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Kevin A Schug - One of the best experts on this subject based on the ideXlab platform.
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bulk derivatization and cation exchange Restricted Access Media based trap and elute liquid chromatography mass spectrometry method for determination of trace estrogens in serum
Analytica Chimica Acta, 2015Co-Authors: Jana Beinhauer, Liangqiao Bian, Hui Fan, Marek Sebela, Maciej Kukula, Jose A Barrera, Kevin A SchugAbstract:Abstract Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p -toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL −1 , and demonstrated good linearity of R 2 from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL −1 . Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.
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bulk derivatization and direct injection of human cerebrospinal fluid for trace level quantification of endogenous estrogens using trap and elute liquid chromatography with tandem mass spectrometry
Journal of Separation Science, 2014Co-Authors: Hui Fan, Barbora Papouskova, Karel Lemr, Jane G Wigginton, Kevin A SchugAbstract:Although there are existing methods for determining estrogen in human bodily fluids including blood plasma and serum, very little information is available regarding estrogen levels in human cerebrospinal fluid (CSF), which is critical to assess in studies of neuroprotective functions and diffusion of neuroprotective estrogens across the blood-brain barrier. To address this problem, a liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of four endogenous estrogens (estrone, 17α-estradiol, 17β-estradiol, and estriol) in human CSF was developed. An aliquot (300 μL) of human CSF was bulk derivatized using dansyl chloride in the sample and 10 μL was directly injected onto a Restricted-Access Media trap column for protein removal. No off-line sample extraction or cleanup was needed. The limits of detection of estrone, 17α-estradiol, 17β-estradiol, and estriol were 17, 28, 13, and 30 pg/mL, respectively, which is in the parts-per-trillion regime. The method was then applied to human CSF collected from ischemic trauma patients. Endogenous estrogens were detected and quantified, demonstrating the effectiveness of this method.
Yuki Hashi - One of the best experts on this subject based on the ideXlab platform.
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on line liquid chromatography mass spectrometry with dilution line to achieve large volume urine injection for the improvement of sensitivity
Journal of Chromatography A, 2008Co-Authors: Yuki HashiAbstract:A unique automated on-line high-performance liquid chromatography-mass spectrometry (LC-MS) method was developed allowing injection of a large volume of urine for the improvement of sensitivity using estrogens as analytes. The urine sample was precipitated by acetonitrile (sample: acetonitrile, 1 :2, v/v) to remove most proteins. Then the supernatant was directly delivered at 0.3 mL/min by a pump, which broke through the limit of autosampler with fixed loop. Then the sample was loaded onto a Restricted Access Media (RAM) pre-column after on-line dilution with NH4Ac solution which was delivered by another pump under high flow-rate. After the addition of on-line dilution line, the content of organic solvent in the sample aliquot was sharply decreased so that the analytes were effectively trapped by pre-column. In addition, another 6-port valve was added to selectively deliver the effluent containing analytes into MS, which minimized the pollution of the MS and matrix effect. After optimization of the condition of extraction method, 3 mL sample (containing I mL urine) could be successfully enriched. The injection volume increased 10 times compared with conventional on-line LC-MS methods for biofluid analysis, significantly improving sensitivity. Moreover, no obvious increase of column pressure was observed after 300 injections. The method was validated by spiking urine. Linearity was determined by sample which was in the range of 1-500 ng/mL. The process efficiency ranged from 70.2 to 106% with RSDs less than 15% with the exception of a few analytes. The limit of detection (LOD) and quantification (LOQ) ranged from 0.3 to 2 ng/mL and 1 to 8 ng/mL, respectively, corresponding a decrease of 1-2 orders of magnitude compared with those of off-line and on-line methods. (c) 2008 Elsevier B.V. All rights reserved.
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automated on line liquid chromatography photodiode array mass spectrometry method with dilution line for the determination of bisphenol a and 4 octylphenol in serum
Journal of Chromatography A, 2006Co-Authors: Min Liu, Yuki Hashi, Fengyun Pan, Jianguo Yao, Guanqun Song, Jinming LinAbstract:A novel on-line liquid chromatography-photodiode array detection-mass spectrometry (LC-DAD-MS) system was established with Restricted-Access Media (RAM) pre-column and dilution line combined with a column-switching valve. The serum samples were injected directly onto pre-column under diluted condition by dilution line. After elution of proteins in the serum, the analytes were backflushed onto an ODS analytical column using a six-port column-switching device. The influence of the composition of the mobile phase, for instance, organic modifer, ionic strength, pH, dilution times and the rotation time of the switching valve have been investigated using bisphenol A (BPA) and 4-octyphenol (4-OP) as analytes. The evaluations for peak responses and sensitivity were conducted by MS, and proteins were removed by RAM-column with DAD monitoring at 280 nm. The peak shape was improved by adding a dilution line, especially in the case of large volume injection (LVI), which increased the sensitivity of the analysis. The selective and sensitive quantification of BPA and 4-OP in serum sample could be finished within 25 min. The method had linearity in the range 0.1-500 ng/mL with a limit of quantification for BPA and 4-OP of 0.1 and 0.5 ng/mL, respectively. The recoveries were in the range of 80-101% with less than 9.0% RSDs. This on-line LC-MS method demonstrates potential application to evaluating the exposure and risk of BPA and 4-OP in human.
Audrius Maruska - One of the best experts on this subject based on the ideXlab platform.
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coupling of solid phase microextraction continuous bed monolithic capillaries with capillary zone electrophoresis for direct analysis of drugs in biological fluids
Electrophoresis, 2008Co-Authors: Reda Jarmalavicienė, Michal Szumski, Olga Kornysova, Ewa Klodzinska, Douglas Westerlund, Stanislas Krawczyk, Donatas Mickevicius, Boguslaw Buszewski, Audrius MaruskaAbstract:Hyperlink robust biocompatible solid-phase microextraction (SPME) devices were prepared using continuous bed (monolithic) Restricted-Access Media (RAM) as the SPME capillary insert. The RAM-based SPME approach was able to simultaneously separate proteins from a biological sample, while directly extracting the active components of caffeine, paracetamol and acetylsalicylic acid from the drug NeoCitramonum. The devices were interfaced with a CZE system and fully automated analysis for sample preconcentration, desorption, separation and quantification of analytes was evaluated. Comparative study of in-line coupled SPME-CZE using RAM and RP capillary inserts was carried out. Using an SPME (RAM) insert, the calculated caffeine, paracetamol and acetylsalicylic acid LODs in a bovine plasma sample were 0.3, 0.8 and 1.9 ng/mL, respectively.
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non particulate continuous bed or monolithic Restricted Access reversed phase Media for sample clean up and separation by capillary format liquid chromatography
Analytical and Bioanalytical Chemistry, 2003Co-Authors: Reda Jarmalaviciene, Olga Kornysova, Douglas Westerlund, Audrius MaruskaAbstract:Restricted-Access reversed-phase non-particulate (continuous bed or monolithic) stationary phases of different hydrophobicity synthesized in 100 μm i.d. fused silica capillaries have been evaluated. A specific property of Restricted-Access Media (RAM) is that they interact with small analytes and exclude big molecules, e.g. proteins, from Access to the active sites and adsorption on the surface. This dual property facilitates direct injection of biological fluids for drug or drug-metabolite analysis. Different RAM and RAM-precursor capillary columns were tested to assess the influence of chromatographic bed morphology on loadability. Inverse size-exclusion chromatography was used for investigation of pore structural properties of the capillary-format continuous beds. The data obtained were used to discuss the mechanism of separation of the biological samples using capillary columns and to propose a model for the topochemical architecture of the RAM investigated. Different morphology of the non-particulate reversed-phase precursors resulted in two types of RAM material shielded with hydrophilic polymer, classified as homogeneous or heterogeneous topochemistry stationary phases. Capillary columns were applied for chromatography of biological fluids. High resolution was obtained, without the need for column switching, when capillary columns operated in gradient conditions. Extensive evaluation of the chromatographic properties (hydrophobicity, efficiency, separation impedance, and loadability) of the non-particulate reversed-phase materials was performed before and after shielding with hydrophilic polymer to generate Restricted-Access properties. Minor changes of hydrophobicity, efficiency, or separation impedance were observed after the shielding.
Dalibor Satinský - One of the best experts on this subject based on the ideXlab platform.
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Polycaprolactone Composite Micro/Nanofibrous Material as an Alternative to Restricted Access Media for Direct Extraction and Separation of Non-Steroidal Anti-Inflammatory Drugs from Human Serum Using Column-Switching Chromatography
'MDPI AG', 2021Co-Authors: Hedvika Raabova, Jakub Erben, Jiři Chvojka, Frantisek Svec, Lucie Chocholoušová Havlíková, Dalibor SatinskýAbstract:Application of the poly-ɛ-caprolactone composite sorbent consisting of the micro- and nanometer fibers for the on-line extraction of non-steroidal anti-inflammatory drugs from a biological matrix has been introduced. A 100 μL human serum sample spiked with ketoprofen, naproxen, sodium diclofenac, and indomethacin was directly injected in the extraction cartridge filled with the poly-ɛ-caprolactone composite sorbent. This cartridge was coupled with a chromatographic instrument via a six-port switching valve allowing the analyte extraction and separation within a single analytical run. The 1.5 min long extraction step isolated the analytes from the proteinaceous matrix was followed by their 13 min HPLC separation using Ascentis Express RP-Amide (100 × 4.6 mm, 5 µm) column. The recovery of all analytes from human serum tested at three concentration levels ranged from 70.1% to 118.7%. The matrix calibrations were carried out in the range 50 to 20,000 ng mL−1 with correlation coefficients exceeding 0.996. The detection limit was 15 ng mL−1, and the limit of quantification corresponded to 50 ng mL−1. The developed method was validated and successfully applied for the sodium diclofenac determination in real patient serum. Our study confirmed the ability of the poly-ɛ-caprolactone composite sorbent to remove the proteins from the biological matrix, thus serving as an alternative to the application of Restricted-Access Media
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poly e caprolactone nanofibrous polymers a simple alternative to Restricted Access Media for extraction of small molecules from biological matrixes
Analytical Chemistry, 2020Co-Authors: Hedvika Raabova, Martina Hakova, Lucie Havlikova, Jakub Erben, Jiři Chvojka, Petr Solich, Frantisek Svec, Dalibor SatinskýAbstract:Poly-e-caprolactone nanofibrous polymer has been used as an alternative to Restricted Access Media for extraction of proteins-containing biological samples and direct transfer in the chromatographi...
Hui Fan - One of the best experts on this subject based on the ideXlab platform.
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bulk derivatization and cation exchange Restricted Access Media based trap and elute liquid chromatography mass spectrometry method for determination of trace estrogens in serum
Analytica Chimica Acta, 2015Co-Authors: Jana Beinhauer, Liangqiao Bian, Hui Fan, Marek Sebela, Maciej Kukula, Jose A Barrera, Kevin A SchugAbstract:Abstract Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p -toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL −1 , and demonstrated good linearity of R 2 from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL −1 . Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.
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bulk derivatization and direct injection of human cerebrospinal fluid for trace level quantification of endogenous estrogens using trap and elute liquid chromatography with tandem mass spectrometry
Journal of Separation Science, 2014Co-Authors: Hui Fan, Barbora Papouskova, Karel Lemr, Jane G Wigginton, Kevin A SchugAbstract:Although there are existing methods for determining estrogen in human bodily fluids including blood plasma and serum, very little information is available regarding estrogen levels in human cerebrospinal fluid (CSF), which is critical to assess in studies of neuroprotective functions and diffusion of neuroprotective estrogens across the blood-brain barrier. To address this problem, a liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of four endogenous estrogens (estrone, 17α-estradiol, 17β-estradiol, and estriol) in human CSF was developed. An aliquot (300 μL) of human CSF was bulk derivatized using dansyl chloride in the sample and 10 μL was directly injected onto a Restricted-Access Media trap column for protein removal. No off-line sample extraction or cleanup was needed. The limits of detection of estrone, 17α-estradiol, 17β-estradiol, and estriol were 17, 28, 13, and 30 pg/mL, respectively, which is in the parts-per-trillion regime. The method was then applied to human CSF collected from ischemic trauma patients. Endogenous estrogens were detected and quantified, demonstrating the effectiveness of this method.