How mobile phase composition and column temperature affect enantiomer elution order of liquid crystals on amylose tris(3‐chloro‐5‐methylphenylcarbamate) as chiral selector

2021 ◽  
Author(s):  
Petra Vaňkátová ◽  
Anna Kubíčková ◽  
Květa Kalíková
Keyword(s):  
Phase Composition ◽  
Liquid Crystals ◽  
Mobile Phase ◽  
Chiral Selector ◽  
Elution Order ◽  
Mobile Phase Composition ◽  
Column Temperature

scholarly journals Revising Reverse-Phase Chromatographic Behavior for Efficient Differentiation of Both Positional and Geometrical Isomers of Dicaffeoylquinic Acids

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Keabetswe Masike ◽  
Ian Dubery ◽  
Paul Steenkamp ◽  
Elize Smit ◽  
Edwin Madala
Keyword(s):  
Phase Composition ◽  
Uv Irradiation ◽  
Mobile Phase ◽  
Elution Order ◽  
Elution Profile ◽  
Plant Metabolites ◽  
Mobile Phase Composition ◽  
Reverse Phase ◽  
Geometrical Isomers ◽  
Column Temperature

Dicaffeoylquinic acids (diCQAs) are plant metabolites and undergo trans-cis-isomerization when exposed to UV irradiation. As such, diCQAs exist in both trans- and cis-configurations and amplify the already complex plant metabolome. However, analytical differentiation of these geometrical isomers using mass spectrometry (MS) approaches has proven to be extremely challenging. Exploring the chromatographic space to develop possible conditions that would aid in differentially separating and determining the elution order of these isomers is therefore imperative. In this study, simple chromatographic parameters, such as column chemistry (phenyl versus alkyl), mobile phase composition (methanol or acetonitrile), and column temperature, were investigated to aid in the separation of diCQA geometrical isomers. The high-performance liquid chromatography photodiode array (HPLC-PDA) chromatograms revealed four isomers post UV irradiation of diCQA authentic standards. The elution profile/order was seen to vary on different reverse-phase column chemistries (phenyl versus alkyl) using different mobile phase composition. Here, the elution profile/order on the phenyl-derived column matrices (with methanol as the mobile phase composition) was observed to be relatively reproducible as compared to the alkyl (C18) columns. Chromatographic resolution of diCQA geometrical isomers can be enhanced with an increase in column temperature. Lastly, the study highlights that chromatographic elution order/profile cannot be relied upon to fathom the complexity of isomeric plant metabolites.

scholarly journals IMPLICATIONS OF MOBILE PHASE COMPOSITION AND PH ON THE CHROMATOGRAPHIC SEPARATION OF AMITRIPTYLINE AND ITS METABOLITE NORTRIPTYLINE

2018 ◽  
Vol 10 (4) ◽  
pp. 132
Author(s):  
Luana Mifsud Buhagiar ◽  
Manuel Scorpiniti ◽  
Nicolette Sammut Bartolo ◽  
Janis Vella Szijj ◽  
Victor Ferrito ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Phase Composition ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Organic Modifier ◽  
Mobile Phase Composition ◽  
Simple Method ◽  
Column Temperature ◽  
Rp Hplc

Objective: Separation of tricyclic compounds sets the keystone for determining parent drug to metabolite concentration ratios and analysing impurities. The combined effects of acetonitrile composition and pH of the mobile phase on the separation of amitriptyline and nortriptyline by reversed-phase high-performance liquid chromatography (RP-HPLC) are presented.Methods: A series of RP-HPLC triplicate runs were carried out using acetonitrile and a phosphate buffer as the mobile phase and a Kinetex® C18 LC Column as the stationary phase using an Agilent 1260 Infinity Series® II liquid chromatography system with UV/visible detection. The stationary phase, column temperature, injection volume and flow rate were kept unchanged during analysis. Mobile phase composition and pH were varied to observe impact on peak shape, resolution and retention time, taking into consideration green analytical chemistry aspects.Results: Optimal chromatographic outcomes were achieved when using the mobile phase made up of 35% acetonitrile and 65% buffer at a pH of 5.6. These conditions resulted in nortriptyline and amitriptyline eluting at 4.66 min and 5.92 min respectively. Increasing the organic modifier content of the mobile phase to 40% completed separation within a run time of 4 min with comparable resolution. The 2 min gained by increasing 5% acetonitrile may not be justified due to potential implications on greening laboratory practices.Conclusion: Reversed-phase chromatography embodies a simple method for the separation of compounds that are similar in structure. Attuning the percentage of organic modifier and buffer pH provides acceptable retention times, without compromising resolution between neighbouring peaks.

Sequential Injection Chromatography with Monolithic Column for Phenothiazines Assay in Human Urine and Pharmaceutical Formulations

2020 ◽  
Vol 16 (7) ◽  
pp. 967-975
Author(s):  
Abubakr M. Idris
Keyword(s):  
Phase Composition ◽  
Human Urine ◽  
Mobile Phase ◽  
Monolithic Column ◽  
Pharmaceutical Formulations ◽  
Pharmaceutical Formulation ◽  
Assay Method ◽  
Sequential Injection ◽  
Mobile Phase Composition ◽  
Sequential Injection Chromatography

Methods: Sequential injection chromatography (SIC) with monolithic column has been proposed with potential benefits for separation and quantification. Objective: To utilize SIC to develop a new assay method for the separation and quantification of some phenothiazines (promethazine, chlorpromazine and perphenazine) in human urine and synthetic pharmaceutical formulations. Methods: The 32 full-factorial design was adopted to study the effect of mobile phase composition on separation efficiency, retention time, peak height and baseline. The separation was conducted on a C18 monolithic column (100 × 4.6 mm) using a mobile phase composition of phosphate: acetonitrile:methanol (60:28:12) at pH 4.0. The detection was carried out using a miniaturized fiber optic spectrometer at 250 nm. Results: Satisfactory analytical features, including number of theoretical plates (1809-6232), peak symmetry (1.0-1.3), recovery (95.5-99.1% in pharmaceutical formulations and 91.6-94.7% in urine), intra-day precision (0.36-1.60% for pharmaceutical formulation and 2.96-3.67 for urine), inter-day precision (1.47-2.28% for pharmaceutical formulation), limits of detection (0.23-0.88 μg/ml) and limits of quantification (0.77-2.90 μg/ml), were obtained. Conclusion: The remarkable advantages of the proposed SIC method are the inexpensiveness in terms of instrumentation and reagent consumption.

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