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The First Online Capillary Electrophoresis-Microscale Thermophoresis (CE-MST) Method for the Analysis of Dynamic Equilibria-The Determination of the Acidity Constant of Fluorescein Isothiocyanate. Molecules 2022; 27:molecules27155010. [PMID: 35956959 PMCID: PMC9370695 DOI: 10.3390/molecules27155010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/02/2022] [Accepted: 08/04/2022] [Indexed: 11/18/2022] Open
Abstract
This article presents the first successful application of a capillary electrophoresis-microscale thermophoresis tandem technique (CE-MST) for determining the values of equilibrium constant, realized by connecting online the CE and MST instruments using a fused-silica capillary. The acid-base dissociation of fluorescein isothiocyanate, expressed by the acidity constant value (pKa), was used as a model. The measurement procedure consisted of introducing a mixture containing the analyte and a deliberately added interferent into the CE capillary, electrophoretic separation of the analyte from the interferent, the detection of the analyte with a CE-integrated detector, detection with a MST detector, and then stopping the flow temporarily by turning off the voltage source to conduct the thermophoretic measurement. The analysis of migration times, peak areas and MST responses obtained concurrently for the same sample allowed us to determine the pKa value using three independent methods integrated within one instrumentation. The analyte was effectively separated from the interferent, and the acidity values turned out to be consistent with each other. An attempt was also made to replace the standard commercial CE instrument with a home-made portable CE setup. As a result, the similar pKa value was obtained, at the same time proving the possibility of increasing cost efficiency and reducing energy consumption. Overall, the CE-MST technique has a number of limitations, but its unique analytical capabilities may be beneficial for some applications, especially when sample separation is needed prior to the thermophoretic measurement.
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The novel Outer Plug Standardization (OPS) calibration strategy applied in a new method for the high-throughput determination of Cl -, NO 3- and SO 4-2 in rainwater samples. Talanta 2021; 235:122820. [PMID: 34517675 DOI: 10.1016/j.talanta.2021.122820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/20/2021] [Accepted: 08/21/2021] [Indexed: 11/24/2022]
Abstract
This paper presents the Outer Plug Standardization - OPS, a novel technique as an alternative for the classic internal standardization using multiple injection in capillary zone electrophoresis is proposed herein. This technique was applied in a new method for the determination of chloride, nitrate and sulfate in rainwater samples. After the injection accuracy was tested and proved to be a minor error source (average 1.26% RSD), the OPS was applied and it improved the intra-day and inter-day precision of the analytical method by 32.5% and 24.7%, respectively. Using a capillary with effective length of 23.5 cm the electrophoretic separation of the three inorganic anions could be achieved in <1 min, with detection limits of 0.05, 0.09 and 0.11 mg L-1 for chloride, nitrate and sulfate, respectively. Also, the statistical t-test was applied to the results obtained for 82 rainwater samples that were collected and analyzed applying both the method developed in this study and the official APHA 4140 method where no statistical difference was noted within a 95% confidence level.
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Tetraalkylammonium-l-tartrate ionic liquids as sole chiral selectors in capillary electrophoresis. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.117842] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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5
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Nowak PM, Sekuła E, Kościelniak P. Assessment and Comparison of the Overall Analytical Potential of Capillary Electrophoresis and High-Performance Liquid Chromatography Using the RGB Model: How Much Can We Find Out? Chromatographia 2020. [DOI: 10.1007/s10337-020-03933-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractThe choice between capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) is not easy and depends on many factors. An attempt to facilitate this choice is this work, in which both techniques have been confronted on the basis of the RGB model, offering a transparent and pictorial way to compare individual parameters as well as the overall analytical potential of each tool.
To ensure the universal nature of the comparison, a simple in composition and chemically diverse model sample was used, accompanied by the data processing method reducing the potential impact of analyte selection. Moreover, permanent coating of the inner surface of the capillary and addition of a surfactant to the separation buffer were considered as the additional factors that may affect the assessment of the CE technique. The presented analysis can be valuable in any discussions about the intrinsic advantages and disadvantages of CE and HPLC, and divagations on how they affect the overall potential and usability of each. We also provide access to the Excel worksheets used for the assessment, which can be easily modified to reevaluate the methods with a different selection of variables, and analyze other possible scenarios.
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Purgat K, Olejarz P, Kośka I, Głowacki R, Kubalczyk P. Determination of homocysteine thiolactone in human urine by capillary zone electrophoresis and single drop microextraction. Anal Biochem 2020; 596:113640. [PMID: 32092290 DOI: 10.1016/j.ab.2020.113640] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/18/2020] [Accepted: 02/18/2020] [Indexed: 12/28/2022]
Abstract
A simple, fast, sensitive and reproducible capillary zone electrophoresis (CZE) method with single drop microextraction (SDME) for determination of homocysteine thiolactone (HTL) in human urine has been developed and validated. The method is characterized by good precision, high accuracy, short analysis time and low consumption of reagents. The procedure consists only of few steps: urine sample centrifugation, dilution with phosphate buffer and methanol, chloroform addition onto the top of donor phase, on-line SDME in CE system, sample separation by CZE and ultraviolet detection of HTL at 240 nm. The background electrolyte was 0.1 M pH 4.75 phosphate buffer. Effective separation was achieved within 6.04 min under the separation voltage of 24 kV (~110 μA). The LOQ and LOD for HTL were 50 and 25 nM urine, respectively. The calibration curve in urine showed linearity in the range of 50-200 nM, with R2 0.9995. The intra- and inter-day precision and recovery were 4.0-14.5% (average 8.7% and 9.3%) and 92.7-115.5% (average 103.6% and 104.8%), respectively. The procedure was successfully applied to analysis of urine samples.
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Affiliation(s)
- Krystian Purgat
- University of Lodz, Faculty of Chemistry, Department of Environmental Chemistry, Poland
| | - Patrycja Olejarz
- University of Lodz, Faculty of Chemistry, Department of Environmental Chemistry, Poland
| | - Izabella Kośka
- University of Lodz, Faculty of Chemistry, Department of Environmental Chemistry, Poland; University of Lodz, Doctoral School of Exact and Natural Sciences, Poland
| | - Rafał Głowacki
- University of Lodz, Faculty of Chemistry, Department of Environmental Chemistry, Poland
| | - Paweł Kubalczyk
- University of Lodz, Faculty of Chemistry, Department of Environmental Chemistry, Poland.
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Cui X, Ni C, Liang C, Gong F, Wang R, Chen G, Zhang Y. Screening and quantitation of forty-six drugs of abuse and toxic compounds in human whole blood by capillary electrophoresis: Application to forensic cases. Microchem J 2019. [DOI: 10.1016/j.microc.2018.09.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Dresler S, Bogucka-Kocka A, Kováčik J, Kubrak T, Strzemski M, Wójciak-Kosior M, Rysiak A, Sowa I. Separation and determination of coumarins including furanocoumarins using micellar electrokinetic capillary chromatography. Talanta 2018; 187:120-124. [PMID: 29853023 DOI: 10.1016/j.talanta.2018.05.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/02/2018] [Accepted: 05/07/2018] [Indexed: 11/19/2022]
Abstract
The conditions of micellar electrokinetic capillary chromatography for separation and simultaneous measurement of coumarins (coumarin, scoparone, isoscopoletin, esculin, esculetin, umbelliferone) including furanocoumarins (xanthotoxin, byakangelicin, isopimpinellin, bergapten, phellopterin, xanthotoxol) have been elaborated. The influence of different parameters, such as the pH of the buffer, sodium cholate (SC) or methanol concentration in the buffer, on the migration time, peak resolution, peak asymmetry, and number of theoretical plates was investigated. The optimum separation of the compounds was achieved using 50-µm i.d. capillaries with a total length of 64.5 cm (56 cm effective length) and a buffer system at pH 9.00 consisting of 50 mM sodium tetraborate, 45 mM SC, and 20% of methanol (v/v). The developed method ensured good repeatability of corrected peak areas and migration times (the relative standard deviations were in the range of 2.8-6.1% and 0.8-4.0%, respectively). The average limit of detection for all studied compounds was below 1.3 µg mL. Moreover, good linearity of the relationship between the peak corrected area and the concentration of the compounds was observed (correlation coefficient >0.99). The method was successfully applied in the quantitative analysis of two different types of samples, i.e. Heracleum sphondylium herb and Aesculus hippocastanum cortex.
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Affiliation(s)
- Sławomir Dresler
- Department of Plant Physiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Anna Bogucka-Kocka
- Chair and Department of Biology and Genetics, Medical University of Lublin, Chodźki 4a, 20-094 Lublin, Poland
| | - Jozef Kováčik
- Department of Biology, University of Trnava, Priemyselná 4, 918 43 Trnava, Slovak Republic
| | - Tomasz Kubrak
- Centre for Innovative Research in Medical and Natural Sciences, Faculty of Medicine, University of Rzeszów, Warzywna 1a, 35-310 Rzeszów, Poland
| | - Maciej Strzemski
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland
| | - Magdalen Wójciak-Kosior
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland
| | - Anna Rysiak
- Department of Ecology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Ireneusz Sowa
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland
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Nowak PM, Woźniakiewicz M, Kościelniak P. Flow variation as a factor determining repeatability of the internal standard-based qualitative and quantitative analyses by capillary electrophoresis. J Chromatogr A 2018; 1548:92-99. [PMID: 29559267 DOI: 10.1016/j.chroma.2018.03.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/08/2018] [Accepted: 03/13/2018] [Indexed: 11/30/2022]
Abstract
The use of migration times and peak areas referred to another sample component - internal standard, brings many benefits in improving reliability of capillary electrophoresis. However, it is quite commonly overlooked that despite relative migration time and peak area ratio are more stable than the absolute values upon alteration in the flow rate, some shift should always be expected. The present work offers a new look at this analytically-important issue. We have derived a simple model allowing to estimate the magnitude of error for the selected pair of molecules of known mobilities upon the given flow alteration. Then, we have confronted the theoretical predictions with the experimental results obtained for the model sample separated in various flow conditions reached by the external pressure manipulation, including several internal standards of different mobilities. A good agreement has been obtained, pointing out that the magnitude of error may be large even for the seemingly "good" internal standards. Several potentially useful means have been tested to address this issue: the use of electrophoretic mobilities and electrophoretic mobility ratios instead migration times in the qualitative analysis, and performing time-correction of peak area ratios, or alternatively, transformation of electropherograms from the time-related scale into the electrophoretic mobility-related scale in the quantitative analysis. We have also considered some additional factors. The results may be of interest for all users dealing with the development and optimization of analytical methods using capillary electrophoresis.
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Affiliation(s)
- Paweł Mateusz Nowak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Gronostajowa St. 2, 30-387 Kraków, Poland.
| | - Michał Woźniakiewicz
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Gronostajowa St. 2, 30-387 Kraków, Poland
| | - Paweł Kościelniak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Gronostajowa St. 2, 30-387 Kraków, Poland
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Nowak PM, Woźniakiewicz M, Gładysz M, Janus M, Kościelniak P. Improving repeatability of capillary electrophoresis-a critical comparison of ten different capillary inner surfaces and three criteria of peak identification. Anal Bioanal Chem 2017; 409:4383-4393. [PMID: 28484810 PMCID: PMC5486911 DOI: 10.1007/s00216-017-0382-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 04/18/2017] [Accepted: 04/25/2017] [Indexed: 01/30/2023]
Abstract
A poor repeatability of migration times caused by the fluctuations of electroosmotic flow (EOF) is an inherent weakness of capillary electrophoresis. Most researchers endeavor to prevent this problem using relative migration times or various capillary coatings which are expensive and not easy in comparison. Herein, we present an original approach to this problem: we apply a model sample designed to induce significant EOF instability, in order to critically compare ten capillary types with different physicochemical characteristics. Moreover, we accompany capillary modification with the evaluation of various criteria of peak identification: migration time, migration times ratio, and electrophoretic mobility. Our results show a great effectiveness of a dynamic coating in the stabilization of migration times, with the average RSD(%) value reduced from 3.5% (bare silica capillary) down to 0.5%. The good outcomes were also obtained for the surfactant-modified silica and amine capillaries. For the capillaries exhibiting significant instability of EOF, electrophoretic mobility turned out to be a more universal and reliable criterion of peak identification than relative migration time. It can be explained by an intrinsic dependency of migration times ratio on EOF change, which should always be considered during the selection of an internal standard.
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Affiliation(s)
- Paweł Mateusz Nowak
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland.
| | - Michał Woźniakiewicz
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Marta Gładysz
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Magdalena Janus
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Paweł Kościelniak
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
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Zarabadi AS, Pawliszyn J, Hajialamdari M. Development of a multichannel microfluidic system with Schlieren imaging microscopy for online chip-based moving boundary electrophoresis. J Chromatogr A 2017; 1484:93-97. [PMID: 28081901 DOI: 10.1016/j.chroma.2017.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 12/30/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
Abstract
The concentration gradient detection method based on the Schlieren optics employed for electrophoresis analyses by extending the technology to a multi-channel system using a prototyped microfluidic chip (thinXXS Micro-technology, Germany). The results prove that coupling a chip-based microfluidic device with Schlieren detection is an appropriate approach to improve the electrophoretic separations. The effects of channel's geometry and dimension were investigated by conducting the experiments in channels with different cross sectional areas. Fast kinetic data acquisition of the charge-coupled device (CCD) camera facilitated recording of a time sequence of optical images, demonstrating the potential of the CCD camera as a powerful tool for studying dynamic processes such as diffusion. Diffusion coefficients of sample proteins were measured under static and dynamic conditions, where the static mode demonstrated more accurate results. Furthermore, the Fourier transformation was employed to improve the Schlieren images for quantitative analysis of the diffusion coefficient measurement.
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Affiliation(s)
- Atefeh S Zarabadi
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, N2 l 3G1, Canada
| | - Janusz Pawliszyn
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, N2 l 3G1, Canada.
| | - Mojtaba Hajialamdari
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2 l 3G1, Canada
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12
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Bidulock ACE, van den Berg A, Eijkel JCT. Improving chip-to-chip precision in disposable microchip capillary electrophoresis devices with internal standards. Electrophoresis 2015; 36:875-83. [PMID: 25522336 DOI: 10.1002/elps.201400399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 01/31/2023]
Abstract
To realize portable systems for routine measurements in point-of-care settings, MCE methods are required to be robust across many single-use chips. While it is well-known internal standards (ISTDs) improve run-to-run precision, a systematic investigation is necessary to determine the significance of chip-to-chip imprecision in MCE and how ISTDs account for it. This paper addresses this question by exploring the reproducibility of Na quantification across six basic, in-house fabricated microchips. A dataset of 900 electrophoerograms was collected from analyzing five concentrations of NaCl with two ISTDs (CsCl and LiCl). While both improved the peak area reproducibility, the Na/Cs ratio was superior to the Na/Li ratio (improving the RSD by a factor of 2-4, depending on the Na concentration). We attribute this to the significant variation in microchannel surface properties, which was accounted for by cesium but not lithium. Microchip dimension and detector variations were only a few percent, and could be improved through commercial fabrication over in-house made microchips. These results demonstrate that ISTDs not only correct for intrachip imprecision, but are also a viable means to correct for chip-to-chip imprecision inherent in disposable, point-of-care MCE devices. However, as expected, the internal standard must be carefully chosen.
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Affiliation(s)
- Allison C E Bidulock
- BIOS/The Lab-on-a-Chip Group, MESA + Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente Twente, The Netherlands
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Furmaniak P, Kubalczyk P, Głowacki R. Determination of homocysteine thiolactone in urine by field amplified sample injection and sweeping MEKC method with UV detection. J Chromatogr B Analyt Technol Biomed Life Sci 2014; 961:36-41. [DOI: 10.1016/j.jchromb.2014.04.051] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 04/16/2014] [Accepted: 04/25/2014] [Indexed: 01/09/2023]
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14
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Ren H, Qiu H, Liang X, Wang X, Jiang S. Determination of inorganic anions in saliva by electroosmotic flow controlled counterflow isotachophoretic stacking under field-amplified sample injection. J Chromatogr B Analyt Technol Biomed Life Sci 2013; 935:75-9. [PMID: 23954658 DOI: 10.1016/j.jchromb.2013.07.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 06/14/2013] [Accepted: 07/23/2013] [Indexed: 12/19/2022]
Abstract
Under a strong counter-electroosmotic flow, five salivary inorganic anions, bromide, iodide, nitrite, nitrate and thiocyanate were determined by field-amplified sample injection in combination with isotachophoretic stacking. Separation and concentration conditions were investigated. A terminating electrolyte, 5mM borate, was added in the sample. Under the optimized conditions, Br(-), I(-) and SCN(-) were concentrated online using 150mM HCl-Tris buffer at pH 7.8 in a bare fused capillary, providing more than ten thousand of sensitivity enrichment compared with normal injections. The relative standard deviations (RSDs, n=5) were less than 1% in migration times, 8% in peak areas. Using direct UV detection at 200nm and 226nm, the limits of detection (LODs, S/N=3) were of 0.002-0.01μM. Unfortunately, NO2(-) and NO3(-) could be observed in purified or deionized water. Therefore, a low dilution factor was applied to saliva samples. Due to the matrix effect, samples were injected in a shorter time, and standard addition method was applied to determine all the five inorganic anions in saliva. The RSDs of the migration times and peak areas were in a range of 0.2-0.4% and 3.0-4.0%, respectively. The LODs were 0.2-2.0μM. The salivary levels of the anions obtained were in accord with the reference data. The external standard method can not be adapted to real samples due to biases caused by electrokinetic injection and errors from high dilutions.
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Affiliation(s)
- Haixia Ren
- Key Laboratory of Chemistry of Northwestern Plant Resources, CAS and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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Wan Ibrahim WA, Abd Wahib SM, Hermawan D, Sanagi MM, Aboul-Enein HY. Separation of Selected Imidazole Enantiomers Using Dual Cyclodextrin System in Micellar Electrokinetic Chromatography. Chirality 2013; 25:328-35. [DOI: 10.1002/chir.22156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 12/28/2012] [Accepted: 01/04/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Wan Aini Wan Ibrahim
- Separation Science and Technology Group (SepSTec), Department of Chemistry, Faculty of Science; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
- Nanotechnology Research Alliance; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
| | - Siti Munirah Abd Wahib
- Separation Science and Technology Group (SepSTec), Department of Chemistry, Faculty of Science; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
| | - Dadan Hermawan
- Nanotechnology Research Alliance; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
- Ibnu Sina Institute for Fundamental Science Studies; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
| | - Mohd Marsin Sanagi
- Nanotechnology Research Alliance; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
- Ibnu Sina Institute for Fundamental Science Studies; Universiti Teknologi Malaysia; 81310 UTM Johor Bahru Johor Malaysia
| | - Hassan Y. Aboul-Enein
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical and Drug Industries Research Division, National Research Centre; Dokki Cairo 12311 Egypt
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Lee SY, Lévesque SA, Sévigny J, Müller CE. A highly sensitive capillary electrophoresis method using p-nitrophenyl 5'-thymidine monophosphate as a substrate for the monitoring of nucleotide pyrophosphatase/phosphodiesterase activities. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 911:162-9. [PMID: 23217320 DOI: 10.1016/j.jchromb.2012.10.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 10/14/2012] [Accepted: 10/26/2012] [Indexed: 12/23/2022]
Abstract
A highly sensitive capillary electrophoresis method has been developed to monitor the activity of nucleotide pyrophosphatases/phosphodiesterases (NPPs) and screen for NPP inhibitors. In this method, p-nitrophenyl 5'-thymidine monophosphate (p-Nph-5'-TMP) was used as an artificial substrate, and separation of reaction products was performed on a dynamically coated capillary. We found that the optimal capillary electrophoresis (CE) conditions were as follows: fused-silica capillary (20cm effective length×75.5μm (id)), electrokinetic injection for 60s, 70mM phosphate buffer containing polybrene 0.002%, pH 9.2, constant current of -80μA, constant capillary temperature of 15°C and detection at 400nm. To allow precise quantification, 2-methyl-4,6-dinitrophenol (dinitrocresol) was applied as an internal standard. The limit of detection (LOD) and the limit of quantification (LOQ) were 137 and 415nM, respectively. This new method was shown to be over 8-fold more sensitive than the conventional spectrophotometric assays and 16-fold more than the previously reported CE procedure, and the results (K(m) values for NPP1 and NPP3, K(i) values for standard inhibitors) obtained were in accordance with previous literature data. Therefore, this new method is an improvement of actual techniques and could be used as a quick and standard analytical technique for the identification and characterization of NPP inhibitors.
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Affiliation(s)
- Sang-Yong Lee
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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El-Kommos ME, Mohamed NA, Abdel Hakiem AF. Selective micellar electrokinetic chromatographic method for simultaneous determination of some pharmaceutical binary mixtures containing non-steroidal anti-inflammatory drugs. J Pharm Anal 2012; 3:53-60. [PMID: 29403796 PMCID: PMC5760936 DOI: 10.1016/j.jpha.2012.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 07/11/2012] [Indexed: 11/15/2022] Open
Abstract
A simple and selective micellar electrokinetic chromatographic (MEKC) method has been developed for the analysis of five pharmaceutical binary mixtures containing three non-steroidal anti-inflammatory drugs (NSAIDs). The investigated mixtures were Ibuprofen (IP)–Paracetamol (PC), Ibuprofen (IP)–Chlorzoxazone (CZ), Ibuprofen (IP)–Methocarbamol (MC), Ketoprofen (KP)–Chlorzoxazone (CZ) and Diclofenac sodium (DS)–Lidocaine hydrochloride (LC). The separation was run for all mixtures using borate buffer (20 mM, pH 9) containing 15% (v/v) methanol and 100 mM sodium dodecyl sulphate (SDS) at 15 kV and the components were detected at 214 nm. Different factors affecting the electrophoretic mobility of the seven investigated drugs were studied and optimized. The method was validated according to international conference of harmonization (ICH) guidelines and United States pharmacopoeia (USP). The method was applied to the analysis of five pharmaceutical binary mixtures in their dosage forms. The results were compared with other reported high performance liquid chromatographic methods and no significant differences were observed.
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Affiliation(s)
- Michael E El-Kommos
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Niveen A Mohamed
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Ahmed F Abdel Hakiem
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
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Deng B, Ye L, Yin H, Liu Y, Hu S, Li B. Determination of pseudolycorine in the bulb of lycoris radiata by capillary electrophoresis combined with online electrochemiluminescence using ultrasonic-assisted extraction. J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:927-32. [DOI: 10.1016/j.jchromb.2011.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 02/26/2011] [Accepted: 03/01/2011] [Indexed: 12/26/2022]
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Picou RA, Kheterpal I, Wellman AD, Minnamreddy M, Ku G, Gilman SD. Analysis of Aβ (1-40) and Aβ (1-42) monomer and fibrils by capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:627-32. [DOI: 10.1016/j.jchromb.2011.01.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 01/21/2011] [Accepted: 01/22/2011] [Indexed: 11/24/2022]
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Fogarty K, McPhee JT, Scott E, Van Orden A. Probing the ionic atmosphere of single-stranded DNA using continuous flow capillary electrophoresis and fluorescence correlation spectroscopy. Anal Chem 2009; 81:465-72. [PMID: 19117467 DOI: 10.1021/ac8019416] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two-beam fluorescence cross-correlation spectroscopy coupled with continuous flow capillary electrophoresis (2bFCCS-CFCE) was used to study the relationship between diffusion and effective charge of a fluorescently labeled 40-base polythymine single-stranded DNA (ssDNA) as a function of Mg2+ concentration. Cross-correlation analysis of the fluorescence monitored from two spatially offset microscopic detection volumes revealed the diffusion and electrophoretic migration of ssDNA at a range of Mg2+ concentrations and electric field strengths. The effective charge of the ssDNA could then be determined using simple calculations. It was found that as the Mg2+ concentration in the buffer solution increased, the diffusion of the ssDNA also increased, while the effective charge of the ssDNA decreased. This was believed to be caused by increased association of the Mg2+ counterions with the negatively charged backbone of the ssDNA, which partially neutralized the negatively charged functional groups and allowed the ssDNA to adopt a more compact structure. To our knowledge, this is the first demonstration of the measurement of effective charge of ssDNA in relation to Mg2+ concentration.
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Affiliation(s)
- Keir Fogarty
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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