Critical evaluation of microextraction pretreatment techniques-Part 2: Membrane-supported and homogenous phase based techniques.

This review follows up on Part 1, which focused on classification and evaluation of single drop and sorbent-based microextraction techniques. Membrane- and homogenous phase-based microextraction techniques are discussed and classified in Part 2. These techniques are more recent than those in Part 1 and considerable attention has been paid to their development.

Critical evaluation of microextraction pretreatment techniques - Part 1: Single drop and sorbent-based techniques.

Sample pretreatment techniques or preconcentration constitute a very important step before the analysis of environmental, clinical, pharmaceutical, and other complex samples. Thanks to extraction techniques it is possible to achieve higher method sensitivities and selectivities. Miniaturization microextraction methods make them more environmentally friendly and only small amounts of samples are required.

Analysis of estrogens and estrogen mimics in edible matrices--a review.

This review provides a brief survey of the biological effects of selected endocrine-disrupting compounds that are formed after internal exposure of organisms. Further, the present analytical methods available for the determination of these compounds in foodstuffs are critically evaluated. The attention is primarily devoted to the methods for sample pretreatment, which are the main source of errors and are usually the most time-consuming step of the whole analysis.

Analysis for estrogens as environmental pollutants--a review.

The approaches to the analysis for estrogen compounds as environmental pollutants are critically reviewed and evaluated on the basis of significant, recent original publications. The importance of sample pretreatment and analyte preconcentration techniques is pointed out, with an emphasis on SPE and on the use of highly selective interactions such as molecular recognition. The hyphenated systems of high-performance gas or liquid chromatography and mass spectrometric techniques are discussed as the basic methods of determination of estrogens in environmental samples.

Gas chromatography/mass spectrometry of oils and oil binders in paintings.

A GC/MS procedure has been developed, optimized, and applied to characterization of oil binders in paintings. The procedure involves hydrolysis of lipids to fatty acids (FAs) and derivatization of FAs to fatty acid methyl esters (FAMEs) by a solution of sodium methanolate in methanol at an elevated temperature. FAMEs are analyzed by temperature-programed GC followed by full-scan MS.

An evaluation of the experimental approaches to detection of small ions in CE.

This review points out some important trends in the development of the detection techniques for small ions in CE. On the basis of selected literature references it briefly discusses some general requirements on detection techniques in CE. Various optical measurements, mass spectrometric approaches and electrochemical detection techniques are dealt with.

Characterization of substituted polyacetylene microstructure by pyrolysis gas chromatography.

A series of substituted acetylenes has been polymerized with WOC14/Ph4Sn metathesis catalyst and [Rh(cod)OMe]2 insertion catalyst, and the thermal degradation of the polyacetylenes prepared has been studied using pyrolysis capillary gas chromatography (Py-GC) with flame ionization and mass spectrometric detection to obtain information on the effect of the catalyst on the head-tail (H-T) isomerism of polyacetylenes (poly(phenylacetylene), poly[(4-methylphenyl)acetylene], poly(benzylacetylene), poly((2-fluorophenyl)acetylene], poly[(3-fluorophenyl)acetylene], and poly[(4-fluoro-phenyl)acetylenel). Cyclotrimers have been found to be the main pyrolysis products in all cases. Direct Py-MS connection was used to determine the temperature profiles of the released pyrolysis products.

An evaluation of GC-MS and HPLC-FD methods for analysis of protein binders in paintings.

Two chromatographic methods have been compared for analysis of protein-binding media used in paintings, namely, HPLC with fluorescence detection and GC-MS. The proteins were hydrolyzed to the corresponding amino acids (AAs) by gaseous HCl and the AAs were derivatized with methyl chloroformate, followed by GC-MS or by HPLC after derivatization with the AccQ fluorescence reagent. The hydrolysis, derivatization reactions and the chromatographic procedures have been optimized and applied to standard binding media, model and real samples of paintings.

Porous polyacrylamide monoliths in hydrophilic interaction capillary electrochromatography of oligosaccharides.

Capillary electrochromatography (CEC) of oligosaccharides in porous polyacrylamide monoliths has been explored. While it is possible to alter separation capacity for various compounds by copolymerization of suitable separation ligands in the polymerization backbone, "blank" acrylamide matrix is also capable of sufficient resolution of oligosaccharides in the hydrophilic interaction mode. The "blank" acrylamide network, formed with a more rigid crosslinker, provides maximum efficiency for separations (routinely up to 350,000 theoretical plates/m for fluorescently-labeled oligosaccharides).

Affinity liquid chromatography and capillary electrophoresis of seminal plasma proteins.

Interactions of boar, bull, and human seminal plasma proteins with heparin and phosphorylcholine were studied by affinity LC using heparin immobilized to a Toyopearl support. A step gradient elution from 0.15 to 1.

Monolithic organic polymeric columns for capillary liquid chromatography and electrochromatography.

This review briefly summarizes the present state of the preparation and use of capillary monolithic columns for liquid chromatography (LC) and electrochromatography (EC). Most important approaches to the preparation of monolithic stationary phases based on organic polymers are outlined and the properties of the monoliths obtained are compared with those of classical particulate phases. A few selected applications of monolithic columns are shown to demonstrate the most important advantages of monolithic capillary columns.

Preparation and testing of stationary phases and modified capillaries for affinity chromatography and affinity capillary electrophoresis of pepsin.

Three stationary phases have been prepared for affinity liquid chromatography isolation and separation of porcine and human pepsin. The phases contain 3,5-diiodo-L-tyrosine (DIT) bound to the supports HEMA BIO VS, HEMA BIO E and EPOXY TOYOPEARL. These phases have been tested on a model sample of porcine pepsin A and applied to human pepsin.

Topographical properties of polymer films deposited in capillaries for electrophoretic separations of large organic molecules.

Topography and thickness of hydrophilic polymer coatings of fused-silica capillaries for capillary electrophoresis (CE) were investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry. Three hydrogels, poly(2-hydroxyethyl methacrylate) [poly(HEMA)], poly(diethylene glycol monomethacrylate) [poly(DEGMA)], and poly(triethylene glycol monomethacrylate) [poly(TEGMA)], were deposited using two procedures, either by simple physical sorption of the polymers, or by derivatization of the capillary wall surface with glycidyl methacrylate (EPMA) followed by polymerization of the appropriate monomers. The performance of the modified capillaries was tested under CE conditions (decrease in the electroosmotic flow, EOF dependence on pH, separation of milk and standard proteins).

Dechlorination ability of municipal waste incineration fly ash for polychlorinated phenols.

Pathways of pentachlorophenol dechlorination have been investigated on municipal waste incineration fly ash at 200 degrees C under nitrogen atmosphere. Thermodynamic calculations have been carried out for these dechlorination conditions using the method of total Gibbs energy minimization for the whole system consisting of gaseous components, i.e.

The importance of capillary electrophoresis, capillary electrochromatography, and ion chromatography in separations of inorganic ions.

The importance of capillary electrophoresis (CE), capillary electrochromatography (CEC), and ion chromatography (IC) in inorganic ion analyses is outlined. Methods for improving the reliability of the CE measurements are briefly described. Selectivity optimization in CE analyses of inorganic cations and anions is discussed.

Some potentialities and drawbacks of contemporary size-exclusion chromatography.

The present state of the chromatographic techniques based on differentiation of solutes according to their molecular sizes is briefly surveyed. Attention is centred on high-performance techniques applied to purification and characterization of natural macromolecules, and on discussion of the chromatographic approaches to the determination of the molecular masses and molecular mass distributions of both natural and synthetic polymers. The basic requirements on the selection of the separation system and the experimental conditions are summarized, demonstrated on a few examples and critically evaluated.

Dehalogenation potential of municipal waste incineration fly ash. I. General principles.

Background, Aims And Scope: It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows dehalogenation properties after heating it to 240-450 degrees C. However, this property is not general, and fly ash samples do not possess dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role.

Proteomics of allergens.

The present state of proteomics research is generally outlined and the character of allergenic compounds briefly elucidated. The principles of experimental approaches to isolation, purification, identification and characterization of allergens and to monitoring of their biological activity are described, with emphasis on the most modern methods. Selected examples are given for illustration and important results are summarized in tables.

Modification of capillary electrophoresis capillaries by poly(hydroxyethyl methacrylate), poly(diethylene glycol monomethacrylate) and poly(triethylene glycol monomethacrylate).

Modification of capillary electrophoresis (CE) capillaries by poly(hydroxyethyl methacrylate) (poly(HEMA), poly(diethylene glycol monomethacrylate) (poly(DEGMA) and poly(triethylene glycol monomethacrylate) (poly(TEGMA), was studied. Methods based on physical adsorption of the modifier and on its chemical binding were compared on the basis of the electroosmotic flow (EOF) reproducibility, the EOF dependence on the pH, the symmetry of the peak of positively charged tyramine, the stability of the coating and the separation of standard and milk proteins in the modified capillaries. Reproducible coatings were obtained by chemical binding of the polymers to the capillary walls and by coating with a solution of a polymer, as also demonstrated by the atomic force microscopy.