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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 ...
Spano Nadia - - 2009
The typical profile of the free amino acids contained in strawberry-tree (Arbutus unedo L.) honey is reported for the first time. An optimized reversed-phase liquid chromatographic (RP-LC) method with phenyl isothiocyanate precolumn derivatization was used. Fourteen free amino acids were identified and quantified in 16 analytical samples. Proline (65.63%) was ...
Hanna Sarah J - - 2009
An investigation of oleic acid and 2,4-dihydroxybenzoic (DHB) acid aerosols was carried out using an aerosol mass spectrometer with pulsed lasers for vaporization and ionization and an ion trap for mass analysis. The extent of ion fragmentation was studied as a function of both vaporization energy and ionization wavelength. Low ...
Olson Mark P - - 2009
Pulsed electrochemical detection (PED) following liquid chromatographic separation has been applied to the indirect determination of amino acids and proteins. Here, the adsorption of these analytes at noble metal electrodes is exploited to suppress the oxidation of polyols and carbohydrates under alkaline conditions to elicit an indirect response. Of the ...
Miyoshi Yurika - - 2009
Two-dimensional-HPLC procedures have been established for the sensitive and selective determination of D-serine (D-Ser) and D-alanine (D-Ala), and their amounts in the tissues and physiological fluids of mice with various D-amino-acid oxidase (DAO) activities have been demonstrated. These two D-amino acids are modulators of the N-methyl-D-aspartate receptor mediated neurotransmission, and ...
Xu Yi - - 2009
In this paper, a new approach for the separation of amino acids on the electrophoresis chip-based low-voltage-driven electrophoresis was reported in detail. This low-voltage-driven electrophoresis process could be realized by powering directly the arrayed electrode pairs with low direct current (DC) voltage to generate a moving electric field along the ...
Jelly Renee - - 2009
The introduction of ninhydrin treatment as a chemical technique for the visualisation of latent fingermarks on porous surfaces revolutionised approaches to forensic fingermark examination. Since then, a range of amino acid sensitive reagents has been developed and such compounds are in widespread use by law enforcement agencies worldwide. This paper ...
Yan Bo - - 2009
PM2.5 filter samples (12-h and 24-h) were collected in urban Atlanta, GA, next to a freeway and 400 m away, as well as at a rural site, with particular focus on exploring on-road emissions, regional transport, and biogenic effects. Detailed speciation of PM2.5 carbonaceous aerosols was conducted by GC/ MS. ...
Soloshonok Vadim A - - 2009
This work has demonstrated that a previously unexplored approach to separation of enantiomers via formation of diastereomeric derivatives with three stereogenic centers has obvious practical potential and deserves further systematic study. The design reported here is based on the unusual application of a configurationally unstable stereogenic nitrogen, which plays a ...
Rombouts Ine - - 2009
A simple accurate method for determining amino acid composition of wheat gluten proteins and their gliadin and glutenin fractions using high-performance anion-exchange chromatography with integrated pulsed amperometric detection is described. In contrast to most conventional methods, the analysis requires neither pre- or post-column derivatization, nor oxidation of the sample. It ...
Sharma Mamta - - 2009
A simple, convenient, and direct one-dimensional (1D) (31)P NMR technique is demonstrated for the detection of alkylphosphonic acids (marker of nerve agents). The results of detection were validated after conducting various in-house exercises. The confidence generated by this study was found very useful in detection of different alkylphosphonic acids spiked ...
Jiang Xuemei - - 2009
This is an original report proposed a CE method for direct analysis of the underivatized amino acids using UV detection with relatively higher sensitivity, which was based on coordination interactions between amino acids and Cu (II) ions. In addition, an online sweeping preconcentration technique was easily combined to improve the ...
Tsesarskaia Mara - - 2009
D-Aspartate (D-Asp) and N-methyl-D-aspartate (NMDA) occur in the neuroendocrine systems of vertebrates and invertebrates, where they play a role in hormone release and synthesis, neurotransmission, and memory and learning. N-methyl-d-glutamate (NMDG) has also been detected in marine bivalves. Several methods have been used to detect these amino acids, but they ...
Kalimuthu Palraj - - 2009
This paper demonstrated the selective determination of folic acid (FA) in the presence of important physiological interferents, ascorbic acid (AA) and uric acid (UA) at physiological pH using electropolymerized film of 5-amino-2-mercapto-1,3,4-thiadiazole (p-AMT) modified glassy carbon (GC) electrode. Bare GC electrode fails to determine the concentration of FA in the ...
Li Min - - 2009
Molecularly imprinted monolithic columns were prepared for chiral separation of tyrosine and its amino acid derivatives by in situ therm-initiated copolymerization of methacrylic acid, 4-vinylpyridine and ethylene glycol dimethacrylate. The enantiomers were rapidly separated on monolithic columns in less than 10 min by pressurized capillary electrochromatography (pCEC). The influences of ...
Kaspar Hannelore H Institute of Functional Genomics, University of Regensburg, Josef-Engert-Strasse 9, 93053 Regensburg, - - 2009
Urinary amino acid analysis is typically done by cation-exchange chromatography followed by post-column derivatization with ninhydrin and UV detection. This method lacks throughput and specificity. Two recently introduced stable isotope ratio mass spectrometric methods promise to overcome those shortcomings. Using two blinded sets of urine replicates and a certified amino ...
Hu Zhongqiao - - 2009
The separation of amino acids (Arg, Phe and Trp) in a liquid chromatography is investigated using molecular dynamics simulations. A bioorganic nanoporous material--glucose isomerase crystal--is used as the stationary phase and water as the mobile phase. The transport velocities of amino acids decrease in the order Arg>Phe>Trp, consistent with experimental ...
Zhai Chun - - 2009
An assembled microfluidic device (AMD) was constructed for highly resolved separation and sensitive amperometric detection of amino acids. In the AMD three polymer retainers were integrated with a quartz capillary and a copper microdisk electrode. A facile ultrasonic method was suggested for the preparation of sampling fracture on the capillary. ...
Sumitomo Keiko - - 2009
A strong denaturant to cleave intramolecular hydrogen bonds in RNA is required for RNA size separation in a small sample volume (<10 nL). We found that carboxylic acids were strong denaturants for RNA and the RNA separation performance was dramatically improved by capillary electrophoresis with a sieving matrix containing acetic ...
Honetschlägerová-Vadinská Marie - - 2009
Enantioseparation performance of two teicoplanin-based chiral stationary phases, Chirobiotic T and Chirobiotic T2, with different teicoplanin coverage and distinct linkage chemistry was compared. Three structurally diverse groups of analytes, amino alcohols (beta-blockers), chlorophenoxypropionic acids, and branched-chain amino acids, in various mobile phase compositions/separation modes were examined. The amino alcohols showed ...
Shimbo Kazutaka - - 2009
A rapid analytical method for amines and amino acids was developed, involving derivatization with the novel reagent 3-aminopyridyl-N-hydroxysuccinimidyl carbamate (APDS), followed by reversed-phase high-performance liquid chromatography and electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). More than 100 different analytes with amino groups, including amino acids in biological fluids such as mammalian ...
Zhou Can-Hua - - 2009
Photodissociation dynamics of o-nitrobenzoic acid at 295 and 355 nm is studied by probing the nascent OH photoproduct employing the single-photon laser-induced fluorescence technique. At both of the photolysis wavelengths, the OH fragments are found to be vibrationally cold but have different rotational state distributions. Upon photolysis at 295 nm, ...
Waldhier Magdalena C - - 2009
Free amino acids are typically quantified as the sum of their enantiomers, because in terrestrial organisms they mainly exist in the left-handed form. However, with increasing understanding of the biological significance of right-handed amino acids interest in enantioselective quantification of amino acids has steadily increased. Initially, electrophoretic and chromatographic methods ...
Smith Colin I - - 2009
We report a three-phase chromatographic method for the separation and analysis of delta(13)C values of underivatized amino acids from biological proteins (keratin, collagen, and casein) using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Both precision and accuracy of delta(13)C values for standard amino acid mixtures over the range of approximately 8 ...
Cho Hwan Sun - - 2009
A new chiral stationary phase (CSP) containing thioester linkages was prepared by bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to mercaptopropylsilica gel. The chiral recognition ability of the new CSP was found to be greater than that of the previously reported CSP containing amide linkages in the resolution of the various alpha-amino acids that ...
Chen Jie - - 2009
BACKGROUND: Sample analysis and data interpretation for urine organic acid analyses (OAA) for metabolic diseases have not evolved significantly over the last two decades. We evaluated a number of potential improvements in the technology in order to increase productivity. Increasing numbers of this very important clinical test are being ordered ...
Gholami Morteza - - 2009
Vancomycin crystalline degradation products (CDPs) have been introduced as one of the newest and most interesting derivatives of vancomycin for enantiomer separation of a wide variety of chiral compounds. In this attempt, a chiral stationary phase (CSP) has been prepared using diol silica gel based on vancomycin CDPs which led ...
Chiesl Thomas N - - 2009
The fluorescent amine reactive probe Pacific Blue succinimidyl ester (PB) is used for the detection of trace amounts of amines and amino acids by microchip capillary electrophoresis on the Mars Organic Analyzer (MOA). The spectral and chemical properties of PB provide a 200-fold increase in sensitivity and improved resolution compared ...
Agrafiotou Panagiota - - 2009
The combined use of a dual-UV detector, a fluorimetric one and of a multiple electrochemical (EC) detector equipped with a dual electrode, consisting of a conventional size 3 mm diameter glassy carbon electrode (GCE) and of a pair of 30 mum thick carbon microfibers, is proposed for the determination of ...
Kan Shidong - - 2009
Salvianolic acid B was separated and purified from Salvia miltiorrhiza Bunge (danshen) by microbial transformation together with chromatography of microsphere resin. The aqueous extract of danshen was transformed by Fusarium graminearum in a bioreactor containing phosphate buffer (PBS), in which rosmarinic acid was transformed into danshensu and caffeic acid and ...
Aït Adoubel Abderrahim - - 2009
Enantiomer separations of underivatised amino acids were carried out by using ligand exchange capillary electrophoresis (LECE). Chiral discrimination is based on the formation of ternary complexes between copper(II), a chiral selector (L-proline or trans-4-hydroxy-L-proline) and an amino acid. All amino acids containing aromatic moieties or not were detected at 214 ...
Ilisz István - - 2009
The application of 3,5-dimethylphenyl-carbamoylated-beta-cyclodextrin (Cyclobond I 2000 DMP) and 2,6-dinitro-4-trifluoromethylphenyl-ether-beta-cyclodextrin-based (Cyclobond DNP) chiral stationary phases for the high-performance liquid chromatographic enantioseparation of unusual beta-amino acids is reported. The investigated amino acids were saturated or unsaturated alicyclic beta-3-homo-amino acids and bicyclic beta-amino acids. Prior to chromatographic analyses, all amino acids were ...
Natalini Benedetto - - 2009
Due to the strong involvement in numerous biochemical processes, the separation and resolution of amino acids is a continuously challenging task. Among the experimental parameters affecting the performances in a Chiral Ligand-Exchange Chromatography (CLEC) environment, the effect of the copper(II) salt counter-ion has received very limited attention. Aimed at evaluating ...
Chen Chuan-Kuo - - 2009
We describe simultaneous analysis of naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and amine derivatives by capillary electrophoresis in conjunction with light-emitting diode-induced fluorescence (LEDIF) detection using poly(ethylene oxide) (PEO) containing cetyltrimethylammonium bromide (CTAB). In the presence of CTAB and acetonitrile (ACN), adsorption of PEO on the capillary wall is suppressed, leading to generation ...
Romero-González Roman R - - 2009
In addition to sample solubility constraints, the use of polarity gradients in normal-phase centrifugal partition chromatography (CPC) for the purification of complex mixtures is also limited by the instability of biphasic systems as a consequence of dramatic changes in the settling times along the gradient, leading in many cases to ...
Pugsley Haley R HR Department of Chemistry, University of Washington, Seattle, WA 98195-1700, - - 2009
A number of algorithms have been developed to correct for migration time drift in capillary electrophoresis. Those algorithms require identification of common components in each run. However, not all components may be present or resolved in separations of complex samples, which can confound attempts for alignment. This paper reports the ...
Zhang Guisen - - 2009
Chiral recognition of dansyl enantiomeric amino acids by microfluidic open tubular CEC (muOTCEC) with fluorescence detection was demonstrated. Avidin was employed as the chiral selector immobilized on the microchannel wall, which functioned as the chiral stationary phase (CSP) by physical adsorption. The condition of CSP on the glass wall was ...
Matsumiya Hiroaki - - 2009
Traces of P(V) and As(V) in sample solutions were converted into heteropoly molybdic acids at pH 1.5 and collected onto polyoxyethylene(20)-4-isononylphenoxy ether-coated Amberlite XAD-4 particles. The desorption was carried out with 0.3 M tetramethylammonium hydroxide solution for the HPLC analysis. Molybdophosphoric and molybdoarsenic acids were separated from excess molybdate by ...
Isemura Tsuguhide - - 2009
Fluorobenzoic acids are important intermediates in the synthesis of antibacterial drugs. Conditions for the separation of mixtures of twenty-five acids by CE have been optimized. A set of conditions with phosphate buffer (pH 3.1), successive multiple ionic-polymer layer (SMIL) coating capillary, and negative separation voltage provided a short time separation ...
Jámbor A - - 2009
A literature overview is given of HPLC methods currently in use to determine amino acids as their 9-fluorenylmethyloxycarbonyl (FMOC) derivatives. On the basis of the detailed literature overview an exhaustive derivatization study was performed with 22 amino acids, applying photodiode array (DAD) and fluorescence (FL) detection simultaneously, in order to ...
Gerssen Arjen - - 2009
A new LC-MS/MS method for the separation and detection of the most prominent marine lipophilic toxin groups comprising okadaic acid, dinophysistoxins, yessotoxins, azaspiracids, pectenotoxins, spirolides and some okadaic acid fatty acid esters has been developed. With this method 28 different marine lipophilic biotoxins can be analysed in a single run. ...
Dolezel Jan - - 2009
Some [(5Z)-(5-arylalkylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl)]acetic acids were prepared as potential antifungal compounds. The general synthetic approach to all synthesized compounds is presented. Lipophilicity of all the discussed rhodanine-3-acetic acid derivatives was analyzed using a reversed phase high performance liquid chromatography (RP-HPLC) method. The procedure was performed under isocratic conditions with methanol as an ...
Ali Ahmed Abdul Bakrudeen - - 2009
Plant secondary metabolites have enormous potential for research and new drug development. Many secondary metabolites have a complex and unique structure and their production is often enhanced by biotic and abiotic stress conditions. Gymnemic acid (C(43)H(68)O(14)), a pentacyclic triterpenoid isolated from the leaves of Gymnema sylvestre, exhibits potent inhibitory effect ...
Chen Chia-Yang - - 2009
Haloacetic acids (HAAs) are a class of byproducts resulting from the reaction of chlorinated disinfectants with natural organic matter. These chemicals have been found in animal studies to possibly influence hepatic, reproductive, and developmental functions, and they may be mutagenic and carcinogenic. Because HAAs are hydrophilic and strongly acidic, it ...
Kumari Sangeeta - - 2009
The most recent version of the kinetic method, i.e. fixed ligand method, is applied towards chiral discrimination of three pairs of enantiomeric hexose monosaccharides under mass spectral conditions. Naturally occurring mononucleotides are used as fixed ligands (FL) and the amino acids are selected as the chiral references (ref) to discriminate ...
Anouti Suzanne - - 2009
A new methodology based on heart-cutting 2-D CE in a single capillary was developed for the chiral separation of a mixture of 22 underivatized amino acids. The first dimension is performed in an achiral BGE (2.3 M acetic acid, pH 2.1) allowing the separation of the analytes as a function ...
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