Search Results
Results 501 - 550 of 2107
< 6 7 8 9 10 11 12 13 14 15 16 >
Arribas Alberto Sánchez - - 2006
In this work we report on the successful use of a composite prepared by dispersion of multi-wall carbon nanotubes (1-5 microm length, 20-50 nm diameter) and copper microparticles within mineral oil as detector for amino acids quantification in flow injection analysis and capillary electrophoresis. The resulting electrode displays a highly ...
Xiong Xin - - 2007
A tert-butyl carbamoylated quinine-based chiral stationary phase (CSP) for direct enantiomer separation of various natural and unnatural amino acid derivatives was studied. The influence of functional groups in the amino acid side chains upon the enantioseparation is discussed with the aim of realizing contributions to their overall chiral recognition. The ...
Lin Chen-Hsing - - 2006
The separation and retention behavior of five aromatic carboxylic acid isomers was investigated by means of high-performance liquid chromatography (HPLC) using a beta-cyclodextrin bonded phase with s-triazine ring in the spacer. The influence of mobile phase pH on the retention was examined. The presence of s-triazine moiety in the spacer ...
Kakiyama Genta - - 2006
A direct method for the separation and quantification of a series of bile acid acyl glycosides using high-performance liquid chromatography coupled to an evaporative light scattering detector (HPLC-ELSD) is described. Complete separation of each of 15 bile acid acyl 24-alpha-glucosides and their 24-beta-anomers and 24-beta-galactosides was achieved by the stepwise ...
Hvattum Erlend - - 2006
Sonazoid is a new contrast agent for ultrasound imaging. The product is an aqueous suspension of perfluorobutane microbubbles coated with phospholipids obtained from hydrogenated egg phosphatidylserine (H-EPS). A normal-phase high-performance liquid chromatographic (HPLC) method with evaporative light scattering detection was developed for quantification of free fatty acids, phosphatidylserine and phosphatidic ...
Dube Simiso - - 2006
An MEKC method was developed for the separation and characterization of phenyl-isothiocyanate (PITC)-labeled amino acids derived from Gonometa rufobrunnae silkworm after microdialysis sample cleanup. The influence of the buffer and SDS concentration on the resolution of the amino acids was investigated. A buffer system consisting of 25 mM phosphate, 10 ...
Gotti Roberto - - 2006
Phanquinone (chemically: 4,7-phenanthroline-5,6-dione) was applied as an original precolumn derivatization reagent for amino acids followed by separation using MEKC with UV detection (240 nm). The derivatization reaction was carried out at 68 degrees C in the presence of aqueous phosphate buffer (pH 8.0) and it was found to be complete ...
Fu Guo-Ni - - 2006
A fast, convenient and sensitive method of capillary zone electrophoresis (CZE) and indirect UV detection was proposed for the determination of 16 amino acids. p-Aminobenzoic acid (PAB) was selected as a background electrolyte (BGE). An isolated cell included a BGE buffer part and an electrode buffer one, which were jointed ...
Ho Yu-Hsiang - - 2006
The MEKC method is described for the quantitative analysis of 17 amino acids (AA) in pharmaceutical products. The method is based on simply derivatizing the AA with (2-naphthoxy)acetyl chloride under mild conditions. The resulting derivatives were separated by MEKC with borate buffer (35 mM; pH 9.50) including 150 mM SDS ...
de Nogales Vasco - - 2006
The acidic dissociation constants of several hydrophobic drugs, amiodarone and a series of antidepressants that show a secondary or tertiary amino group, were determined in a 50% methanol/water mixture by capillary zone electrophoresis. The electrophoretic behavior of buffers prepared from sodium acetate, tris(hydroxymethyl) aminomethane hydrochloride, sodium hydrogenphosphate, ammonium chloride, ethanolamine, ...
Carrasco-Pancorbo Alegría - - 2007
Two different families of compounds, i.e., phenolic and amino acids have been separated by capillary electrophoresis using a physically adsorbed polymer as capillary coating. The polymer used was N,N-dimethylacrylamide-ethylpyrrolidine methacrylate (DMA-EpyM) and it provided an stable coating by only flushing the capillary with a DMA-EpyM aqueous solution for 2min between ...
Tsukagoshi Kazuhiko - - 2006
Molecular recognition of mono- and disaccharides was performed making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis (CE) with a chemiluminescence (CL) detection system. p-Iodophenylboronic acid acted as an enhancer for luminol-horseradish peroxidase-hydrogen peroxide CL reaction. p-Iodophenylboronic acid was injected as a sample into ...
Ptolemy Adam S - - 2006
Capillary electrophoresis (CE) represents a versatile platform for integrating sample pretreatment with chemical analysis because of its ability to tune analyte electromigration and band dispersion properties in discontinuous electrolyte systems. In this article, a single-step method that combines on-line sample preconcentration with in-capillary chemical derivatization is developed for rapid, sensitive, ...
Chou Wa Lok Jacky - - 2006
Acoustic wave detection of various underivatized amino acids that were hydrodynamically introduced into and electrokinetically migrated along a capillary tube has been achieved. The detection principle is based on the measurement of the ultrasonic absorption and density change of the aqueous amino acid samples as they pass by the detection ...
Qu Qishu - - 2006
A new ultraviolet (UV) labeling reagent, p-acetamidobenzenesulfonyl fluoride (PAABS-F), was designed and synthesized to label and determine the amino acids by capillary electrophoresis (CE) with diode-array detector (DAD). PAABS-F is very stable and easy to synthesize. It reacted with primary or secondary amino acids very quickly under facile conditions to ...
Sázelová Petra - - 2006
Capillary zone electrophoresis (CZE) and capillary isotachophoresis (CITP) were applied for the determination of peptide purity degree and counter-ion content in lecirelin, the synthetic analogue of luteinizing hormone-releasing hormone (LHRH). CZE analyses were carried out in acidic background electrolyte (100 mM H3PO4, 50 mM Tris, pH 2.25) in bare fused ...
Zampolli M - - 2006
The target of the in-situ research of optical activity in extraterrestrial samples stimulated an extended investigation of a GC-MS method based on the derivatization of amino acids by using a mixture of perfluorinated alcohols and perfluorinated anhydrides. Amino acids are converted to their N(O,S)-perfluoroacyl perfluoroalkyl esters in a single-step procedure, ...
Hu Zhen - - 2006
A micellar electrokinetic capillary electrophoresis (MEKCE) method for the determination of cholic acid (CA), hyodeoxycholic acid (HDCA) and chenodeoxycholic acid (CDCA) in artificial Calculus Bovis and its four medicinal preparations is described. The buffer solution consisted of 40 mM disodic phosphate and 40 mM sodium dodecylsulfate (SDS) adjusted to pH ...
Lian Hongzhen - - 2007
The chromatographic fingerprints of industrial o-toluic acid, m-toluic acid and p-toluic acid have been established by HPLC-UV detection according to their impurity groups. HPLC separation of all relative substances involved in the groups was developed on a Kromasil C(18) column by using methanol-water-NH(4)Ac-HAc buffer (100mM, pH 4.70) 15/65/20 (v/v/v) as ...
Tamaya Kaori - - 2006
In single-column anion-exchange chromatography, the retention volume of some monovalent inorganic anions (Cl(-), Br(-), NO(3)(-), NCS(-) and NO(2)(-)) were observed as a function of the pH of a mobile phase at a fixed concentration of 2-phenylmalonic acid or 1,4-benzenediacetic acid used as an eluent. The experimental retention volume of such ...
Karasová Gabriela - - 2006
Five end-capped octadecyl RP stationary phases, among which one was a polar embedded stationary phase, were tested for the analysis of benzoic acid derivatives using two mobile phases with or without addition of formic acid (water pH was measured by a common approach; pH of water with addition of formic ...
Xiao Jian Bo - - 2006
A rapid revised phase high-performance liquid chromatographic (RP-HPLC) method for the determination of six organic acids in Bayer liquors is reported. Oxalic, tartaric, acetic, succinic, glutaric and butene dicarboxylic acid were separated and quantified in 10 min. First time repeatability, reproducibility and recoveries were determined out for these acids in ...
Chang Po-Ling - - 2006
This paper describes the in-column derivatization, stacking, and separation of amino acids by CE in conjunction with light-emitting diode-induced fluorescence using naphthalene-2,3-dicarboxaldehyde (NDA). According to the relative electrophoretic mobilities and the migration direction in tetraborate solution (pH 9.3), the injection order is cyanide, then amino acids, then NDA. Once poly(ethylene ...
Barrado E - - 2006
A new chromatographic modality that does not require high pressures and also allows renewal of the stationary phase as desired is reported. The technique is based on a thin layer paramagnetic stationary phase (Fe3O4-SiO2) retained on the inner wall of a minicolumn through the action of an external magnetic field, ...
Bernabé-Zafón Virginia - - 2006
The oligomers of fatty alcohol ethoxylates (FAEs) exhibit large sensitivity differences in mass spectrometry with electrospray ionisation (ESI-MS) and atmospheric pressure chemical ionization (APCI). Standards of the oligomers from m=1 to 7 ethylene oxide units (EOs) and linear alkyl chains from n=10 to 18 carbon atoms were infused to examine ...
Li Jianguo - - 2006
A novel method for highly sensitive detection of primary and secondary amino acids with selective derivatization using acetaldehyde as a new derivatization reagent was proposed by capillary electrophoresis (CE) coupled with electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(II). The precolumn derivatization of these amino acids with acetaldehyde was performed in aqueous solution ...
Zhi Wenbo - - 2006
Establishment of hydrophilic organic/salt-containing aqueous two-phase system and purification of salvianolic acid B from crude extract of S. miltiorrhiza by counter-current chromatography with said system were studied. Ethanol and n-propanol were selected to constitute biphasic systems with ammonia sulphate, sodium chloride and phosphate separately, and related system characteristics including phase ...
Forlay-Frick Peter - - 2006
Three new tetraoxa-diaza derivatives of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane (R-1, R-2 and R-3) and three commercially available crown ethers, 18-crown-6 (18C6), (+)-18-crown-6-tetracarboxilic acid (18C6H4) and 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane, were investigated to separate the positional isomers of aminophenol, aminobenzoic acid and aminocresol. The running electrolyte, in which the crown ethers were dissolved, was a 50 mM ...
Tsukamoto Yuhki - - 2006
The isotope-labeled benzofurazan derivatization reagent for carboxylic acids, 7-(N,N-dimethylaminosulfonyl)-4-(aminoethyl)piperazino-2,1,3-benzoxadiazole (d6) [DBD-PZ-NH2 (D)] was synthesized. DBD-PZ-NH2 (D) was used for the accurate quantification of fatty acids by liquid chromatography/mass spectrometry (LC/MS). The standard fatty acids were derivatized with DBD-PZ-NH2 (D) to the stable isotope-labeled compounds for the fatty acids derivatives of ...
Hyun Myung Ho - - 2006
Preparation of liquid chromatographic chiral stationary phases (CSPs) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid and their application are reviewed. The various methods of connecting (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to silica gel covalently or dynamically are demonstrated. The CSPs based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid have been very successful for the resolution of various primary amino compounds ...
Zusková Iva - - 2006
The dependence of the effective electrophoretic mobility on pH of the background electrolyte was experimentally determined by capillary zone electrophoresis (CZE) for cationic forms of amino acids. The pH of the background electrolytes was in the highly acidic range, 1.6-2.6 pH units, to ensure a high degree of protonation of ...
Mori Masanobu - - 2006
Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) ...
Liang Lina - - 2006
Speciation analysis of selenomethylcysteine (SeMeCys), selenomethionine (SeMet) and selenocystine (SeCys) has been performed using a direct amino acid analysis method with high-performance anion-exchange chromatography (HPAEC) coupled with integrated pulsed amperometric detection (IPAD). Three selenoamino acids could be baseline-separated from 19 amino acids using gradient elution conditions for amino acids and ...
Cesla Petr - - 2006
A possibility of using capillary electrophoresis for separation of anacardic acids (6-alkylsalicylic acids) has been studied. Conventional micellar electrokinetic chromatography (MEKC) in non-coated fused silica capillaries and reversed-flow micellar electrokinetic chromatography (RF-MEKC) in capillaries coated with polydimethylacrylamide was applied for separation of anacardic acids extracted from cashew nuts. Influence of ...
Murkovic Michael - - 2006
The analysis of carbohydrates and amino acids in green coffee is of the utmost importance since these two classes of compounds act as precursors of the Maillard reaction during which the colour and aroma are formed. During the course of the Maillard reaction potentially harmful substances like acrylamide or 5-hydroxymethyl-furfural ...
Mori Masanobu - - 2006
Ion-exclusion/adsorption chromatography of dimethylsulfoxide (DMSO) and its derivatives, i.e., methanesulfinic acid (MSI), methanesulfonic acid (MSA) and sulfuric acid (SA), was developed in order to clear the decomposition mechanism of DMSO on quality-test of TiO(2)-photocatalyst in water. The separation was achieved by the adsorption effect for DMSO and ion-exclusion effect for ...
Fantacuzzi Marialuigia - - 2006
The enantiomeric separation of some demethylated analogues of clofibric acid, namely 2-(6-chloro-benzothiazol-2-ylsulfanyl)-, 2-(6-methoxy-benzothiazol-2-ylsulfanyl)-, 2-(quinolin-2-yloxy)-, 2-(6-chloro-quinolin-2-yloxy)-, 2-(7-chloro-quinolin-4-yloxy)-propionic acid (compounds A-E, respectively), has been studied by CZE and nano-LC using for the first technique two beta-CD derivatives and vancomycin added to the BGE and vancomycin-modified silica particles for the second one, with ...
Kautenburger Ralf - - 2006
Detailed information on the geochemical behavior of radioactive and toxic metal ions under environmental conditions (in geological matrices and aquifer systems) is needed in order to assess the long-term safety of waste repositories. This includes knowledge of the mechanisms of relevant geochemical reactions, as well as associated thermodynamic and kinetic ...
Wang Chunling - - 2006
The capillary electrophoresis (CE) system with optical fiber light-emitting diode (optical fiber LED) induced fluorescence detector was developed for the analysis of the excitatory amino acids (EAAs) tagged with naphthalene-2,3-dicarboxaldehyde (NDA). The separation of EAAs was carried out in an uncoated fused-silica capillary (50 cm x 75 microm i.d.) with ...
Laamanen Pirkko-Leena - - 2006
A new method of nonaqueous capillary electrophoresis (NACE) with UV spectrophotometric detection was developed and optimized for the simultaneous determination of seven carboxylates (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), nitrilotriacetic acid (NTA), 1,3-diaminopropane-N,N,N',N'-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)) as copper complexes. The method ...
Zhang Hua - - 2006
Erythrocytes were fused with liposome for intracellular derivatization of amino acids in cells. The fusion efficiency was evaluated with capillary electrophoresis (CE) and laser-induced fluorescence (LIF) detection. Reagent fluorescein isothiocyanate (FITC) was enveloped in liposomes and introduced into erythrocytes by fusion between liposomes and erythrocytes. The amino acids in the ...
Pardasani Deepak - - 2006
Detection and identification of environmental signatures of chemical warfare agents is an important aspect of verification program of Chemical Weapons Convention (CWC). Alkylphosphonic acids (APAs) are ultimate and persistent degradation products of nerve agents. Their identification in a sample submitted for off-site analysis infers possible indication of contamination with nerve ...
Pobozy Ewa - - 2006
In the present study a sensitive method for the quantification of main free amino acids in saliva using capillary electrophoresis with laser induced fluorescence detection was developed. As background electrolyte 20 mM borate buffer pH 9.5 was used. Amino acids were separated after derivatization with fluorescein isothiocyanate (FITC) and the ...
Gatti R - - 2006
The use of anisoin as pre-chromatographic reagent for LC analysis of guanidino compounds is proposed. The reagent reacts (5 min at 100 degrees C) with guanidino function and the resulting adducts can be chromatographed under reversed-phase conditions. A fluorescence detector (lambda(ex)=325 nm; lambda(em)=435 nm) was used to detect guanidino adducts. ...
Chen Yongjing - - 2006
Effect of mixed eluents which contain zwitterions such as 2-(N-morpholino)ethanesulfonic acid (MES), 3-(N-morpholino)propanesulfonic acid (MOPS), 2-(cyclohexylamino)ethanesulfonic acid (CHES) and 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS) and carbonate for suppressed conductivity ion chromatography (IC) were studied. The retention behaviors of all species were affected with different anion exchange columns when adding some zwitterion into ...
Zhao J - - 2006
The seed of Ziziphus jujube Mill. var. spinosa (Bunge) Hu ex H. F. Chou, Suanzaoren in Chinese, is one of commonly used Chinese medicines. Saponins and fatty oil contains several fatty acids in Suanzaoren are responsible for its therapeutic activities. In this study, a new HPLC coupled with evaporative light ...
Bonoli Matteo - - 2006
1,2-Dioleyl-3-trymethylammoniumpropane (DOTAP) lipid vesicles were employed as coating precursors to obtain a semipermanent cationic lipid bilayer in silica capillary. The coating procedure was relatively fast and simple. Reliable results for the separation of four basic proteins (alpha-chymotrypsinogen A, ribonuclease A, cytochrome C, lysozyme) were obtained by using an acetate buffer ...
Mori Masanobu - - 2006
Vacancy ion-exclusion chromatography (VIEC) for inorganic acids such as H(2)SO(4), HCl, H(3)PO(4), HNO(3), HI and HF is tested on a polymethacrylate-based weakly acidic cation-exchange resin column in the H(+)-form. That is, mixture of inorganic acids in the mobile phase is adsorbed to the resin phase passing through the separation column, ...
Carabias-Martínez Rita - - 2006
CE in nonaqueous media was used to study the migrating behavior of two weakly basic s-triazine pesticides and one of their metabolites. The target pesticides were selected to be representative for each of the two main groups: propazine and deethylatrazine for the chloro-s-triazines group and ametryn for the methylthio-s-triazines group. ...
Huang Ting - - 2006
A protein-bonded porous-layer open-tubular (PLOT) column has been synthesized and applied to the separation of amino acids by CEC. The porous layer was coated on the capillary inner wall by in situ polymerization of 2-hydroxyethyl methacrylate and 2-vinyl-4,4-dimethylazlactone in the presence of 1-decanol as a porogen inside a fused-silica capillary ...
< 6 7 8 9 10 11 12 13 14 15 16 >