Capacity factors and peak widths in the gradient elution reversed phase separation of high molar mass polystyrenes

1997 ◽  
Vol 46 (1-2) ◽  
pp. 12-16 ◽  
Author(s):  
T. L. Pang ◽  
P. E. Kavanagh
Keyword(s):  
Phase Separation ◽  
Molar Mass ◽  
Gradient Elution ◽  
Reversed Phase ◽  
High Molar Mass ◽  
Peak Widths

scholarly journals Temperature Gradient Interaction Chromatography: A Perspective

2021 ◽  
Author(s):  
Lian R. Hutchings ◽  
Antonella Pagliarulo
Keyword(s):  
Liquid Chromatography ◽  
Temperature Gradient ◽  
Molar Mass ◽  
Reversed Phase ◽  
Normal Phase ◽  
Branched Polymers ◽  
Size Exclusion ◽  
Advanced Technique ◽  
High Molar Mass ◽  
Exclusion Chromatography

AbstractThe application of temperature gradient interaction chromatography (TGIC) as an advanced technique for the characterisation of polymers is discussed, in comparison to other liquid chromatography techniques and in particular the ubiquitous size exclusion chromatography. Specifically, the use of reversed-phase TGIC for the interrogation of complex branched polymers and normal-phase TGIC for characterisation of high-molar mass end-functionalised polymers is highlighted.

Paper Chemistry: Interactions of thermo mechanical pulp fractions with high molar mass cationic polyacrylamides: Part 2. Flocculation

2010 ◽  
Vol 25 (3) ◽  
pp. 310-318 ◽  
Author(s):  
Tero Taipale ◽  
Janne Laine ◽  
Susanna Holappa ◽  
Jonni Ahlgren ◽  
Juan Cecchini
Keyword(s):  
Molar Mass ◽  
High Molar Mass ◽  
Mechanical Pulp ◽  
Paper Chemistry

Reversed-Phase High Performance Liquid Chromatographic Analysis of Three First Line Anti-Tuberculosis Drugs

2019 ◽  
Vol 69 (12) ◽  
pp. 3590-3592
Author(s):  
Nela Bibire ◽  
Romeo Iulian Olariu ◽  
Luminita Agoroaei ◽  
Madalina Vieriu ◽  
Alina Diana Panainte ◽  
...  
Keyword(s):  
High Performance ◽  
Biological Fluids ◽  
Gradient Elution ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Assay Method ◽  
Active Pharmaceutical Ingredients ◽  
First Line ◽  
Pharmaceutical Ingredients ◽  
Liquid Chromatographic

Active pharmaceutical ingredients such as isoniazid, pyrazinamide and rifampicin are among the most important first-line anti-tuberculosis drugs. A simple, rapid and sensitive reversed phase-high performance liquid chromatographic assay method for the simultaneous determination of isoniazid, pyrazinamide and rifampicin has been developed. Separation of the interest compounds was achieved in a 10 min chromatographic run in gradient elution mode on a Zorbax SB-C18 stainless steel column (150 � 4 mm, 5 mm) using a guard column containing the same stationary phase. The gradient elution was carried out with a mobile phase of 10% CH3CN aqueous solution for channel A and 50% CH3CN in pH = 6.8 phosphate buffer (20 mM), to which 1.5 mL triethylamine were added for channel B. Quantification of the analyzed substances was carried out spectrophotometrically at 269 nm. Detection limits of 0.48 mg/L for isoniazid, 0.52 mg/L for pyrazinamide and 0.48 mg/L for rifampicin were established for the developed assay method. The present work showed that the proposed analysis method was advantageous for simple and rapid analysis of the active pharmaceutical ingredients in pharmaceuticals and biological fluids.

Improved separation of C12-C22 fatty acid phenacyl esters by reversed phase column liquid chromatography

1986 ◽  
Vol 51 (12) ◽  
pp. 2722-2726 ◽  
Author(s):  
Tomáš Haniš ◽  
Miroslav Smrž ◽  
Pavel Klír ◽  
Karel Macek ◽  
Zdeněk Deyl
Keyword(s):  
Volume Concentration ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Isocratic Elution ◽  
Water Gradient ◽  
Phenacyl Esters ◽  
Acetonitrile Concentration ◽  
Phase Column ◽  
Reversed Phase Column ◽  
Critical Pairs

Phenacyl esters of C12-C22 fatty acids were separated on Separon SGX C18 column, using a gradient elution with methanol-acetonitrile-water. The proposed gradient showed better resolution of the critical pairs C18:3-C14:0, C16:1-C20:4, and C16:0-C18:1 than the gradient elution with methanol-water or acetonitrile-water, or than the isocratic elution with methanol-acetonitrile-water. The optimum volume concentration (83%) of the sum of both methanol and acetonitrile was maintained constant for 35 min; in this period the acetonitrile concentration decreased linearly from the initial 42-60% to 0% while the methanol concentration increased from the initial 41-23% to 83% at the same rate. After 35 min the elution was completed with a methanol-water gradient. The whole analysis can be performed within 63 min at a flow rate 1 ml/min.

scholarly journals Highly Efficient MOF Catalyst Systems for CO2 Conversion to Bis-Cyclic Carbonates as Building Blocks for NIPHUs (Non-Isocyanate Polyhydroxyurethanes) Synthesis

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 628
Author(s):  
Adolfo Benedito ◽  
Eider Acarreta ◽  
Enrique Giménez
Keyword(s):  
Molar Mass ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Catalyst System ◽  
Cyclic Carbonate ◽  
Ammonium Bromide ◽  
Cyclic Carbonates ◽  
High Molar Mass ◽  
Highly Efficient ◽  
Free Process

The present paper describes a greener sustainable route toward the synthesis of NIPHUs. We report a highly efficient solvent-free process to produce [4,4′-bi(1,3-dioxolane)]-2,2′-dione (BDC), involving CO2, as renewable feedstock, and bis-epoxide (1,3-butadiendiepoxide) using only metal–organic frameworks (MOFs) as catalysts and cetyltrimethyl-ammonium bromide (CTAB) as a co-catalyst. This synthetic procedure is evaluated in the context of reducing global emissions of waste CO2 and converting CO2 into useful chemical feedstocks. The reaction was carried out in a pressurized reactor at pressures of 30 bars and controlled temperatures of around 120–130 °C. This study examines how reaction parameters such as catalyst used, temperature, or reaction time can influence the molar mass, yield, or reactivity of BDC. High BDC reactivity is essential for producing high molar mass linear non-isocyanate polyhydroxyurethane (NIPHU) via melt-phase polyaddition with aliphatic diamines. The optimized Al-OH-fumarate catalyst system described in this paper exhibited a 78% GC-MS conversion for the desired cyclic carbonates, in the absence of a solvent and a 50 wt % chemically fixed CO2. The cycloaddition reaction could also be carried out in the absence of CTAB, although lower cyclic carbonate yields were observed.

scholarly journals Determination of Antiviral Drugs and Their Metabolites Using Micro-Solid Phase Extraction and UHPLC-MS/MS in Reversed-Phase and Hydrophilic Interaction Chromatography Modes

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2123
Author(s):  
Luboš Fical ◽  
Maria Khalikova ◽  
Hana Kočová Vlčková ◽  
Ivona Lhotská ◽  
Zuzana Hadysová ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Tandem Mass ◽  
Phase Extraction ◽  
Hydrophilic Interaction

Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC.

scholarly journals High Molar Mass Polycarbonate via Dynamic Solution Transcarbonation Using Bis(methyl salicyl) Carbonate, an Activated Carbonate

2021 ◽  
pp. 2100186
Author(s):  
Annelore Aerts ◽  
Camiel Kroonen ◽  
Jan Henk Kamps ◽  
Rint P. Sijbesma ◽  
Johan P. A. Heuts
Keyword(s):  
Molar Mass ◽  
High Molar Mass ◽  
Dynamic Solution

Synthesis of high molar mass poly(12-hydroxydodecanoic acid) in brønsted acid ionic liquids

Polymer ◽  
2010 ◽  
Vol 51 (6) ◽  
pp. 1218-1221 ◽  
Author(s):  
Elise-Marie Dukuzeyezu ◽  
Hervé Lefebvre ◽  
Martine Tessier ◽  
Alain Fradet
Keyword(s):  
Ionic Liquids ◽  
Molar Mass ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
High Molar Mass ◽  
Brönsted Acid
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