摘要:

In this first part of a two part series, the pore structure of zirconia-silica composite stationary phase supports was examined using size exclusion chromatography. The study found that the pore structure was more complex than pure zirconia surfaces. With these composite materials, the pore dimensions are primarily dependent on the concentration of the silicon doping, the temperature of calcination, and the presence of salts during calcination. Silicon concentration influences the phase crystallization which, in turn, alters the temperature at which micropores transform to mesopores. Calcination in the presence of sodium chloride increased the surface area and pore volume of the support.

ISSN:1082-6076    

DOI:10.1080/10826079808005889

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this Part II of a two-part series, we examined the pore structure of zirconia-silica mixed oxide supports that were prepared using a variety of calcination conditions. Nitrogen sorption was used to evaluate the pore structure, offering a comparison to the size exclusion results presented in Part I. Pore volumes and surface areas of zirconia-silica composites, calcined in the presence of sodium chloride, were found to be higher compared to the composite calcined in the absence of sodium chloride. The pore diameter was observed to increase as the temperature of calcination increased.

ISSN:1082-6076    

DOI:10.1080/10826079808005890

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A high performance liquid chromatographic method was developed for the kinetic investigation on the acidic hydrolysis of lorazepam in 0.01, 0.1, and 1.0 M hydrochloric acid solutions. In this study, the simultaneous determination of lorazepam and its main degradation product was performed on a reversed phase BDS C-8 column. The mobile phase consisted of a mixture of methanol: acetonitrile: buffer solution containing 0.005 M KH

ISSN:1082-6076    

DOI:10.1080/10826079808005891

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Separation of the enantiomers of two series of seven organic phosphonates on π acidic N-(3,5-dinitrobenoyl) leucine chiral stationary phase is described. Enantiomer resolution is highly dependent on the mobile phase composition and the structure of the enantiomers. One of seven enantiomers can be separated using hexane-2-propanol mobile phase, other enantiomers can be partly separated only. The six out of seven enantiomers are separated and the retention times of all enantiomers are significantly decreased using ethanol instead of 2-propanol. The separation of all enantiomers is hardly affected by varying column temperature (10–40°C).

ISSN:1082-6076    

DOI:10.1080/10826079808005892

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

N-Hydroxysuccinimidyl-3-indolylacetate (SIIA) was firstly synthesized in a very simple route and used as a pre-column derivatizing reagent, which can react with amino compounds selectively under mild conditions. Its derivatives of peptides and their hydrolysates were separated and determined by reversed-phase high performance liquid chromatography (HPLC). In a mobile phase of methanol-water (17:83, v:v) containing 10 mmol/L citric acid-sodium phosphate buffer (pH 3.8), the derivatives of glutathione (GSSG), glycyl glycine (Gly-Gly), glutamic acid (Glu), cystine ((Cys)

ISSN:1082-6076    

DOI:10.1080/10826079808005893

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A simple and rapid isocratic enantiomeric separation of several racemic drugs with two stereogenic centers, namely for-moterol, labetalol, nadolol, indenolol, and U-54494A, was achieved under normal phase mode using a urea-type chiral stationary phase (CSP) column of (S)-indoline-2-carboxylic acid and (R)-1-(α-naphthyl) ethylamine, known as Chirex 3022 column. Labetalol and formoterol were resolved successfully into its four enantiomers. Furthermore, racemate mixture of U-54494A has been resolved into its individual enantiomers. However, nadolol and indenolol was partially separated.

ISSN:1082-6076    

DOI:10.1080/10826079808005894

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A high-performance liquid chromatographic (HPLC) method was developed for biphenyl dimethyl dicarboxylate (DDB) detection in human serum and bioequivalence (BE) of two commercial DDB tablets was evaluated in 14 normal male subjects. The most suitable extracting solvent for DDB in serum was evaluated among dichloromethane, ether, ethylacetate, hexane, and pentane. Pentane:ether (9:1) mixture showed good extraction recovery of DDB from serum and also excluded serum components, which interfere the peak of DDB when assayed. HPLC conditions were as follows: UV absorbance detector, 280 nm; column, μ-Bondapak C

ISSN:1082-6076    

DOI:10.1080/10826079808005895

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A rapid assay was developed on the RP HPTLC C

ISSN:1082-6076    

DOI:10.1080/10826079808005896

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A method using liquid chromatography with diode-array detection, LC-DAD, has been developed for the determination of the pesticide diflubenzuron and some of its major metabolites, such as 2,6-difluorobenzamide, 4-chlorophenylurea, and 4-chloroaniline in pine-needles. Samples were extracted into acetonitrile and further cleaned-up through aminopropyl cartridge. LC was performed on a C18column using acetonitrile-methanol-water (50:2:48) as mobile phase at 1 mL min−1at room temperature.

ISSN:1082-6076    

DOI:10.1080/10826079808005897

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An HPLC procedure for determining phenoxy acid herbicides in waters is described. A LichroSpher RP select B octadecyl-silane analytical column and spectrophotometric detection at 230 nm were used. Adequate retention was achieved with a mobile phase containing MeOH/phosphate buffer 10−2M pH 2.5/PnOH (50/42/8, v/v). The herbicides were isolated from water samples by using a single solid phase extraction procedure with C18solid-phase columns. An enrichment factor of 500 is achieved. The coefficients of variation of the method were generally lower than 2.7% at 0.4 μg L−1herbicide concentration levels. Recoveries ranged between 93 and 118%. The results obtained indicate that the proposed method is well suitable for monitoring phenoxy acid herbicides in compliance with the European Community standard for drinking water.

ISSN:1082-6076    

DOI:10.1080/10826079808005898

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor