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Anouti Suzanne - - 2010
The use of transient moving chemical reaction boundary (tMCRB) was investigated for the on-line preconcentration of native amino acids in heart-cutting 2D-CE with multiple detection points using contactless conductivity detection. The tMCRB focusing was obtained by using ammonium formate (pH 8.56) as sample matrix and acetic acid (pH 2.3) as ...
Momchilova Svetlana M - - 2010
A protocol for separation of positionally isomeric trans- and cis-octadecenoic fatty acids as their p-methoxyphenacyl esters, using a single column silver ion high-performance liquid chromatography (Ag-HPLC) with UV detection, is described. The procedure involves hydrolysis of oil to free fatty acids, derivatization to p-methoxyphenacyl esters, purification and separation by Ag-HPLC. ...
Hauff Simone - - 2010
Fatty acid methyl esters obtained from a fish oil sample were fractionated by non-aqueous reversed-phase high-performance liquid chromatography (RP-HPLC) using three serially connected C(18)-columns and pure methanol as the eluent. The HPLC fractions were analyzed by gas chromatography-electron ionization mass spectrometry in the selected ion monitoring mode. Data analysis and ...
Chatzigeorgiou Petros - - 2010
The structural modifications of the amino acid DL-Norvaline have been studied using differential scanning calorimetry (DSC) and Raman spectroscopy. DSC results showed that this amino acid undergoes two solid-solid phase transitions at -116.9 and -76.1 degrees C in the temperature range -130 to +300 degrees C. Raman spectroscopy was applied ...
Hauff Simone - - 2010
Gas chromatography in combination with electron ionization mass spectrometry (GC/EI-MS) was used to determine the fatty acids of a membrane lipid from Bacillus megaterium. Special attention was put on the structure and absolute configuration of a monoenoic fatty acid previously described in this sample. GC/EI-MS operated in the selected ion ...
Zheng Yan-Song - - 2010
Pure enantiomers of carboxylic acids are a class of important biomolecules, chiral drugs, chiral reagents, etc. Analysis of the enantiomers usually needs expensive instrument or complex chiral receptors. However, to develop simple and reliable methods for the enantiomer analysis of acids is difficult. In this paper, chiral recognition of 2,3-dibenzoyltartaric ...
Armenta Jenny M JM Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, - - 2010
An AccQ*Tag ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (AccQ*Tag-UPLC-ESI-MS/MS) method for fast, reproducible, and sensitive amino acid quantitation in biological samples, particularly, the malaria parasite Plasmodium falciparum is presented. The Waters Acquity TQD UPLC/MS system equipped with a photodiode array (PDA) detector was used for amino acid separation and ...
Gatti Rita - - 2010
The use of 2,5-dimethyl-1H-pyrrole-3,4-dicarbaldehyde as a precolumn derivatization reagent for HPLC analysis of amino acids is proposed. The compound reacts under mild conditions (10min at ambient temperature) with primary amino groups. The derivatization conditions to obtain quantitative reaction were optimised by considering different parameters (temperature, pH and reagent concentration) using ...
Lee Taeho - - 2010
(-)-(18-Crown-6)-2,3,11,12-tetracarboxylic acid-bonded silica was used as the chiral stationary phase in capillary electrochromatography (CEC) for enantioseparation of some alpha-amino acids. Separation data in CEC were measured in mobile phases of varying pH, and composition of methanol and buffer, and compared with those in capillary liquid chromatography (CLC). In CEC better ...
Turkia Heidi - - 2010
Determination of carboxylic acids in Gluconobacter oxydans fermentations of wheat straw hydrolyzate was carried out. This matrix is of complex composition containing carbohydrates, organic compounds (e.g., amino acids, toxins), and inorganic salts making the analysis challenging even with separation techniques. A method based on capillary electrophoresis with indirect UV detection ...
Dietzen Dennis J - - 2010
Analysis of clinically relevant amino acids using ion-exchange chromatography coupled to photometric detection has been an indispensable component in the detection of inborn errors of metabolism for six decades. Detection of amino acids using mass spectrometry offers advantages in speed and analytic specificity. Employing methanol extraction and controlled butylation, C8 ...
Gotoh Naohiro - - 2010
The characteristics of a non-endcapped polymeric ODS column for the resolution of triacylglycerol positional isomers (TAG-PI) were examined using a recycle HPLC-atmospheric pressure chemical ionization/mass spectrometry system. A pair of TAG-PI containing saturated fatty acids at least 12 carbons was separated. Except for TAG-PI containing elaidic acid, pairs of TAG-PI ...
He Quan - - 2010
The optical resolution of p-chloromandelic acid using (R)-alpha-phenylethylamine as resolving agent was presented. The effect of solvents, molar ratio of racemate to the resolving agent, filtration temperature as well as the amount of solvent on resolution was investigated by orthogonal experimentation. The binary melting point phase diagram and crystal structure ...
Miramon H?l?ne - - 2010
This study deals with the separation by capillary zone electrophoresis (CE) of hardly soluble synthetic polypeptides such as poly(L-alanine). The characterization of the molar mass distribution of these polypeptides with neutral lateral chain is a prerequisite for a good understanding of the relationship between their structure and their biological activity. ...
Rovio Stella - - 2010
Capillary zone electrophoresis (CZE) with indirect UV detection was used in developing a method for the simultaneous determination of inorganic anions, aliphatic and heterocyclic organic acids in various processed samples. The analytes were determined simultaneously in 10 min using an electrolyte containing 20mM 2,3-pyrazine dicarboxylic acid, 65mM tricine, 2mM BaCl(2), ...
Kao Yu-Yen - - 2010
We describe simultaneous analysis of naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and NDA-biogenic amine derivatives by CE in conjunction with light-emitting diode-induced fluorescence detection using poly(ethylene oxide) (PEO) solutions containing sodium dodecyl sulfate (SDS). After sample injection, via EOF 0.1% PEO prepared in 100mM TB solution (pH 9.0) containing 30 mM SDS entered ...
Gajd?tsy G - - 2009
A three-channel, highly sensitive, fiber optic device is presented to measure acid concentration in lead-acid batteries during their operation. The refractive index and thereby the concentration of sulfuric acid is measured by a bent, silica glass fiber tip, stripped off its cladding. Sensor heads of the device are small enough ...
Flieger J - - 2010
The addition of the homologous series of perfluorinated acids-trifluoroacetic acid (TFAA), pentafluoropropionic acid (PFPA), heptafluorobutyric acid (HFBA) to mobile phases for reversed-phase high-performance liquid chromatography (RP-HPLC) of beta-blockers was tested. Acidic modifiers were responsible for acidification of mobile phase (pH 3) ensuring the protonation of the beta-blockers and further ion ...
Absalan Ghodratollah - - 2010
In this paper, partitioning behaviors of typical neutral (Alanine), acidic (Glutamic acid) and basic (Lysine) amino acids into imidazolium-based ionic liquids [C(4)mim][PF(6)], [C(6)mim][PF(6)], [C(8)mim][PF(6)], [C(6)mim][BF(4)] and [C(8)mim][BF(4)] as extracting solvents were examined. [C(6)mim][BF(4)] showed the best efficiency for partitioning of amino acids. The partition coefficients of amino acids in ionic ...
Jin Jing Yu - - 2009
Liquid chromatographic enantiomer separation of several N-benzyloxycarbonyl (CBZ) and N-tert-butoxycarbonyl (BOC) alpha-amino acids and their corresponding ethyl esters was performed on covalently immobilized chiral stationary phases (CSPs) (Chiralpak IA and Chiralpak IB) and coated-type CSPs (Chiralpak AD and Chiralcel OD) based on polysaccharide derivatives. The solvent versatility of the covalently ...
Stockton Amanda M - - 2009
The Mars Organic Analyzer (MOA) has enabled the sensitive detection of amino acid and amine biomarkers in laboratory standards and in a variety of field sample tests. However, the MOA is challenged when samples are extremely acidic and saline or contain polyvalent cations. Here, we have optimized the MOA analysis, ...
Kawasaki Hideya - - 2009
The pyrolytic highly oriented graphite polymer film (PGS) was first employed to analyze low-mass analytes in environmental analysis by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). PGS is a synthetic uniform and highly oriented graphite polymer film with high thermal anisotropic conductivity. We have found that negative ion mode SALDI-MS using ...
Zhu Xingyu - - 2009
A glycosphingolipid analogue (12-azidododecyl beta-lactoside) as a saccharide primer has been shown to be useful for the synthesis of oligosaccharide libraries by mammalian cells. In the present study, CE-ESI-MS was employed to elucidate the structure of glycosphingolipid analogues derived from 12-azidododecyl beta-lactoside (Lac-C12N3) by mammalian cells. MDCK cells and COLO201 ...
Liu Qian - - 2009
Recently, amino acid ionic liquids (AAILs) have attracted much research interest. In this paper, we present the first application of AAILs in chiral separation based on the chiral ligand exchange principle. By using 1-alkyl-3-methylimidazolium L-proline (L-Pro) as a chiral ligand coordinated with copper(II), four pairs of underivatized amino acid enantiomers-dl-phenylalanine ...
Shi Tianyu - - 2009
This work presents an high-performance liquid chromatography method for the determination of amino acids after precolumn derivatization with 4-chloro-3,5-dinitrobenzotrifluoride (CNBF) which can readily react with both primary and secondary amines. The precolumn derivatization conditions, including the CNBF concentration, reaction pH, temperature and reaction time were investigated for method optimization. In ...
Li Aimin - - 2009
Fulvic acids from the soil of Peking University (PF) and a Nordic river (NF) were separated into well defined sub-fractions using sequential elution techniques based on eluent polarity. The chemical properties of the fractions including: PF1 and NF1 (eluted by 0.01 M HCl), PF2 and NF2 (eluted by 0.01 M ...
Jiang Zhengjin - - 2010
It is believed that the enantiorecognition mechanism based on macrocyclic antibiotics involves multimodal interactions via hydrogen bonding, pi-pi interaction, steric hindrance, hydrophobic interaction and so on. A variety of enantiomeric N-benzoylated amino acids were separated using balhimycin (A) or its analogues bromobalhimycin (B) and dechlorobalhimycin (C) as chiral mobile phase ...
Mai Thanh Duc - - 2009
A fast separation of alkali and alkaline earth metal cations and ammonium was carried out by capillary electrochromatography on monolithic octadecylsilica columns of 15 cm length and 100 microm inner diameter using water/methanol mixtures containing acetic acid as mobile phase. On-column contactless conductivity detection was used for quantification of these ...
Hamase Kenji - - 2010
A validated two-dimensional HPLC system combining a microbore-monolithic ODS column and a narrowbore-enantioselective column has been established for a sensitive and simultaneous analysis of hydrophilic amino acid enantiomers (His, Asn, Ser, Gln, Arg, Asp, allo-Thr, Glu and Thr) and the non-chiral amino acid, Gly, in biological samples. To accomplish this ...
Florini Nicola - - 2010
A neodymium-(S)-PDTA (PDTA = N,N,N',N'-tetrakis[(hydroxycarbonyl)methyl]-1,2-diaminopropane) complex was found exceptionally useful in the quantitative determination of enantiomer ratios of water-soluble natural amino acids by (13)C-NMR. The method is demonstrated on mixtures of L- and D-enantiomers of various amino acids. The interactions of the chiral shift reagent with the amino acid molecules ...
Yang Seung-Ok - - 2009
Creating a plant-cell suspension culture involves first transferring the callus into liquid media, but there are no objective criteria for selecting the location of the callus to be transferred. In this study, inner and outer cells of Catharanthus roseus with various elicitors in solid-state cultures were differentiated by (1)H NMR ...
Bailey-Shaw Y A - - 2009
Jamaican agro-industries generate large quantities of wastes, which are either discarded or under-utilized. In order to evaluate the possible utilization of these wastes, it is necessary that the profiles of the major biochemical groups be developed. This paper describes the determination of the amino acid composition of coffee, citrus, and ...
Qi Li - - 2009
A novel method of chiral ligand-exchange CE was developed with L-amino acylamides as a chiral ligand and zinc(II) as a central ion. It has been demonstrated that these chiral complexes, such as Zn(II)-L-alaninamide, Zn(II)-L-prolinamide, and Zn(II)-L-phenylalaninamide, are suitable for use as chiral selectors for the enantioseparation of either individual pair ...
Wang Shumin - - 2009
Sodium cholate (SC), beta-CD, hydroxypropyl (HP)-beta-CD, HSA, and the dual mixtures of them were evaluated for the analysis of aspartic acid (Asp) and glutamic acid (Glu) enantiomers fluorescently tagged with 5-(4,6-dichloro-s-triazin-2-ylamino) fluorescein (DTAF) by CE with LIF detection. Among the investigated chiral selectors and the dual selector systems, the dual ...
Li Honglin - - 2009
A fluorescent chemodosimeter for cysteine detection and bio-imaging has been described which displays an excellent selectivity for cysteine over homocysteine, glutathione and other amino acids.
Zhao Shulin - - 2009
A method based on microchip electrophoresis (MCE) with chemiluminescence (CL) detection was developed for the determination of ascorbic acid (AA) and amino acids including tryptophan (Trp), glycine (Gly) and alanine (Ala) present in single cells. Cell injection, loading, lysing, electrophoretic separation and CL detection were integrated onto a simple cross ...
Sun Xuefei - - 2009
Recently, we reported the synthesis, fabrication, and preliminary evaluation of poly(ethylene glycol) (PEG)-functionalized polymeric microchips that are inherently resistant to protein adsorption without surface modification in capillary electrophoresis (CE). In this study, we investigated the impact of cross-linker purity and addition of methyl methacrylate (MMA) as a comonomer on CE ...
Tano Chiharu - - 2009
To investigate the influence of stereogenic centers of sugar-based surfactants for enantiomeric separation, four n-dodecyl thioglycoside sulfates (CMC 1.5-3.6 mM) were chosen as micelle-forming surfactants and five dansylated hydrophobic amino acids were used as test analytes. The analytes were mutually separated by these micelles exhibiting almost similar migration times independent ...
Pittler Elfriede - - 2009
This work deals with the application of silica-based ligand-exchange chiral stationary phases (CSPs) for the enantioseparation of underivatized amino acids, alpha-hydroxy acids, and dipeptides with packed CEC. Two different possibilities of preparing silica-based CSPs are presented. One phase contains L-4-hydroxyproline chemically bonded via a spacer to 3 mum silica material. ...
Penteado José Carlo Pires - - 2009
This paper describes the development and application of an RP HPLC method using a C(18) monolithic stationary phase for the separation and quantification of extra- and intracellular amino acids in a batch cultivation of the marine alga Tetraselmis gracilis. Fluorimetric detection was made after separation of the o-phthaldialdehyde 2-mercaptoethanol (OPA-2MCE) ...
Messina Antonella - - 2009
The enantioseparation of carboxylic acids, including amino acid dansyl-derivatives, 2-arylpropionic acids and 2-aryloxypropionic acids, was tested by CEC on a porous silica sol-gel monolithic column that was prepared by polycondensation of tetramethoxysilane in acidic conditions and post-gelation heat treatment (120 degrees C for 3 h) in the presence of urea, ...
Yamamoto Kazuhiro - - 2009
A simple method was developed for monitoring the permeation of medium-chain fatty acids of C8 (octanoic acid) and C10 (decanoic acid) through CaCo-2 cell monolayers by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). The detection was made based on the electrochemical reduction prepeak of quinone caused by acids, requiring the ...
Fuss Werner - - 2009
The parity-violating effect of the weak force is much too small to be statistically significant for the origin of biological homochirality. Other physical interactions such as with circularly polarized light (CPL) are larger and are discussed in the literature as an effect on small molecules such as amino acids or ...
Zimmer Martin - - 2009
Etching of silicon with mixtures of hydrofluoric acid and nitric acid is a widely used process in silicon solar cell fabrication. One precondition for an optimized usage of the acidic etching baths is the exact knowledge of the chemical bath composition. In this paper, we investigated a fast and online-capable ...
Limaye Mukta V - - 2009
High coercivity (9.47 kOe) has been obtained for oleic acid capped chemically synthesized CoFe(2)O(4) nanoparticles of crystallite size approximately 20 nm. X-ray diffraction analysis confirms the formation of spinel phase in these nanoparticles. Thermal annealing at various temperatures increases the particle size and ultimately shows bulk like properties at particle ...
Hou Songmei - - 2009
Determination of amino acids by mass spectrometry (MS) is an important technique to investigate soil nitrogen transformation and cycling as amino acids being the major nitrogen-containing compounds in soil organic matter. However, researchers have long faced a critical problem in coupling an efficient separation technique to a sensitive MS detection ...
Ilisz Istv?n - - 2010
Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural beta(2)-amino acids on a new chiral stationary phase, using the 11-methylene-unit spacer of aminoundecylsilica gel for the bonding of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as selector. The nature and concentration of the acidic and organic modifiers, the pH, ...
Jámbor A - - 2009
This paper, as a novelty to this field, presents the deproteinization and derivatization of plasma's free amino acids (PFAAs), simultaneously, in a single step, with the acetonitrile (ACN) containing 9-fluorenylmethyloxycarbonyl chloride (FMOC) reagent. Deproteinization and derivatization, were studied with 22 amino acids, applying photodiode array (DAD) and fluorescence (FL) detection, ...
Tseng Wei-Lung - - 2009
We report a novel means for chiral separation and stacking of amino acids by MEKC with LED-induced fluorescence detection. Naphthalene-2,3-dicarboxaldehyde, hydroxypropyl-beta-cyclodextrin (Hp-beta-CD), SDS, and poly(ethylene oxide) (PEO) serve as a derivatized agent, chiral selector, pseudostationary phase, and concentrated medium, in sequence. To improve speed, resolution, and stacking efficiency, the analysis ...
Shimbo Kazutaka - - 2009
We have developed novel precolumn derivatization reagent, p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS), for sensitive analyses of amino acids using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). TAHS, an activated carbamate, was reacted briefly with the amino group to form a ureide bond under mild condition. The derivatives provided selective ...
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