Professor David McCalley's Outputs (65)

Further investigations of the effect of pressure on retention in ultra-high-pressure liquid chromatography (2010)
Journal Article

In this study, we investigated further the large increases in retention with pressure that we observed previously in RP-LC especially for ionised solutes. These findings were initially confirmed on a conventional silica C18 column, which gave extreme... Read More about Further investigations of the effect of pressure on retention in ultra-high-pressure liquid chromatography.

How to obtain good peak shapes and efficiences in liquid chromatography in reversed-phase and hydrophilic interaction separations (2009)
Presentation / Conference Contribution

Practical assessment of frictional heating effects and thermostat design on the performance of conventional (3 μm and 5 μm) columns in reversed-phase high-performance liquid chromatography (2009)
Journal Article

A practical investigation of frictional heating effects in conventional C18 columns was undertaken, to investigate whether problems found for sub-2 μm columns were also present for those of particle size 3 μm and 5 μm and different internal diameter.... Read More about Practical assessment of frictional heating effects and thermostat design on the performance of conventional (3 μm and 5 μm) columns in reversed-phase high-performance liquid chromatography.

Some new advantages of HILIC over RP-LC for the separation of drugs and other ionisable compounds (2009)
Presentation / Conference Contribution

A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography (2009)
Journal Article

Column overloading is very common during the separations of basic analytes in analytical scale reversed-phase liquid chromatography (RPLC). Due to the complex interactions of ionic analytes with stationary and mobile phases, only a very small amount... Read More about A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography.

Problems in the analysis of pharmaceuticals and other basic solutes in HPLC: Some solutions using recently developed columns (2008)
Presentation / Conference Contribution

Investigation of the effect of pressure on retention of small molecules using reversed-phase ultra-high-pressure liquid chromatography (2008)
Journal Article

The effect of inlet pressure on the retention of a series of low molecular weight acids, bases and neutrals, was investigated at constant temperature in reversed-phase liquid chromatography using a commercial ultra-high-pressure system (Waters UPLC i... Read More about Investigation of the effect of pressure on retention of small molecules using reversed-phase ultra-high-pressure liquid chromatography.

Evaluation of the properties of a superficially porous silica stationary phase in hydrophilic interaction chromatography (2008)
Journal Article

The sample capacity, column efficiency (and its variation with flow) of a superficially porous unbonded silica phase (Halo) was investigated using hydrophilic interaction chromatography (HILIC), particularly for separation of basic compounds. Sample... Read More about Evaluation of the properties of a superficially porous silica stationary phase in hydrophilic interaction chromatography.

Estimation of the extent of the water-rich layer associated with the silica surface in hydrophilic interaction chromatography (2008)
Journal Article

The possible presence of a mobile phase layer rich in water on the surface of silica columns used under conditions typical in hydrophilic interaction chromatography was investigated by the injection of a small hydrophobic solute (benzene) using aceto... Read More about Estimation of the extent of the water-rich layer associated with the silica surface in hydrophilic interaction chromatography.

Superficially porous silica stationary phases in hydrophilic interaction chromatography (2008)
Presentation / Conference Contribution

Analysis of basic compounds by reversed-phase high-performance liquid chromatography using hybrid inorganic/organic phases at high pH (2008)
Journal Article

The retention and mass overload of five bases and a quaternary ammonium compound were studied on a bridged ethyl hybrid inorganic/organic phase (XBridge C18) over a pH range 2.7-12.0 using acetonitrile-phosphate and carbonate buffers. Some comparison... Read More about Analysis of basic compounds by reversed-phase high-performance liquid chromatography using hybrid inorganic/organic phases at high pH.

Is hydrophilic interaction chromatography with silica columns a viable alternative to reversed-phase liquid chromatography for the analysis of ionisable compounds? (2007)
Journal Article

The separation of acidic, neutral and particularly basic solutes was investigated using a bare silica column, mostly under hydrophilic interaction chromatography (HILIC) conditions with water concentrations >2.5% and with >70% acetonitrile (ACN). Pro... Read More about Is hydrophilic interaction chromatography with silica columns a viable alternative to reversed-phase liquid chromatography for the analysis of ionisable compounds?.

A study of retention and overloading of basic compounds with mixed-mode reversed-phase/cation-exchange columns in high performance liquid chromatography (2007)
Journal Article

The retention and overload of bases were studied on two new mixed-mode, silica based phases possessing ionic carboxylate functionalities of different acidity embedded within a hydrophobic ligand (SiELC Primesep™). At low pH, good peak shapes were obt... Read More about A study of retention and overloading of basic compounds with mixed-mode reversed-phase/cation-exchange columns in high performance liquid chromatography.

Study of overload for basic compounds in reversed-phase high performance liquid chromatography as a function of mobile phase pH (2006)
Journal Article

The retention and overloading properties for eight basic solutes and two quaternary ammonium compounds were studied over the pH range 2.7-10.0 using phosphate and carbonate buffers. At low pH, a hybrid inorganic-organic silica-ODS phase (XTerra RP-18... Read More about Study of overload for basic compounds in reversed-phase high performance liquid chromatography as a function of mobile phase pH.

Overload for ionized solutes in reversed-phase high-performance liquid chromatography (2006)
Journal Article

Overloading occurs for submicrogram quantities of ionized solutes particularly when using low ionic strength mobile phases at low pH (e.g., formic acid), even with highly inert silica RP-HPLC columns of normal dimensions. Much higher loads can produc... Read More about Overload for ionized solutes in reversed-phase high-performance liquid chromatography.

Study of overloading of basic drugs and peptides in reversed-phase high-performance liquid chromatography using pH adjustment of weak acid mobile phases suitable for mass spectrometry (2005)
Journal Article

Serious losses in column efficiency for ionised basic drugs and peptides occur due to overloading of C18 phases when weak acid mobile phases of low ionic strength suitable for mass spectrometric detection are used. Measurable changes in retention tim... Read More about Study of overloading of basic drugs and peptides in reversed-phase high-performance liquid chromatography using pH adjustment of weak acid mobile phases suitable for mass spectrometry.

Comparison of an organic polymeric column and a silica-based reversed-phase for the analysis of basic peptides by high-performance liquid chromatography (2005)
Presentation / Conference Contribution

The performance of a purely polymeric and a Type B silica-based C 18 reversed-phase column was compared for the analysis of the basic peptide bradykinin and some analogues in order to assess the contribution of silanol interactions to peak shape. Goo... Read More about Comparison of an organic polymeric column and a silica-based reversed-phase for the analysis of basic peptides by high-performance liquid chromatography.

Effect of buffer on peak shape of peptides in reversed-phase high performance liquid chromatography (2004)
Journal Article

The effect of changing the buffer at constant low pH in the mobile phase is investigated with respect to the separation of a mixture of basic peptides. Considerably worse peak shapes, leading to poorer resolution of complex peptide mixtures, were obt... Read More about Effect of buffer on peak shape of peptides in reversed-phase high performance liquid chromatography.

Rationalization of retention and overloading behavior of basic compounds in reversed-phase HPLC using low ionic strength buffers suitable for mass spectrometric detection (2003)
Journal Article

The retention and overloading behavior of some basic (and acidic) compounds has been studied on different RP-HPLC columns in buffers of varying ionic strength. Anomalous retention patterns of acids and bases were found on one phase in low-pH, volatil... Read More about Rationalization of retention and overloading behavior of basic compounds in reversed-phase HPLC using low ionic strength buffers suitable for mass spectrometric detection.

Overloading study of bases using polymeric RP-HPLC columns as an aid to rationalization of overloading on silica-ODS phases (2002)
Journal Article

The separation of ionized bases by reversed-phase liquid chromatography with alkyl silica columns often leads to severely tailed bands that are highly detrimental. Band shape and its dependence on sample mass are notably different when mobile-phase p... Read More about Overloading study of bases using polymeric RP-HPLC columns as an aid to rationalization of overloading on silica-ODS phases.