摘要:

Interest in zirconia as a chromatography support has increased considerably recently because of its chemical inertness and its promise as a useful support, particularly in biological systems. While studies have mainly focused on applications using zirconia or the control of complex elution behaviour that is often observed on this surface, many of the papers presented have not considered the importance of using materials with optimised pore structures. As a result, the efficiency of some separations may have been compromised. In this review we focus on what is perhaps the most important feature of such supports, namely, the pore structure and recent developments in this area. We have not attempted to review the many applications of zirconia in chromatography as they have been comprehensively reviewed by Nawrocki and co-workers in 19931and again as a new material for biotechnology in 1994.2In these reviews the usefulness of zirconia was demonstrated by the many applications that were referenced, particularly with respect to the chromatography of biological species.

ISSN:1082-6076    

DOI:10.1080/10826079808003587

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The retention behaviour of aprotic neutral molecules in Ion Interaction Chromatography was investigated. The study demonstrates that their retention, for an aqueous mobile phase (phosphate buffer pH 7.2-methanol, 85:15 v/v) containing the ion-interaction reagent (IIR) in the range 0–25 mM, decreases with increasing IIR concentration. Silanophilic interactions were accounted for by comparison of results obtained with either a silica based or a styrene-divinylbenzene based C18stationary phase, under otherwise identical conditions. The retention behaviour of neutral molecules was elucidated on the basis of the exhaustive Ion Interaction retention model and evidence was obtained to support the proposition that the decreased retention is the result of an adsorption competition between tested analytes and ion-interaction reagent for inner layer sites on the stationary phase.

ISSN:1082-6076    

DOI:10.1080/10826079808003588

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Aromatic acids were evaluated as eluents for ion exclusion chromatography of organic acids with non-suppressed conductivity detection. The separation of organic acids, performed on an Aminex HPX-87H ion-exclusion column, using a variety of aromatic carboxylic acid eluents, is described in detail. Phthalic acid was found to be a suitable eluent for the separation of the organic acid tested, giving reasonable resolution and detection sensitivity. When 1 mM phthalic acid was used as eluent, an excellent separation of eight acids was achieved in 20 min. Calibration plots for the test acids were linear in the range 10−2M to 10−5M with detection limits of the order of 10−6M Compared to eluent containing sulfuric acid, the proposed method permits a more sensitive detection for the organic acids tested due to the lower background conductance of the eluent used. The proposed method was used for the determination of organic acids in plant tissue extracts with direct injection of sample extract.

ISSN:1082-6076    

DOI:10.1080/10826079808003589

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A liquid stationary phase, poly(methyloctadecylsiloxane), was immobilized on a silica support, in the proportion 50:50 m/m, by gamma radiation doses of 20 to 90 kGy, with the purpose of obtaining a highly stable chromatographic stationary phase. This stationary phase exhibited higher efficiency and shorter analysis times than similar columns prepared with commercial C18packings.

ISSN:1082-6076    

DOI:10.1080/10826079808003590

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Anomalous micellization behaviour consisting in the simultaneous presence of two kinds of micelles was observed in the micellar system polystyrene-block-poly(methyl methacrylate) in 1,4-dioxane/cyclohexane. This anomaly already known, particularly from static light scattering studies of various micellar systems, was now observed by size exclusion chromatography/low-angle laser light scattering technique. For the solvent mixture 1,4-dioxane/70 vol. % cyclohexane, this method enabled a partial size exclusion chromatography separation of the regular and anomalous micelles and allowed to estimate the weight-average molecular weight of both. Anomalous micellization was reliably detected by size exclusion chromatography although the static light scattering data provided only weak confirmation of this phenomenon.

ISSN:1082-6076    

DOI:10.1080/10826079808003591

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Capillary zone electrophoretic method for the one run enantioseparation of methamphetamine and its related metabolites (amphetamine, 4-hydroxymethamphetamine, 4-hydroxyamphet-amine, norephedrine and 4-hydroxy-norephedrine) was developed. Six different cyclodextrins (α-cyclodextrin, β-cyclodextrin, hydroxypropyl-β-cyclodextrin, dimethyl-β-cyclodextrin, epi-chlorhydrin-β-cyclodextrin polymer and γ-cyclodextrin) were tested.

ISSN:1082-6076    

DOI:10.1080/10826079808003592

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Determination of Na+, K+, Mg2+, and Ca2+in seawater is currently performed by using either laborious wet chemical methods or physical ones requiring complicated and expensive instruments. The present study assessed the feasibility of using capillary electrophoresis (CE) as an alternative method for analysis of these metal ions in seawater samples and the robustness of CE in determination of the metal ions in samples of complex matrices. Imidazole was added in various electrophoretic media to provide UV absorbing background for indirect detection and 18-crown-6 was utilized to manipulate selectivity through complexation. Na+, Mg2+, and Ca2+in seawater samples could be determined in an electrophoretic medium of 40 mM 18-crown-6 and 10 mM imidazole at pH 4.5 with an internal standard of Li+, but quantitative determination of K+had to be carried out in another separate run by using an electrophoretic medium of relatively low concentration of 18-crown-6 to improve the precision of the quantitative results. It was demonstrated that CE could be a fast, simple and low cost means for the determination of Na+, K+, Mg2+and Ca2+in seawater with fairly good robustness.

ISSN:1082-6076    

DOI:10.1080/10826079808003593

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The qualitative and quantitative analysis of phenolic acids was carried out using methods of HPLC with the diode array detector (DAD). The quantitative analysis of chosen phenolic acids was carried out using the Multicomponent Analysis method (MCA). Solid-phase extraction was applied for the purification of crude extract from aerial part of three species of fam.Asteraceae(Chrysanthemum maximumRam.(DC),Chrysanthemum segetumL.,Rudbeckia laciniataL.). The choice of optimal conditions of analysis was made using DryLab+ software.

ISSN:1082-6076    

DOI:10.1080/10826079808003594

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Fluorescence detection provides a highly sensitive and selective method of detection for polycyclic aromatic hydrocarbons (PAHs). However, the acquisition of fluorescence spectral data for purposes of peak identification has hitherto only been reported using techniques which interrupt chromatographic runs or rely on complex additional instrumentation. The application and limitations of acquiring fluorescence spectra using a commercially available detector during routine chromatography are discussed.

ISSN:1082-6076    

DOI:10.1080/10826079808003595

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The interaction of 20 nonsteroidal anti-inflammatory drugs with a model protein was studied by reversed-phase high-performance liquid chromatography and the relationship between the strength of interaction and the physicochemical parameters of drugs was elucidated by principal component analysis followed by modified nonlinear mapping and cluster analysis. It was established that the polarity and and sterical parameters of drugs exert the highest influence on the interaction. Cluster analysis and nonlinear mapping using the absolute values of principal component loadings explain more precisely the interaction than the traditional nonlinear mapping and cluster analysis do.

ISSN:1082-6076    

DOI:10.1080/10826079808003596

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor