Capillary electrophoretic study of synthesis of polyhexamethyleneguanidine

Synthesis of polyhexamethyleneguanidine hydrochloride was studied by capillary electrophoresis. A procedure for determining the reaction components was developed.     

Electroviscous Forces on a Charged Cylinder Moving Near a Charged Wall

The refined theory of the electroviscous lift forces is presented for the case when the separation distance between the particle and the wall is larger than the double-layer thickness. The theory is based on the lubrication approximation for motion of a long cylinder near a solid wall in creeping flow. The approximate analytical formula for the lift force valid for Pe相似文献   

Study of a gentamicin-selective membrane polymer matrix by infrared spectroscopy

To establish the composition of the gentamicin complex (GNMC) of copper(II) in the polymer matrix of an ion-selective membrane (ISM), we investigated spectra of the ISM upon both incorporation of the GNMC and its complex with copper(II) by the IR spectrometry method. A number of spectral changes were revealed: the appearance and disappearance of some absorption bands and batho- and hypsochromic shifts accompanied by the substantial rearrangement of the bands’ intensities. The observed effects are indicative of the change of the distribution of the charge within the molecule, the formation of new bonds, and rotational transformation in the formation of a chelate cycle. This confirms not only the presence of a complex in the polymer matrix but also that its structure is identical to the one found in solution before.     

Multistep flow-membrane filtration,gel-permeation chromatography,and spectrophotometric determination of polydisperse compounds

To determine the molecular weight distribution of natural polydisperse compounds (peat humic acids) and synthetic substituted polyvinyls, membrane filtration, gel-permeation chromatography, and spectrophotometric determination procedures were developed. The determination limit of polyvinyls was 0.1–0.2 mg/mL. The absorbance of polyvinyl solutions was a linear function of the concentration over the range 0.1–6.0 mg/mL. It was found that the size-fraction distributions of both humic substances and substituted polyvinyls depended not only on the molecular weight, but also the molecular conformation.     

Size and phase fractionation of water components by membrane filtration Distribution patterns for arsenic, iron and manganese in aqueous effluents of tin ore settling plant

The possibility of on-line membrane size-fractionation of water components and simultaneous separation of particulate and dissolved matter at each filtration stage has been shown. The distribution patterns have been studied for As, Fe and Mn in effluent samples of tin ore tailings (Altenberg, Saxony, Germany). The seepage composition is characterized by high concentrations of Fe and As. The particulate and dissolved components were separated in five fractions between 0.025 and 8 μm. It was suggested that the distribution patterns of As and Fe compounds depend on the chemical conditions at the sampling sites. Manganese exists mainly in solvated forms in the liquid fractions.     

Detection and quantification of chitosan aggregates by pressure-assisted capillary zone electrophoresis

An approach to the detection and determination of chitosan aggregates in acetic acid solutions is proposed using pressure-assisted capillary zone electrophoresis. Processes of chitosan aggregation are studied depending on the composition of dispersion medium and storage time. The presence of several species of positively charged chitosan aggregates is revealed for the first time. Particle sizes in the range 20–2500 nm are determined by scanning electron microscopy and static and dynamic light scattering. The dependence of the shape of electropherograms on particle size distribution obtained under the same conditions is found. A trend to changing electrophoretic mobility depending on the size of the aggregate is observed, which enables the approximate evaluation of the polydispersity of chitosan solutions. Chitosan is used for the effective dynamic modification of capillaries, which does not require the introduction of a modifier into the background electrolyte.     

Determination of polyhexamethyleneguanidine by capillary electrophoresis

The electrophoretic behavior of polyhexamethyleneguanidine hydrochloride (PHMG HC), hexamethylenediamine (HMDA), and guanidine hydrochloride (GHC) was studied. It was shown that PHMG HC and the initial toxic components of its synthesis, GMDA and GHC, can be separated. A procedure was developed for determining PHMG HC oligomers, GMDA, and GHC in aqueous solutions in concentrations from 0.007 to 0.05 mg/mL by capillary electrophoresis. The procedure was applied to the analysis of model mixtures of these compounds.     

Application of pressure in capillary zone electrophoresis to study the aggregation of chitosan 2-hydroxybutoxypropylcarbamate

It is demonstrated that the use of pressure extends the possibilities of capillary zone electrophoresis in studying aggregative states of substances, ensuring the detection of the presence of several types of aggregates with different electrophoretic mobilities. The electropherograms of chitosan 2-hydroxybutoxypropylcarbamate (CHBPC) in citrate solutions with pH 3.1, 4.5, and 5.8 indicate the dependence of aggregation on pH. A comparison of the data for CHBPC obtained by capillary zone electrophoresis, static light scattering, and scanning electron microscopy revealed a relationship between the electrophoretic mobility and sizes of aggregates, varying from 140 nm to several micrometers. The size of aggregates can be estimated by hydrodynamic contribution to their mobility. The effectiveness of the use of CHBPC for the dynamic modification of capillaries is shown.     

Characterization of calcium hydroxyapatite polycrystalline nanoparticles by capillary zone electrophoresis and scanning electron microscopy

A systematic study of factors affecting the parameters of the electrophoretic separation of synthetic nanocrystals of calcium hydroxyapatite is performed. Data of capillary zone electrophoresis and scanning electron microscopy are compared. Optimal conditions for the determination of calcium hydroxyapatite by capillary zone electrophoresis are selected. It is shown that calcium hydroxyapatite nanoparticles are polydisperse; the nanostructures exist in a variety of clusters and floccules with characteristic sizes, which is confirmed by the coinciding data of capillary zone electrophoresis and scanning electron microscopy. A linear dependence of the normalized total area of calcium hydroxyapatite nanoparticles on their concentration in suspension is obtained.