Use Of Isotachophoresis Research Articles

Dynamics of mercury content changes in snow in the heating season on the example of the city of Siedlce

Abstract The paper presents the results of research on the content of mercury in snow samples with the use of isotachophoresis. Snow samples were collected in December 2017 as well as in January and February 2018. Samples were collected in Siedlce in places where the individual heating of houses, mainly by hard coal, was visible. The highest mean content of mercury amounting to 0.36 μg/dm3 of water was determined in the snow samples collected in January 2018 in the Żwirowa housing development, and the lowest – 0.25 μg/dm3 in two housing developments: Nowe Siedlce and Topolowa, also collected in January. The snow samples collected in the Żwirowa housing development were characterised by the highest contamination with mercury compared to all the other samples collected for the analysis. The research is a continuation of pollution monitoring in the town of Siedlce in connection with the European Union recommendations on environmental protection and the ‘clean air’ programme implemented in Poland.

Isotachophoresis-Based Surface Immunoassay.

In the absence of amplification methods for proteins, the immune-detection of low-abundance proteins using antibodies is fundamentally limited by binding kinetic rates. Here, we present a new class of surface-based immunoassays in which protein-antibody reaction is accelerated by isotachophoresis (ITP). We demonstrate the use of ITP to preconcentrate and deliver target proteins to a surface decorated with specific antibodies, where effective utilization of the focused sample is achieved by modulating the driving electric field (stop-and-diffuse ITP mode) or applying a counter flow that opposes the ITP motion (counterflow ITP mode). Using enhanced green fluorescent protein (EGFP) as a model protein, we carry out an experimental optimization of the ITP-based immunoassay and demonstrate a 1300-fold improvement in limit of detection compared to a standard immunoassay, in a 6 min protein-antibody reaction. We discuss the design of buffer chemistries for other protein systems and, in concert with experiments, provide full analytical solutions for the two operation modes, elucidating the interplay between reaction, diffusion, and accumulation time scales and enabling the prediction and design of future immunoassays.

Increasing the sensitivity of microfluidics based immunoassays using isotachophoresis

We have developed a microfluidic device that enhances the sensitivity of protein immunoassays by preconcentrating the protein sample using isotachophoresis (ITP). Two approaches were followed to study the sensitivity gain achieved that way. The first approach was using antibody-coated magnetic beads loaded into a microchannel to capture the proteins within the ITP sample zone. The second was to directly bind the antibodies to the microchannel surface. The use of ITP increased the sensitivity of both the direct and the bead-based immunoassay and lowered the model protein's detection limit. Our setup also uses electrokinetic injection for sample charging, thereby sparing the need for integrating mechanical components such as pumps or valves and reducing the complexity of the setup. This work demonstrates the feasibility of using ITP as a preconcentration mechanism of proteins in immunoassays. The protein was concentrated by a factor of 100 and the assay's limit of detection was in the picomolar range. ITP can be applied to any sample of mixed content, separating and preconcentrating the desired analyte before it reaches the detection region with immobilized antibodies, without the need for separating and concentrating the sample in an independent step.

Direct determination of valproate in serum by zone electrophoresis–isotachophoresis on a column‐coupling chip

AbstractA feasibility study was performed using zone electrophoresis (ZE) coupled on‐line with isotachophoresis (ITP) sample pretreatment on a poly(methyl methacrylate) column‐coupling chip with integrated conductivity detection for direct determination of drugs in serum. Valproic acid (an antiepileptic drug), having a therapeutic range of 0.35–0.69 mmol/L (50–100 mg/L), was a test analyte while reference serum samples served as proteinaceous matrices. ITP provided in the ITP‐ZE combination a multitask sample pretreatment: (1) separation of the analyte from the serum matrix and its concentration into a narrow ITP band, (2) removal of the matrix constituents migrating in the ITP stack from the separation compartment of the chip, (3) ITP stacking of the drug released on a continuous electrophoretic decomposition of the drug‐protein complex. A high sample loadability, closely linked with the use of ITP in the first separation stage, made it possible to inject diluted serum samples with the aid of a 0.95 μL sample channel of the chip. Consequently, a 1–2 μmol/L concentration limit of quantitation for valproate from the response of the conductivity detector in the ZE stage of the combination was reached. The drug could be reliably determined in less than 10 minutes also in instances when its concentration in serum was below the lower value of the therapeutic range. 90–94% recoveries of valproate from serum samples were obtained in its direct ITP‐ZE determination when the filtration of the diluted serum (a 0.45 μm pore size filter) was the only pre‐column sample handling operation. No disturbances attributable to the precipitation of proteins from the loaded samples in the chip channels were detected.

Determination of bromate in drinking water by zone electrophoresis-isotachophoresis on a column-coupling chip with conductivity detection.

The use of capillary zone electrophoresis (CZE) on-line coupled with isotachophoresis (ITP) sample pretreatment (ITP-CZE) on a poly(methylmethacrylate) chip, provided with two separation channels in the column-coupling (CC) arrangement and on-column conductivity detection sensors, to the determination of bromate in drinking water was investigated. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the ITP-CZE separations. A high sample load capacity, linked with the use of ITP in this combination, made possible loading of the samples by a 9.2 microL sample injection channel of the chip. In addition, bromate was concentrated by a factor of 10(3) or more in the ITP stage of the separation and, therefore, its transfer to the CZE stage characterized negligible injection dispersion. This, along with a favorable electric conductivity of the carrier electrolyte solution, contributed to a 20 nmol/L (2.5 ppb) limit of detection for bromate in the CZE stage. Sample cleanup, integrated into the ITP stage, effectively complemented such a detection sensitivity and bromate could be quantified in drinking water matrices when its concentration was 80 nmol/L (10 ppb) or slightly less while the concentrations of anionic macroconstituent (chloride, sulfate, nitrate) in the loaded sample corresponding to a 2 mmol/L (70 ppm) concentration of chloride were still tolerable. The samples containing macroconstituents at higher concentrations required appropriate dilutions and, consequently, bromate in these samples could be directly determined only at proportionally higher concentrations.

Isotachophoretic crystallization of ionogenic substances in electrolyte solutions

Grounds are given for the use of isotachophoresis for the crystallization of ionogenic substances from electrolyte solutions. Regulating function is the basis of this new isotachophoresis trend. A device for isotachophoretic crystallization in capillaries, based on a capillary isotachophoresis instrument is described. The process of sodium chloride crystallization from aqueous solution is described in detail. The applicability of the general rules formulated is confirmed by crystallization of potassium and sodium chlorides, cesium nitrate and potassium perchlorate in cationic isotachophoresis, and potassium bichromate in anionic isotachophoresis.

17] Isotachophoresis

Isotachophoresis has proved to be a useful method for quantitative analysis of low molecular weight substances, especially in diluted samples. It offers some advantages for the analysis of high molecular weight substances, particularly in terms of its effective separation capabilities. Here a continuation of the present spectrum of the applications can be expected. Analytical isotachophoresis (ITP) is one of the modes of capillary electrophoresis and is suitable for analyzing the mixtures of ionogenic substances in solutions. The ITP steady state has three special features. The first is the absence of any background electrolyte in the separated zones. The second feature is the self-sharpening effect that manifests itself in that the boundaries, between the migrating sample zones, are permanently sharp. The third feature is the concentrating effect that may be characterized as follows: (1) the concentration in each sample zone is constant throughout this zone and (2) the value of this concentration is a function of the mobility of this sample and is directly proportional to the concentration of the leading substance. The use of ITP may be of special value, as an on-line preseparation technique for capillary zone electrophoresis, where the concentrating (stacking) power of ITP, is combined with the detection sensitivity of capillary zone electrophoresis (CZE), and thus the full resolving power of CZE can be utilized. Isotachophoresis can be used in the first stage, thus creating sharp zones of accumulated analytes that can serve then as a sampling stack for CZE.

Comparison of isotachophoresis, capillary zone electrophoresis and high-performance liquid chromatography for the determination of salbutamol, terbutaline sulphate and fenoterol hydrobromide in pharmaceutical dosage forms

Reversed-phase high-performance liquid chromatography (RP-HPLC), isotachophoresis (ITP) and capillary zone clectrophoresis (CZE) were applied to the determination of salbutamol, terbutaline sulphate and fenoterol hydrobromide in commercially available pharmaceutical dosage forms. The comparison showed that especially with the use of ITP, high concentrations of other charged sample components can disturb the separation process. If special attention is paid to ensure a complete separation, all methods give comparable results. For the regression lines of the calibration graphs, regression coefficients of at least ca. 0.999 and nearly zero intercepts are obtained with relative standard deviations of ca. 1–2% for peak area or zone lengths. By applying the different techniques, often different components of the sample matrix can be detected, i.e., a more complete impression of the sample composition can be obtained by using all the three techniques.

Use of isotachophoresis as a reference method for the simultaneous determination of barium and strontium

When using X-ray fluorescence spectrometry for the determination of alkali and alkaline earth metals in a silica matrix, frequent recalibration with reference samples is necessary. Determination of metals in these reference samples is carried out using classical analysis. The latter was not possible with barium and strontium in the presence of each other owing to mutual interference. Isotachophoresis, using a 0.02 mol/1 potassium—citrate leading electrolyte of pH 5.0 and magnesium chloride as a terminator proved suitable. At concentration ratios in the range 1:10 to 10:1 the accuracy and precision were well within the 1% requirement.

Isotachophoretic Examination of Interaction of Intercalators with Ribodinucleoside Monophosphates

The isotachophoretic behavior of ribodinucleoside monophosphates (XpY) was studied in aqueous solution in the presence of intercalators under neutral pH conditions. The interaction of intercalators with the ribodinucleoside monophosphates was studied by the electrophoretic retardation of the nucleotides. Among the acridine-type intercalators, proflavine and quinacrine interacted favorably with ribodinucleoside monophosphates following the order CpG>GpOUpA, while 9-aminoacridine interacted in the order UpA>GpC≈CpG. Anthraquinone-type intercalators behaved similarly, among these, 1,5-bis[(diethylaminoethyl)amino]anthraquinone interacted with the nucleotides more strongly than did 1,8-bis[(diethylaminoethyl)amino]anthraquinone. Use of isotachophoresis is discussed as a rapid and convenient method for the characterization of DNA intercalators.

Использование изотахофореза при постоянном напряжении для определения подвижности

Использование изотахофореза при постоянном напряжении для определения подвижности

Use of isotachophoresis to monitor the synthesis and purification of l-α-amino-ϵ- ketopimelate

Use of isotachophoresis to monitor the synthesis and purification of l-α-amino-ϵ- ketopimelate

Nucleotide isotachophoretic assay: Method and application for determination of ATP/ADP ratio in several rat tissues

AbstractSeparation of ATP and ADP was achieved in isotachophoresis by using malonate, inorganic phosphate (Pi), creatine phosphate and lactate as spacers, which isolate these nucleotides from other UV‐absorbing products in rat tissues. By combining isotachophoresis with enzymatic end‐point analysis of several rat tissues, calibration for ATP and ADP was achieved obtaining an operative calibration curve that allows the use of isotachophoresis as the only analytical technique in further assays. ATP and ADP quantities of rat skeletal and smooth muscle, heart, liver, kidney and lung were determined by isotachophoresis. Individual variation was also calculated by analyzing 30 animals in the same control conditions, muscular tissues showing the greatest values for ATP and ADP, whereas kidney and lung show the smaller values. ATP/ADP ratio is discussed as a representative parameter for describing the energy content in biological tissues, there are also experimental reasons which imply that other product concentrations in this parameter not be included. This ATP/ADP ratio is calculated in the rat tissues studied, as well as its individual variation, obtaining the larger values for muscular tissues and the smaller for kidney. A great individual variation is found in kidney, followed by heart and skeletal muscle, and the most constant values are found in liver and smooth muscle. The results obtained in this calibration method for isotachophoresis assay suggest the use of a similar procedure in order to apply this technique for other nucleotide analysis.

The use of isotachophoresis in the analysis of the energy metabolism in the human heart during cardioplegia for open heart surgery: W.Schmidt, E. Jansson, M. Grynfarb, V. Bomfim, and L. Kaijser. Departments of Clinical Physiology and Thoracic Surgery, Karolinska Sjukhuset, Stockholm, Sweden

The use of isotachophoresis in the analysis of the energy metabolism in the human heart during cardioplegia for open heart surgery: W.Schmidt, E. Jansson, M. Grynfarb, V. Bomfim, and L. Kaijser. Departments of Clinical Physiology and Thoracic Surgery, Karolinska Sjukhuset, Stockholm, Sweden

Application of kinetically labile complex equilibria to the separation of anions by isotachophoresis

The kinetics of complex equilibria are briefly discussed from the viewpoint of their use in isotachophoresis. The possibility of separating some anions on the basis of the kinetically labile complex equilibria was studied and the composition of leading electrolytes suitable for this type of separation is discussed. A successful separation of some anions that differ in their stability constants with Ca 2+ illustrates the separation of anions according to stability constants.

Design of a high-resolution detection system for use in isotachophoresis

Design of a high-resolution detection system for use in isotachophoresis