Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns

AbstractTemperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.

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Wide-Bore Capillary Gas Chromatographic Determination of Organophosphorus Pesticide Residues in Foods: Interlaboratory Trial

Journal of AOAC International ◽

10.1093/jaoac/77.1.92 ◽

1994 ◽

Vol 77 (1) ◽

pp. 92-101

Author(s):

Charles H Parfitt

Keyword(s):

Pesticide Residues ◽

Stationary Phases ◽

Packed Column ◽

Capillary Columns ◽

Packed Columns ◽

Detector Response ◽

Official Method ◽

Methyl Silicone ◽

Interlaboratory Trial

Abstract Wide-Bore capillary columns are often used as alternatives to traditionally packed columns for gas chromatographic (GC) determination of pesticide residues in foods. Fused silica columns with cross-linked, bonded stationary phases are reproducible, rugged, and easy to use and are substantially more inert than their packed column equivalents. An interlaboratory trial was conducted in 5 U.S. Food and Drug Administration laboratories to determine the practicability of using isothermal wide-bore capillary GC as an alternative to the packed column GC systems used in AOAC Official Methods for determining pesticide residues in foods. Two wide-bore capillary columns with flame photometric detection were evaluated with respect to the following: linearity of detector response; repeatability of response for equal and unequal injection volumes of standard solutions; accuracy of quantitating pesticides in food extracts when the injection volumes or analyte concentrations of the standard solution and the food extract are different; recoveries of 23 pesticides from 5 fortified food extracts, calculated from both duplicate and single injections; and relative retention times. Before shipment, food extracts supplied to participants were fortified with pesticides after preparation and extraction of the foods by Official Method 985.22. The performance of wide-bore capillary columns with cross-linked bonded methyl silicone and methyl phenyl silicone stationary phases was equal or superior to that of the packed columns specified in the Official Method.

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Novel thermoresponsive polymer outperforming Pluronic® F127

10.21203/rs.3.rs-104434/v1 ◽

2020 ◽

Author(s):

Anna Constantinou ◽

Valeria Nele ◽

James Doutch ◽

Roman Moiseev ◽

Vitaliy Khutoryanskiy ◽

...

Keyword(s):

Self Assembly ◽

Biomedical Applications ◽

Ex Vivo ◽

Structural Characteristics ◽

Thermoresponsive Polymer ◽

Scanning Calorimetry ◽

Thermoresponsive Polymers ◽

Crosslinked Networks ◽

Gelation Concentration ◽

Physically Crosslinked

Abstract Thermoresponsive polymers featuring the appropriate combination of structural characteristics, i.e. architecture, composition, and molar mass (MM), can form physically crosslinked networks in a solvent upon changes in temperature. This fascinating class of polymers finds utility in various sectors such as formulation science and tissue engineering. Here, we report a novel thermoresponsive triblock terpolymer which out-performs the most commonly used and commercially available thermoresponsive polymer, Poloxamer P407 (also known as Pluronic® F127) in terms of gelation concentration. Specifically, the in-house synthesised polymer forms gels at lower concentrations that is an advantage in biomedical applications. To elucidate the differences in their macroscale gelling behaviour, we investigate their micellization via differential scanning calorimetry, and their nanoscale self-assembly behaviour in detail by means of small-angle neutron scattering by simultaneously recording their rheological properties (Rheo-SANS). Two different gelation mechanisms for the two polymers are revealed and proposed. Ex vivo gelation study upon intracameral injections demonstrated excellent potential for its application to improve drug residence in the eye.

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Effects of terminal group and chain length on temperature-responsive chromatography utilizing poly(N-isopropylacrylamide) synthesized via RAFT polymerization

RSC Advances ◽

10.1039/c5ra15906g ◽

2015 ◽

Vol 5 (89) ◽

pp. 73217-73224 ◽

Cited By ~ 10

Author(s):

Yuki Hiruta ◽

Yuhei Nagumo ◽

Atsushi Miki ◽

Teruo Okano ◽

Hideko Kanazawa

Keyword(s):

Chain Length ◽

Functional Group ◽

Raft Polymerization ◽

Stationary Phases ◽

Terminal Group ◽

Temperature Dependent ◽

Temperature Responsive ◽

Silica Beads ◽

Elution Behavior ◽

Terminal Functional Group

Even using the same homo poly(N-isopropylacrylamide) immobilized silica beads as stationary phases, terminal functional group and chain length significantly affected temperature-dependent elution behavior of steroids.

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Parametric Studies of Microstructural Performance Effects in Solid Oxide Cells

Volume 6A: Energy ◽

10.1115/imece2014-39021 ◽

2014 ◽

Author(s):

Zachary K. van Zandt ◽

George J. Nelson

Keyword(s):

Pore Diameter ◽

Cell Polarization ◽

Solid Oxide ◽

Transfer Model ◽

Co2 Gas ◽

Pore Sizes ◽

Gas Streams ◽

Performance Effects ◽

Parametric Studies ◽

Electrochemical Potentials

A distributed charge transfer model has been developed to analyze solid oxide fuel cells and electrolyzers operating in H2-H2O and CO-CO2 atmospheres. The model couples mass transport based on the dusty-gas model, ion and electron transport in terms of charged species electrochemical potentials, and electrochemical reactions defined by Butler-Volmer kinetics. The model is validated by comparison to published experimental data, particularly cell polarization curves for both fuel cell and electrolyzer operation. Parametric studies have been performed to compare the effects of microstructure on the performance of SOFCs and SOECs operating in H2-H2O and CO-CO2 gas streams. Compared to the H2-H2O system, the power density of the CO-CO2 system shows a greater sensitivity to porosity and tortuosity. Analyses of the effects of the pore diameter suggest the H2-H2O and CO-CO2 systems are affected by changes in pore diameter in a similar manner. However, the concentration losses of the CO-CO2 system are significantly higher than those of the H2-H2O system for the pore sizes analyzed. While both systems can be shown to improve in performance with higher porosity, lower tortuosity, and larger pore sizes the results of these parametric studies imply that CO-CO2 systems would benefit more from such microstructural changes. These results further suggest that objectives for tailoring microstructure in solid oxide cells operating in CO-CO2 are distinct from objectives for more common H2-focused systems.

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CdS Nanoparticles with a Thermoresponsive Polymer: Synthesis and Properties

Journal of Nanomaterials ◽

10.1155/2012/451506 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Aslam Khan

Keyword(s):

Room Temperature ◽

Sodium Sulfide ◽

Organic Ligand ◽

Cds Nanoparticles ◽

Particle Sizes ◽

Thermoresponsive Polymer ◽

Temperature Responsive ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Absorption Measurements

This paper describes the synthesis of thermoresponsive colloidal nanocomposites based on CdS and poly(N-isopropylacrylamide). The CdS nanoparticles were prepared at room temperature from cadmium chloride and sodium sulfide salts in the presence of an organic ligand, 3-mercaptopropionic acid (MPA). The as-prepared MPA-bound CdS nanoparticles were stable for more than 30 days and exhibited good optical properties. The effect of various ratios of MPA/Cd2+and H2O/DMF (dimethylformamide) on the particle size of the CdS nanoparticles was investigated using UV-vis absorption measurements. Transmission electron microscopy studies showed that the particle sizes were approximately 4 nm in diameter, which is consistent with the size obtained using UV-vis spectroscopy. The CdS nanocomposite showed a temperature-responsive phenomenon as its temperature increased from 20 to 45°C.

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Temperature responsive chromatography for therapeutic drug monitoring with an aqueous mobile phase

Scientific Reports ◽

10.1038/s41598-021-02998-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kenichi Nagase ◽

Teruno Nishiyama ◽

Masakazu Inoue ◽

Hideko Kanazawa

Keyword(s):

Therapeutic Drug Monitoring ◽

Organic Solvents ◽

Drug Monitoring ◽

Mobile Phase ◽

Therapeutic Drug ◽

Modified Silica ◽

Chromatography Column ◽

Temperature Responsive ◽

Silica Beads ◽

Elution Behavior

AbstractTherapeutic drug monitoring is a key technology for effective pharmacological treatment. In the present study, a temperature-responsive chromatography column was developed for safe and simple therapeutic drug monitoring without the use of organic solvents. Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel-modified silica beads were prepared via a condensation reaction and radical polymerization. The temperature-dependent elution behavior of the drugs was observed using a PNIPAAm-modified silica-bead packed column and an all-aqueous mobile phase. Sharp peaks with reproducible retention times were observed at temperatures of 30 °C or 40 °C because the PNIPAAm hydrogel on the silica beads shrinks at these temperatures, limiting drug diffusion into the PNIPAAm hydrogel layer. The elution behavior of the sample from the prepared column was examined using a mixture of serum and model drugs. The serum and drugs were separated on the column at 30 °C or 40 °C, and the concentration of the eluted drug was obtained using the calibration curve. The results show that the prepared chromatography column would be useful for therapeutic drug monitoring because the drug concentration in serum can be measured without using organic solvents in the mobile phase and without any need for sample preparation.

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Monitoring of the Variation in Pore Sizes of Woven Geotextiles with Uniaxial Tensile Strain

Applied Sciences ◽

10.3390/app12010374 ◽

2021 ◽

Vol 12 (1) ◽

pp. 374

Author(s):

Wenfang Zhao ◽

Xiaowu Tang ◽

Keyi Li ◽

Jiaxin Liang ◽

Weikang Lin ◽

...

Keyword(s):

Pore Size ◽

Tensile Strain ◽

Pore Diameter ◽

Filter Design ◽

Uniaxial Tensile ◽

Distribution Diagram ◽

Pore Sizes ◽

Large Pore ◽

Small Pore ◽

Pore Opening

Characteristic pore-opening size O95 or O90 has been widely used in the filter design of woven geotextiles. These manufactured products have different pore size proportions of large pore diameters, medium pore diameters, and small pore diameters, respectively. Therefore, uncertainties still exist regarding the prediction of geotextile pore diameter variations under the uniaxial tensile strain. This paper investigates the variations in five characteristic pore-opening sizes O95, O80, O50, O30, and O10, with uniaxial tensile strain by using the image analysis method. The large pore diameters, medium pore diameters, and small pore diameters show different variation behaviors as the uniaxial tensile strain increases. Fifteen specific pores are selected and then their pore diameter variations are monitored under each tensile strain of 1%. The colorful pore size distribution diagram is a visual way to identify the variation of pores arranged in the tension direction (warp direction) and the direction perpendicular to tensile loads (weft direction). The various pore diameters are proved to agree well with the bell-shaped Gaussian distribution. The results exhibit an accurate prediction of the variation in large pore sizes, medium pore sizes, and small pore sizes, respectively, for all tested woven geotextiles with uniaxial tensile strain.

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Glass transition in temperature-responsive poly(butyl methacrylate) grafted polymer brushes. Impact of thickness and temperature on wetting, morphology, and cell growth

Journal of Materials Chemistry B ◽

10.1039/c8tb00088c ◽

2018 ◽

Vol 6 (11) ◽

pp. 1613-1621 ◽

Cited By ~ 8

Author(s):

Yurij Stetsyshyn ◽

Joanna Raczkowska ◽

Ostap Lishchynskyi ◽

Kamil Awsiuk ◽

Joanna Zemla ◽

...

Keyword(s):

Glass Transition ◽

Cell Growth ◽

Polymer Brushes ◽

Butyl Methacrylate ◽

Grafted Polymer ◽

Temperature Responsive ◽

Biocompatible Coating

PBMA as temperature-responsive and biocompatible coating.

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A novel approach for calculating packed column height based on new correlation of mass transfer coefficient

Polish Journal of Chemical Technology ◽

10.1515/pjct-2015-0008 ◽

2015 ◽

Vol 17 (1) ◽

pp. 48-54

Author(s):

Ahmad Rahbar-Kelishami ◽

Hossein Bahmanyar ◽

Zahra Hajamini

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Conventional Method ◽

Packed Column ◽

Packed Columns ◽

Column Height ◽

Transfer Coefficients ◽

New Correlation ◽

Novel Approach

Abstract The calculation of column’s height plays an important role in packed columns precise design. This research is based on experimentally measurement of mass transfer coefficients in different heights of packed column to predict its height. The objective of presented work is to introduce a novel conceptual method to predict column height via new correlation for mass transfer coefficient. As the mass transfer coefficient is decreased with increase of column height, the HTU’s are not constant figures along the column so this new approach is called increasing HTU’s. The results of the proposed idea were compared with other correlations and the conventional method i.e. constant HTU’s. Since the results are in very good agreement with experimental data comparing to conventional method, it seems this approach can be a turning point in design of all differential columns like packed columns. Making use of this method is suggested for design of differential columns.

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