scholarly journals Evaluation of the Electrostatic Contribution to the Retention of Modified Nucleosides and Nucleobases by Zwitterionic Hydrophilic Interaction Chromatography

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Diego García-Gómez ◽  
Encarnación Rodríguez-Gonzalo ◽  
Rita Carabias-Martínez
Keyword(s):  
Electrostatic Interaction ◽  
Salt Concentration ◽  
Mobile Phase ◽  
Hydrophilic Interaction Chromatography ◽  
Modified Nucleosides ◽  
Hydrophilic Interaction ◽  
Low Salt ◽  
Electrostatic Contribution ◽  
Quantitative Basis ◽  
Clinical Interest

This work explores the benefits and limitations, on a quantitative basis, of using zwitterionic hydrophilic interaction chromatography (ZIC-HILIC) for the separation of several modified nucleosides and nucleobases of clinical interest. The target compounds were hydroxylated and methylated derivatives: 8-hydroxy-guanine, 8-hydroxy-guanosine, 8-hydroxy-2′-deoxyguanosine, 1-methyl-guanine, 7-methyl-guanine, and 9-methyl-guanine. A quantitative evaluation of the electrostatic interaction based on a systematic study of the nature and concentration of the salts in the mobile phase has been carried out. From the obtained results, it may be concluded that separation is based on a mechanism of partition and interaction through weak electrostatic forces: the contribution of the electrostatic interaction to the retention of the charged analytes reaching values between 25 and 52% at low salt concentration. However, the electrostatic contribution decreased progressively as the salt concentration rose.

scholarly journals Evaluating the Adsorbed Water Layer on Polar Stationary Phases for Hydrophilic Interaction Chromatography (HILIC)

2019 ◽  
Author(s):  
Yong Guo ◽  
Nidhi Bhalodia ◽  
Bassel Fattal ◽  
Ioannis Serris
Keyword(s):  
Mobile Phase ◽  
Stationary Phases ◽  
Volume Ratio ◽  
Quantitative Measure ◽  
Water Layer ◽  
Adsorbed Water ◽  
Quantitative Information ◽  
Hydrophilic Interaction Chromatography ◽  
Hydrophilic Interaction ◽  
Column Temperature

The water-rich liquid layer immobilized on the surface of the polar stationary phases is critical to the retention of polar compounds in hydrophilic interaction chromatography (HILIC). Although the presence of the adsorbed water layer has been investigated and confirmed by multiple techniques, there is a lack of quantitative measure that can be easily determined and linked to chromatographic parameters. This study proposes a simple measure termed volume ratio (the ratio of the adsorbed water layer volume and the mobile phase volume) that provides a relative, but quantitative information on the adsorbed water layer and may be linked to the phase ratio. The volume ratio can be easily determined using toluene elution volume. The volume ratio values are measured in 25 polar stationary phases in various mobile phase conditions. In addition to the acetonitrile content in the mobile phase, ammonium acetate concentration in the mobile phase and column temperature also have significant influences on the volume ratio and the adsorbed water layer.

scholarly journals Overloading study of ionized compounds in hydrophilic interaction chromatography

Chemija ◽  
2018 ◽  
Vol 29 (4) ◽  
Author(s):  
Inga Baškirova ◽  
Vilma Olšauskaitė ◽  
Audrius Padarauskas
Keyword(s):  
Mobile Phase ◽  
Stationary Phases ◽  
Hydrophilic Interaction Chromatography ◽  
Ionic Interactions ◽  
Loading Capacity ◽  
Hydrophilic Interaction ◽  
Ph Values ◽  
Opposite Trend ◽  
Mobile Phases ◽  
Acidic Compounds

The overloading behaviour of charged acidic (acetylsalicylic acid and nicotinic acid) and basic (creatinine and 1-ethyl-2,3-dimethylimidazolium) solutes was investigated on two stationary phases (bare silica and amidebonded silica) in the hydrophilic interaction chromatography separation mode at three mobile phase pH values (3.0, 5.0 and 7.0). On the bare silica both cationic solutes showed the increased peak tailing as the sample load increased. However, on the amide phase they exhibited a quite different overloading behaviour. The peak shapes for creatinine showed the increased tailing whereas for 1-ethyl-2,3-dimethylimidazolium peak fronting occurs with the sample load. Anionic solutes on both phases showed the increased peak fronting as the sample load increased. In neutral and slightly acidic mobile phases the loadability of the bare silica phase was much higher for bases than for acids. In addition, the loading capacity for the bases increases with pH whereas an opposite trend was observed for the acidic compounds. The amide phase gave similar loading capacity values for both types of solutes and its loadability is less sensitive to pH changes, compared to that of bare silica. The obtained results indicate that ionic interactions with dissociated surface silanols play an important role in the overloading behaviour of charged solutes.

scholarly journals Evaluating Relative Retention of Polar Stationary Phases in Hydrophilic Interaction Chromatography

Separations ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 42 ◽  
Author(s):  
Guo ◽  
Bhalodia ◽  
Fattal
Keyword(s):  
Mobile Phase ◽  
Stationary Phases ◽  
Hydrophilic Interaction Chromatography ◽  
Retention Data ◽  
Hydrophilic Interaction ◽  
Model Compounds ◽  
Testing Procedures ◽  
Relative Retention ◽  
Wide Range ◽  
The Right

A large number of polar stationary phases with diverse chemistry have been developed for various applications in hydrophilic interaction chromatography (HILIC). However, column manufacturers employ different testing procedures to evaluate retention of the polar stationary phases. This renders the retention data impossible for comparison and makes it difficult for the users to select the right stationary phase based on retention. We have evaluated 25 polar stationary phases using cytosine and uracil as the model compounds in various mobile phase conditions. These stationary phases show a wide range of retention characteristics for the model compounds. The ranking of the stationary phases does not change drastically with the acetonitrile level in the mobile phase.

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