Determination of plasma heparin by micellar electrokinetic capillary chromatography

The micellar electrokinetic capillary chromatography (MECC) method is reported for the separation of heparin, and for the possibility of direct determination of free heparin in plasma. The conditions for MECC were: pH 8.5, 25 mM sodium dodecyl sulfate (SDS), 25 mM borate buffer, with a 30 cmx50 mum ID fused-silica capillary. The sample was detected with a UV-detector at 270 nm with heparin as external standard. The recovery rate was 95.6-98.7%. This method was linear in the range 80-7000 U l(-1). The within-run and between-run relative standard deviations were lower than 3.1 and 4.5%, respectively. It is suggested that this MECC method may be used to determine blood samples containing high levels of heparin.     

三种维生素的毛细管电泳和胶束电动毛细管色谱法分离与安培电化学检测

以自制毛细管电泳－电化学检测系统对ＶＣ,ＶＢ１和ＶＢ６的毛细管区带电泳和胶束电动色谱的分离与检测情况进行了初探。结果表明,在０．０１ｍｏｌ／ＬＮＨ３－ＮＨ４Ｃｌ介质中,检测电势定于５１０～５４０ｍＶ（对ＳＣＥ）时,三种维生素均有较好的ＣＺＥ图,对ＶＣ的分离效率达４６８８００块理论板。使用十二烷基硫酸钠时,分离效果欠佳。     

部分水溶性维生素胶束电动毛细管色谱行为研究

详细探讨了十二烷基硫酸钠浓度、硼砂浓度、溶液PH值、电泳电压对部分水溶性维生素胶束电动毛细管色谱行为的影响,在优化条件下,4min内完成5种水溶性维生素的分离。     

HPLC-MS and MECC analysis of coumarins

Summary MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prepared from 50 mM boric acid, 10 mM sodium tetraborate and 100 mM sodium hydroxide. The buffer solution contained 50 mM SDS and, as organic modifier 1%n-propanol. The applied voltage was 25 kV and the temperature of the capillary was kept constant at 20°C. HPLC baseline separation of the coumarin mixture was obtained by use of a reversed-phase column and an acetonitrile-water solvent gradient. UV detection was performed at 205 nm. Peak assignment and purity control were achieved by HPLC-mass spectrometry with either an electrospray interface or an atmospheric-pressure chemical-ionization interface. Compounds were detected in either negative- or positive-ion modes. These MECC and HPLC-MS methods are suitable for ‘fingerprint’ analysis of a number of coumarin-containing plants, e.g. Fr.Ammi visnagae, Rd.Scopoliae and Rd.Imperatoriae.     

Effect of Micelle Composition on Acidic Drugs Separation Behavior by Micellar Electrokinetic Capillary Chromatography

Micellar electrokinetic capillary chromatography (MECC) is a branch of capillary electrophoretic techniques, in which surfactant micelles are added to the electrolyte solution as pseudostationary phase. Separation in MECC is based on electrophoretic mobilities of the analytes when partitioned into micelles1. In this work, four acidic drugs similar in structure with aryl carboxylic acid were separated by MECC. The effects of type of surfactant, such as anionic surfactant SDS, nonionic …     

毛细管电泳电化学法分离检测盐酸克伦特罗、特布他林和沙丁胺醇

建立了毛细管电泳电化学法对盐酸克伦特罗、特布他林和沙丁胺醇进行分离检测。方法采用胶束电泳体系,以铂圆盘为工作电极,考察了检测电位、缓冲液浓度和pH、十二烷基硫酸钠(SDS)浓度、分离电压等因素的影响。3个分离物在10 kV的分离电压、缓冲体系为15 mmol/L(pH 9.0)硼砂+20 mmol/L SDS条件下得到分离。盐酸克伦特罗、特布他林和沙丁胺醇的线性范围分别为2.0～400,3.5～700,5.0～1000μg/L。方法已用于猪肉样品的检测。     

Capillary zone electrophoresis in the analysis of dyes and other compounds employed in the dye-manufacturing and dye-using industries

High resolution separation of several dyes and related intermediates, as well as other compounds employed in the dye-manufacturing and dye-using industries, has been achieved using capillary zone electrophoresis (CZE).

The analysis of anionic dyes and some non-coloured anionic intermediates has been achieved using 10 mM Na₂B₄O₇−40 mM sodium dodecyl sulphate (SDS) buffer; high-resolution separations of water soluble anionic, neutral and cationic intermediates were also achieved using this micellar buffer. Micellar electrokinetic capillary chromatography (MECC) has also been developed for the analysis of aqueous insoluble, electrically neutral compounds by incorporating a co-solvent, acetonitrile, into a micellar buffer. In addition, MECC has been used successfully for following all the major steps involved in the synthesis of a disperse dye.     

Analysis of the Aerial Parts of Verbena officinalis L. by Micellar Electrokinetic Capillary Chromatography

A micellar electrokinetic capillary chromatography (MECC) method was developed for the qualitative and quantitative determination of five marker compounds (iridoid glycosides, flavonoids and phenylethanoids) in Verbena officinalis. Optimum separation was achieved using a 50 mM sodium borate solution (pH 9.3), containing 50 mM sodium dodecylsulfate (SDS) as surfactant, at an applied voltage of 25 kV and a temperature of 30 °C, respectively. Because of their different absorption maxima, the compounds were detected either at 205 or 235 nm. Calibration data confirmed linearity of the detector response within the concentration range injected (R² from 0.997 to 0.999), and revealed detection limits ranging from 5.0 g mL^–1 (verbascoside) to 13.6 g mL^–1 (hastatoside). The five markers were readily assignable in several samples of Verbena.     

Enantiomer separation of miconazole by capillary electrophoresis with dual cyclodextrin systems.

A cyclodextrin-modified micellar capillary electrophoretic method (MECC) was developed using mixtures of beta, cyclodextrins (beta-CD) and mono-3-O-phenylcarbamoyl-beta-CD as chiral additives for the chiral separation of miconazole with the dual CDs systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L beta-CD and 15 mmol/L mono-3-O-phenylcarbamoyl-beta-CD containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the beta-CD and the mono-3-O-phenylcarbamoyl-beta-CD concentration was performed to determine the optimal conditions with respect to the resolution. Good repeatability of the method was obtained.     

Analysis of neutral and sialylatedN-liked oligosaccharides by micellar electrokinetic capillary chromatography with addition of a divalent cation

Summary Micellar electrokinetic capillary chromatography (MECC) has been investigated as an alternative mode of analyzing oligosaccharides released from glycoproteins. The influence on the separation of experimental parameters such as the concentrations of surfactant and electrolyte and the addition of divalent cations was examined. Solubilization, of neutral oligosaccharides by micelles was demonstrated whereas for the sialylated oligosaccharides the electrophoretic mobility remained the predominant factor. The addition of Mg⁺⁺ to sodium dodecyl sulfate (SDS)solutions provided an effective means of enhancing the selectivioty of the separation through both an increase of the time window and the differential complexation of carbohydrate with this divalent cation.     

Simultaneous Separation and Determination of Benzoic Acid Compounds in the Plant Medicine by High Performance Capillary Electrophoresis

A simple and inexpensive high performance capillary electrophoresis (HPCE) was applied to separate five benzoic acid compounds simultaneously. The investigation was carried out by micellar electrokinetic capillary chromatography (MECC). To avoid a time‐consuming and tedious procedure, orthogonal experimental design OA₉ (3⁴) for separation experiments was applied to find the optimal conditions in terms of the resolution and analytical time. The best conditions for separation were obtained using a 20 mM borax and 30 mM sodium dodecyl sulfate (SDS) buffer (pH 9.8) containing 2 mM β‐CD and 4% methanol (v/v). Online UV detection was performed at 250 nm. A voltage of 16 kV was applied and the temperature was controlled at 25 °C. Injection was performed for 5 s. The method was validated for the quantification of benzoic acid, salicylic acid and ortho‐aminobenzoic acid in Radix Isatidis, a traditional plant medicine with removal of endotoxin. The separation and determination were satisfactory and quick.     

Retention of eleven priority phenols using micellar electrokinetic chromatography

The use of micellar electrokinetic chromatography (MECC) for the separation of eleven substituted phenols listed by the United States Environmental Protection Agency as priority pollutants was investigated. Solutions of potassium and sodium dodecyl sulphate in phosphate-borate buffer of pH 6.6, 7.0 and 7.5 were used as the electrophoretic media. Satisfactory separation of the eleven phenols was obtained using a 180-microns capillary at 10 kV and pH 6.6 with a solution containing both sodium and potassium dodecyl sulphate. Observations on the retention behaviour of the phenols in MECC were related to their physico-chemical properties.     

Analysis of B6 vitamers by micellar electrokinetic capillary chromatography with laser-excited fluorescence detection

Micellar electrokinetic capillary chromatography (MECC) involves the application of a high voltage (10 to 40 kV) across a capillary column (25 to 75 microns i.d.) that is filled with a solution containing micelles. The mobile phase in this work consists of sodium dodecyl sulfate in an aqueous phosphate/borate buffer system. Pyridoxine (vitamin B6) and five of its metabolites are separated, with efficiencies as high as 60,000 theoretical plates/meter. Pyridoxic acid, a metabolite of B6, is separated and quantitated in human urine using laser-excited fluorescence detection. Limits of detection are less than a picogram injected.     

Studies of iridoid glycosides using liquid chromatography/electrospray ionization tandem mass spectrometry

Fragmentation pathways of five iridoid glycosides have been studied by using electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)). The first-stage MS data of the five iridoid glycosides were compared. The MS spectra showed that the adduct ions of iridoid glycosides and the formate anion were diagnostic ions to distinguish iridoid glycosides with a carboxyl group at the C-4 position or an ester group at the C-4 position. The MS fragmentation pathways of the five iridoid glycosides were also studied. Analyzing the product ion spectra of iridoid glycosides, some neutral losses were observed, such as H(2)O, CO(2) and glucose residues, which were very useful for the identification of the functional groups in the structures of iridoid glycosides. Furthermore, specific loss of one molecule of methyl 3-oxopropanoate or 3-oxopropanic acid was firstly discussed, which corresponded to the isomerization of the hemiacetal group in the structure of iridoid aglycone. According to the fragmentation mechanisms and HPLC/MS(n) data, the structures of five iridoid glycosides in a crude extract of Gardenia jasminoisdes fruit have been identified. Three compounds were compared with standards and the other two were identified as shanzhiside and genipin gentibioside by their MS(n) data without standard compounds. In order to further validate the veracity of the deduction, genipin gentiobioside was isolated from the extract of Gardenia jasminoisdes fruit using Purification Factory and was further identified by C- and H-NMR.     

The effect of injection procedures on efficiency in micellar electrokinetic capillary chromatography

Summary Micellar electrokinetic capillary chromatography (MECC) involves the application of a high voltage (10–30 KV) across a capillary column (75μm i.d.) which is filled with a solution containing micelles. The mobile phase in this work consisted of sodium dodecyl sulfate in an aqueous borate/phosphate buffer system. Injection parameters in MECC were investigated to minimize the contribution to band-broadening resulting from the injection process. Efficiencies as high as 240,000 theoretical plates/meter are reported.     

电中性物质的毛细管胶束电动色谱

在自制的高效毛细管电泳装置上,使用内径为0.05毫米,长为450毫米的熔融石英毛细管,十二烷基硫酸钠胶束溶液,254nm检测波长,进行了电中性化合物的毛细管胶束电动色谱研究。并将乙醇-水混合溶剂引入体系,成功地进行了多环芳烃的分离。考察了电场强度,SDS浓度及乙醇含量对柱效的影响。     

Phase-transfer catalytic determination of phenols as methylated derivatives by gas chromatography with flame ionization and mass-selective detection

A microemulsion electrokinetic chromatographic (MEEKC) method was developed for the separation of six catechins, specific marker phytochemicals of Cistus species. The MEEKC method involved the use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent and butan-1-ol as co-solvent. In order to have a better stability of the studied catechins, the separation was performed under acidic conditions (pH 2.5 phosphate buffer). The effects of SDS concentration and of the amount of organic solvent and co-solvent on the analyte resolution were evaluated. The optimized conditions (heptane 1.36% (w/v), SDS 2.31% (w/v), butan-1-ol 9.72% (w/v) and 50 mM sodium phosphate buffer (pH 2.5) 86.61% (w/v)) allowed a useful and reproducible separation of the studied analytes to be achieved. These conditions provided a different separation profile compared to that obtained under conventional micellar electrokinetic chromatography (MECK) using SDS. The method was validated and applied to the determination of catechin and gallocatechin in lyophilized extracts of Cistus incanus and Cistus monspeliensis.     

Iridoid-glycoside isolation and purification from Premna fulva leaves

Premna fulva Craib, rich in iridoid glycosides, is widely used to treat periarthritis, osteoproliferation, pain, and other diseases. However, no studies have reported effective purification methods for obtaining iridoid glycosides as active materials. This paper describes an efficient strategy for separating iridoid glycosides from Premna fulva leaves using high-speed counter-current chromatography and preparative high-performance liquid chromatography. A two-phase solvent system, ethyl acetate/n-butanol/water (7.5:2.5:10, v/v), was selected for high-speed counter-current chromatography separation. The proposed method effectively separated and purified four iridoid glycosides and four lignans, including three new iridoid glycosides ( 4–6 ) and five known compounds ( 1–3, 7, 8 ), from Premna fulva leaves, indicating that high-speed counter-current chromatography combined with prep-HPLC can efficiently isolate catalpol derivatives from the genus Premna. Additionally, the in vitro anti-inflammatory activities of all isolated compounds were analyzed using lipopolysaccharide-stimulated RAW 264.7 cells, and the results indicated that six compounds ( 1 and 3–7 ) exhibited potential anti-inflammatory activities.     

Determination of heterocyclic compounds by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography (MECC) based on sodium cholate (NaCh) and sodium dodecyl sulphate (SDS) was developed for the determination of aromatic amino acids and heterocyclic legume constituents. The influence of temperature, voltage, micellar system, pH, zwitterion and modifier concentrations in the buffer on migration times, peak areas, resolution and number of theoretical plates was investigated. This MECC method makes possible the sensitive determination of the individual compounds with detection limits in the picomole range. Up to 300 000 theoretical plates per metre of capillary were obtained together with satisfactory linearity and repeatability of the NaCh method. The applicability of MECC to samples prepared from plant material, following a fast and simple technique of isolation, purification and group separation, is illustrated by selected examples.