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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
McCalley, D. V. (2024). Practical examination of flow rate effects and influence of the stationary phase water layer on peak shape and retention in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1715, Article 464608. https://doi.org/10.1016/j.chroma.2023.464608

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
McCalley, D. V. (2023). Understanding and managing peak shape for basic solutes in reversed-phase high performance liquid chromatography. Chemical Communications, 59(51), 7887-7899. https://doi.org/10.1039/d3cc01535a

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
Taylor, M. R., Kawakami, J., & McCalley, D. V. (2023). Managing sample introduction problems in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1700, Article 464006. https://doi.org/10.1016/j.chroma.2023.464006

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
McCalley, D. V. (2022). Influence of metals in the column or instrument on performance in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1663, Article 462751. https://doi.org/10.1016/j.chroma.2021.462751

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
Mccalley, D., & Stoll, D. R. (2021). But my peaks are not Gaussian! Part 3: Physicochemical causes of peak tailing. LCGC North America, 39(11), 526–533, 539

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
Lardeux, H., Duivelshof, B. L., Colas, O., Beck, A., McCalley, D. V., Guillarme, D., & D’Atri, V. (2021). Alternative mobile phase additives for the characterization of protein biopharmaceuticals in liquid chromatography – Mass spectrometry. Analytica Chimica Acta, 1156, Article 338347. https://doi.org/10.1016/j.aca.2021.338347

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
McCalley, D. V. (2021). Evaluation of a linear free energy relationship for the determination of the column void volume in hydrophilic interaction chromatography. Journal of Chromatography A, 1638, Article 461849. https://doi.org/10.1016/j.chroma.2020.461849

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
McCalley, D. V. (2020). Managing the column equilibration time in hydrophilic interaction chromatography. Journal of Chromatography A, 1612, Article 460655. https://doi.org/10.1016/j.chroma.2019.460655

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
McCalley, D. V., & Guillarme, D. (2020). Evaluation of additives on reversed-phase chromatography of monoclonal antibodies using a 1000 Å stationary phase. Journal of Chromatography A, 1610, Article 460562. https://doi.org/10.1016/j.chroma.2019.460562

© 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
McCalley, D. V. (2019). Hydrophilic interaction liquid chromatography: An update. Lc Gc Europe, 32(3), 114-125

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
Heaton, J. C., Smith, N. W., & McCalley, D. V. (2019). Retention characteristics of some antibiotic and anti-retroviral compounds in hydrophilic interaction chromatography using isocratic elution, and gradient elution with repeatable partial equilibration. Analytica Chimica Acta, 1045, 141-151. https://doi.org/10.1016/j.aca.2018.08.051

© 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
McCalley, D. V. (2018). A study of column equilibration time in hydrophilic interaction chromatography. Journal of Chromatography A, 1554, 61-70. https://doi.org/10.1016/j.chroma.2018.04.016

© 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
McCalley, D. V. (2018). A study of the analysis of acidic solutes by hydrophilic interaction chromatography. Journal of Chromatography A, 1534, 64-74. https://doi.org/10.1016/j.chroma.2017.12.045

© 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
McCalley, D. V. (2017). Understanding and manipulating the separation in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1523, 49-71. https://doi.org/10.1016/j.chroma.2017.06.026

© 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
McCalley, D. V. (2017). Effect of mobile phase additives on solute retention at low aqueous pH in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1483, 71-79. https://doi.org/10.1016/j.chroma.2016.12.035

© 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
McCalley, D. V. (2016). Recent developments in support materials for use in high performance liquid chromatography

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
Yui, Y., Miyazaki, S., Ma, Y., Ohira, M., Fiehn, O., Ikegami, T., …Tanaka, N. (2016). 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. Journal of Chromatography A, 1450, 45-52. https://doi.org/10.1016/j.chroma.2016.04.076

© 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
Tanaka, N., & McCalley, D. V. (2016). Core-Shell, Ultrasmall Particles, Monoliths, and Other Support Materials in High-Performance Liquid Chromatography. Analytical Chemistry, 88(1), 279-298. https://doi.org/10.1021/acs.analchem.5b04093

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
Heaton, J. C., Heaton, J., & McCalley, D. V. (2016). Some factors that can lead to poor peak shape in hydrophilic interaction chromatography, and possibilities for their remediation. Journal of Chromatography A, 1427, 37-44. https://doi.org/10.1016/j.chroma.2015.10.056

© 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
Russell, J. J., Heaton, J. C., Underwood, T., Boughtflower, R., & McCalley, D. V. (2015). Performance of charged aerosol detection with hydrophilic interaction chromatography. Journal of Chromatography A, 1405, 72-84. https://doi.org/10.1016/j.chroma.2015.05.050

© 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.

Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range (2015)
Journal Article
McCalley, D. V. (2015). Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range. Journal of Chromatography A, 1411, 41-49. https://doi.org/10.1016/j.chroma.2015.07.092

© 2015 Elsevier B.V. Retention factor and column efficiency measurements were made for 14 test compounds comprising acids, bases and neutrals on two pairs of amide and bare silica HILIC columns, each pair obtained from a different manufacturer. The c... Read More about Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range.

The impact of pressure and frictional heating on retention, selectivity and efficiency in ultra-high-pressure liquid chromatography (2014)
Journal Article
McCalley, D. V. (2014). The impact of pressure and frictional heating on retention, selectivity and efficiency in ultra-high-pressure liquid chromatography. Trends in Analytical Chemistry, 63, 31-43. https://doi.org/10.1016/j.trac.2014.06.024

© 2014 Elsevier B.V. The effects of pressure and frictional heating deserve serious consideration in ultra-high-pressure liquid chromatography (UHPLC) separations, as the pressures used can be three times greater than those in conventional high-perfo... Read More about The impact of pressure and frictional heating on retention, selectivity and efficiency in ultra-high-pressure liquid chromatography.

Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure (2014)
Journal Article
Okusa, K., Iwasaki, Y., Kuroda, I., Miwa, S., Ohira, M., Nagai, T., …Tanaka, N. (2014). Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure. Journal of Chromatography A, 1339, 86-95. https://doi.org/10.1016/j.chroma.2014.02.077

A high-density, polymeric C18 stationary phase (Inertsil ODS-P) or a polymeric C30 phase (Inertsil C30) provided improved resolution of the isomeric fatty acids (FAs), FA methyl esters (FAMEs), triacylglycerols (TAGs), and tocopherols with an increas... Read More about Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure.

Comparison of peak shape in hydrophilic interaction chromatography using acidic salt buffers and simple acid solutions (2014)
Journal Article
Heaton, J. C., Russell, J. J., Underwood, T., Boughtflower, R., & McCalley, D. V. (2014). Comparison of peak shape in hydrophilic interaction chromatography using acidic salt buffers and simple acid solutions. Journal of Chromatography A, 1347, 39-48. https://doi.org/10.1016/j.chroma.2014.04.026

The retention and peak shape of neutral, basic and acidic solutes was studied on hydrophilic interaction chromatography (HILIC) stationary phases that showed both strong and weak ionic retention characteristics, using aqueous-acetonitrile mobile phas... Read More about Comparison of peak shape in hydrophilic interaction chromatography using acidic salt buffers and simple acid solutions.

Comparison of the kinetic performance and retentivity of sub-2μm core-shell, hybrid and conventional bare silica phases in hydrophilic interaction chromatography (2014)
Journal Article
Heaton, J. C., & McCalley, D. V. (2014). Comparison of the kinetic performance and retentivity of sub-2μm core-shell, hybrid and conventional bare silica phases in hydrophilic interaction chromatography. Journal of Chromatography A, 1371, 106-116. https://doi.org/10.1016/j.chroma.2014.10.013

© 2014 Elsevier B.V. The separation performance and retention properties of four sub-2μm underivatised silica materials were evaluated in the hydrophilic interaction chromatography (HILIC) mode. These included an organic/inorganic hybrid silica, conv... Read More about Comparison of the kinetic performance and retentivity of sub-2μm core-shell, hybrid and conventional bare silica phases in hydrophilic interaction chromatography.

Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography (2013)
Journal Article
Heaton, J. C., Wang, X., Barber, W. E., Buckenmaier, S. M., & McCalley, D. V. (2014). Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography. Journal of Chromatography A, 1328, 7-15. https://doi.org/10.1016/j.chroma.2013.12.058

The kinetic performance of a bare silica and C18 phase prepared from the same sub-2. μm and 3.5. μm base materials were compared in the HILIC and RP mode using both charged and neutral solutes. The HILIC column was characterised using the neutral sol... Read More about Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography.

Influence of phase type and solute structure on changes in retention with pressure in reversed-phase high performance liquid chromatography (2013)
Journal Article
Fallas, M. M., Tanaka, N., Buckenmaier, S. M., & McCalley, D. V. (2013). Influence of phase type and solute structure on changes in retention with pressure in reversed-phase high performance liquid chromatography. Journal of Chromatography A, 1297, 37-45. https://doi.org/10.1016/j.chroma.2013.04.006

The influence of pressure on the retention of several types of solute, including acids, bases and neutrals, was studied by the use of restriction capillaries added to the end of various monomeric and polymeric octadecylsilyl-modified 5. μm particle s... Read More about Influence of phase type and solute structure on changes in retention with pressure in reversed-phase high performance liquid chromatography.

Practical investigation of the factors that affect the selectivity in hydrophilic interaction chromatography (2013)
Journal Article
Kumar, A., Heaton, J. C., & McCalley, D. V. (2013). Practical investigation of the factors that affect the selectivity in hydrophilic interaction chromatography. Journal of Chromatography A, 1276, 33-46. https://doi.org/10.1016/j.chroma.2012.12.037

Retention data for a series of 29 compounds comprising acids, bases and neutrals were obtained on six different hydrophilic interaction (HILIC) columns including bare silica, zwitterionic and those bonded with neutral bonded ligands. The principal ai... Read More about Practical investigation of the factors that affect the selectivity in hydrophilic interaction chromatography.

The effect of pressure and mobile phase velocity on the retention properties of small analytes and large biomolecules in ultra-high pressure liquid chromatography (2012)
Journal Article
Fekete, S., Veuthey, J. L., McCalley, D. V., & Guillarme, D. (2012). The effect of pressure and mobile phase velocity on the retention properties of small analytes and large biomolecules in ultra-high pressure liquid chromatography. Journal of Chromatography A, 1270, 127-138. https://doi.org/10.1016/j.chroma.2012.10.056

A possible complication of ultra-high pressure liquid chromatography (UHPLC) is related to the effect of pressure and mobile phase velocity on the retention properties of the analytes. In the present work, numerous model compounds have been selected... Read More about The effect of pressure and mobile phase velocity on the retention properties of small analytes and large biomolecules in ultra-high pressure liquid chromatography.

A comparison of overload behaviour for some sub 2μm totally porous and sub 3μm shell particle columns with ionised solutes (2012)
Journal Article
Buckenmaier, S. M. C., Fallas, M. M., & McCalley, D. V. (2012). A comparison of overload behaviour for some sub 2μm totally porous and sub 3μm shell particle columns with ionised solutes. Journal of Chromatography A, 1235, 49-59. https://doi.org/10.1016/j.chroma.2012.02.027

The overloading performance of some 2.7 μm shell and sub 2 μm totally porous columns, including one pair manufactured from similar materials with similar bonding chemistries, was compared using strongly acidic and basic probe compounds. In general, t... Read More about A comparison of overload behaviour for some sub 2μm totally porous and sub 3μm shell particle columns with ionised solutes.

Contributions to reversed-phase column selectivity. II. Cation exchange (2011)
Journal Article
Marchand, D. H., Carr, P. W., McCalley, D. V., Neue, U. D., Dolan, J. W., & Snyder, L. R. (2011). Contributions to reversed-phase column selectivity. II. Cation exchange. Journal of Chromatography A, 1218(40), 7110-7129. https://doi.org/10.1016/j.chroma.2011.07.085

The contribution of cation exchange to solute retention for type-B alkylsilica columns (made from high-purity silica) has been examined in terms of the hydrophobic-subtraction (H-S) model of reversed-phase column selectivity. The relative importance... Read More about Contributions to reversed-phase column selectivity. II. Cation exchange.

Determination of catecholamines in urine using hydrophilic interaction chromatography with electrochemical detection (2011)
Journal Article
Kumar, A., Hart, J. P., & McCalley, D. V. (2011). Determination of catecholamines in urine using hydrophilic interaction chromatography with electrochemical detection. Journal of Chromatography A, 1218(25), 3854-3861. https://doi.org/10.1016/j.chroma.2011.04.034

The determination of catecholamines in urine was investigated using hydrophilic interaction chromatography (HILIC) as an alternative to the commonly used reversed-phase (RP) method. A number of different approaches were explored, including per-aqueou... Read More about Determination of catecholamines in urine using hydrophilic interaction chromatography with electrochemical detection.

Some practical comparisons of the efficiency and overloading behaviour of sub-2μm porous and sub-3μm shell particles in reversed-phase liquid chromatography (2011)
Journal Article
Mccalley, D. V. (2011). Some practical comparisons of the efficiency and overloading behaviour of sub-2μm porous and sub-3μm shell particles in reversed-phase liquid chromatography. Journal of Chromatography A, 1218(20), 2887-2897. https://doi.org/10.1016/j.chroma.2011.02.068

At their optimum flow, sub-3 μm superficially porous or " shell" particles demonstrate similar efficiency to sub-2 μm totally porous particles. The performance of 0.21. cm i.d shell columns is however inferior to those of 0.46. cm i.d., presumably du... Read More about Some practical comparisons of the efficiency and overloading behaviour of sub-2μm porous and sub-3μm shell particles in reversed-phase liquid chromatography.

Performance of silica monoliths for basic compounds. Silanol activity (2011)
Book Chapter
McCalley, D. V. (2011). Performance of silica monoliths for basic compounds. Silanol activity. In K. K. Unger, N. Tanaka, & E. Mactejevas (Eds.), Monolithic silicas in separation science (173-188). Weinheim, Germany: Wiley VCH

The large majority of pharmaceuticals, and in addition many compounds of biomedical significance, contain ionisable basic groups. This chapter considers the analysis of these important compounds on silica monolith columns.

A systematic investigation of the effect of sample diluent on peak shape in hydrophilic interaction liquid chromatography (2010)
Journal Article
Ruta, J., Rudaz, S., McCalley, D. V., Veuthey, J. L., & Guillarme, D. (2010). A systematic investigation of the effect of sample diluent on peak shape in hydrophilic interaction liquid chromatography. Journal of Chromatography A, 1217(52), 8230-8240. https://doi.org/10.1016/j.chroma.2010.10.106

The aim of this study was to evaluate the importance of sample diluents to improve peak shapes in hydrophilic interaction liquid chromatography (HILIC), using low molecular weight (

Instrumental considerations for the effective operation of short, highly efficient fused-core columns. Investigation of performance at high flow rates and elevated temperatures (2010)
Journal Article
McCalley, D. V. (2010). Instrumental considerations for the effective operation of short, highly efficient fused-core columns. Investigation of performance at high flow rates and elevated temperatures. Journal of Chromatography A, 1217(27), 4561-4567. https://doi.org/10.1016/j.chroma.2010.04.070

Fused core or superficially porous columns offer the advantages of higher efficiency compared with totally porous columns of the same particle size, but similar operating pressures. However, their performance may be adversely affected by extra-column... Read More about Instrumental considerations for the effective operation of short, highly efficient fused-core columns. Investigation of performance at high flow rates and elevated temperatures.

Study of the selectivity, retention mechanisms and performance of alternative silica-based stationary phases for separation of ionised solutes in hydrophilic interaction chromatography (2010)
Journal Article
McCalley, D. V. (2010). Study of the selectivity, retention mechanisms and performance of alternative silica-based stationary phases for separation of ionised solutes in hydrophilic interaction chromatography. Journal of Chromatography A, 1217(20), 3408-3417. https://doi.org/10.1016/j.chroma.2010.03.011

The separation of a mixture of neutral, strongly acidic and strongly basic compounds was studied in hydrophilic interaction chromatography using a bare silica phase, and bonded silica phases with diol, zwitterionic, amide and hydrophilic/hydrophobic... Read More about Study of the selectivity, retention mechanisms and performance of alternative silica-based stationary phases for separation of ionised solutes in hydrophilic interaction chromatography.

The challenges of the analysis of basic compounds by high performance liquid chromatography: Some possible approaches for improved separations (2010)
Journal Article
McCalley, D. V. (2010). The challenges of the analysis of basic compounds by high performance liquid chromatography: Some possible approaches for improved separations. Journal of Chromatography A, 1217(6), 858-880. https://doi.org/10.1016/j.chroma.2009.11.068

This review considers some of the difficulties encountered with the analysis of ionised bases using reversed-phase chromatography, such as detrimental interaction with column silanol groups, and overloading which both lead to poor peak shapes. Method... Read More about The challenges of the analysis of basic compounds by high performance liquid chromatography: Some possible approaches for improved separations.

Further investigations of the effect of pressure on retention in ultra-high-pressure liquid chromatography (2010)
Journal Article
Fallas, M. M., Neue, U. D., Hadley, M. R., & McCalley, D. V. (2010). Further investigations of the effect of pressure on retention in ultra-high-pressure liquid chromatography. Journal of Chromatography A, 1217(3), 276-284. https://doi.org/10.1016/j.chroma.2009.11.041

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.

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
Fallas, M. M., Hadley, M. R., & McCalley, D. V. (2009). 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. Journal of Chromatography A, 1216(18), 3961-3969. https://doi.org/10.1016/j.chroma.2009.03.007

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.

A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography (2009)
Journal Article
Dai, J., Carr, P. W., & McCalley, D. V. (2009). A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography. Journal of Chromatography A, 1216(12), 2474-2482. https://doi.org/10.1016/j.chroma.2009.01.036

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.

Investigation of the effect of pressure on retention of small molecules using reversed-phase ultra-high-pressure liquid chromatography (2008)
Journal Article
Fallas, M. M., Neue, U. D., Hadley, M. R., & McCalley, D. V. (2008). Investigation of the effect of pressure on retention of small molecules using reversed-phase ultra-high-pressure liquid chromatography. Journal of Chromatography A, 1209(1-2), 195-205. https://doi.org/10.1016/j.chroma.2008.09.021

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
McCalley, D. V. (2008). Evaluation of the properties of a superficially porous silica stationary phase in hydrophilic interaction chromatography. Journal of Chromatography A, 1193(1-2), 85-91. https://doi.org/10.1016/j.chroma.2008.04.007

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
McCalley, D. V., & Neue, U. D. (2008). Estimation of the extent of the water-rich layer associated with the silica surface in hydrophilic interaction chromatography. Journal of Chromatography A, 1192(2), 225-229. https://doi.org/10.1016/j.chroma.2008.03.049

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.

Analysis of basic compounds by reversed-phase high-performance liquid chromatography using hybrid inorganic/organic phases at high pH (2008)
Journal Article
Davies, N. H., Euerby, M. R., & McCalley, D. V. (2008). Analysis of basic compounds by reversed-phase high-performance liquid chromatography using hybrid inorganic/organic phases at high pH. Journal of Chromatography A, 1178(1-2), 71-78. https://doi.org/10.1016/j.chroma.2007.11.040

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
McCalley, D. V. (2007). Is hydrophilic interaction chromatography with silica columns a viable alternative to reversed-phase liquid chromatography for the analysis of ionisable compounds?. Journal of Chromatography A, 1171(1-2), 46-55. https://doi.org/10.1016/j.chroma.2007.09.047

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
Davies, N. H., Euerby, M. R., & McCalley, D. V. (2007). A study of retention and overloading of basic compounds with mixed-mode reversed-phase/cation-exchange columns in high performance liquid chromatography. Journal of Chromatography A, 1138(1-2), 65-72. https://doi.org/10.1016/j.chroma.2006.10.002

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
Davies, N. H., Euerby, M. R., & McCalley, D. V. (2006). Study of overload for basic compounds in reversed-phase high performance liquid chromatography as a function of mobile phase pH. Journal of Chromatography A, 1119(1-2), 11-19. https://doi.org/10.1016/j.chroma.2005.11.096

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
McCalley, D. V. (2006). Overload for ionized solutes in reversed-phase high-performance liquid chromatography. Analytical Chemistry, 78(8), 2532-2538. https://doi.org/10.1021/ac052098b

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
McCalley, D. V. (2005). 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. Journal of Chromatography A, 1075(1-2), 57-64. https://doi.org/10.1016/j.chroma.2005.02.090

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)
Journal Article
McCalley, D. V. (2005). Comparison of an organic polymeric column and a silica-based reversed-phase for the analysis of basic peptides by high-performance liquid chromatography. Journal of Chromatography A, 1073(1-2), 137-145. https://doi.org/10.1016/j.chroma.2004.10.023

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
McCalley, D. V. (2004). Effect of buffer on peak shape of peptides in reversed-phase high performance liquid chromatography. Journal of Chromatography A, 1038(1-2), 77-84. https://doi.org/10.1016/j.chroma.2004.03.038

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
McCalley, D. V. (2003). Rationalization of retention and overloading behavior of basic compounds in reversed-phase HPLC using low ionic strength buffers suitable for mass spectrometric detection. Analytical Chemistry, 75(14), 3404-3410. https://doi.org/10.1021/ac020715f

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
Buckenmaier, S. M., McCalley, D. V., & Euerby, M. R. (2002). Overloading study of bases using polymeric RP-HPLC columns as an aid to rationalization of overloading on silica-ODS phases. Analytical Chemistry, 74(18), 4672-4681. https://doi.org/10.1021/ac0202381

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.

Bile metabolites of polycyclic aromatic hydrocarbons in three species of fish from the severn estuary (2002)
Journal Article
Ruddock, P. J., Bird, D. J., & McCalley, D. V. (2002). Bile metabolites of polycyclic aromatic hydrocarbons in three species of fish from the severn estuary. Ecotoxicology and Environmental Safety, 51(2), 97-105. https://doi.org/10.1006/eesa.2001.2131

Six metabolites of polycyclic aromatic hydrocarbons (PAHs) were identified and quantified from the bile of 31 common eels (Anguilla anguilla), 29 European flounders (Pleuronectes flesus), and 15 conger eels (Conger conger) collected from the Severn E... Read More about Bile metabolites of polycyclic aromatic hydrocarbons in three species of fish from the severn estuary.

Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs (2001)
Journal Article
McCalley, D. V., Luxton, R. W., Bird, D. J., Hart, J. P., Kirsch, N., Kirsch, N., …McCalley, D. V. (2001). Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs. Analyst, 126(11), 1936-1941. https://doi.org/10.1039/b108008n

This paper describes the fabrication of a sensor for 1-hydroxypyrene (1-OHP) based on a screen-printed carbon electrode (SPCE) modified with a molecularly imprinted polymer (MIP); 1-OHP was chosen as a model metabolite of polyaromatic hydrocarbons (P... Read More about Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs.