共查询到20条相似文献,搜索用时 31 毫秒
1.
Jaworska M Stańczyk M Wilk M Kłaczkow G Anuszewska E Barzał J Rzepecki P 《Amino acids》2012,43(4):1653-1661
A new approach for the separation of 6-aminoquinolyl-carbamyl (AQC)-derivatized amino acids has been proposed. The chromatography used ion-pairing mechanism to increase the method selectivity. Mobile phase was based on triethylamine buffer containing N,N-dimethyloctylamine as a modifier. A number of factors, buffer composition and pH, counterion concentration, temperature and acetonitrile gradient profile, were optimized to achieve final chromatographic conditions. With the presented analytical method, the separation and identification of 34 AQC-amino acids and amino compounds present in human plasma is possible. The results of validation proved the applicability of the method for quantification of 27 amino acids in biological samples. The ultrafiltration proposed as deproteinization procedure gave repeatable and reliable results for the amino acids under investigation. This method introduced in routine testing can be a suitable tool for amino acid profiling in plasma including all aspects of clinical application. 相似文献
2.
Summary Using capillary electrophoresis, the enantiomers of a number of dansyl amino acids were resolved using native-cyclodextrin. The neutral chiral host resolved analytes possessing a negative charge at pH 9, the conditions employed in this study. Organic modifiers added to the running buffer were particularly adept at enhancing chiral recognition between the guest and host molecule in capillary electrophoresis. This work examined the effects of methanol, dimethylformamide, and acetonitrile on the resolution, migration time, and efficiency of twelve dansyl amino acids. Examples are given of the separation of racemic dansyl amino acids utilizing this technique and conditions necessary to achieve enantioselectivity. 相似文献
3.
首次报道用乙醇系统分析PTC-氨基酸的新方法中各衍生物获得最佳分离的建立过程。PTC-氨基酸衍生后溶于A溶液,然后进样于4μmNovaPakC18柱(3.9mm×150mm)。系统的优化步序包括全面调控流动相的pH值与TEA浓度、乙醇梯度程序、柱温等诸多影响HPLC色谱行为的因素。最适条件为:A溶液含0.14MG酸钠、0.75ml/LTEA、PH6.35;B溶液为100%乙醇;柱温30℃。通过优化的乙醇梯度最终在约44min内将15种PTC-氨基酸很好地分离。此法可用于替代代表新科技水平的PTC-氨基酸乙腈分析系统。 相似文献
4.
Piccinini AM Schmid MG Pajpanova T Pancheva S Grueva E Gübitz G 《Journal of biochemical and biophysical methods》2004,61(1-2):11-21
This paper deals with the chiral separation of Fmoc- and Z-derivatives of natural and unnatural sulfur containing amino acids by micro-HPLC. The separations were carried out in microbore columns packed with a new material based on Ristocetin A bonded to 3.5 microm silica gel. The columns were run in the normal phase, polar organic mode as well as in the reversed phase mode, whereby best results were obtained with the reversed-phase mode using mixtures of triethylamine acetate (TEAA) buffer and methanol as mobile phases. 相似文献
5.
High-performance liquid chromatography of uroporphyrinogen and coproporphyrinogen isomers with amperometric detection. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A reversed-phase h.p.l.c. system, with an ODS-Hypersil column with acetonitrile or methanol in ammonium acetate buffer as mobile phase, is described for the separation of uro-and copro-porphyrinogen isomers. The porphyrinogens are detected amperometrically with sensitivity comparable with that of the fluorescent detection of porphyrins. The effects of pH, buffer concentration and organic modifiers on retention and resolution were studied. The method is suitable for both analytical and preparative separation of porphyrinogens. 相似文献
6.
Optimization of the separation lactic acid enantiomers in body fluids by capillary electrophoresis 总被引:3,自引:0,他引:3
Saavedra L Barbas C 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,766(2):235-242
The optimization of the separation conditions of the two optical isomers of lactic acid by a factorial design is reported. Initially, different chiral selectors were systematically investigated and then a experimental design with three quantitative factors (cyclodextrin concentration and background buffer pH and concentration) were evaluated. Optimal conditions for obtaining a resolution higher than 1.5 were: phosphate buffer 200 mM at pH=6.0 with 413 mM 2-hydroxypropyl-beta-cyclodextrin added (HP-beta-CD), 20 degrees C, -20 kV of applied potential and polyacrylamide-coated capillary. The method was validated for the measurement in plasma and it was applied to the identification of both isomers in body fluids such as urine, amniotic fluid and cerebrospinal fluid. Samples were centrifuged and diluted (1:4) prior to the analysis. 相似文献
7.
Toshifumi Miyazawa Kazumi Hamahara Mikiko Matsuoka Yoshimi Shindo Takashi Yamada 《Biotechnology letters》1998,20(4):389-392
Through the kinetically controlled approach, employing the methyl ester as an acyl donor, non-protein aliphatic amino acids were incorporated into peptides using papain in an aqueous buffer, while the incorporation of non-protein aromatic amino acids was achieved by exploiting -chymotrypsin in an aqueous buffer or acetonitrile with low water content. © Rapid Science Ltd. 1998 相似文献
8.
A direct, isocratic, and simple reversed-phase HPLC method was described for the separation of enantiomers of the proton pump inhibitor, rac-pantoprazole (PAN) using cellulose-based chiral stationary phases (Chiralcel OD-R and Chiralcel OJ-R). Some structurally related chiral benzimidazole sulfoxides, rac-omeprazole (OME) and raclansoprazole (LAN), were also studied. Chiralcel OJ-R was successful in the resolution of enantiomers of rac-PAN and rac-OME, while Chiralcel OD-R was most suitable for resolving the enantiomers of rac-LAN. Highest enantioselectivity to rac-PAN and rac-OME was achieved on Chiralcel OJ-R by using acetonitrile as an organic modifier, whereas methanol afforded better resolution of rac-LAN on Chiralcel OD-R than acetonitrile. Increases in buffer concentration and column temperature decreased retention and did not improve the resolution of the enantiomers on both columns. Using a mixture of 50 mM sodium perchlorate solution and acetonitrile as a mobile phase at a flow rate of 0.5 ml/min, maximum separation factors of 1.26 and 1.13 were obtained for the enantiomers of rac-PAN and rac-OME using a Chiralcel OJ-R column, while maximum separation factor of 1.16 was obtained for the enantiomers of rac-LAN using a Chiralcel OD-R column. © 1995 Wiley-Liss, Inc. 相似文献
9.
In this study, tert-butyl carbamoylated quinine as chiral selector was immobilized on nonporous silica (NPS) 1.5 μm particles developed by MICRA, and this new chiral stationary phase (CSP) was packed into a 3.3 cm column (4.6 mm ID). A series of various N-protected α-amino acids was chosen as chiral selectands, including 3.5-dinitrobenzyloxycarbonyl amino acids (DNZ-AAs). In order to optimize the chromatographic conditions with this novel CSP and to apply it to the resolution of acidic analytes the following parameters have been varied and studied: pH of the mobile phase, buffer concentration, and percentage of methanol or acetonitrile in the mobile phase. DryLabR software was applied to optimize enantioseparation by simulating chromatographic functions of experimental conditions for isocratic and/or gradient runs. Thus, we were able to resolve a set of test compounds within several minutes, whereby our attention was particularly drawn to the resolution of DNZ-AA derivatives. Chirality 9:157–161, 1997. © 1997 Wiley-Liss, Inc. 相似文献
10.
The separation of o-phthalaldehyde derivatives of amino acids by reversed-phase chromatography on octylsilica columns 总被引:5,自引:0,他引:5
Amino acids were reacted with o-phthalaldehyde and 2-mercaptoethanol and were separated using a simple linear gradient from 10 to 65% methanol over 15 min on an octyl silica (C8) column by reversed-phase chromatography. The separation obtained was found to be sensitive to the pH, ionic strength, and tetrahydrofuran concentration of aqueous solvent A [THF: sodium acetate (45 mM), pH 5.7, (4:96)]. These effects were characterized and used to design a rapid (17 min) separation of the amino acids commonly found in acid hydrolysates of proteins. A more involved procedure was used to separate the more complex mixture of amino acids that are found in enzymatic hydrolysates of proteins or in physiological fluids. The simplicity of the methods allows their use on different chromatographic systems with little or no alteration. 相似文献
11.
William H. Church C. Shawn Lee Katherine M. Dranchak 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,700(1-2):67-75
Addition of cyclodextrins (CDs) to the electrolyte buffer in the capillary zone electrophoresis (CZE) separation of derivatized amino acids was evaluated in terms of fluorescence signal enhancement, resolution, and migration time effects. Maximum fluorescence signal enhancement was observed with separation buffers containing 4M β-cyclodextrin or 10 mM hydroxypropyl β-cyclodextrin. Resolution values decreased as the CD concentrations increased. Migration times were dependent on CD concentration. Inclusion complex formation constants calculated using changes in migration time showed slight agreement with those calculated by the steady-state fluorescence enhancement technique. Analysis of 20 μl of rat brain microdialysate by CZE using 4 mM β-cyclodextrin in borate buffer resulted in baseline resolution of glutamate and aspartate in 3.6 min. The results of this work indicate that, when used as separation buffer additives, cyclodextrins are capable of increasing the fluorescence signal and decreasing the migration times of NDA-derivatized acidic amino acids. 相似文献
12.
Karin Persson Ove strm 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,697(1-2)
The separation of pilocarpine and its degradation products by micellar electrokinetic capillary chromatography (MECC) has been optimized by using fractional factorial design of the experiments. Critical parameters were identified in a screening design, and an optimization design was used to optimize the separation. The optimal separation method was based on a borate buffer with sodium dodecyl sulfate (SDS). It is concluded that by using fractional factorial design it is possible to improve the separation of pilocarpine, it trans epimer, isopilocarpine and their hydrolysis products, pilocarpic acid and isopilocarpic acid. 相似文献
13.
Tryptic peptide mapping of ubiquitin and derivatives using reverse-phase high performance liquid chromatography 总被引:1,自引:0,他引:1
The conditions for tryptic digestion and subsequent peptide mapping of the ATP-dependent proteolysis cofactor ubiquitin and its derivatives are described. In aqueous solution, the native ubiquitin which is composed of 76 amino acids undergoes only a single cleavage at arginine-74. Full digestion of ubiquitin was obtained in 6.5 M urea, although cleavages at lysine-33 and arginine-74 were slow. Peptide mapping was achieved by reverse-phase high-performance liquid chromatography with a C18 column using a trifluoroacetic acid/triethylamine buffer system and acetonitrile as eluants. The peptides, separated using a linear gradient, were identified by amino acid analysis. Derivatives analyzed by this method include oxidized, monoiodotyrosyl, and diiodotyrosyl ubiquitin. This technique will be useful in examining peptides of chemically modified ubiquitin with respect to extent and specificity of modification. In addition, this technique will be useful in comparing ubiquitin peptides of different organisms. 相似文献
14.
Summary Derivatization of primary amino acids with orthophthalaldehyde and -mercaptoethanol forms derivatives that can be detected by absorbance at 340 nm. These were separated by reverse-phase high performance liquid chromatography (HPLC). A step- or more complex gradient (acetonitrile/phosphate buffer gradient) was used. The effects of several parameters (pH, ionic strength, etc) were characterized and used to design a rapid separation of the amino acids commonly found in physiological fluids. The method described is rapid, sensitive and precise as sensitivity limits are about 25 pmol and the separation time, injection to injection, is 16 min. 相似文献
15.
Debajyoti Goswami Ramkrishna Sen Jayanta Kumar Basu Sirshendu De 《Bioresource technology》2009,100(18):4067-4073
In this study, response surface methodology was applied to optimize process variables like temperature, pH, enzyme concentration (mg/g oil), and buffer concentration (g/g oil) for hydrolysis of castor oil using Candida rugosa lipase. A 24 full factorial central composite design was used to develop the quadratic model that was subsequently optimized and the optimal conditions were as follows: temperature 40 °C, pH 7.72, enzyme concentration 5.28 mg/g oil, buffer concentration 1 g/g oil and there was 65.5% conversion in 6 h. These predicted optimal conditions agreed well with the experimental results. This is the first report on the application of response surface methodology in castor oil hydrolysis using C. rugosa lipase with higher percentage conversion in 6 h. 相似文献
16.
Separation of tocopherol and tocotrienol isomers using normal- and reverse-phase liquid chromatography 总被引:1,自引:0,他引:1
This optimization study for tocopherols and tocotrienols involved both normal- and reverse-phase liquid chromatography using various columns and mobile phases. Normal-phase systems showed elution of the homologs in order of increasing polarity with separation based on methyl substituents on the chromanol moiety. Reverse-phase systems showed class separation based on the saturation of the phytyl side chain; the more saturated tocopherols were retained on the column longer. When the Zorbax ODS was used with an isocratic ternary acetonitrile:methanol:methylene chloride (60:35:5) mixture, the optimized resolution was greater than 2.0 and separation was achieved in less than 13 min, but there was no separation of beta- and gamma-tocopherols. The normal-phase silica and amino columns provided separation of all available isomers with resolution greater than 1.1 and separation times of less than 5.5 and less than 10 min, respectively. Optimized isocratic binary solvent mixtures of hexane:2-propanol were used for silica (99:1) and amino (98:2) columns. Derivative spectra showed differences depending on substituents in the chromanol moiety but not the phytyl side chain. Second- and fourth-derivative spectra gave the best differentiation of the vitamin E isomers. 相似文献
17.
The purpose of present research work was to prepare calcium alginate beads containing water-soluble drug metronidazole using
32 factorial design, with drug concentration and curing time as variables. Curing time was kept as low as possible to improve
entrapment with increasing drug concentration. Mostly the drugs which had been encapsulated were water insoluble to facilitate
drug encapsulation; a characteristic drug release as whole process is aqueous based. Entrapment efficiency was in the range
of 81% to 96% wt/wt, which decreased with decrease in polymer concentration and increase in curing time. The beads were spherical
with size range between 1.4 and 1.9 mm. Scanning electron microscope (SEM) photomicrographs revealed increase in the leaching
of drug crystals with increased curing time and high drug concentrations. In acidic environment, the swelling ratio was 200%
in 30 minutes, but in basic medium, it increased to a maximum of 1400% within 120 minutes. In acidic medium, the swelling
and drug release properties were influenced by drug solubility, whereas in phosphate buffer these properties were governed
by the gelling of polymer and exhibited curvilinear and quadratic functions of both the variables, respectively. 相似文献
18.
Use of a Novel Sub‐2 µm Silica Hydride Vancomycin Stationary Phase in Nano‐Liquid Chromatography. II. Separation of Derivatized Amino Acid Enantiomers
下载免费PDF全文
![点击此处可从《Chirality》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A novel vancomycin silica hydride stationary phase was synthesized and the particles of 1.8 µm were packed into fused silica capillaries of 75 µm internal diameter (I.D.). The chiral stationary phase (CSP) was tested for the separation of some derivatized amino acid enantiomers by using nano‐liquid chromatography (nano‐LC). Some experimental parameters such as the type and the content of organic modifier, the pH, and the concentration of the buffer added to the mobile phase were modified and the effect on enantioselectivity, retention time, and enantioresolution factor was studied. The separation of selected dansyl amino acids (Dns‐AAs), e.g., Asp, Glu, Leu, and Phe in their enantiomers was initially achieved utilizing a mobile phase containing 85% (v/v) methanol (MeOH) and formate buffer measuring the enantioresolution factor and enantioselectivity in the range 1.74–4.17 and 1.39–1.59, respectively. Better results were obtained employing a more polar organic solvent as acetonitrile (ACN) in the mobile phase. Optimum results (Rs 1.41–6.09 and α 1.28–2.36) were obtained using a mobile phase containing formate buffer pH 2.5/water/MeOH/ACN 6:19:12.5:62.5 (v/v/v/v) in isocratic elution mode at flow rate of 130 nL/min. Chirality 27:767–772, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
19.
Porras SP Valkó IE Jyske P Riekkola ML 《Journal of biochemical and biophysical methods》1999,38(2):89-102
Non-aqueous capillary electrophoresis was used to study the separation selectivity of positively charged drug substances and negatively charged diuretics. Study was made of the effects of organic solvent composition and the background electrolyte on the separation. The separation selectivity could be altered considerably by varying the methanol/acetonitrile composition. In addition, the migration order and the resolution of the pharmaceuticals could be altered merely by changing the electrolyte cation or the anion. The electrolytes tested were alkali metal acetates, ammonium acetate, ammonium chloride and ammonium bromide. As with aqueous background electrolyte solutions, the electroosmotic flow was decreased with increasing size of the alkali metal cation of the electrolyte in methanol/acetonitrile 50:50 (v/v). 相似文献
20.
Capella-Peiró ME Bose D Rubert MF Esteve-Romero J 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,839(1-2):95-101
Capillary zone electrophoresis was optimized to quantitatively determine codeine and paracetamol via central composite factorial design. Critical parameters (concentration, buffer, pH, voltage) assessed effects on resolution, analysis time and efficiencies. Optimum separation conditions were achieved using phosphate buffer 20 mM (pH 6.8) and voltage (15 kV). The optimized procedure easily determined codeine and paracetamol with separation in less than 3 min. Calibration curves (R > 0.999) were prepared, with LODs of 13.5 and 340 ng mL(-1) for codeine and paracetamol, respectively, and a good R.S.D.% (<3%). This method was applied to determine codeine and paracetamol in pharmaceutical formulations; recoveries coincided with stated contents. 相似文献