Michal Roth

Institute of Analytical Chemistry, Czech Academy of Sciences, Fluid Phase Separations, Faculty Member

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Papers by Michal Roth

Effect of column inlet concentration profile on the sensitivity of analysis. A quantitative assessment

Journal of Chromatography, 1987

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Sensitive identification of milk protein allergens using on-line combination of transient isotachophoresis/micellar electrokinetic chromatography and capillary isoelectric focusing in fused silica capillary with roughened part

Food Chemistry, May 1, 2022

A method for on-line concentration of milk proteins from large sample volumes using combination o... more A method for on-line concentration of milk proteins from large sample volumes using combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) in fused silica capillary with an inner roughened part has been developed. The method utilizes reversible dynamic adsorption of proteins onto a thin layer of PEG 4000 on the roughened surface of the capillary. In addition, the tITP/MEKC method was combined with capillary isoelectric focusing (CIEF) for on-line concentration, separation, identification and sensitive determination of proteins in skimmed milk. The method allows analysis of up to 50 μL of sample. This study has focused on the four important whey proteins, bovine serum albumin (BSA), α-lactalbumin (α-LA), and two genetic variants of β-lactoglobulin (β-LG A and β-LG B). The proteins were identified on the basis of their migration times and characteristic pI values. The pI values of BSA, α-LA, β-LG A, and β-LG B were determined as 4.7, 4.4, 5.1, and 5.2, respectively. Limits of detection for BSA, α-LA and both β-LG variants were found as 1.2, 1.0 and 1.0 pg mL-1, respectively. The linearity of calibration curves was characterized by the R2 = 0.9982. The method provided highly reproducible results as the relative standard deviations of the migration times and peak areas of the examined proteins did not exceed 1.6%.

Capillary electrophoretic methods for classification of methicillin-resistant Staphylococcus aureus (MRSA) clones

Analytica Chimica Acta

Bacteriophage replication on permissive host cells in fused silica capillary with nanostructured part as potential of electrophoretic methods for developing phage applications

Talanta, 2021

Phage therapy could offer a safe and effective alternative to antibiotic treatment of infections ... more Phage therapy could offer a safe and effective alternative to antibiotic treatment of infections caused by Grampositive bacterium Staphylococcus aureus that have emerged as a significant threat in hospital and community environment and is attracting growing interest among clinicians. The legislation process of approving the phage therapeutics by pharmaceutical authorities requires rapid analytical techniques for assessment of phage activity. Here, we present a three-step method for on-line monitoring the phage effect on bacterial cells dynamically adhered from microliter volumes of high conductivity matrix onto the inner surface of fused silica capillary with a part etched with supercritical water. Phage K1/420 particles of the Kayvirus genus generated by propagation on the host S. aureus cells together with the uninfected cells were concentrated, separated and detected using capillary electrophoretic methods. The phage interactions with selected S. aureus strains exhibiting differences in phage susceptibility were compared. The method allowed determination of the phage burst size and time of phage latent period in analyzed strains. Apart from enumeration of bacteriophages by the plaque assays, the proposed method is suitable for phage activity testing.

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Fabrication of monolithic capillary columns with inner diameter 50–530 μm employing a mixture of pentaerythritol tetraacrylate and polyhedral oligomeric silsesquioxane‐methacrylate as crosslinkers

Journal of Separation Science, 2022

Highly crosslinked monolithic capillary columns with inner diameters in the range of 50–530 μm we... more Highly crosslinked monolithic capillary columns with inner diameters in the range of 50–530 μm were prepared by radical polymerization of pentaerythritol tetraacrylate, polyhedral oligomeric silsesquioxane‐methacrylate, and n‐octadecyl methacrylate in the presence of methanol, dodecyl alcohol, and polyethylene glycol lauryl ether. Columns were evaluated by inverse size‐exclusion chromatography employing a set of polystyrene standards of narrow molecular‐size distribution and by scanning electron microscopy. Chromatographic performance under reversed‐phase conditions was also evaluated. The combination of two effective crosslinkers as pentaerythritol tetraacrylate and polyhedral oligomeric silsesquioxane‐methacrylate in the polymerization mixture allows for the preparation of robust and efficient monolithic capillary columns within a fairly wide range of internal diameters.

Evaluation of tertiary phosphate esters as stationary phases for gas—liquid chromatography

Journal of Chromatography A, 1984

Abstract Fifteen tertiary phosphate esters were tested for their polarity and volatility. The pol... more Abstract Fifteen tertiary phosphate esters were tested for their polarity and volatility. The polarities of the phosphates investigated range from that of polyphenyl ethers to that typical of Carbowaxes, and their volatilities are by about one to three orders of magnitude lower than that of squalane. The merits of tertiary phosphate esters as stationary phases for gas—liquid chromatography are discussed.

Comparison of the distribution constants of benzene in different chromatographic sorbent-gas systems. Determined by direct measurement of sorption equilibria and calculated from gas chromatographic retention data

Journal of Chromatography A, 1981

... Janak et al.22 first applied an adsorbent (Tenax GC) to equilibration trapping. having obtain... more

Rapid Isolation, Propagation, and Online Analysis of a Small Number of Therapeutic Staphylococcal Bacteriophages from a Complex Matrix

ACS Infectious Diseases, 2020

A method for fast isolation, propagation and characterization of very low-count bacteriophages ac... more A method for fast isolation, propagation and characterization of very low-count bacteriophages active against pathogenic bacterial strains is described in this study. Bacteriophages in the count of 102 phage particles were dynamically adhered from the maximum 10 mL of blood plasma sample onto the nano-structured part of the fused silica capillary. One-step propagation of phage particles of the genus Kayvirus inside the etched capillary on 104 Staphylococcus aureus host cells increased their amount to 6×104 phage particles. Phage particles were on-line concentrated and separated by capillary electrophoretic methods. No phage replication occurred when the phage resistant S. aureus or Escherichia coli cells were used. Two-step phage propagation in the capillary allowed increase total virion count up to 6×105 phage particles and subsequent off-line matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry analysis of the phage zone collected after capillary electrophoresis. Relative standard deviations of the phage peak area were at most 2.3%. We expect that the method of isolating bacteriophages from blood plasma and their simultaneous identification will facilitate clinical studies of phage preparations and contribute to pharmacokinetics studies during phage therapy. The approach is also suitable for capturing and enrichment of new phages from environment when susceptible indicator strain is available.

Correlation of gas chromatographic specific retention volumes of homologous compounds with temperatures and methylene number

Journal of Chromatography A, 1980

The specific retention volumes of homologous compounds can be expressed by log v, = &z/T')-Iq/T f... more The specific retention volumes of homologous compounds can be expressed by log v, = &z/T')-Iq/T f plr + s, where n is the number of methylene groups in the solute molecule, T is the absolute temperature and p, q, r and s are constants related to the thermodynamic properties of the chromatographic system. Generally, the specific retention volumes measured for four homologues at different temperatures are suflkient for determining the constants of the equation. The accuracy of the V, values calculated for given n,T data by the equation is commensurate with the precision of replicate determinations of the V, value of a given compound on a given instrument.

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Correlation and quantum-chemical interpretation of electrochemical reduction of substituted β-chlorovinyl ketones

Collection of Czechoslovak Chemical Communications, 1981

p-Substituted phenyl-2-chlorovinyl ketones undergo two-electron reduction at mercury dropping ele... more p-Substituted phenyl-2-chlorovinyl ketones undergo two-electron reduction at mercury dropping electrode in 0.1M-H2SO4/CH3OH medium. Localization energy calculations have shown the carbon-halogen bond to be the reaction centre in these molecules containing three potential reaction centres; in accordance with results of preparative electrolysis the first reaction step consists in reductive splitting off of the halogen. The half-wave potential values of individual derivatives correlate successfully with the calculated values of localization energies; the deviations found with the non-substituted and phenylsubstituted derivatives differing from the other compounds by magnitude of their π electron system are ascribed to the approximations involved in the simple HMO method.

Solute retention in supercritical fluid chromatography as a function of pressure: A thermodynamic analysis

The Journal of Supercritical Fluids, 1990

Abstract The pressure dependence of the solute retention in a hypothetical, isothermal, isobaric,... more Abstract The pressure dependence of the solute retention in a hypothetical, isothermal, isobaric, chromatographic column is discussed in terms of the thermodynamic properties involved. In general, the logarithm of the solute capacity ratio decreases with increasing pressure along an S-shaped curve. To a first approximation, the point of inflection occurs at the pressure corresponding to the maximum compressibility of the mobile-phase fluid at the column temperature. The occurrence of a high-pressure minimum in retention at a constant temperature of the column is possible but unlikely to be observed within the practical range of operating pressure in supercritical fluid chromatography (SFC. The pressure course of the solute retention in SFC is compared with the pressure dependence of the solute solubility in pure solid-supercritical fluid phase equilibria. The sorption of the mobile phase into the stationary phase is shown to be a significant source of uncertainty in the thermodynamic interpretation of the solute retention in SFC.

Identification of Aspergillus Conidia in Bronchoalveolar Lavage Using Offline Combination of Capillary Electrophoresis in Supercritical Water-Treated Fused Silica Capillary and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Analytical Chemistry

Diagnosis of fungal infection in lung parenchyma is relatively difficult. Bronchoscopy with bronc... more Diagnosis of fungal infection in lung parenchyma is relatively difficult. Bronchoscopy with bronchoalveolar lavage is very useful in its diagnosing. Therefore, a method for rapid on-line concentration and analysis of Aspergillus conidia in bronchoalveolar lavage fluid using combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) with subsequent off-line identification of the separated conidia by matrix-assisted laser desorption/ionization time-of-ﬂight mass spectrometry (MALDI-TOF MS) is described in this study. In the proposed procedure, conidia were first dynamically adhered onto the roughened part of the inner surface of fused silica capillary prepared by etching with supercritical water. Then the adhered conidia were desorbed, concentrated, and separated using combination of tITP and MEKC. Finally, the fractions containing the separated conidia were collected from the capillary and analyzed by MALDI-TOF MS. Adhesion efficiency under the optimized experimental conditions was about 80 %. This rapid diagnosis will contribute to timely initiation of therapy and increase the patient's chances of survival.

Isolation of Quaternary Benzo[c]phenanthridine Alkaloids from Macleaya microcarpa ( maxim.) fedde: Comparison of Maceration, Soxhlet Extraction and Pressurised Liquid Extraction

Phytochemical Analysis, 2012

Macleaya microcarpa (Papaveraceae family) has been of considerable interest in recent years as a ... more Macleaya microcarpa (Papaveraceae family) has been of considerable interest in recent years as a prospective source of quaternary benzo[c]phenanthridine alkaloids (QBAs) related to many pharmaceutical beneficial effects. For this purpose, a quantitative, efficient and fast method to isolate the QBAs from the plant material is required. To optimise and compare pressurised liquid extraction (PLE) with Soxhlet extraction and maceration in order to estimate extraction conditions for fast and efficient isolation of QBAs contained in the roots of Macleaya microcarpa. The QBAs were extracted by PLE, Soxhlet extraction and maceration at different conditions (solvent, time, etc.). Reversed phase HPLC with diode-array detector was utilised for their determination and quantification. To optimise the PLE procedure, the variable parameters, including temperature (40-150 °C), sample-to-inert material ratio, extraction time (5-30 min) and number of extraction cycles (1-4), were also tested. Quantitative determination of QBAs resulted in 0.2-2.8 mg/g, 0.3-2.5 mg/g and 0.3-3.1 mg/g for PLE, Soxhlet extraction and maceration. To produce the yields mentioned above, PLE required only up to 30 min compared with 21 h for Soxhlet extraction and 49 days for maceration. PLE provided an effective and fast extraction of QBAs from M. microcarpa roots and can be recommended as an alternative isolation method to conventional techniques for QBAs from the plant sources.

Immobilization of natural lipid biomembranes and their interactions with choline carboxylates. A nanoplasmonic sensing study

Biochimica et Biophysica Acta (BBA) - Biomembranes

Cohesive Energy Densities Versus Internal Pressures of Near and Supercritical Fluids

Molecules

Over half a century ago, Wiehe and Bagley suggested that a product of the internal pressure and m... more Over half a century ago, Wiehe and Bagley suggested that a product of the internal pressure and molar volume of a liquid measures the energy of nonspecific intermolecular interactions whereas the cohesive energy reflects the total energy of intermolecular interactions in the liquid. This conjecture, however, has never been considered in connection with near and supercritical fluids. In this contribution, the cohesive energy density, internal pressure and their ratios are calculated from high precision equations of state for eight important fluids including water. To secure conformity to the principle of corresponding states when comparing different fluids, the calculations are carried out along the line defined by equality between the reduced temperature and the reduced pressure of the fluid (Tr = Pr). The results provide additional illustration of the tunability of the solvent properties of water that stands apart from those of other near and supercritical fluids in common use. In ...

Supercritical water-treated fused silica capillaries in analytical separations: Status review

Journal of chromatography. A, Jan 2, 2018

Near- and supercritical water (SCW) has recently been shown to provide an unusual but effective t... more Near- and supercritical water (SCW) has recently been shown to provide an unusual but effective tool to roughen the inner surface or manipulate the internal diameter of fused silica capillaries for analytical separation methods In this review, the to-date existing variants of instrumental arrangement for etching the fused silica capillaries with SCW are described, the currently accessible morphologies of SCW-etched capillaries are outlined, and both existing and prospective applications of the SCW-etched capillaries in analytical separations are briefly discussed. Relative merits of SCW and other agents to treat the inner surfaces of fused silica capillaries are also mentioned.

Pre-concentration and separation of bacteria by volume coupling electrophoresis on supercritical water-etched fused silica capillary with two segments of different internal diameters and inner surface roughnesses

Analytical and bioanalytical chemistry, Jan 23, 2017

The transient isotachophoretic stacking and sweeping was used for the on-line large-volume sample... more The transient isotachophoretic stacking and sweeping was used for the on-line large-volume sample pre-concentration of bacteria, Escherichia coli and Staphylococcus aureus cells (methicillin-susceptible or methicillin-resistant), in the initial stage of micellar electrokinetic chromatography using a non-ionogenic surfactant or of capillary electrophoresis, respectively. These procedures were employed in single-piece fused silica capillary etched with supercritical water with two different internal diameter segments featuring different inner surface roughness. Large volumes (maximum 2.8 μL) of the high conductivity sample matrices, physiological saline solution, urine or blood (with purification step), spiked with examined cells were injected into the wider end of a capillary with an inlet inner diameter 195 μm. This novel on-line combination of preconcentration strategies for cells produced an up to 680-fold increase in sensitivity for E. coli or S. aureus cells. The average calcula...

Interaction second virial coefficients for (CO2+n-CmH2m+2) with (m=21 to 40) from supercritical fluid chromatography

The Journal of Chemical Thermodynamics

Partition Coefficients of Organics between Water and Carbon Dioxide Revisited: Correlation with Solute Molecular Descriptors and Solvent Cohesive Properties

Environmental science & technology, Jan 6, 2016

High-pressure phase behavior of systems containing water, carbon dioxide and organics has been im... more High-pressure phase behavior of systems containing water, carbon dioxide and organics has been important in several environment- and energy-related fields including carbon capture and storage, CO2 sequestration and CO2-assisted enhanced oil recovery. Here, partition coefficients (K-factors) of organic solutes between water and supercritical carbon dioxide have been correlated with extended linear solvation energy relationships (LSERs). In addition to the Abraham molecular descriptors of the solutes, the explanatory variables also include the logarithm of solute vapor pressure, the solubility parameters of carbon dioxide and water, and the internal pressure of water. This is the first attempt to include also the properties of water as explanatory variables in LSER correlations of K-factor data in CO2-water-organic systems. Increasing values of the solute hydrogen bond acidity, the solute hydrogen bond basicity, the solute dipolarity/polarizability, the internal pressure of water and ...

Fused silica capillaries with two segments of different internal diameters and inner surface roughnesses prepared by etching with supercritical water and used for volume coupling electrophoresis

Electrophoresis, May 22, 2017

In this work, single-piece fused silica capillaries with two different internal diameter segments... more In this work, single-piece fused silica capillaries with two different internal diameter segments featuring different inner surface roughness were prepared by new etching technology with supercritical water and used for volume coupling electrophoresis. The concept of separation and online pre-concentration of analytes in high conductivity matrix is based on the online large-volume sample pre-concentration by the combination of transient isotachophoretic stacking and sweeping of charged proteins in micellar electrokinetic chromatography using non-ionogenic surfactant. The modified surface roughness step helped to the significant narrowing of the zones of examined analytes. The sweeping and separating steps were accomplished simultaneously by the use of phosphate buffer (pH 7) containing ethanol, non-ionogenic surfactant Brij 35, and polyethylene glycol (PEG 10000) after sample injection. Sample solution of a large volume (maximum 3.7 μL) dissolved in physiological saline solution was...

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