Extension of the Internal Standard Method for Determination of Thermodynamic Acidity Constants of Compounds Sparingly Soluble in Water by Capillary Zone Electrophoresis.

The paper extends applicability of the internal standard method published in 2009 (Fuguet E. , (17), 3646). Although the original capillary zone electrophoresis method was suggested to determine thermodynamic acidity constants of compounds sparingly soluble in aqueous solutions by carrying out only runs at two different pH values (, without the need to perform many experiments over the appropriate pH range including the form of a low-ionized analyte), we proved that the approach also virtually overcomes any interactions of the analyte in mixed solvents, so that the experiments can be carried out in a methanol-water buffer where the solubility is much better.

Rapid HPLC Method for Determination of Isomaltulose in the Presence of Glucose, Sucrose, and Maltodextrins in Dietary Supplements.

This paper presents a rapid HPLC method for the separation of isomaltulose (also known as Palatinose) from other common edible carbohydrates such as sucrose, glucose, and maltodextrins, which are commonly present in food and dietary supplements. This method was applied to determine isomaltulose in selected food supplements for special diets and athletic performance. Due to the selectivity of the separation system, this method can also be used for rapid profiling analysis of mono-, di-, and oligosaccharides in food.

Indol-2-Carboxylic Acid Esters Containing N-Phenylpiperazine Moiety - Preparation and Cholinesterase-inhibiting Activity.

Background: The indole derivatives and the N-phenylpiperazine fragment represent interesting molecular moieties suitable for the research of new potentially biologically active compounds. This study was undertaken to identify if indol-2-carboxylic acid esters containing N-phenylpiperazine moiety possess acetylcholinesterase and butyrylcholinesterase inhibitory activity.

Materials And Methods: The study dealt with the synthesis of a novel series of analogs of 1H-indole-2- carboxylic acid and 3-methyl-1H-indole-2-carboxylic acid.

Rapid HPLC method for monitoring of lactulose production with a high yield.

An HPLC method suitable for rapid monitoring of lactulose production by isomerization from lactose was developed. The separation of lactose and lactulose under hydrophilic interaction liquid chromatography (HILIC) mode was achieved with resolution 1.5 within 5 min.

Determination of glucosamine and monitoring of its mutarotation by hydrophilic interaction liquid chromatography with evaporative light scattering detector.

Saccharides and their derivatives are typical polar analytes without a suitable UV-chromophore that are nowadays analyzed by HPLC (high-performance liquid chromatography) under HILIC (hydrophilic interaction liquid chromatography) mode. Usually an evaporative light scattering detector (ELSD) is utilized which, however, gives a nonlinear response. A procedure to overcome the problem of mutarotating (time-varying) analytes recorded with such a nonlinear response detector is described.

Feasibility of Fraction Collection in HPLC Systems with Evaporative Light Scattering Detector: Analysis of Pectinatella magnifica.

The use of a liquid chromatography (LC) splitter inserted between an HPLC column and an evaporative light scattering detector (ELSD) is described. This paper aims to show the feasibility of using the splitter in an HPLC-ELSD system to fractionate a model mixture of analytes, namely salicin (2-(hydroxymethyl)-phenyl-β-d-glucopyranoside) and glucose. The retention factors and efficiency of the separation were studied under various temperatures and water contents in the mobile phase in order to clarify the mechanism of polyols separation on a diol column under the conditions of hydrophilic liquid chromatography (HILIC).

Assessment of Chemical Impact of Invasive Bryozoan Pectinatella magnifica on the Environment: Cytotoxicity and Antimicrobial Activity of P. magnifica Extracts.

, an invasive bryozoan, might significantly affect ecosystem balance due to its massive occurrence in many areas in Europe and other parts of the world. Biological and chemical analyses are needed to get complete information about the impact of the animal on the environment. In this paper, we aimed to evaluate in vitro cytotoxic effects of five extracts prepared from using LDH assay on THP-1 cell line.

Fast separation and determination of free myo-inositol by hydrophilic liquid chromatography.

A fast liquid chromatography method for separation and determination of myo-inositol is reported. Determination of the biologically important isomer of inositols, myo-inositol, was optimized to avoid overlapping to possible interferents according to European Pharmacopoeia (glycerol, d-mannitol) and saccharose. The method in HILIC mode is extremely selective to other carbohydrates which allows to separate myo-inositol from allo- and d-chiro-inositol with resolution 12.

Marine natural products: bryostatins in preclinical and clinical studies.

Context: Bryostatins represent an important group of pharmaceutically promising substances. These compounds are produced by commensal microorganisms naturally occurring in marine invertebrates, mainly in bryozoans. The most frequently investigated substance is bryostatin-1, which is a highly oxygenated macrolide with a polyacetate backbone.

Monitoring of mutarotation of monosaccharides by hydrophilic interaction chromatography.

Calibration based on the "single-point calibration method", a simple exponential transformation of the response function of an evaporative light scattering detector was improved and applied to analysis of selected saccharides under hydrophilic interaction chromatography mode (a polar phase LiChrospher100 DIOL, mobile phase acetonitrile/water). The improved approach to the calibration procedure yielded a calibration curve with an excellent linearity (quality coefficient <5%). This quantitative evaluation of chromatograms of D-galactose suggested that not only anomers but even pyranose and furanose forms of the anomers could be resolved--the resulting calculations of abundance of the anomeric form strongly correlated with data from the literature obtained mostly by NMR studies (analogous results were also obtained for D-arabinose, D-glucose, and D-mannose).

Electroosmotic flow changes due to interactions of background electrolyte counter-ions with polyethyleneimine coating in capillary zone electrophoresis of proteins.

The properties and behavior of polyethyleneimine (PEI) covalently coated capillaries with respect to different background electrolytes used in capillary zone electrophoresis (CZE) are described. The coating stability and changes of inner surface charge in the capillary were followed by measurement of electroosmotic flow (EOF). Interest was focused mainly on conjugate bases of carboxylic acids as anionic background electrolyte components (acetate, citrate, malate, malonate, tartrate, and succinate).

Continuous mode of operation for large volume dosing in analytical carrier ampholyte-free isoelectric focusing of proteins applied to off-line detection of fractions.

Mass spectrometry is being increasingly used for analysis of proteome complex samples. Sample preparation is often necessary to remove matrix interferences and to concentrate analytes prior to MS measurement. A useful method for this purpose is Carrier Ampholyte Free-Isoelectric Focusing (CAF-IEF).

Optimization of solid-phase extraction using artificial neural networks in combination with experimental design for determination of resveratrol by capillary zone electrophoresis in wines.

Solid-phase extraction (SPE) is often used for preconcentration of analytes from biological samples. Such an analytical step requires optimization for obtaining reliable results. Optimization in analytical chemistry is traditionally still often done with relaxation method, when an optimal value of a single variable is searched for (single variable approach (SVA)).

Simultaneous determination of trans-resveratrol and sorbic acid in wine by capillary zone electrophoresis.

A method for separation and determination of sorbic acid, a food and beverage preservative, and trans-resveratrol, a biomedically active substance, in wine by capillary zone electrophoresis is described. A solid-phase extraction step on C18-column prior to the electrophoretic separation providing lower detection limits was used for trans-resveratrol determination. For determination of sorbic acid direct analysis of wine (without a preconcentration step) was used.

Electrophoretic behavior of adamantane derivatives possessing antiviral activity and their determination by capillary zone electrophoresis with indirect detection.

Separation and determination of adamantane derivatives with antiviral activity, namely amantadine (1-adamantan amine), memantine (1-amino-3,5-dimethyl adamantane) and rimantadine (alpha-methyl-1-adamantane methylamine), were examined by capillary zone electrophoresis. After optimization, an indirect detection method using 5 mM 4-methylbenzylamine in ethanol/water solution (1:4) as simultaneously absorbing and buffering background electrolyte with detection at 210 nm was found suitable for determination of the individual compounds (limit of detection was 0.35 mg L(-1) for memantine hydrochloride, S/N = 3).