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Liu Renmin - - 2007
A chromatographic method using 12% cross-linked agarose gel Superose 12 as the separation medium was developed for isolation and purification of the chemical constituents from the pericarp of Sophora japonica L. The mobile phase used for the separation was 2% acetic acid and 7% acetic acid in gradient elution. As ...
Danel Cécile - - 2007
An analytical method for the enantioseparation of the 9-hydroxyrisperidone, main metabolite of the antipsychotic risperidone (Risp), was developed by CD-EKC in the dual CDs mode using anionic and neutral CDs at acidic pH 2.5. Preliminary experiments allowed us to select the more suitable couple of CDs composed of sulfated-alpha-CD and ...
Han Yanli - - 2007
A novel method has been developed for the on-column labeling of amino acid enantiomers with 9-fluoroenylmethyl chloroformate (FMOC), followed by chiral CE with a binary chiral selector system and UV detection. Efficient labeling was achieved by sequential injection of amino acids, borate buffer, and FMOC labeling solution at 0.2 psi ...
Tan Xulin - - 2007
A novel chiral stationary phase (CSP) for HPLC was prepared by bonding (R)-1-phenyl-2-(4-methylphenyl)ethylamine amide derivative of (S)-valine to aminopropyl silica gel through a 2-amino-3,5-dinitro-1-carboxamido-benzene unit. The CSP was used for the separation of some amino acid derivatives and pyrethroid insecticides by chiral HPLC. Satisfactory baseline separation required optimization of the ...
Darvish M - - 2007
Phenylketonuria (PKU) and Maple Syrup Urine Disease (MSUD) are two inborn metabolic diseases which are carried by autosomal recessive genes in man. These genetic errors result in accumulation of phenylalanine (in PKU) or valine, leucine and isoluecin (in MSUD). At high concentrations, amongst other problems, these amino acids cause mental ...
Herrero Miguel - - 2007
In this work, chiral and nonchiral MEKC methods have been combined with LIF detection (MEKC-LIF) to identify and quantify a group of D- and L-amino acids (D/L-aa) in different microalgae samples. The combination of the nonchiral and chiral-MEKC-LIF methods made the identification of the microalgae amino acids easier, previously derivatized ...
Qi Li - - 2007
A novel method of chiral ligand-exchange CE was developed with either L- or D-lysine (Lys) as a chiral ligand and zinc(II) as a central ion. This type of chiral complexes was explored for the first time to efficiently separate either individual pairs of or mixed aromatic amino acid enantiomers. Using ...
Messina Antonella - - 2007
For the study of the stereoselective degradation of the herbicide 2-aryloxipropionic acid dichlorprop (DCPP) in soil, a porous monolithic chiral column (100 microm id) was prepared by in situ copolymerization of glycidyl methacrylate, methyl methacrylate and ethylene glycol dimethacrylate in the presence of formamide and 1-propanol as the porogen solvents. ...
Habel Andreas - - 2007
1-phenylethyl isocyanate (1-PEIC), a chiral derivatisation reagent for the resolution of secondary alcohols is a powerful tool to determine the configuration and enantiomeric excess of medium- to long-chain secondary alcohols by capillary gas chromatography. The separation of 1-phenylethylcarbamates (1-PECs) of secondary alcohols was systematically evaluated depending on the position of ...
Choi Hee Jung - - 2007
Two types of secondary amino alcohols were successfully resolved on a liquid chromatographic chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid. The secondary amino alcohols containing a secondary amino group connected directly to the stereogenic center were resolved much better than those containing a hydroxyl group attached directly to the stereogenic ...
Gioia M G - - 2007
A reversed-phase liquid chromatographic method (RP-LC) is proposed and validated for the analysis of branched-chain amino acids (l-leucine, l-isoleucine and l-valine) in new pharmaceutical formulations. The pre-column derivatization reaction of these amino acids with 2,4-dinitrofluorobenzene (DNFB) has been investigated considering the matrix effect. The compound reacts at 60 degrees C ...
Zhou Lili - - 2008
The enantioselectivity of two protein chiral stationary phases, alpha1 acid glycoprotein (AGP) and ovomucoid protein (OVM) are compared. Neutral, basic and acidic pharmaceutical compounds were screened on both stationary phases. Selected parameters such as mobile phase pH, temperature, and organic modifier were varied in order to achieve chiral separations. Relations ...
Ibrahim Hany - - 2007
Non-steroidal anti-inflammatory drugs (NSAIDs) such as piroxicam and mefenamic acid are commonly prescribed to treat inflammation, pain and fever. Similarly acetylsalicylic acid is used to prevent strokes and heart attacks. A rapid and selective method was developed for the simultaneous assay of three NSAIDs and salicylic acid via HPLC with ...
Procházková Barbora - - 2007
The use of carrier ampholyte-free IEF (CAF-IEF) with ITP mobilization and conductivity detection in ITP mode for preconcentration and analysis of amino acids is demonstrated. The analytical procedure consists of three subsequent steps. In the first step, amino acids are continuously dosed from an infinite volume reservoir by electromigration to ...
Li Fei - - 2007
Three phenylpropanoids (ferulic acid, chlorogenic acid, and caffeic acid) are simultaneously separated and determined within 13 min by a new capillary electrophoresis method using 15 mmol/L sodium borate (pH 8.71) as run buffer. The optimum conditions for the separation as well as the analytical characteristics, such as the calibration graph ...
Meng Zhe - - 2007
The concentration of long-chain fatty acids (LCFAs) in human serum is closely related to human health. It is therefore important to develop a fast, low-cost, efficient method for their determination. In this study, by using fast temperature programming and micro-bore short capillary columns, a fast gas chromatography method was developed ...
Pumera Martin - - 2007
Microfluidic devices have been widely used to derivatize, separate, and detect amino acids employing many different strategies. Virtually zero-dead volume interconnections and fast mass transfer in small volume microchannels enable dramatic increases in on-chip derivatization reaction speed, while only minute amounts of sample and reagent are needed. Due to short ...
Moustafa Nagy Emam - - 2007
The oxidized lubricating naphthenic base oil was used as a stationary phase for the separation of short-chain free fatty acids (SFFA) either as a pure sample or an aqueous solution containing 0.9-1.2 mg/L of each acid. It is found that the oil oxidation for 20 h improved the separation of ...
Temporini Caterina - - 2007
The chiral recognition mechanism of Penicillin G Acylase (PGA) was investigated with a set of 18 new chiral acidic compounds. A series of 2-aryloxyalkyl- and 2-arylalkyl-2-aryloxyacetic acids in which the absolute configuration has been reported to exert a strong influence on pharmacological activity, were synthesized and analysed on PGA-based chiral ...
Lamos Shane M SM Department of Chemistry, Saint Michael's College, One Winooski Park, Colchester, Vermont 05439, - - 2007
Labeling reagents that differ only in their isotopic composition offer a powerful approach to achieve relative quantification between samples by ESI-MS. Heavy and light isotopic forms of cholamine, which contain a positively charged quaternary ammonium group, were synthesized and tested as new labeling reagents for the relative quantification of carboxylic ...
Maier Vítezslav - - 2007
A modified partial filling method for chiral separation of DL-lactic acid as the model chiral compound with vancomycin chloride as the chiral selector was developed by CE with contactless conductivity detection. Electrokinetic partial filling technique (EK-PFT) was used as an alternative method to the conventional hydrodynamic partial filling method. EK-PFT, ...
Tang Weihua - - 2007
Enantioseparations of fourteen dansyl amino acids were achieved by using a positively-charged single-isomer beta-cyclodextrin, mono-(3-methyl-imidazolium)-beta-cyclodextrin chloride, as a chiral selector. Separation parameters such as buffer pH, selector concentration, separation temperature, and organic modifier were investigated for the enantioseparation in order to achieve the maximum possible resolution. Chiral separation of dansyl ...
Kmecz Ildikó - - 2007
Racemic N-methylamphetamine (rac-MA) was resolved with 2R,3R-tartaric acid (TA) and its derivatives (O,O'-dibenzoyl-(2R,3R)-tartaric acid monohydrate (DBTA) and O,O'-di-p-toluoyl-(2R,3R)-tartaric acid (DPTTA)), individually and using them in different combinations. After partial diastereomeric salt formation, the free enantiomers were extracted by supercritical fluid extraction using carbon dioxide as solvent. DBTA and DPTTA are ...
Herrero Miguel - - 2007
In this work, a new chiral micellar electrokinetic chromatography with laser-induced fluorescence detection (chiral-MEKC-LIF) method is proposed to identify and quantify D- and L-amino acids in three lines of transgenic maize and their corresponding nontransgenic parental lines grown under identical conditions. The optimized procedure includes amino acids extraction, derivatization with ...
Kawasaki Yoshito - - 2007
The advanced Marfey's method consists of a chromatography technique for the separation of amino acids into each enantiomer by derivatization with 1-fluoro-2,4-dinitrophenyl-5-L-leucinamide (L-FDLA), and a detection method using liquid chromatography/mass spectrometry (LC/MS) which can determine the non-empirically the absolute configuration of various amino acids including the non-protein ones. However, this ...
Ma Lianjia - - 2007
Silica-based, reversed-phase liquid chromatographic (RPLC) stationary phases are very widely used to separate basic compounds in acidic eluents due to their high efficiency, good mechanical strength, and the versatile selectivity offered by different functional groups and the chemistry on the silica surface. However, the stability in acid of most silica-based ...
Savitski Mikhail M - - 2007
Analysis of a database containing over 20,000 high-resolution collision-activation mass spectra of tryptic peptide dications was employed to study the relative specificity of neutral losses from backbone fragments. The high resolution of the FTMS instrument allowed for the first time the first isotope of the water loss and the monoisotope ...
Chasse Tyson - - 2007
Unique properties of the fluorine atom stimulate widespread use and development of new organofluorine compounds in agrochemistry, biotechnology and pharmacology applications. However, relatively few synthetic methods exhibit a high degree of fluorination selectivity, which ultimately results in the presence of structurally related fluorinated isomers in the synthetic product. This outcome ...
Reiner Clarissa - - 2007
Whereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic ...
Yang Wen-Chu - - 2007
This paper focuses on the development of an enhanced LC/ESI-MS method for the identification and quantification of fatty acids through derivatization. Fatty acids were derivatized with 2-bromo-1-methylpyridinium iodide and 3-carbinol-1-methylpyridinium iodide, forming 3-acyloxymethyl-1-methylpyridinium iodide (AMMP). This process attaches a quaternary amine to analytes and enabled ESI-MS in the positive mode ...
Findeisen Anna - - 2007
The exudates of conifers consist mainly of diterpenoic acids of the abietane and pimarane type (abietic, neoabietic, dehydroabietic, palustric, pimaric, isopimaric, levopimaric and sandaracopimaric acid) and larixol acetate. These natural resins were used as adhesives, coatings, varnishes or plasticizers in artistic and historic works since ancient times. For the purpose ...
Garscha Ulrike - - 2007
8-Hydroxyoctadeca-9Z,12Z-dienoic acid (8-HODE) and 10-hydroxyoctadeca-8E,12Z-octadecadienoic acid (10-HODE) are produced by fungi, e.g., 8R-HODE by Gaeumannomyces graminis (take-all of wheat) and Aspergillus nidulans, 10S-HODE by Lentinula edodes, and 10R-HODE by Epichloe typhina. Racemic [8-(2)H]8-HODE and [10-(2)H]10-HODE were prepared by oxidation of 8- and 10-HODE to keto fatty acids by Dess-Martin periodinane ...
Xu Yan - - 2007
This report describes a method to simultaneously determine 11 low-molecular-weight (LMW) organic acids and 16 chlorinated acid herbicides within a single run by a portable CE system with contactless conductivity detection (CCD) in a poly(vinyl alcohol) (PVA)-coated capillary. Under the optimized condition, the LODs of CE-CCD ranged from 0.056 to ...
Horáková Jana - - 2007
A new on-line preconcentration technique was developed that makes possible to determine nanomolar concentrations of weak acidic analytes in CE. The method consists of long-running electrokinetic sample injection and stacking (electrokinetic immobilization) of the analytes at a boundary of two electrolytes with different pH values (pH 9.5 and 2.5) and ...
Yao Xiao - - 2007
A method based on capillary electrophoresis with electrochemical detection has been employed for the separation and determination of homocysteine, cysteine, reduced glutathione, ascorbic acid and uric acid. Effects of several important factors such as the acidity and concentration of the running buffer, separation voltage, injection time and detection potential were ...
Jacob Shana Sunny - - 2007
In this study, aristolochic acid in different herbal medicines containing a mixture of varying herb species was identified through fingerprint pattern similarities. Aristolochic acid I and II are nephrotoxic compounds naturally present in the Aristolochia plant species that are commonly used in Chinese herbal medicines. Twenty-four commercially available herbal formulations ...
Jin Jing Yu - - 2007
The liquid chromatographic enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) protected alpha-amino acids was performed on nine polysaccharide-derived chiral stationary phases (CSPs). The cellulose derived coated CSPs, Chiralcel OD-H (separation factor = 1.09-2.70) and Chiralcel OD (separation factor = 1.08-2.55), had the best performance of all the CSPs for resolution of N-FMOC ...
Wang Jin-Zhao - - 2007
A simple HPLC method for the simultaneous determination of phenylglyoxylic acid (PGA), mandelic acid (MA), styrene glycol (SG) and hippuric acid (HA) in cell culture medium was developed. Analysis was performed on a C(18) column with a mobile phase composed of methanol-potassium dihydrogen phosphate (pH 2.5; 10 mM; 10:90, v/v) ...
Zheng J - - 2007
As an organic salt, ionic liquids are widely used as new solvent media. In this paper, three positional isomers, such as o-amino benzoic acid, m-amino benzoic acid, and p-amino benzoic acid are separated with four different ionic liquids as additives to the mobile phase using reversed-phase (RP) high-performance liquid chromatography ...
Zhao Xinfeng - - 2007
A micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of four bioactive constituents (morroniside, loganin, paeoniflorin and paeonal) in the Chinese patent medicine Liuwei Dihuang Pills is established. A carrier composed of 0.2M boric acid, 0.02 M sodium dodecyl sulfate (SDS) and 5% acetonitrile (pH was adjusted to 10.5 ...
Toya Yoshihiro - - 2007
We have developed a metabolic flux analysis method that is based on (13)C-labeling patterns of the intracellular metabolites directly measured by capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). The flux distribution of the central carbon metabolism in Escherichia coli was determined by this new approach and the results were compared with ...
Breadmore Michael C - - 2007
The separation of fatty acids derivatised with Nile Blue (NB) by CE with detection using a red light-emitting diode (LED) was examined. NB was selected as the derivatisation agent due to its high molar absorption coefficient of 76,000 M(-1) cm(-1) at 633 nm, making it well suited for sensitive absorbance ...
Hamase Kenji - - 2007
D-amino acids are the candidates of novel physiologically active substances and the marker molecules of diseases in mammals. In the present study, the two-dimensional determination of small amounts of D-amino acids in mammals has been performed after sensitive pre-column fluorescence derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). The two-dimensional HPLC system includes the ...
Straka Robert J - - 2007
Triglycerides are increasingly being recognized as a risk factor for cardiovascular disease. Research efforts to identify sources of variability in triglyceride-lowering response to the lipid-lowering drug fenofibrate require quantification of the active acidic form of this PPAR-alpha agonist. Anion-exchange solid-phase extraction, in combination with reverse-phase high-performance liquid chromatography (HPLC), rapidly ...
Hsieh Ming-Mu - - 2007
The combination of capillary electrophoresis (CE) and light-emitting diode-induced fluorescence (LED-IF) detection has been demonstrated in the analysis of major amino acids in tea leaves and beverages. The separation efficiency of amino acids, which were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA), depended on the capillary length and PEO concentration. We suggested that ...
Zhao Xiaoli - - 2007
A comparative study on the use of cetyltrimethylammonium bromide (CTAB)-coated silica and sodium dodecyl sulphate (SDS)-coated alumina mixed hemimicelles-based solid-phase extraction (SPE) for the pre-concentration of six perfluorinated compounds (PFCs) in environmental water samples was presented. The six analytes heptafluorobutyric acid (HFBA), perfluoroheptanic acid (PFHeA), perfluorooctanic acid (PFOA), perfluorooctanic sulfonic ...
Weisz Adrian - - 2007
This work involves the preparative separation of some isomeric dicarboxylic acids using pH-zone-refining counter-current chromatography (CCC), a relatively new preparative technique for the separation of ionizable compounds. The paper concentrates especially on the separation of a synthetic mixture of closely related cis and trans pairs of 1-methyl- and 1,3-dimethyl-1,3-cyclohexanedicarboxylic acids. ...
Adcock Jacqui L - - 2007
We have combined the generation of solvent gradients using milliGAT pumps, chromatographic separations with monolithic columns and chemiluminescence detection in an instrument manifold that approaches the automation and separation efficiency of HPLC, whilst maintaining the positive attributes of flow injection analysis (FIA), such as manifold versatility, speed of analysis and ...
Qu Qishu - - 2007
The effect of a divalent cation (Mg2+) and 3 monovalent cations (Na+, Li+, and K+) as buffer additives on the electroosmotic flow (EOF) was investigated in order to improve the separation performance of p-acetamidobenzenesulfonyl fluoride (PAABS-F) derivatives of 20 standard amino acids by micellar electrokinetic chromatography (MEKC). The EOF can ...
Cesla Petr - - 2007
Fourteen azodyes containing one to five acidic groups were separated by capillary zone electrophoresis (CZE). The effects of the pH and beta-cyclodextrin additive to the background electrolyte on the separation of sulphonated azodyes were investigated. The effects of the working conditions significantly differ in non-coated fused silica capillaries and in ...
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