摘要:

With using short capillary column packed with porous and non-porous ODS stationary phases, high speed separation of 6 neutral aromatic compounds within 36 s by capillary electrochromatography (CEC) has been performed. Good reproducibility of the migration times for those solutes in high speed CEC was observed with RSD less than 1%. Both the linear velocity of EOF and the current linearly increases with the applied voltage, which means that the thermal effect by Joule heating was small. However, the capacity factor of solutes was found to decrease with the increase of the applied voltage, which was caused by the fact that about several seconds needed for the increase of voltage from 0 to applied value on a commercial CE instrument made larger contributions to the migration times of the early eluted compounds than those of lately eluted ones during high speed CEC, and voltage effect would increase with the higher applied voltage used. The linear relationship between the logarithm of capacity factor and the number of carbon for homologous compounds was observed, and positive value of slope means that the hydrophobicity of solutes is one of the main contribution factors to retention in high speed CEC packed with ODS stationary phases.

ISSN:1082-6076    

DOI:10.1081/JLC-100102053

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Flow/hyperlayer field flow fractionation (Fl/Hy FFF) has been applied for the rapid separation and size characterization of core-shell type poly(l-lactide) (PLLA) microspheres which are widely studied as a potential drug carrier due to its biodegradability. Examined microspheres are prepared by varying the entrapped amount of the retinoic acid as an anti-cancer therapeutic and varying PEG-PLLA copolymers. It is demonstrated that the separation of PLLA microspheres can be achieved within 5 min. by Fl/Hy FFF and the particle size distribution (PSD) is readily obtained from the experimental fractograms. From the size distribution of PLLA particles obtained by Fl/Fl FFF, it is shown that PSD increases with the amount of drug loaded but it does not seriously change with the addition of PEG-PLLA copolymers.

ISSN:1082-6076    

DOI:10.1081/JLC-100102054

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Taking into account the growing interest in applying capillary ion electrophoresis (CIE) for the determination of inorganic ions in real samples, this work focuses on CIE analysis of K+, Na+, Ca2+, Mg2+, and Mn2+in botanical and food reference materials.

ISSN:1082-6076    

DOI:10.1081/JLC-100102055

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Taxol shows promise for the treatment of a variety of human cancers, including leukemia and certain ovarian, breast, and lung tumors. In this work, the separation of taxol from Korean Yew tree was studied with solvent extraction and liquid chromatography. The content of taxol in the tree was analyzed to be 0.064 mg/g of dry powder. Methanol was used to extract taxol and the resulting extract was concentrated by the partition of water and methylene chloride. In the pretreatment step with open tubular chromatography, the first mobile phase was methylene chloride/acetone, 97/3 vol. % and the second mobile phase methylene chloride/acetone, 75/25 vol. %. The sample containing taxol was further purified by varying the composition of solvent, flow rate, and injection amount in analytical chromatography.

ISSN:1082-6076    

DOI:10.1081/JLC-100102056

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Field–Flow Fractionation (FFF) is a relatively new technique for characterizing colloidal materials and macromolecules. It is an elution technique and the retention volume under selected experimental conditions is immediately related to the number and weight average particle diameter or to the particle mass. The accuracy in the determination of the above parameters for a given colloid or macromolecule is dependent on a number of experimental parameters among which the surface potential of the particles, the nature, pH and ionic strength of the suspending medium, the effective Hamaker constant, the concentration and pretreatment of the sample, as well as, the relaxation time and the applied field strength.

ISSN:1082-6076    

DOI:10.1081/JLC-100102057

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Conventional and potential barrier methodologies of Field–Flow Fractionation are used to separate and characterize colloidal particles of haematite and titanium dioxide.

ISSN:1082-6076    

DOI:10.1081/JLC-100102058

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Separation of selected lanthanoid elements was performed by high speed countercurrent chromatography (CCC) employing a support–free stationary phase of 2–ethylhexylphosphonic acid mono–2–ethylhexyl ester (EHPA) in toluene. Middle lanthanoids (Sm, Eu, Gd, Tb, Dy) were chromatographically eluted in their increasing order of extractability by passing the aqueous mobile phase of pH buffers. The mixtures of lanthanoid elements of different concentrations were isolated into individual elements of high purity by one–step chromatographic operation.

ISSN:1082-6076    

DOI:10.1081/JLC-100102059

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A high performance liquid chromatographic procedure has been developed for the assay of a cefepime and metronidazole mixture in aqueous solution. The separation and quantitation were achieved on a phenyl column at ambient temperature using a mobile phase of 94.5:5.5 v/v water-acetonitrile containing 0.015 M pentane sulfonic acid sodium salt (adjusted to pH 3.4 with glacial acetic acid and then 4.0 with 45% potassium hydroxide) at a flow rate of 1.5 mL/min with detection of both analytes at 280 nm. The separation was achieved within 10 min with sensitivity in the ng/mL range for each analyte. The method showed linearity for cefepime and metronidazole in the 18.77 – 300.2 and 9.39 – 150.1 μg/mL ranges, respectively. Accuracy and precision were in the 0.52 – 2.40 and 0.63 – 2.77% ranges, respectively, for both analytes. The limits of detection for cefepime and metronidazole were 125 and 63 ng/mL, respectively, based on a signal to noise ratio of 3 and a 10 μL injection.

ISSN:1082-6076    

DOI:10.1081/JLC-100102060

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Recent studies have shown that granisetron incurs glucuronide conjugation in the rat. This metabolic reaction may facilitate biliary excretion and reabsorption of the drug through enterohepatic circulation. This study was designed to evaluate the biliary excretion of granisetron employing a specially designed microdialysis shunt probe to monitor biliary drug concentrations without fluid losses. To avoid obstruction of the bile duct or bile salt waste, the shunt linear probe connected the bile duct between liver and duodenum. The utility of this microdialysis design was demonstrated by studying the hepatic metabolism and biliary excretion of granisetron in the rats. Following intravenous administration (3 mg/kg), granisetron was measurable in the bile microdialysate. Samples were eluted with a mobile phase containing 25 mM acetate buffer (pH 5.3): acetonitrile (78:22, v/v). The 25 mM acetate buffer was prepared with 25 mM sodium acetate with pH adjusted to 5.3 by glacial acetic acid. It was concluded that the in vivo microdialysis technique yielded useful data on the biliary excretion of granisetron.

ISSN:1082-6076    

DOI:10.1081/JLC-100102061

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel chromatographic system introduced here internally generates a concentration gradient of ammonium sulfate (AS) along a long channel to fractionate proteins according to their solubility in AS solution. The separation column consists of a pair of discs with mutually mirror-imaged spiral channels that are separated by a semipermeable membrane. The disc assembly is mounted on a seal-less continuous flow centrifuge. A concentrated AS solution is introduced into the upper channel while a water solution is passed through the lower channel in the opposite direction in a rotating column. A mixture of proteins injected into the water channel moves along an AS gradient of increasing concentration that has been established in the water solution. Each protein species precipitates at a different AS concentration along the gradient. By decreasing the concentration of the AS solution its concentration in the water is decreased, causing the protein to redissolve and to reprecipitate further down the channel. The eluate is continuously monitored and collected using a fraction collector.

ISSN:1082-6076    

DOI:10.1081/JLC-100102062

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor