Electrophoretic Mobility Values Research Articles

Capillary Electrophoresis as a Complementary Analytical Tool for the Separation and Detection of Nanoplastic Particles.

Capillary electrophoresis (CE) is presented as a technique for the separation of polystyrene nanoparticles (NPs, particle diameters ranging from 30 to 300 nm) through a bare fused silica capillary and ultraviolet detection. The proposed strategy was also assessed for other types of nanoplastics, finding that stronger alkaline conditions, with an ammonium hydroxide buffer (7.5%, pH = 11.9), enabled the separation of poly(methyl methacrylate), polypropylene, and polyethylene NP for the first time by means of CE for particle diameters below 200 nm. Particle behavior has been investigated in terms of its effective electrophoretic mobility, showing an increasing absolute value of effective electrophoretic mobility from the smaller to the larger sizes. On the other hand, the absolute value of surface charge density decreased with increasing size of NPs. It was demonstrated and quantified that the separation mechanism was a combination of linear and nonlinear electrophoretic effects. This work is the first report on the quantification of nonlinear electrophoretic effects on nanoplastic particles in a CE system.

An innovative detection technique for capillary electrophoresis: Localized terahertz emission-time domain spectroscopy

Terahertz (THz) time-domain spectroscopy (TDS) is a recently emerging analysis method which can provide unique information on molecular vibration and rotation induced by inter/intra-molecular interactions. Although the application of THz-TDS to high-performance microscale separation methods like capillary electrophoresis (CE) has been anticipated, it has been hindered due to the diffraction limit of THz wave (typically, hundreds µm). In order to realize CE-THz-TDS, in this study, we placed a narrow open-tubular capillary on the surface of a GaAs semiconductor substrate as a “localized” THz-emitter. By focusing femtosecond pulsed laser beams at the surface of a gallium arsenide (GaAs) substrate closest to the capillary, THz waves were locally generated to pass through the capillary, so that THz absorbance spectra were obtained from the capillary which has narrower inner diameter than the diffraction limit. As a typical result from acetic acid analysis in the CE-THz-TDS platform, information on the refractive index and extinction coefficient was obtained, which showed non-linear and linear concentration dependence, respectively, similar to conventional THz-TDS using large liquid cells. Finally, CE-THz-TDS analysis of several carboxylic acids was demonstrated. Two acids were successfully separated and detected with THz-TDS, where their electrophoretic mobility values were estimated as close to those obtained with conventional contactless conductivity detection. Our proposed CE-THz-TDS showed the potential for the systematic analysis of inter/intra-molecular weak interactions like hydrogen bonds, which are unable to obtain with conventional detectors.

Shielding behavior of electrokinetic properties of polystyrene latex particle by the adsorption of neutral poly(ethylene oxide)

To understand the shielding of electrokinetics of colloidal particles by polymer coating, we measured the electrophoretic mobility of negatively charged polystyrene sulfate latex (PSL) adsorbed with electrostatically neutral polyethylene oxide (PEO) chains with various molecular weights under different ionic strengths. We confirmed that substantial adsorbed neutral polymer on the particle surface would decrease the absolute value of electrophoretic mobility. Even though the polymer layer is sufficiently thicker compared to the thickness of electric double layer (EDL), the electrophoretic mobility (EPM) never vanishes, which indicates the incompleteness of electrokinetic shielding by an adsorbed neutral polymer. To relate such interesting phenomena, a simple mathematical model has been proposed to evaluate the electrophoretic mobility, assuming the presence of a scaling structure of adsorbed permeable polymer layer does not influence the Poisson–Boltzmann distribution of ions in the electric double layer (EDL). An analytical expression of electrophoretic mobility under Debye-Hu¨ckel approximation has been derived using the method of Ohshima-Kondo theory, which successfully justifies the experimentally obtained data.

Binding Constants Determination of Ofloxacin and Ornidazole Enantiomers with Sulfated β-Cyclodextrin as Single Ligand by Capillary Electrophoresis using Three Different Linear Plotting Methods

The aim of this research is to use capillary electrophoresis to establish/determine the binding constants for ofloxacin and ornidazole enantiomers with the negatively charged chiral selector sulfated-β-cyclodextrin (S-β-CD). Using electrophoretic mobility values of ofloxacin and ornidazole enantiomers at various concentrations of S-β-CD used in the context of background electrolyte (BGE), binding constants were calculated using three separate linearization plots, namely double-reciprocal, X-reciprocal and Y-reciprocal. The R-ofloxacin enantiomer-S-β-CD complex had the highest inclusion affinity of the ofloxacin and ornidazole enantiomers, which matched with previously reported estimation. Every enantiomer-S-β-CD complex’s binding constants, as well as thermodynamic binding parameters, were calculated at different temperatures. The host-guest binding constants using double reciprocal fit showed greater linearity (R2 > 0.99) at all temperature ranges measured (15-30 ºC) as compared to the other two fit approaches. The thermodynamic complexation parameters were found to be dependent on the temperature of the enantiomers, as seen by the linear van’t Hoff (15-30 ºC) plot.

In Ukrainian

Development of methods for controlling the change in the functional cover and the energy composition of the surface of detonation synthesis diamond nanopowders is necessary to create stable suspensions and materials from them. The aim of this work is to study changes in the electrokinetic and electrophysical characteristics of the powder as a result of the modification of detonation synthesis diamond nanopowders using a liquid-phase thermochemical treatment. Diamond nanopowders of grades ASUD-75 - ASUD-99 with different sp2-hybridization carbon content, manufactured at the V.I. Bakul National Academy of Sciences of Ukraine from the product of detonation synthesis of diamond from the company "ALIT" (Zhytomyr) investigated. Diamond nanopowders of ASUD-90 grade after their modification by means of liquid-phase thermochemical treatment using: a melt of alkalis, a mixture of nitric and sulfuric acids, a mixture of chromic and sulfuric acids were investigated by electrophoresis using a device "Dzeta-potential-analizer" company "Mikromeritiks". Electrokinetic characteristics of diamond nanopowders: the magnitude and sign of the electrokinetic potential, electrophoretic mobility are determined. The methods were used to study the physicochemical characteristics of nanopowders: electrical resistivity, carbon content of sp2-hybridization, mass fraction of impurities in the form of an incombustible residue, and specific surface area. In this work, it was established by electrophoresis that the value of the electrokinetic potential and electrophoretic mobility of the powder decrease by 2-10 times with a decrease in the mass fraction of sp2-hybridization carbon from 23.6 to 0 wt%. Using the ASUD-90 nanopowder as an example, it is shown that the modification of the nanopowder by the liquid-phase method using thermochemical treatment with mixtures of oxidants leads to a decrease in the values ​​of electrophoretic mobility by 1.1-7.5 times and electrokinetic potential by 1.1-7.3 times. It was found by dielectric measurement that the tangent of the dielectric loss angle of diamond nanopowders of grades ASUD-90 - ASUD-99 is in the range 0.3046 - 0.3146. Modification of the ASUD-90 grade nanopowder using a liquid-phase thermochemical treatment leads to a change in the interval of the dielectric loss tangent, namely 0.2450-0.3249. According to the degree of increase in the ratio of the dielectric loss tangent from 0% humidity to 100% humidity, the methods for modifying nanopowders can be arranged as follows: modifying using a melt of alkalis (ASUD-90-1 sample, S = 12.8%) <mixture of chromic and sulfuric acids (sample ASUD-90-3, S = 13.8%) <mixture of nitric and sulfuric acids (sample ASUD-90-2, S = 20.8 %).

Approximate analytic expressions for the electrophoretic mobility of spheroidal particles

Approximate analytic expressions are derived for the electrophoretic mobility of spheroidal particles (prolate and oblate) carrying low zeta potential in an electrolyte solution under an applied tangential or transverse electric field. The present approximation method, which is based on the observation that the electrophoretic mobility of a particle is determined mainly by the distortion of the applied electric field by the presence of the particle. The exact expression for the equilibrium electric potential distribution around the particle, which can be expressed as an infinite sum of spheroidal wave functions, is not needed in the present approximation. The electrophoretic mobility values calculated with these approximate expressions for spheroidal particles with constant surface potential or constant surface charge density are in excellent agreement with the exact numerical results of previous reports with the relative errors less than about 4%.

Isolation and Characterization of Red Bean and Green Bean Protein using the Extraction Method and Isoelectric pH

Stunting children need food intake with higher protein and essential amino acids such as lysine and leucine than normal children. Red Beans (Phaseolus Vulgaris L.) and Green Beans (Phaseolus Radiatus L.) have protein content, respectively 22.07 ± 0.13% and 19.99 ± 0.07%, and are rich in essential amino acids lysine and leucine needed by a stunting child. The Development of food products with high protein concentrations (high protein food) such as isolates/protein concentrates is an important subject that must be done. This study aims to determine the technique of isolating red bean and green bean protein through extraction and deposition methods at isoelectric pH. The research method used is an experimental method with descriptive data analysis. Identification of isoelectric pH of red bean and green bean protein is done through electrophoretic mobility (cm2/Vs) testing on samples that have been conditioned at 3 different depositional pHs namely pH 3.00, 4.00, and 5.00. The results showed the isoelectric pH value of red bean and green bean protein, namely pH 4.56 and pH 4.81 respectively, where the pH had electrophoretic mobility values equal to zero. The process of isolating red bean and green bean protein produces protein powder with a protein content of 79.22 ± 0.06% and 80.69 ± 0.06%, respectively. Based on the weight yield, red bean and green bean protein concentrate powder had a yield of 14.88% and 16.75%, respectively.

Zeta potential and electrophoretic mobility for the recovery of a saline soil with organic amendments

ABSTRACT The accumulation of salts in the soil profile produces conditions that affect the growth of crops. The effects of these conditions on crops and the intensity of these effects depend on the quantity and type of salts that predominate and are also influenced by soil characteristics and climate, among other aspects. The salinization of agricultural soils is a serious problem facing agriculture today. The use of organic amendments has increased in recent years, acting on the texture of the soil, correcting compaction or granularity problems, and influencing chemical and/or biological reactions. The objectives of this work were to analyze the use of compost and vermicompost using different analysis techniques to determine the influence of conditions on the remediation of a saline soil. In saturation extracts of soil, compost, and vermicompost, a Zeta potential value 2.34-2.44 times more negative (more-stable colloids) than that in the soil colloids was observed in the amendments. The values of electrophoretic mobility were more negative in the organic amendments compared with the soil. This is the first time that these parameters have been reported for these purposes and for a saline soil. In this study, the soil has low organic matter content (1.65%), so these amendments are expected to improve soil quality and texture, achieving the recovery of saline soils.

Preparative free-flow electrophoresis, a versatile technology complementing gradient centrifugation in the isolation of highly purified cell organelles.

Free-flow electrophoresis (FFE) exploits differences in the overall charge of bio-particles separating cells, organelles, macromolecules, ions, etc. according to their distinct electrophoretic mobility and isoelectric point (pI) values. Indeed, around a neutral pH organelles usually exhibit a negative surface charge, migrating in an electric field from the cathode toward the anode. Since its introduction more than five decades ago by Barrollier etal., Z. Naturforsch. 1958, 13b, 745-755 and Hannig, Z. Anal. Chem. 1961, 181, 244-254, FFE has become an established analytical and preparative separation method for the isolation of a variety of organelles. Particularly, in sophisticated, multistep separating processes to separate subpopulations of organelles, it has gained, meanwhile, a position as a versatile technology and essential element. Relying on the distinct surface charges instead of buoyant densities of cell organelles, the FFE technology is best supporting a preceding centrifugation-based fractionation of subcellular compartments in the second dimension. In the following review, the two-step isolation and purification of subpopulations of classic animal and plant cell organelles will be mainly exemplified.

Dynamic light scattering and electrophoretic mobility studies of starch-fatty acid complexes in solution

Electrophoretic mobility and dynamic light scattering measurements were carried out to investigate the physical characteristics of amylose inclusion complexes with a series of long chain fatty acids, in alkaline solution (0.1 N or 0.01 N KOH). Amylose molecules exhibited lower values of electrophoretic mobility compared to those of the amylose-fatty acid complexes. The presence of amylopectin affected the electrophoretic mobility of starch–fatty acid complexes. Particle size distribution measurements of amylose-fatty acid complexes in aqueous suspension (pH 4.6) were performed employing the laser light scattering technique. The size of the diameter of the complexes in alkaline solution was found to be much smaller than that of the size of the complexes in aqueous suspension. The results are discussed in the light of solvent contribution to the conformational changes of the complexes occurred in the environments employed.

Dynamics of nonlinear electrophoretic motion of dielectric microparticles in nematic liquid crystal

The dynamics of dielectric microparticles motion in nematic liquid crystal cells with in-plane electrodes was investigated. It was found that the microparticles motion was driven by the Stokes drag and electrophoretic forces in the middle part of the electrodes gap. At low electric field strengths (E<0.4V/μm), the electrophoresis of microparticles is linear whereas for E>0.4V/μm it has nonlinear nature, due to the induced charges in electric double layers near the microparticles boundary (q~E2). Independently on the NLC alignment, this nonlinearity leads to the cubic dependence of the microparticles velocity on the electric field strength (v~E3). But, the value of nonlinear electrophoretic mobility (μ(3)) of microparticles is a function of the alignment and the parameters of NLC as well as the dielectric permittivity of the microparticles. Near the electrodes, the dielectrophoretic and the elastic trapping forces significantly influence the motion dynamics of microparticles.

Acidity of substituted cathinones studied by capillary electrophoresis using the standard and fast alternative approaches

Cathinone derivatives are notorious but still weakly characterized molecules, known mainly as components of the designer and illicit drugs. The knowledge on their acidity is scarce and incomplete, therefore, we decided to determine the pKa values for six of them: 2-methylmethcathinone, 3-methylmethcathinone, 4-methylmethcathinone, α-pyrrolidinovalerophenone, methylenedioxypyrovalerone and ephedrone. For that purpose we employed capillary electrophoresis, which is known for its accurateness in comparison to other analytical techniques. We used and compared two methodologically different approaches. The standard method relied on measuring electrophoretic mobility across the broad pH range and fitting the sigmoidal function. The obtained pKa values were in the range 8.59–9.10, thus these molecules remain mostly protonated and positively ionized in the physiological conditions. The alternative two-values (TVM) and one-value methods (OVM), proposed by us previously, have been used herein for the first time to the cationic molecules. TVM enables estimation of pKa using only two electrophoretic mobility values, referring to the total and partial ionization. OVM requires only a single measurement because mobility of ion is predicted theoretically. Both TVM and OVM yielded only a small deviation of pKa from the standard approach, averagely 0.07–0.09pH unit. Two important issues have also been addressed: the potential of a maximally fast calculation method using no repetition at the given pH, and the accuracy of method with regard to pH attributed to partial ionization. As a whole, the analytical potential of the TVM/OVM approach seems to be huge and invaluable for fast pKa screening/estimation.

Electrophoretic mobility of carboxyl latex particles: effects of hydrophobic monovalent counter-ions

To investigate the effect of hydrophobicity on the charge reversal of colloidal particles, we measured and analyzed the electrophoretic mobility (EPM) of carboxyl latex particles in mixed electrolytes solutions containing potassium chloride KCl and tetraphenylphosphonium chloride TPPCl. Tetraphenylphosphonium (TPP+) ion strongly adsorbs on the particle surface due to its hydrophobicity and thus causes the charge reversal/overcharging. Measurements of EPM were carried out as functions of pH, ionic strength, and the mixed molar ratio of X = [TPP+]/[K+] to unveil the influence of surface charge on hydrophobic interaction. Experimental EPM was analyzed by using 1-pK H Stern Gouy Chapmann model with the Ohshima equation including the relaxation effect or the Smoluchowski equation neglecting the relaxation effect for calculating theoretical EPM values. Our results demonstrate that carboxyl latex particles show charge reversal indicated by positive EPMs at low pH due to the accumulation of TPP+ ions on the surface and the reversed EPM values at low pH are augmented with increasing the mixed molar ratio of X = [TPP+]/[K+]. Also, we observed that charge re-reversal at higher pH as the deprotonation of surface carboxyl groups proceeded. The pH at which the charge re-reversal occurred increased with increasing the mixed molar ratio. From the comparison between our experiments and theoretical analysis, we found that the intrinsic energy of adsorption decreases with increasing the surface charge density to describe the observed charge re-reversal. These results indicate that the intrinsic adsorption energy of TPP+, which is probably due to hydrophobic interaction, decreases with increasing the surface charge density.

DESIGN AND EVALUATION OF A NEW ELECTROPHORETIC MOBILITY MEASUREMENT INSTRUMENT USING MICROELECTROPHORESIS SYSTEM WITH IMAGE PROCESSING METHOD

Electrophoretic mobility (EPM) measurement on biological particles in fluids is well established. The current method in measuring EPM is using laser which the target particles are not visible. Additional morphology information is critical for the EPM measurement. Image processing is a promising method to obtain the EPM together with the morphology information. In this study, a setup of micro electrophoresis system with a compact CCD microscope was constructed. This setup was equipped with image processing method for capturing the images of the moving particles in an electric field. With the image processing method (Horn–Schunck method), the images captured were processed in real time to obtain the EPM of the particle. Velocity of the particles was then measured and the particles’ EPM was obtained. With the captured images of the particles in real time, the system can present the image of the targeted particle together with the EPM value. The setup of this prototype was calibrated with discrete particles (Polystyrene microsphere size of 10[Formula: see text][Formula: see text]m[Formula: see text] 5%) and with a magnification value of 125[Formula: see text]X. This system is suitable for the surface charge measurement of discrete particle with size in between 4[Formula: see text][Formula: see text]m and 20[Formula: see text][Formula: see text]m. Comparison of commercialized device with our laboratory setup for calibration on EPM of polystyrene beads had a variance of solely 13%. Measurement on yeast cells, normal (hFob 1.19) and cancer bone cells (U2OS) indicated that the EPM of yeast became highly negative in the pH value of 4.5 and 6.5. The negative EPM of the cancer cell is slightly larger than that of the normal cell for pH ranging from 4.4 to 5.0. In conclusion, the real-time EPM measurement set up for this study is able to display the real-time images of the moving particles in fluid suspension during measurement.

Solid Phase Micro Membrane Tip Extraction and Capillary Electrophoresis of Metformin in Urine Samples

Background: Metformin is very important anti-hyperglycemic drug for non-insulin reliant diabetes mellitus. It excretes through urine. Therefore, its analysis is an important issue; especially with versatile capillary electrophoresis method. Introduction: Inexpensive solid phase micro membrane tip extraction (SPMMTE) and capillary electrophoretic (CE) methods were presented for monitoring of metformin in urine sample. Method: Iron nano composite adsorbent was prepared by green chemistry for SPMMTE. CE experimental conditions were fused silica capillary (60 cm x 50 µm I.D.), phosphate buffer (50 mM, 3.0 pH) as back ground electrolyte (BGE), 20 kV applied voltage, 254 nm detection, 20 seconds injection time and 27±1 ºC working temperature. Results: The values of electrophoretic mobility, electroosmotic mobility, migration time, number of theoretical plates and velocity were 2.71 x 10-2 cm2V-1s-1, 3.50 x 10-4 cm2V-1s-1, 10.05 minutes, 14,400 and 5.42 cm min-1, correspondingly. The % recoveries of metformin in the laboratory prepared solution in water and urine samples were 90 and 80%. Conclusion: It was observed that the developed SPMMTE and CE methods may be used to analyse metformin in any urine sample. Keywords: Fe nano composite adsorbent, solid phase membrane tip extraction, capillary electrophoresis, metformin, urine sample, analysis.

Characterization of complexes between phenethylamine enantiomers and β-cyclodextrin derivatives by capillary electrophoresis-Determination of binding constants and complex mobilities.

To optimize chiral separation conditions and to improve the knowledge of enantioseparation, it is important to know the binding constants K between analytes and cyclodextrins and the electrophoretic mobilities of the temporarily formed analyte-cyclodextrin-complexes. K values for complexes between eight phenethylamine enantiomers, namely ephedrine, pseudoephedrine, methylephedrine and norephedrine, and four different β-cyclodextrin derivatives were determined by affinity capillary electrophoresis. The binding constants were calculated from the electrophoretic mobility values of the phenethylamine enantiomers at increasing concentrations of cyclodextrins in running buffer. Three different linear plotting methods (x-reciprocal, y-reciprocal, double reciprocal) and nonlinear regression were used for the determination of binding constants with β-cyclodextrin, (2-hydroxypropyl)-β-cyclodextrin, methyl-β-cyclodextrin and 6-O-α-maltosyl-β-cyclodextrin. The cyclodextrin concentration in a 50 mM phosphate buffer pH 3.0 was varied from 0 to 12 mM. To investigate the influence of the binding constant values on the enantioseparation the observed electrophoretic selectivities were compared with the obtained K values and the calculated enantiomer-cyclodextrin-complex mobilities. The different electrophoretic mobilities of the temporarily formed complexes were crucial factors for the migration order and enantioseparation of ephedrine derivatives. To verify the apparent binding constants determined by capillary electrophoresis, a titration process using ephedrine enantiomers and β-cyclodextrin was carried out. Furthermore, the isothermal titration calorimetry measurements gave information about the thermal properties of the complexes.

Cranberry Proanthocyanidins - Protein complexes for macrophage activation.

In this work we characterize the interaction of cranberry (Vaccinium macrocarpon) proanthocyanidins (PAC) with bovine serum albumin (BSA) and hen egg-white lysozyme (HEL) and determine the effects of these complexes on macrophage activation and antigen presentation. We isolated PAC from cranberry and complexed the isolated PAC with BSA and HEL. The properties of the PAC-protein complexes were studied by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), gel electrophoresis and zeta-potential. The effects of PAC-BSA complexes on macrophage activation were studied in RAW 264.7 macrophage like cells after treatment with lipopolysaccharide (LPS). Fluorescence microscopy was used to study the endocytosis of PAC-BSA complexes. The effects of the PAC complexes on macrophage antigen presentation were studied in an in vitro model of HEL antigen presentation by mouse peritoneal mononuclear cells to a T-cell hybridoma. The mass spectra of the PAC complexes with BSA and HEL differed from the spectra of the proteins alone by the presence of broad shoulders on the singly and doubly charged protein peaks. Complexation with PAC altered the electrophoretic mobility shift assay in native agarose gel and the electrophoretic mobility (ζ-potential) values. These results indicate that the PAC-protein complexes are stable and alter the protein structure without precipitating the protein. Fluorescence microscopy showed that the RAW 264.7 macrophages endocytosed BSA and PAC-BSA complexes in discrete vesicles that surrounded the nucleus. Macrophages treated with increasing amounts of PAC-BSA complexes had significantly reduced COX-2 and iNOS expression in response to treatment with lipopolysaccharide (LPS) in comparison to the controls. The PAC-HEL complexes modulated antigen uptake, processing and presentation in murine peritoneal macrophages. After 4 h of pre-incubation, only trace amounts of IL-2 were detected in the co-cultures treated with HEL alone, whereas the PAC-HEL complex had already reached the maximum IL-2 expression. Cranberry PAC may increase the rate of endocytosis of HEL and subsequent expression of IL-2 by the T-cell hybridomas. These results suggest that PAC-protein complexes modulate aspects of innate and acquired immune responses in macrophages.

Characterization of a hybrid-smectite nanomaterial formed by immobilizing of N-pyridin-2-ylmethylsuccinamic acid onto (3-aminopropyl)triethoxysilane modified smectite and its potentiometric sensor application

A novel N-pyridin-2-ylmethylsuccinamic acid-functionalized smectite nanomaterial was synthesized by immobilizing of N-pyridin-2-ylmethylsuccinamic acid through chemical bonding onto (3-aminopropyl)triethoxysilane modified smectite. The structural, thermal, morphological and surface properties of raw, silane-grafted and the N-pyridin-2-ylmethylsuccinamic acid-functionalized smectites were investigated by various characterization techniques. The thermal analysis data showed the presence of peaks in the temperature range from 200 °C to 600 °C due to the presence of physically adsorbed silanes, intercalated silanes, surface grafted silanes and chemically grafted silane molecules between the smectite layers. The powder x-ray diffraction patterns clearly indicated that the aminopropyl molecules also intercalated into the smectite interlayers as bilayer arrangement whereas N-pyridin-2-ylmethylsuccinamic acid molecules were only attached to 3-aminopropyltriethoxysilane molecules on the external surface and edges of clay and they did not intercalate. Fourier transform infrared spectroscopy confirms N-pyridin-2-ylmethylsuccinamic acid molecules bonding through the amide bond between the amine group of aminopropyltriethoxysilane molecules and a carboxylic acid functional group of N-pyridin-2-ylmethylsuccinamic acid molecules. The guest molecules functionalized onto the smectite caused significant alterations in the textural and morphological parameters of the raw smectite. The anchoring of N-pyridin-2-ylmethylsuccinamic acid molecules led to positive electrophoretic mobility values when compared to starting materials. N-pyridin-2-ylmethylsuccinamic acid-functionalized smectite was employed as an electroactive ingredient in the structure of potentiometric PVC-membrane sensor. The sensor exhibited more selective potentiometric response towards chlorate ions compared to the other common anionic species.

Determination of chloramphenicol in biological matrices by solid-phase membrane micro-tip extraction and capillary electrophoresis.

Solid-phase membrane micro-tip extraction (SPMMTE) and capillary electrophoresis (CE) methods were developed and validated for analysis of chloramphenicol in human plasma and urine samples. Iron composite nanoparticles were prepared using green technology. CE was carried out using a silica capillary (60 cm × 50 μm i.d.), phosphate buffer (50 mm, 8.0 pH)-acetonitrile (95:5, v/v) as the background electrolyte, 10 kV voltage, 280 nm detection, 20 s injection time and 27 ± 1°C temperature. Frusemide was used as an internal standard. The values of migration time, electrophoretic mobility, electrophoretic velocity and theoretical plates of chloramphenicol were 12.254 min, 4.44 × 10, 7.41 × 10 and 11,227. The limits of detection and quantitation of chloramphenicol were 0.1 and 1.0 μg/mL. Recovery of chloramphenicol in the standard solution was 95%. Solid-phase membrane micro-tip extraction and capillary electrophoresis methods may be used to analyze chloramphenicol in human plasma and urine samples of any patient.

Polyvinylpyrrolidone-sodium dodecylsulfate complex is a family of pseudo-polyanions with different charge densities: Evidence from capillary electrophoresis, capillary viscosimetry and conductometry

Accordance with the previously supposed polyelectrolyte-like behaviour of neutral polymer-anionic surfactant complexes, direct evidence for the formation of the pseudo-polyanions in polyvinylpyrrolidone (PVP)-sodium dodecylsulfate (SDS) solution is put forward in this paper by capillary electrophoresis (CE) experiments in assistance with capillary viscosimetry and conductometry. The contradictory phenomena of the absolute value of relative electrophoretic mobility (re) increasing while the ionization degree (α) decreasing with the increasing specific clusterization [Г] in aqueous PVP-SDS solution are explained by the finding that the PVP-SDS complex is eventually a family of PVP-SDS pseudo-polyanions with different charge densities. And it is found countercations playing an important role in the formation of the PVP-SDS pseudo-polyanions in virtue of bridge effect.