and surface tension of three binary liquid systems: ethanoic acid+nitrobenzene, propanoic acid+nitrobenzene, and butanoic acid+nitrobenzene have been determined at 25, 35, and 45°C, over the whole composition range. The excess molar volumes, viscosities, Gibbs energies for the activation of flow, and surface tension were evaluated and fitted to a Redlich-Kister type of equation. The Grunberg-Nissan parameter d was also calculated. Binary viscosity data were fitted to the models of McAllister, Heric, Krishnan, and Laddha, Auslander, and Teja and Rice. Surface tension data were fitted to the models of Zihao and Jufu, Rice, and Teja, and an empirical two-constant model. 相似文献
14.
Continuous production of L-aspartic acid 总被引:2,自引:0,他引:2
For the continuous production ofl-aspartic acid from fumaric acid and ammonia by the action of aspartase, the enzyme extracted fromEscherichia coli orE. coli cells having high aspartase activity were immobilized by various methods.
In 1973 we succeeded in the industrial production ofl-aspartic acid usingE. coli cells immobilized with polyacrylamide gel.
For the improvement of this process, we developed a novel technique using κ-carrageenan as the immobilizing matrix forE. coli cells. Further, EAPc-7 strain, having higher aspartase activity, was contracted from the parentE. coli by continuous cultivation with a definite medium. The aspartase activity was about seven times higher than that of the parent
cells. In 1982 we changed from the conventional method to the improved method, using EAPc-7 strain immobilized with κ-carrageenan. 相似文献
15.
P. C. Gopalratnam N. S. Mason R. E. Sparks 《Applied biochemistry and biotechnology》1984,10(1-3):213-220
Schistosomiasis is among the top five diseases in the world in terms of morbidity, affecting perhaps 200 million people in
tropical and subtropical countries. Antischistosomal drugs are toxic and rapidly metabolized. Hence, they must be given in
a number of spaced doses. In spite of this there are severe side effects leading to poor patient compliance. This is an ideal
situation for the application of sustained drug release to avoid the toxic peak concentration of drug.
This study was carried out using Astiban acid, an antimonial drug that is effective againstS. mansoni. Unfortunately, the drug is sufficiently soluble that 50 mg will dissolve in 100 mL water in less than a minute. To permit
sustained release of intramuscularly injected drug, microcapsules of astiban acid in poly(d,l-lactic acid) were formed by coacervation.
Release studies show that an appreciable fraction of the drug is available at the surface for rapid solution. After this surface
drug dissolves, the remaining drug is released slowly with half-times of many hours. After the initial burst, the release
of drug follows Higuchi’s equation up to approximately 80% release, with exponentially decreasing release rates thereafter. 相似文献
16.
Wang Jinhua Li Chun Bao Borong Wu Minghong Zheng Weifang Zhang Shengdong 《Radiation Physics and Chemistry》2009,78(12):1145-1147
This paper reports the effect of HNO3 on radiation stability and radiolysis product of N,N-Diethylhydroxylamine (DEHA), which is used as a reducer in the reprocessing of spent fuel. Results show that with the addition of HNO3, radiation stability of DEHA is weakened obviously, the volume fraction of H2, CH4 and C2H4 decreases but the concentration of CH3COOH increases. As to 1.0 and 2.0 M HNO3, the concentration of CH3CHO increases, but it decreases when HNO3 is 3.0 M. 相似文献
17.
18.
采用在线扫集-胶束毛细管电动色谱法(sweeping-MEKC)分离测定扛板归中的阿魏酸、咖啡酸和原儿茶酸。采用未涂层熔融石英毛细管(50 cm×50μm,有效柱长36 cm);环境温度25℃;缓冲体系为20 mmol/L NaH2PO4-80mmol/L十二烷基磺酸钠(SDS)-12.5%乙腈(V/V)(pH 2.20),紫外检测波长为216 nm,运行分离电压-20 kV,进样时间100 s。在优化条件下,3种有机酸均在20 min内出峰,峰面积RSD均小于5%。检出限分别达到98.52,118.73和27.27μg/L。 相似文献
19.
Continuous production of lactic acid in a cell recycle reactor 总被引:3,自引:0,他引:3
Eric Ohleyer Harvey W. Blanch Charles R. Wilke 《Applied biochemistry and biotechnology》1985,11(4):317-332
The production of lactic acid from glucose has been demonstrated using a CSTR (continuous stirred-tank reactor) with cell
recycle. Studies were conducted withLactobacillus delbrueckii at a fermentation temperature of 42°C and a pH of 6.25. A cell density of 140 g dry weight/L and a volumetric productivity
of 150 g/L.h, with complete glucose consumption, were obtained. It was not possible to obtain a lactic acid concentration
above 60 g/L because of product inhibition. A cell purge was not necessary to maintain high viability bacteria culture or
to obtain a steady state. At steady state the net cell growth appeared to be negligible. The specific glucose consumption
for cell maintenance was 0.33 g glucose/g cells-h. 相似文献
20.
Simultaneous determination of silicic acid, Ca, Mg and Al in mineral water and composite tablets by Ion chromatography 总被引:1,自引:0,他引:1
Q. Xu C. Xu W. Zhang Y. P. Wang L. T. Jin H. Haraguchi A. Itoh K. Tanaka 《Chromatographia》2001,53(1-2):81-84
Summary A simple, selective and sensitive ion-chromatography method was investigated for simultaneously determining silicic acid,
Ca2+, Mg2+, Al3+ and anions (Cl− and NO
3
−
) in real samples. It involved a single-column ion-chromatograph with sodium hydroxide-methanol-water eluent and conductometric
detection. Cations were converted to complex anions by adding EDTA to the sample solution. A set of well-defined peaks of
silicic acid, Ca2+, Mg2+, Al3+, Cl− and NO
3
−
were obtained. Detection limits using 3.3σ (σ=standard deviation of blank solution) were 1.25×10−6 M for H3SiO
4
−
, 1.32×10−6 M for Ca2+, 1.28×10−6 M for Mg2+, 1.33×10−6 M for Al3+, 1.31×10−6 M for Cl− and 1.24×10−6 M for NO
3
−
. The method was successfully applied to analysis of mineral water and composite tablets. 相似文献