Professor David McCalley's Outputs (65)

Practical examination of flow rate effects and influence of the stationary phase water layer on peak shape and retention in hydrophilic interaction liquid chromatography (2023)
Journal Article

The effect of flow velocity on retention and peak shape of neutral, acidic and basic probe compounds was studied using seven different UHPLC hydrophilic interaction chromatography (HILIC) columns. Surprisingly on some columns, the retention factor k... Read More about Practical examination of flow rate effects and influence of the stationary phase water layer on peak shape and retention in hydrophilic interaction liquid chromatography.

Understanding and managing peak shape for basic solutes in reversed-phase high performance liquid chromatography (2023)
Journal Article

While other separation mechanisms can challenge the dominance of reversed phase (for example in the separation of native proteins), reversed phase liquid chromatography is the method of choice for the analysis of a wide variety of samples. However, b... Read More about Understanding and managing peak shape for basic solutes in reversed-phase high performance liquid chromatography.

Managing sample introduction problems in hydrophilic interaction liquid chromatography (2023)
Journal Article

Sample injection can cause serious problems in hydrophilic interaction liquid chromatography (HILIC) when the injection solvent has higher elution strength than the mobile phase (mp). It can lead to asymmetric peak shapes and poor efficiency. The pro... Read More about Managing sample introduction problems in hydrophilic interaction liquid chromatography.

Influence of metals in the column or instrument on performance in hydrophilic interaction liquid chromatography (2021)
Journal Article

A method is proposed for measuring the relative contribution of extracolumn and column effects to the detrimental interactions which occur between metal-sensitive solutes and the complete HPLC system. The method involves the substitution of a length... Read More about Influence of metals in the column or instrument on performance in hydrophilic interaction liquid chromatography.

But my peaks are not Gaussian! Part 3: Physicochemical causes of peak tailing (2021)
Journal Article

Although symmetric peaks with Gaussian shapes are predicted by models of the chromatographic process, "perfect peaks" are not observed often outside of textbooks. Several physico-chemical phenomena can lead to asymmetric peak shapes, including analyt... Read More about But my peaks are not Gaussian! Part 3: Physicochemical causes of peak tailing.

Alternative mobile phase additives for the characterization of protein biopharmaceuticals in liquid chromatography – Mass spectrometry (2021)
Journal Article

When analyzing large complex protein biopharmaceuticals, ion-pairing agents imparting low pH are widely used as mobile phase additives to improve the chromatographic performance. However, one of the most effective additives in RPLC and HILIC, trifluo... Read More about Alternative mobile phase additives for the characterization of protein biopharmaceuticals in liquid chromatography – Mass spectrometry.

Evaluation of a linear free energy relationship for the determination of the column void volume in hydrophilic interaction chromatography (2021)
Journal Article

The application of a linear free energy relationship (LFER) to a variety of hydrophilic interaction chromatography columns with different bonded ligands and pore sizes was studied in order to determine their void volume Vm. The method was based on th... Read More about Evaluation of a linear free energy relationship for the determination of the column void volume in hydrophilic interaction chromatography.

Managing the column equilibration time in hydrophilic interaction chromatography (2019)
Journal Article

For a wide variety of hydrophilic interaction chromatography stationary phases, a repeatable partial equilibration was demonstrated in gradient elution after purging with as little as 12 column volumes of mobile phase. Relative standard deviations of... Read More about Managing the column equilibration time in hydrophilic interaction chromatography.

Evaluation of additives on reversed-phase chromatography of monoclonal antibodies using a 1000 Å stationary phase (2019)
Journal Article

© 2019 Elsevier B.V. A wide pore (1000 Å) diphenyl stationary phase was evaluated for the analysis of monoclonal antibodies (mAbs), comparing a conventional mobile phase of acetonitrile-water containing overall 0.1% trifluoracetic acid (TFA) with a s... Read More about Evaluation of additives on reversed-phase chromatography of monoclonal antibodies using a 1000 Å stationary phase.

Hydrophilic interaction liquid chromatography: An update (2019)
Journal Article

This article is an update on the technique of hydrophilic interaction liquid chromatography (HILIC) and covers recent ideas on the mechanism of separation, and how it may be manipulated to suit the separation of particular sample types. The advantage... Read More about Hydrophilic interaction liquid chromatography: An update.

Retention characteristics of some antibiotic and anti-retroviral compounds in hydrophilic interaction chromatography using isocratic elution, and gradient elution with repeatable partial equilibration (2018)
Journal Article

© 2018 Elsevier B.V. The separation of some zwitterionic, basic and neutral antibiotic and antiretroviral compounds was studied using hydrophilic interaction chromatography (HILIC) on bare silica, bonded amide and urea superficially porous phases. T... Read More about Retention characteristics of some antibiotic and anti-retroviral compounds in hydrophilic interaction chromatography using isocratic elution, and gradient elution with repeatable partial equilibration.

A study of column equilibration time in hydrophilic interaction chromatography (2018)
Journal Article

© 2018 Elsevier B.V. The time taken to achieve full column equilibration for isocratic analysis of acidic, basic, and neutral solutes in hydrophilic interaction liquid chromatography (HILIC) was compared using the mobile phase disturbance method, col... Read More about A study of column equilibration time in hydrophilic interaction chromatography.

A study of the analysis of acidic solutes by hydrophilic interaction chromatography (2017)
Journal Article

© 2017 Elsevier B.V. The analysis of acidic solutes was compared on a cross-linked bonded amino phase and a neutral hybrid inorganic-organic amide phase, previously shown to give reasonable retention of acidic solutes. The amino column gave strong se... Read More about A study of the analysis of acidic solutes by hydrophilic interaction chromatography.

Understanding and manipulating the separation in hydrophilic interaction liquid chromatography (2017)
Journal Article

© 2017 Elsevier B.V. Hydrophilic interaction liquid chromatography (HILIC) has emerged as a valuable complimentary technique to reversed-phase (RP), being especially suited for the analysis of polar and ionised solutes, which are difficult to retain... Read More about Understanding and manipulating the separation in hydrophilic interaction liquid chromatography.

Effect of mobile phase additives on solute retention at low aqueous pH in hydrophilic interaction liquid chromatography (2016)
Journal Article

© 2016 Elsevier B.V. Trifluoracetic acid (TFA) added to the aqueous acetonitrile mobile phase induces some unexpected changes in the ionic component of retention in hydrophilic interaction separations when using Type B silica and amide-bonded silica... Read More about Effect of mobile phase additives on solute retention at low aqueous pH in hydrophilic interaction liquid chromatography.

Recent developments in support materials for use in high performance liquid chromatography (2016)
Journal Article

A number of advances have taken place in the last decade in the area of support materials for high performance liquid chromatography (HPLC). These developments have included the use of very small porous particles (< 2.0 micron diameter), new types of... Read More about Recent developments in support materials for use in high performance liquid chromatography.

Distinction of synthetic dl-α-tocopherol from natural vitamin E (d-α-tocopherol) by reversed-phase liquid chromatography. Enhanced selectivity of a polymeric C18 stationary phase at low temperature and/or at high pressure (2016)
Journal Article

© 2016 Elsevier B.V. Separation of diastereomers of DL-α-tocopherol was studied by reversed-phase liquid chromatography using three types of stationary phases, polymeric ODS, polymeric C30, and monomeric ODS. Polymeric ODS stationary phase (Inertsil... Read More about Distinction of synthetic dl-α-tocopherol from natural vitamin E (d-α-tocopherol) by reversed-phase liquid chromatography. Enhanced selectivity of a polymeric C18 stationary phase at low temperature and/or at high pressure.

Core-Shell, Ultrasmall Particles, Monoliths, and Other Support Materials in High-Performance Liquid Chromatography (2016)
Journal Article

A review of the developments that have taken place in the area of supports for high performance liquid chromatography in recent years.

Some factors that can lead to poor peak shape in hydrophilic interaction chromatography, and possibilities for their remediation (2016)
Journal Article

© 2015 Elsevier B.V. Some factors which present difficulties for obtaining good peak shape in hydrophilic interaction chromatography (HILIC) were studied. The effect of injection solvent composition and volume was systematically investigated using a... Read More about Some factors that can lead to poor peak shape in hydrophilic interaction chromatography, and possibilities for their remediation.

Performance of charged aerosol detection with hydrophilic interaction chromatography (2015)
Journal Article

© 2015 The Authors. The performance of the charged aerosol detector (CAD) was investigated using a diverse set of 29 solutes, including acids, bases and neutrals, over a range of mobile phase compositions, particularly with regard to its suitability... Read More about Performance of charged aerosol detection with hydrophilic interaction chromatography.