Email: vitezslav.maier@upol.cz
Location: 17. listopadu 12, Olomouc
Phone: (+420) 585634417
Fax: (+420) 585 634 433
Oblast výzkumu:
Elektromigrační metody, bezkontaktní voddivostní detekce, spojení CE-MS, spojení CE-LIF, separace opticky aktivních látek, on-line prekoncentrace.
Kvalifikace:
Mgr.: analytická chemie, PřF UP Olomouc
Ph.D.: analytická chemie, PřF UP Olomouc
Publications
2011
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J. Znaleziona, V. Maier, J. Petr, J. Chrastina, and J. Sevcik, “MEKC Determination of Nilutamide in Human Serum Using Sweeping in High
Salt Sample Matrix,” CHROMATOGRAPHIA, vol. 74, iss. 1-2, pp. 151-155, 2011.
[Bibtex]@article ISI:000291745400019, Author = Znaleziona, Joanna and Maier, Vitezslav and Petr, Jan and Chrastina, Jan and Sevcik, Juraj, Title = MEKC Determination of Nilutamide in Human Serum Using Sweeping in High Salt Sample Matrix, Journal = CHROMATOGRAPHIA, Year = 2011, Volume = 74, Number = 1-2, Pages = 151-155, Month = JUL, Abstract = The determination of the antiandrogen drug nilutamide in human serum by MEKC using flutamide as an internal standard is described. Several parameters influencing the separation, such as the running electrolyte composition concerning the micelle concentration and pH, are discussed. MEKC separation was achieved within 7 min using 50 mM sodium borate pH 9.0 with the addition of 50 mM sodium dodecylsulfate at +20 kV. The proposed method was applied to determination of nilutamide in spiked human serum samples after protein precipitation with acetonitrile. The increasing of sensitivity for determination of nilutamide in serum was done by sweeping in a high salt concentration sample matrix when the injection of a larger volume of sample diluted in 150 mM NaCl was applied. The limit of detection after the preconcentration step for nilutamide was 26 mu g L(-1)., DOI = 10.1007/s10337-011-2019-1, ISSN = 0009-5893, Unique-ID = ISI:000291745400019, -
J. Znaleziona, V. Maier, V. Ranc, and J. Sevcik, “Determination of rosiglitazone and metformin in human serum by CE-ESI-MS,” JOURNAL OF SEPARATION SCIENCE, vol. 34, iss. 10, pp. 1167-1173, 2011.
[Bibtex]@article ISI:000290635400010, Author = Znaleziona, Joanna and Maier, Vitezslav and Ranc, Vaclav and Sevcik, Juraj, Title = Determination of rosiglitazone and metformin in human serum by CE-ESI-MS, Journal = JOURNAL OF SEPARATION SCIENCE, Year = 2011, Volume = 34, Number = 10, Pages = 1167-1173, Month = MAY, Abstract = A new method for the determination of anti-diabetic drugs metformin and rosiglitazone based on the use of capillary electrophoresis with electrospray mass spectrometry was developed. The proposed method allowed their separation within 11 min by using 50 mM formic acid at +20 kV. Positive electrospray ionization and selected ion monitoring [M+H](+) of metformin (m/z=130) and rosiglitazone (m/z=358) were performed. Several important experimental parameters influencing electrospray ionization of metformin and rosiglitazone were studied. The final composition of sheath liquid was water/methanol/formic acid (50:49.5:0.5, v/v/v), at a flow rate of 2 mu L/min. The developed method was applied for the determination of metformin and rosiglitazone simultaneously in human serum after protein precipitation with acetonitrile. The limits of detection of developed method were 4.42 and 2.14 ng/mL for rosiglitazone and for metformin, respectively, which is sufficient for therapeutic serum concentration levels monitoring for both studied drugs., DOI = 10.1002/jssc.201000823, ISSN = 1615-9306, Unique-ID = ISI:000290635400010, -
V. Ranc, A. Stanova, J. Marak, V. Maier, J. Sevcik, and D. Kaniansky, “Preparative isotachophoresis with surface enhanced Raman scattering as a
promising tool for clinical samples analysis,” JOURNAL OF CHROMATOGRAPHY A, vol. 1218, iss. 2, pp. 205-210, 2011.
[Bibtex]@article ISI:000286700600003, Author = Ranc, Vaclav and Stanova, Andrea and Marak, Jozef and Maier, Vitezslav and Sevcik, Juraj and Kaniansky, Dusan, Title = Preparative isotachophoresis with surface enhanced Raman scattering as a promising tool for clinical samples analysis, Journal = JOURNAL OF CHROMATOGRAPHY A, Year = 2011, Volume = 1218, Number = 2, Pages = 205-210, Month = JAN 14, Abstract = A surface enhanced Raman scattering (SERS) spectrometry is an interesting alternative for a rapid molecular recognition of analytes at very low concentration levels. The hyphenation of this technique with advanced separation methods enhances its potential as a detection technique. Until now, it has been hyphenated mainly with common chromatographic and electrophoretic techniques. This work demonstrates for a first time a power of preparative isotachophoresis-surface enhanced Raman scattering spectrometry (pITP-SERS) combination on the analysis of model analyte (buserelin) in a complex biological sample (urine). An off-line identification of target analyte was performed using a comparison of Raman spectra of buserelin standard with spectra obtained by the analyses of the fractions from preparative isotachophoretic runs. SERS determination of buserelin was based on the method of standard addition to minimize the matrix effects. The linearity of developed method was obtained in the concentration range from 0.2 to 1.5 nmol L(-1) with coefficient of determination 0.991. The calculated limit of detection is in tens of pico mols per liter. (C) 2010 Elsevier B.V. All rights reserved., DOI = 10.1016/j.chroma.2010.11.025, ISSN = 0021-9673, Unique-ID = ISI:000286700600003,
2010
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D. Jirovsky, Z. Bartosova, J. Skopalova, and V. Maier, “Electrochemical characterization of repaglinide and its determination in
human plasma using liquid chromatography with dual-channel coulometric
detection,” JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL
AND LIFE SCIENCES, vol. 878, iss. 31, pp. 3243-3248, 2010.
[Bibtex]@article ISI:000285118100006, Author = Jirovsky, David and Bartosova, Zdenka and Skopalova, Jana and Maier, Vitezslav, Title = Electrochemical characterization of repaglinide and its determination in human plasma using liquid chromatography with dual-channel coulometric detection, Journal = JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES, Year = 2010, Volume = 878, Number = 31, Pages = 3243-3248, Month = DEC 1, Abstract = A simple fast and sensitive HPLC method employing dual-channel coulometric detection for the determination of repaglinide in human plasma is presented The assay involved extraction of repaglinide by ethyl acetate and isocratic reversed-phase liquid chromatography with dual-channel coulometric detection The mobile phase composition was 50mM disodium hydrogen phosphate/acetonitrile (60 40 v/v) pH of the mobile phase 7 5 set up with phosphoric acid For all analyses the first cell working potential was +380 mV the second was +750 mV (vs Pd/H(2)) Calibration curve was linear over the concentration range of 5-500 nmol L(-1) Rosiglitazone was used as an internal standard The limit of detection CLOD) was established at 28 nmol L(-1) and the lower limit of quantification (LLOQ) at 85 nmol L(-1) The developed method was applied to human plasma samples spiked with repaglinide at therapeutical concentrations It was confirmed that the method is suitable for pharmacokinetic studies or therapeutic monitoring (C) 2010 Elsevier B V All rights reserved, DOI = 10.1016/j.jchromb.2010.09.029, ISSN = 1570-0232, Unique-ID = ISI:000285118100006, -
K. Vitkova, J. Petr, V. Maier, J. Znaleziona, and J. Sevcik, “Study of electromigration effects on a pH boundary during the on-line
electrokinetic preconcentration by capillary electrophoresis,” ELECTROPHORESIS, vol. 31, iss. 16, pp. 2771-2777, 2010.
[Bibtex]@article ISI:000281732900010, Author = Vitkova, Katerina and Petr, Jan and Maier, Vitezslav and Znaleziona, Joanna and Sevcik, Juraj, Title = Study of electromigration effects on a pH boundary during the on-line electrokinetic preconcentration by capillary electrophoresis, Journal = ELECTROPHORESIS, Year = 2010, Volume = 31, Number = 16, Pages = 2771-2777, Month = AUG, Abstract = A contribution to the description of electrokinetic effects on the pH boundary formed by sodium borate pH 9.5 and sodium phosphate pH 2.5 electrolytes for on-line preconcentration of weak acids is presented in this article. Simulations of electrokinetic injections together with experimental studies using contactless conductivity detection verified that the preconcentration is induced mainly by dissociation changes of analytes on the pH boundary and transient ITP state. Moreover, a study of the addition of organic solvent to the injection electrolyte was performed with impressive results. Subnanomolar LODs of hydroxybenzoic acids were achieved with 80\% of methanol in the injection electrolyte which represents more than 70 000-fold preconcentration in comparison with classical CZE method., DOI = 10.1002/elps.200900663, ISSN = 0173-0835, Unique-ID = ISI:000281732900010, -
R. Knob, J. Marak, A. Stanova, V. Maier, D. Kaniansky, and J. Sevcik, “Determination of brominated phenols in water samples by on-line coupled
isotachophoresis with capillary zone electrophoresis,” JOURNAL OF CHROMATOGRAPHY A, vol. 1217, iss. 20, pp. 3446-3451, 2010.
[Bibtex]@article ISI:000277893500014, Author = Knob, Radim and Marak, Jozef and Stanova, Andrea and Maier, Vitezslav and Kaniansky, Dusan and Sevcik, Juraj, Title = Determination of brominated phenols in water samples by on-line coupled isotachophoresis with capillary zone electrophoresis, Journal = JOURNAL OF CHROMATOGRAPHY A, Year = 2010, Volume = 1217, Number = 20, Pages = 3446-3451, Month = MAY 14, Abstract = A method for determination of nine brominated phenols as environmental risk compounds was developed by on-line coupled capillary isotachophoresis and capillary zone electrophoresis (ITP-CZE). For ITP step, 1 x 10(-2) mol L(-1) hydrochloric acid with 3 x 10(-2) mol L(-1) ammediol pH 9.1 was used as the leading electrolyte, and 3 x 10(-2) mol L(-1) beta-alanine with 2 x 10(-2) mol L(-1) sodium hydroxide pH 10.05 was used as the terminating electrolyte. As the background electrolyte for CZE separation, 2.5 x 10(-2) mol L(-1) beta-alanine with 2.5 x 10(-2) mol L(-1) lysine pH 9.6 was used. All electrolytes contained 0.05\% or 0.1\% (m/v) hydroxyethylcellulose to suppress the electroosmotic flow. UV detection at wavelength 220nm was used. Detection limits in order of tens of nmol L(-1) were achieved. Good repeatability of migration times (less than 0.33\% RSD) and good repeatability of peak areas (less than 7.19\% RSD) at concentration level 5 x 10(-8) mol L(-1) were observed. Developed ITP-CZE method was applied to determination of brominated phenols in spiked tap and river water samples. (C) 2010 Elsevier B.V. All rights reserved., DOI = 10.1016/j.chroma.2010.03.006, ISSN = 0021-9673, Unique-ID = ISI:000277893500014, -
K. Vitkova, M. Pechova, J. Petr, J. Znaleziona, V. Ranc, V. Maier, and J. Sevcik, “A fast determination of yohimbine in pharmaceuticals by micellar
electrokinetic chromatography,” CENTRAL EUROPEAN JOURNAL OF CHEMISTRY, vol. 8, iss. 2, pp. 273-277, 2010.
[Bibtex]@article ISI:000276548300005, Author = Vitkova, Katerina and Pechova, Marketa and Petr, Jan and Znaleziona, Joanna and Ranc, Vaclav and Maier, Vitezslav and Sevcik, Juraj, Title = A fast determination of yohimbine in pharmaceuticals by micellar electrokinetic chromatography, Journal = CENTRAL EUROPEAN JOURNAL OF CHEMISTRY, Year = 2010, Volume = 8, Number = 2, Pages = 273-277, Month = APR, Abstract = A method for the fast determination of yohimbine, a potent adrenoreceptor antagonist used for the treatment of sexual dysfunctions, is proposed in this article. MEKC under basic and acidic conditions (sodium borate, pH 9.5 and sodium phosphate, pH 2.5) with SDS was developed. The effect of the experimental parameters, e. g. pH, SDS concentration and injection time, on yohimbine migration was also studied. Both methods were validated in terms of linearity, limits of detection and quantification, accuracy, and precision using caffeine as an internal standard. The application for the determination of yohimbine in hand-made medicaments is also investigated in this study., DOI = 10.2478/s11532-009-0149-1, ISSN = 1895-1066, Unique-ID = ISI:000276548300005, -
A. Stanova, J. Marak, V. Maier, V. Ranc, J. Znaleziona, J. Sevcik, and D. Kaniansky, “Analysis of buserelin in urine by online combination of capillary zone
electrophoresis with electrospray mass spectrometry,” ELECTROPHORESIS, vol. 31, iss. 7, SI, pp. 1234-1240, 2010.
[Bibtex]@article ISI:000276811000015, Author = Stanova, Andrea and Marak, Jozef and Maier, Vitezslav and Ranc, Vaclav and Znaleziona, Joanna and Sevcik, Juraj and Kaniansky, Dusan, Title = Analysis of buserelin in urine by online combination of capillary zone electrophoresis with electrospray mass spectrometry, Journal = ELECTROPHORESIS, Year = 2010, Volume = 31, Number = 7, SI, Pages = 1234-1240, Month = APR, Abstract = A fast and precise analysis of the synthetic peptide buserelin in urine using CZE-ESI-MS method has been demonstrated. Formic acid at 50 mmol/L concentration served as backgroud electrolyte in CZE stage and it is compatible with MS detection in positive ionization mode. Two injection modes were tested, i.e. pressure (50 mbar for 5 s) and electrokinetic injection (5 kV for 5 s), of which electrokinetic injection provided better calibration parameters. Buserelin LODs were 0 47 mu g/mL in water and 0 63 mu g/mL in ten times diluted urine samples using pressure injection, while they were 0.32 mu g/mL in water and 0.34 mu g/mL in ten times diluted urine samples using electrokinetic injection Repeatability of buserelin migration times was below 6\% (pressure injection mode) and 1\% (electrokinetic injection mode) Repeatability of buserelin peak area in SIM mode (m/z = 620.5 +/- 0.5) was less than 12\% (pressure injection mode) and 5 8\% (electrokinetic injection mode). In this work, no interferences were observed during the analyses of spiked urine samples., DOI = 10.1002/elps.200900422, ISSN = 0173-0835, Unique-ID = ISI:000276811000015, -
I. Palikova, J. Vostalova, A. Zdarilova, A. Svobodova, P. Kosina, R. Vecera, D. Stejskal, J. Proskova, J. Hrbac, P. Bednar, V. Maier, D. Cernochova, V. Simanek, and J. Ulrichova, “Long-Term Effects of Three Commercial Cranberry Products on the
Antioxidative Status in Rats: A Pilot Study,” JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, vol. 58, iss. 3, pp. 1672-1678, 2010.
[Bibtex]@article ISI:000274269000041, Author = Palikova, Irena and Vostalova, Jitka and Zdarilova, Adela and Svobodova, Alena and Kosina, Pavel and Vecera, Rostislav and Stejskal, David and Proskova, Jitka and Hrbac, Jan and Bednar, Petr and Maier, Vitezslav and Cernochova, Drahomira and Simanek, Vilim and Ulrichova, Jitka, Title = Long-Term Effects of Three Commercial Cranberry Products on the Antioxidative Status in Rats: A Pilot Study, Journal = JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, Year = 2010, Volume = 58, Number = 3, Pages = 1672-1678, Month = FEB 10, Abstract = Cranberry (Vaccinium macrocarpon Ait. Ericaceae) fruits and juice are widely used for their antiadherence and antioxidative properties. Little is known however about their effects on clinical chemistry markers after long-term consumption. This study was conducted to evaluate the effect of three commercial cranberry products, NUTRICRAN90S, HI-PAC 4.0, and PACRAN on the antioxidative status of rodents, divided into three experimental groups. The products were given as dietary admixtures (1500 mg of product/kg of stock feed) for 14 weeks to male Wistar rats (Groups 2-4) and a control Group 1 which received only stock feed. There were no significant cranberry treatment-related effects on oxidative stress parameters, catalase, glutathione peroxidase, glutathione reductase, glutathione transferase, superoxide dismutase, total antioxidant capacity, thiobarbituric acid reactive substances, advanced oxidation protein products, total SH-groups, or any other measured clinical chemistry markers. Hematological parameters, body weight, and food consumption were also unaffected by intake of cranberries. Only liver glutathione reductase activity and glutathione levels were significantly lower in Group 4 than in Group 1. Plasma alkaline phosphatase alone was significantly decreased in Group 2. No gross pathology, effects on organ weights, or histopathology were observed. No genotoxicity was found, and total cytochrome P450 level in liver was unaffected in all groups. The levels of hippuric acid and several phenolic acids were significantly increased in plasma and urine in Groups 2-4. The concentration of anthocyanins was under the detection threshold. The dietary addition of cranberry powders for 14 weeks was well tolerated, but it did not improve the antioxidative status in rats., DOI = 10.1021/jf903710y, ISSN = 0021-8561, Unique-ID = ISI:000274269000041, - J. Skopalova, D. Jirovsky, Z. Bartosova, and V. Maier, “Electrochemical Behavior of Antidiabetics Repaglinide and Rosiglitazone
and their Determination by Liquid Chromatography with Electrochemical
Detection,” in MODERN ELECTROCHEMICAL METHODS XXX, 2010, pp. 149-153.
[Bibtex]@inproceedings ISI:000283050900034, Author = Skopalova, Jana and Jirovsky, David and Bartosova, Zdenka and Maier, Vitezslav, Editor = Navratil, T and Jiri, B, Title = Electrochemical Behavior of Antidiabetics Repaglinide and Rosiglitazone and their Determination by Liquid Chromatography with Electrochemical Detection, Booktitle = MODERN ELECTROCHEMICAL METHODS XXX, Year = 2010, Pages = 149-153, Note = 30th Modern Electrochemical Methods, Jetrichovice, CZECH REPUBLIC, MAY 24-28, 2010, Abstract = A voltammetric behavior of two antidiabetic drugs repaglinide and rosiglitazone was investigated on glassy carbon electrode using cyclic and differential pulse voltammetry. Oxidation of the both drugs occurred in the entire tested pH range of 2-9 giving well defined anodic current responses. Suitable conditions for coulometric detection of the drugs at porous-carbon electrode were found on the basis of voltammetric experiments. A simple and highly sensitive reverse-phase liquid chromatography method with coulometric detection was developed and applied to the determination of nanomolar concentractions of the drugs in spiked human plasma., ISBN = 978-80-254-6710-7, Unique-ID = ISI:000283050900034,
2009
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J. Petr, O. Ryparova, J. Znaleziona, V. Maier, and J. Sevcik, “On-line combination of CE and microscopy: An insight into the migration
of microorganisms,” ELECTROPHORESIS, vol. 30, iss. 22, pp. 3863-3869, 2009.
[Bibtex]@article ISI:000272474900009, Author = Petr, Jan and Ryparova, Olga and Znaleziona, Joanna and Maier, Vitezslav and Sevcik, Juraj, Title = On-line combination of CE and microscopy: An insight into the migration of microorganisms, Journal = ELECTROPHORESIS, Year = 2009, Volume = 30, Number = 22, Pages = 3863-3869, Month = NOV, Abstract = identification of microbial contamination by CE has interested many researchers mainly because of the high speed of CE analysis. However, the CE separation of such big structures brings a lot of questions mainly about the behavior of microorganisms and about the mechanism of separation. In this work, we constructed a simple apparatus where a microscope was used as one detector and a UV detector was used as the second one and we made the comparison of three typical setups for CE of microorganisms. Saccharomyces cerevisiae was chosen as a model microorganism and was analyzed in bare fused-silica capillaries, covalently modified capillaries and dynamically modified capillaries by poly(ethylene oxide) or CTAB. Results showed that the use of CE instrument directly connected with a microscope could be advantageous for the study of separation mechanisms and/or migration behavior., DOI = 10.1002/elps.200900230, ISSN = 0173-0835, Unique-ID = ISI:000272474900009, -
V. Maier, J. Znaleziona, D. Jirovsky, J. Skopalova, J. Petr, and J. Sevcik, “Determination of antihyperglycemic drugs in nanomolar concentration
levels by micellar electrokinetic chromatography with non-ionic
surfactant,” JOURNAL OF CHROMATOGRAPHY A, vol. 1216, iss. 20, pp. 4492-4498, 2009.
[Bibtex]@article ISI:000265956100025, Author = Maier, Vitezslav and Znaleziona, Joanna and Jirovsky, David and Skopalova, Jana and Petr, Jan and Sevcik, Juraj, Title = Determination of antihyperglycemic drugs in nanomolar concentration levels by micellar electrokinetic chromatography with non-ionic surfactant, Journal = JOURNAL OF CHROMATOGRAPHY A, Year = 2009, Volume = 1216, Number = 20, Pages = 4492-4498, Month = MAY 15, Abstract = A method for the separation of six selected antihyperglycemic (antidiabetic) drugs (tolbutamide, gliclazide, glimepiride, glibenclamide, repaglinide, and glipizide) was developed with use of micellar electrokinetic chromatography. Two non-ionic poly(ethylene glycol)-based surfactants Genapol X-080 and Triton X-114 (reduced) were studied as neutral pseudostationary phases. High alkaline pH 10.0 was used to obtain negative charges of separated antidiabetic drugs and non-ionic surfactants were employed for selectivity alteration. Both non-ionic surfactants provided good selectivity at concentration 0.2\% (v/v) in sodium borate buffer and the separation of six drugs was obtained within 5 min. An on-line preconcentration method based on reversed electrode polarity switching was employed for the determination of anti hyperglycemic drugs in blood serum after acetonitrile protein precipitation. The limits of detection ranged from 20.8 nmol L-(1) for tolbutamide to 6.5 nmol L(-1) for glibenclamide, respectively. (C) 2009 Elsevier B.V. All rights reserved., DOI = 10.1016/j.chroma.2009.03.052, ISSN = 0021-9673, Unique-ID = ISI:000265956100025, -
J. Petr, O. Ryparova, V. Ranc, P. Hinnerova, J. Znaleziona, M. Kowalska, R. Knob, V. Maier, I. Frebort, K. Lemr, and J. Sevcik, “Assessment of CE for the identification of microorganisms,” ELECTROPHORESIS, vol. 30, iss. 3, pp. 444-449, 2009.
[Bibtex]@article ISI:000264357500002, Author = Petr, Jan and Ryparova, Olga and Ranc, Vaclav and Hinnerova, Petra and Znaleziona, Joanna and Kowalska, Marta and Knob, Radim and Maier, Vitezslav and Frebort, Ivo and Lemr, Karel and Sevcik, Juraj, Title = Assessment of CE for the identification of microorganisms, Journal = ELECTROPHORESIS, Year = 2009, Volume = 30, Number = 3, Pages = 444-449, Month = FEB, Abstract = The assessment of capillary electrophoresis for separation and identification of microorganisms is described in this article. The work brings a comparison of the application of uncoated capillaries modified with poly(ethylene oxide) and coated capillaries for the separation of model microorganisms Saccharomyces cerevisiae and Escherichia coli with Tris-borate-EDTA and Tris-citrate-fructose as electrolytes. The best separation was achieved in the coated capillary using 1 mM Tris-citrate-fructose buffer, pH 6.9. A simple identification based on the migration time and UV spectrum was found unsatisfactory and thus a method based on a post-separation cultivation and sequential analysis was developed. Off-line combination with mass spectrometric analysis with the use of desorption electrospray was shown to be an interesting alternative in a study of microorganisms. Mass spectra allowed distinguishing among analyzed cells., DOI = 10.1002/elps.200800232, ISSN = 0173-0835, Unique-ID = ISI:000264357500002, - J. Petr, V. Maier, J. Znaleziona, K. Vitkova, V. Ranc, and J. Sevcik, “On-line Preconcentration on pH Boundary – the Beauty of Capillary
Electrophoresis,” CHEMICKE LISTY, vol. 103, iss. 8, pp. 661-666, 2009.
[Bibtex]@article ISI:000269243500006, Author = Petr, Jan and Maier, Vitezslav and Znaleziona, Joanna and Vitkova, Katerina and Ranc, Vaclav and Sevcik, Juraj, Title = On-line Preconcentration on pH Boundary - the Beauty of Capillary Electrophoresis, Journal = CHEMICKE LISTY, Year = 2009, Volume = 103, Number = 8, Pages = 661-666, Abstract = The beauty of capillary electrophoresis is shown on preconcentration of some phenolics. The method is based on the electrokinetic injection of phenolics into a sodium borate electrolyte (pH 9.5) at the pH boundary formed by sodium phosphate (pH 2.5) followed by mobilization and separation by replacing the injection vial with the vial containing micellar environment. This technique allows determination of nanomolar concentrations of phenolics., ISSN = 0009-2770, Unique-ID = ISI:000269243500006,
2008
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J. Petr, K. Vitkova, V. Ranc, J. Znaleziona, V. Maier, R. Knob, and J. Sevcik, “Determination of some phenolic acids in Majorana hortensis by capillary
electrophoresis with online electrokinetic preconcentration,” JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, vol. 56, iss. 11, pp. 3940-3944, 2008.
[Bibtex]@article ISI:000256445300008, Author = Petr, Jan and Vitkova, Katerina and Ranc, Vaclav and Znaleziona, Joanna and Maier, Vitezslav and Knob, Radim and Sevcik, Juraj, Title = Determination of some phenolic acids in Majorana hortensis by capillary electrophoresis with online electrokinetic preconcentration, Journal = JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, Year = 2008, Volume = 56, Number = 11, Pages = 3940-3944, Month = JUN 11, Abstract = An online accumulation/mobilization preconcentration technique based on a dynamic pH junction technique and electrokinetic injection was employed for analysis of phenolic acids (sinapic; ferulic, coumarinic, caffeic, syringic, vanillic, and 4-hydroxybenzoic acid) in extracts from Majorana hortensis leaves. Samples were extracted by pressurized solvent extraction with acetone at 150 degrees C and 15 MPa. The capillary electrophoretic method employed 50 mmol.L-1 sodium borate, pH 9.5, as the sample electrolyte, 50 mmol.L-1 sodium phosphate, pH 2.5, as the background electrolyte, and 50 mmol.L-1 sodium phosphate, pH 2.5, with 60 mmol.L-1 sodium dodecyl sulfate as the mobilization electrolyte. The method allowed 720-fold to 5560-fold preconcentration of the phenolic acids during 30 min of electrokinetic accumulation with detection limits from 0.38 to 4.22 ng.mL(-1)., DOI = 10.1021/jf8000179, ISSN = 0021-8561, Unique-ID = ISI:000256445300008, -
J. Znaleziona, J. Petr, R. Knob, V. Maier, and J. Sevcik, “Dynamic coating agents in CE,” CHROMATOGRAPHIA, vol. 67, iss. S, pp. S5-S12, 2008.
[Bibtex]@article ISI:000256533700003, Author = Znaleziona, Joanna and Petr, Jan and Knob, Radim and Maier, Vitezslav and Sevcik, Juraj, Title = Dynamic coating agents in CE, Journal = CHROMATOGRAPHIA, Year = 2008, Volume = 67, Number = S, Pages = S5-S12, Note = 10th Symposium on Advances in Chromatography and Electrophoresis and Chiranal, Palacky Univ, Olomouc, CZECH REPUBLIC, JUN 24-27, 2007, Organization = Czech Chem Soc, Working Grp Chromatog \& Electrophoresis, Abstract = In capillary electrophoresis (CE) dynamic coating agents are commonly used for manipulating or reversing electroosmotic flow (EOF) and suppressing adsorption of analytes by the silica surface. In this paper we review general aspects of dynamic coating in CE and discuss features and facts concerning formation of the EOF and determination of its magnitude., DOI = 10.1365/s10337-007-0509-y, ISSN = 0009-5893, Unique-ID = ISI:000256533700003, - O. Ryparova, J. Petr, M. Kowalska, J. Znaleziona, R. Knob, V. Maier, I. Frebort, and J. Sevcik, “Analysis of Microorganisms by Capillary Electrophoresis,” CHEMICKE LISTY, vol. 102, iss. 12, pp. 1121-1126, 2008.
[Bibtex]@article ISI:000262061500007, Author = Ryparova, Olga and Petr, Jan and Kowalska, Marta and Znaleziona, Joanna and Knob, Radim and Maier, Vitezslav and Frebort, Ivo and Sevcik, Juraj, Title = Analysis of Microorganisms by Capillary Electrophoresis, Journal = CHEMICKE LISTY, Year = 2008, Volume = 102, Number = 12, Pages = 1121-1126, Abstract = Utilization of capillary electrophoresis for screening identification of Escherichia coli in water (faecal contamination) and pharmaceuticals is described. The method uses an electrolyte 4.5 mM in Tris, 4.5 mM in H(3)BO(3) and 0.1 mM in EDTA with 0.0125 \% poly(ethylene oxide). A brief survey of the published methods for analysis of microorganisms by capillary electrophoresis is given., ISSN = 0009-2770, Unique-ID = ISI:000262061500007,
2007
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J. Horakova, J. Petr, V. Maier, J. Znaleziona, A. Stanova, J. Marak, D. Kaniansky, and J. Sevcik, “Combination of large volume sample stacking and dynamic pH junction for
on-line preconcentration of weak electrolytes by capillary
electrophoresis in comparison with isotachophoretic techniques,” JOURNAL OF CHROMATOGRAPHY A, vol. 1155, iss. 2, pp. 193-198, 2007.
[Bibtex]@article ISI:000247855200010, Author = Horakova, Jana and Petr, Jan and Maier, Vitezslav and Znaleziona, Joanna and Stanova, Andrea and Marak, Jozef and Kaniansky, Dusan and Sevcik, Juraj, Title = Combination of large volume sample stacking and dynamic pH junction for on-line preconcentration of weak electrolytes by capillary electrophoresis in comparison with isotachophoretic techniques, Journal = JOURNAL OF CHROMATOGRAPHY A, Year = 2007, Volume = 1155, Number = 2, Pages = 193-198, Month = JUL 6, Note = 15th International Symposium on Capillary Electroseparation Techniques, Paris, FRANCE, AUG 28-30, 2006, Abstract = An on-line preconcentration capillary electrophoresis (CE) technique, which combines a large volume sample stacking with a dynamic pH junction technique, is introduced in this paper. This dynamic pH junction with co-electroosmotic migration is formed between sodium borate pH 9.5 and sodium phosphate pH 2.5 with 150 mM sodium dodecylsulfate (SDS). A full capillary based injection allows determination of weak acidic compounds at ppb concentration levels (achieved LOD for benzoic acid was 11 nmol L-1). The proposed preconcentration method was compared with ITP/ITP (LOD 120 nmol L-1), ITP/CZE (LOD 740 nmol L-1) and a simple CZE method (LOD 23,330 nmol L-1). The analytical potential of this method was assessed with juice test samples. (C) 2007 Elsevier B.V. All rights reserved., DOI = 10.1016/j.chroma.2007.01.075, ISSN = 0021-9673, Unique-ID = ISI:000247855200010, -
V. Maier, J. Petr, R. Knob, J. Horakova, and J. Sevcik, “Electrokinetic partial filling technique as a powerful tool for
enantiomeric separation of DL-lactic acid by CE with contactless
conductivity detection,” ELECTROPHORESIS, vol. 28, iss. 11, pp. 1815-1822, 2007.
[Bibtex]@article ISI:000247279800020, Author = Maier, Vitezslav and Petr, Jan and Knob, Radim and Horakova, Jana and Sevcik, Juraj, Title = Electrokinetic partial filling technique as a powerful tool for enantiomeric separation of DL-lactic acid by CE with contactless conductivity detection, Journal = ELECTROPHORESIS, Year = 2007, Volume = 28, Number = 11, Pages = 1815-1822, Month = JUN, Abstract = A modified partial filling method for chiral separation Of DL-lactic acid as the model chiral compound with vancomycin chloride as the chiral selector was developed by CE with contactless conductivity detection. Electrokinetic partial filling technique (EK-PFT) was used as an altemative method to the conventional hydrodynamic partial filling method. EK-PFT, in contrast to the hydrodynamic partial filling technique, allowed the removal of the chloride counterions from the chiral selector which otherwise led to poor sensitivity in conductivity detection. The baseline separation Of DL-lactic acid as the model analyte was achieved in 5 min in a polyacrylamide-coated capillary. The best resolution was achieved by electrokinetic partial filling of vancomycin cations from the injection solution containing 5 nunol/L oxalate L-histidiniumat pH 4.5 with 10 mmol/L vancomycin chloride. Computer simulation was used to explain the observed phenomena in the boundary between the inject vial and the capillary during the EK-PFT of vancomycin cations., DOI = 10.1002/elps.200600578, ISSN = 0173-0835, Unique-ID = ISI:000247279800020, -
J. Horakova, J. Petr, V. Maier, E. Tesarova, L. Veis, D. W. Armstrong, B. Gas, and J. Sevcik, “On-line preconcentration of weak electrolytes by electrokinetic
accumulation in CE: Experiment and simulation,” ELECTROPHORESIS, vol. 28, iss. 10, pp. 1540-1547, 2007.
[Bibtex]@article ISI:000246923300011, Author = Horakova, Jana and Petr, Jan and Maier, Vitezslav and Tesarova, Eva and Veis, Libor and Armstrong, Daniel W. and Gas, Bohuslav and Sevcik, Juraj, Title = On-line preconcentration of weak electrolytes by electrokinetic accumulation in CE: Experiment and simulation, Journal = ELECTROPHORESIS, Year = 2007, Volume = 28, Number = 10, Pages = 1540-1547, Month = MAY, Abstract = A new on-line preconcentration technique was developed that makes possible to determine nanomolar concentrations of weak acidic analytes in CE. The method consists of long-running electrokinetic sample injection and stacking (electrokinetic immobilization) of the analytes at a boundary of two electrolytes with different pH values (pH 9.5 and 2.5) and consequent mobilization of the stacked uncharged analytes in a micellar system (containing SDS micelles). Several factors including buffer concentration, pH, applied voltage, time of preconcentration, and SDS concentration were tested to optimize the analysis method. An about 4600-fold increase of the sample concentration (in comparison with the standard CZE) can be achieved during the preconcentration step. Two preservatives applied in food industry - benzoic acid and sorbic acid were used as model samples. The applicability of the proposed method in food analysis was demonstrated by determination of nanomolar concentrations of benzoic acid in sunflower oil. An extended version of the computer program Simul was used for modeling both the preconcentration and mobilization processes taking place in the capillary., DOI = 10.1002/elps.200600681, ISSN = 0173-0835, Unique-ID = ISI:000246923300011, -
D. Friedecky, J. Tomkova, V. Maier, A. Janost’akova, M. Prochazka, and T. Adam, “Capillary electrophoretic method for nucleotide analysis in cells:
Application on inherited metabolic disorders,” ELECTROPHORESIS, vol. 28, iss. 3, pp. 373-380, 2007.
[Bibtex]@article ISI:000244425600014, Author = Friedecky, David and Tomkova, Jana and Maier, Vitezslav and Janost'akova, Anna and Prochazka, Martin and Adam, Tomas, Title = Capillary electrophoretic method for nucleotide analysis in cells: Application on inherited metabolic disorders, Journal = ELECTROPHORESIS, Year = 2007, Volume = 28, Number = 3, Pages = 373-380, Month = FEB, Abstract = Purine and pyrimidine nucleotides influence many metabolic pathways and their analogs have been widely used in medicine. A capillary electrophoretic method was developed for measuring intracellular nucleotides. The final BGE consisted of 40 mM citric acid with addition of 0.8 mM CTAB titrated by gamma-aminobutyric acid to pH 4.4. The electrophoretic separations were carried out in an uncoated silica capillary (id/od - 75/375 mu m; effective/total length - 90/97 cm). The method allows a complete separation of 21 nucleotides and deoxynucleotides within 15 min with separation efficiencies up to 400 000 theoretical plates per meter. Due to the use of an acidic separation medium, the method offers a high selectivity toward the studied analytes versus possible interferences from matrices. Sample preparation was optimized in order to shorten work-time and prevent analyte degradation. The method was applied for analyzing nucleotides in human erythrocytes and Chinese hamster ovary cells. Diagnostic potential for inherited metabolic disorders of nucleotide metabolism is presented., DOI = 10.1002/elps.200600262, ISSN = 0173-0835, Unique-ID = ISI:000244425600014,
2006
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J. Petr, V. Maier, J. Horakova, J. Sevcik, and Z. Stransky, “Capillary isotachophoresis from the student point of view – images and
the reality,” JOURNAL OF SEPARATION SCIENCE, vol. 29, iss. 18, pp. 2705-2715, 2006.
[Bibtex]@article ISI:000243338800002, Author = Petr, Jan and Maier, Vitezslav and Horakova, Jana and Sevcik, Juraj and Stransky, Zdenek, Title = Capillary isotachophoresis from the student point of view - images and the reality, Journal = JOURNAL OF SEPARATION SCIENCE, Year = 2006, Volume = 29, Number = 18, Pages = 2705-2715, Month = DEC, Abstract = A review of some fundamental aspects of ITP from the student point of view, imaginations of some basic facts and laws, use of ITP, and the recent trends are presented. The results of theoretical computations of ITP separation processes are added for comparison of imaginations with the exact mathematical description., DOI = 10.1002/jssc.200600249, ISSN = 1615-9306, Unique-ID = ISI:000243338800002, -
J. Petr, V. Maier, J. Horakova, and J. Sevcik, “Simultaneous contactless conductivity detection and UV detection for the
study of separation of tamsulosin enantiomers in discontinuous
electrolyte systems by CE,” ELECTROPHORESIS, vol. 27, iss. 23, pp. 4735-4745, 2006.
[Bibtex]@article ISI:000242903000017, Author = Petr, Jan and Maier, Vitezslav and Horakova, Jana and Sevcik, Juraj, Title = Simultaneous contactless conductivity detection and UV detection for the study of separation of tamsulosin enantiomers in discontinuous electrolyte systems by CE, Journal = ELECTROPHORESIS, Year = 2006, Volume = 27, Number = 23, Pages = 4735-4745, Month = DEC, Abstract = This work shows the potential of using discontinuous electrolyte systems for the separation of tamsulosin enantiomers by CE. Sulfated P-cyclodextrin was used as a chiral selector. In acidic electrolytes, sulfated P-cyclodextrin migrates as an anion and the analyte (tamsulosin) migrates as a cation. Due to this, four experimental arrangements were proposed. These arrangements differ in composition of electrolytes in the inlet compartment, in the capillary and in the outlet compartment. The separation of tamsulosin enantiomers in acetate buffers with sodium and Tris counterions was studied. Simultaneous contactless conductivity detection and UV detection were used for the study of the separation mechanism in these systems. Mobilities of sulfated beta-cycloclextrin were used for the calculation of the time when the analyte migrates through the BGE zone with the selector. The simulation program Simul 4.0 was used for the calculations of the concentration profiles of the electrolyte components dependent on the time of the separation. The mechanism of enantioseparation in these arrangements was suggested., DOI = 10.1002/elps.200600063, ISSN = 0173-0835, Unique-ID = ISI:000242903000017, -
V. Maier, J. Horakova, J. Petr, D. Drahonovsky, and J. Sevcik, “Using of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium
tetrafluoroborate as additive to the background electrolyte in capillary
electrophoresis,” JOURNAL OF CHROMATOGRAPHY A, vol. 1103, iss. 2, pp. 337-343, 2006.
[Bibtex]@article ISI:000234879600019, Author = Maier, V and Horakova, J and Petr, J and Drahonovsky, D and Sevcik, J, Title = Using of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate as additive to the background electrolyte in capillary electrophoresis, Journal = JOURNAL OF CHROMATOGRAPHY A, Year = 2006, Volume = 1103, Number = 2, Pages = 337-343, Month = JAN 27, Abstract = We synthesised and used new type of quaternary ammonium salt [S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate] as effective additive to acidic background electrolytes. We used this quaternary ammonium salt as effective agent for capillary zone electrophoresis separation of model mixture of five tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine and clomipramine) as model analytes. We observed that addition of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate ([HMDP](+) [BF4](-)) to acidic background electrolytes leads to suppression of magnitude of electroosmotic flow (EOF) and gradually change the direction of the EOF. Baseline separation of five TAs was achieved by using of 91.1 mmol L-1 (20 g L-1) of [HMDP](+) [BF4](-) in 25 mmol L-1 sodium phosphate pH 2.5, where electroosmotic mobility was -11.3 x 10(-9) m(2) V-1 s(-1). We achieved baseline separation of five TAs with using of [HMDP](+) [BF4](-) as water solution too. We observed that [HMDP](+) [BF4](-) Can be used as buffer additive, which offers relatively smaller anodic electroosmotic flow instead of cationic surfactants that are mostly used for genarating of anodic electroosmotic flow in capillary electrophoresis. (c) 2005 Elsevier B.V. All fights reserved., DOI = 10.1016/j.chroma.2005.11.011, ISSN = 0021-9673, Unique-ID = ISI:000234879600019, - J. Horakova, V. Maier, and J. Sevcik, “On-line preconcentration techniques in capillary electrophoresis,” CHEMICKE LISTY, vol. 100, iss. 3, pp. 163-168, 2006.
[Bibtex]@article ISI:000236139700002, Author = Horakova, J and Maier, V and Sevcik, J, Title = On-line preconcentration techniques in capillary electrophoresis, Journal = CHEMICKE LISTY, Year = 2006, Volume = 100, Number = 3, Pages = 163-168, Abstract = Preconcentration is a very important issue for achievement of low detection limits. Various on-line preconcentration modes, various electrolyte compositions, pH values and mechanisms responsible for the focusing effect are described in literature. The main modes of stacking, sweeping and transient isotachophoresis are discussed. Some of the described methods are combinations of major techniques of preconcentration and less known focusing techniques. References for optimization of focusing conditions and routine use of on-line preconcentration are given., ISSN = 0009-2770, Unique-ID = ISI:000236139700002,
2005
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V. Maier, J. Horakova, J. Petr, E. Tesarova, P. Coufal, and J. Sevcik, “Chiral separation of tamsulosin by capillary electrophoresis,” JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS, vol. 39, iss. 3-4, pp. 691-696, 2005.
[Bibtex]@article ISI:000232209700047, Author = Maier, V and Horakova, J and Petr, J and Tesarova, E and Coufal, P and Sevcik, J, Title = Chiral separation of tamsulosin by capillary electrophoresis, Journal = JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS, Year = 2005, Volume = 39, Number = 3-4, Pages = 691-696, Month = SEP 15, Abstract = Enantiomers of (+/-) 5-[2 (R,S)-\[2-(o-ethoxyphenoxy) ethyl] amino\ propyl]-2-methoxy-benzenesulfonamide (tamsulosin, drug frequently used in the treatment of prostate diseases) were separated by capillary electrophoresis (CE). An acidic background electrolyte (BGE) with sulfated-beta-cyclodextrin (S-P-CD) was used to create a chiral separation environment. Baseline separation of the isomers was achieved during 5 min using cathodic electro-osmotic flow (EOF) (countercurrent mode). The quantification limits were 5.3 x 10(-6) Mol l(-1) for R-isomer and 5.7 x 10(-6) Mol l(-1) for S-isomer. The R.S.D. values of peak area were 0.54\% for R-isomer and 0.75\% for S-isomer. The results achieved enable determination of 0.5\% of optical impurity. (c) 2005 Elsevier B.V. All rights reserved., DOI = 10.1016/j.jpba.2005.04.023, ISSN = 0731-7085, Unique-ID = ISI:000232209700047, - J. Petr, V. Maier, J. Horakova, E. Tesarova, and J. Sevcik, “How to achieve successful chiral separation by capillary electrophoresis,” CHEMICKE LISTY, vol. 99, iss. 3, pp. 190-194, 2005.
[Bibtex]@article ISI:000227483400007, Author = Petr, J and Maier, V and Horakova, J and Tesarova, E and Sevcik, J, Title = How to achieve successful chiral separation by capillary electrophoresis, Journal = CHEMICKE LISTY, Year = 2005, Volume = 99, Number = 3, Pages = 190-194, Abstract = This work is devoted to enhancing the potential of capillary electrophoresis as a separation technique. Improvement of chiral resolution of organic bases in an acid electrolyte using sulfated P-cyclodextrin as an anionic chiral selector is demonstrated on an example of chiral separation of tamsulosin and ephedrine. Better resolution of enantiomers; of the bases can be achieved by changing the concentration of a chiral selector in compartments of the separation system (inlet - capillary - outlet). Migration of the chiral selector in the direction opposite to that of the cationic analytes was utilized and thus the resolution could be improved. The best resolution was obtained if the chiral selector was in the working electrolyte in the capillary and outlet vial while the inlet vial contained only the background electrolyte. In contrast, if the chiral selector is either only in the capillary or in the whole electrophoresis system, a lower resolution was obtained though both the systems are most frequently employed in practice., ISSN = 0009-2770, Unique-ID = ISI:000227483400007,