Columns | Column: Column Watch

This “Column Watch” installment presents many of the highlighted topics and trends observed at the 52nd International Symposium on High Performance Liquid Phase Separations and Related Techniques (HPLC 2024).

This article covers liquid chromatography columns and accessories commercially released after Pittcon 2023 through the 2024 conference.

High performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) is a potential method of choice for the analysis of carbohydrates.

We explore advancements in silica particles for liquid chromatography, focusing on the shift toward improved monodispersity and its impact on chromatographic parameters, efficiency, backpressure, and sensitivity in high-performance liquid chromatography (HPLC).

This retrospective focuses on trends and topics that were discussed at the annual HPLC symposium in Duesseldorf, Germany.

Analyzing representative standard mixtures, APIs, and synthetic impurities shows that when TRLC is combined with RPLC in 2D-LC, separation performance is improved. We explain why.

Nonspecific adsorption leads to poor peak shapes and poor performance from HPLC systems, but coating-enabling technologies can serve as a potential solution. We explain how.

Our annual review of new liquid chromatography columns and accessories, introduced at Pittcon and other events over the past 12 months.

TRLC can obtain separations similar to those of reversed-phase LC while using only water as the mobile phase.

The application of porous layer open tubular (PLOT) columns can be expanded beyond light compounds to separations of analytes with heavier boiling points.

At HPLC 2022, we heard about new research and developments, in areas such as column technologies, portable instrumentation, and machine learning, among others.

With a new prototype, we explore how to improve the resolution power and usability of LC–MS instruments for routine analysis in pharmaceutical applications.

Knowing the variables that most affect the sample loading capacity in a porous layer open tubular (PLOT) column is vital to determining how much sample to inject.

Our yearly report on liquid chromatography (LC) columns and accessories commercially released over the past year.

New developments in metal-organic frameworks (MOFs) for LC seek to control MOF distribution on the silica surface, improve understanding of the role of the substrate, and enhance robustness and reproducibility.

Here, a new automated active pharmaceutical ingredient (API) extraction platform is integrated with online liquid chromatography (LC) to assess drug product potency. The platform dissolves the tablet coating (if present), disintegrates the tablet, and disperses and solubilizes the tablet for analysis.

This study illustrates the importance of column selection during GC method development.

Three-dimensional (3D) printing shows promise for creating stationary phases with tailored geometries. We present a method that overcomes limitations of other approaches, and can produce columns with a feature resolution of 10 μm.

Technology improvements have reignited interest in open-tubular LC, which promises high efficiency, low backpressure, and more environmentally sustainable separations.

Solid adsorbent gas chromatography (GC) columns, such as porous layer open tubular (PLOT) columns, are the best option for GC analysis of C1–C5 hydrocarbons, but water can affect retention and selectivity. We review the effects of water for different types of PLOT columns, and explain how to prevent or remediate the problem.

We present our annual review of new liquid chromatography columns and accessories, introduced between spring 2020 and spring 2021.

Mixed-mode chromatography columns are on the rise. We review recent fundamental research, stationary phase development and design, and areas of application.

Recombinant adeno-associated viral therapy (rAAV) products are particularly complex. Are liquid chromatography and LC–MS the right tools for their characterization?

This article will review historical bonding techniques still in use for manufacturing high performance liquid chromatography (HPLC) stationary phases today, and also examine some emerging technologies that may be able to tackle unmet needs in novel platforms and phase construction.

The traditional bonding techniques used to manufacture silica-particle-based HPLC stationary phases provide many benefits, but can emerging technologies tackle unmet needs? We assess current approaches and the potential for improvements.

The strategies described here can improve the efficiency and analyte recovery of chromatographic methods used to characterize monoclonal antibodies and antibody– drug conjugates.

We explore what’s new in the liquid chromatography columns and accessories commercially released over the past year.

At the 43rd International Symposium on Capillary Chromatography (ISCC 2019) in Fort Worth, Texas, a panel addressed the current challenges and potential future directions in capillary liquid chromatography. How can their vision be achieved?

This “Column Watch” installment reports on highlights from the 48th International Symposium on High Performance Liquid Phase Separations and Related Techniques (HPLC 2019), held June 16 to 20 in Milan, Italy.

Superficially porous particles have demonstrated separation efficiency gains compared to totally porous particles. The total pore blocking technique provides the purest possible measure of column packing quality. Here, we explain this technique and show what it has revealed.

We examine the evolution of hybrid particle columns, highlighting examples of separations enabled by this technology.

With SEC, special care is required to achieve in practice the chromatographic efficiency that is expected from theory.

Our annual review of new liquid chromatography columns and accessories.

We assess the advantages and disadvantages of 1.0-mm diameter columns.

New strategies for “bottom-up” analysis of therapeutic proteins, using faster enzymes, new buffer systems, and optimal column chemistries, enable analysts to perform these studies much faster and with fewer artifacts.

Topics that stood out at HPLC 2018 include advances in large-molecule separations, multidimensional separations, 3D printing, chiral separations, and HILIC. Also, many speakers addressed separation fundamentals, including ways to increase speed, generate higher throughput, and add selectivity.

Various strategies to improve LC-MS sensitivity in order to enhance signal-to-noise ratio, and help you realize the hidden potential of this method are discussed.

Many manufacturers now offer columns using superficially porous particles that are 2-µm and smaller. When should you use them?

What can metal–organic frameworks offer for liquid chromatography?

Our annual review of new liquid chromatography columns and accessories, including columns for reversed-phase, HILIC, chiral, SEC, GPC, ion-exchange, and SFC separations of small and large molecules.

Despite the theoretical promise of reduced plate heights (h) < 1, most modern UHPLC columns can only deliver plate heights in the range from 1.4 to 2.5. However, improved packing procedures, a better understanding of the colloidal properties of particle suspensions, and the study of the rheological behavior of packed beds and the final bed structure should lead us to practical solutions that can double the column efficiencies.

A number of approaches for peak shape measurement are available in modern chromatography software. We discuss the advantages and drawbacks of those approaches, and present a new concept, “total peak shape analysis.”

To resolve and quantitate monoclonal antibodies and antibody–drug conjugates, analytical scientists need various chromatographic modes, such as sizeexclusion, ion-exchange, hydrophobic interaction, and hydrophilic interaction chromatography. Here, we provide advice for making the most of each mode.

Topics that stood out at HPLC 2017 include advances in large-molecule separations, multidimensional chromatography, HILIC, and chiral separations.

A model set of analytes and selected applications are used to demonstrate the effects that buffers can have on the selectivity of a separation and the sensitivity of a reversed-phase analysis when using MS detection.

In biphenyl phases, the surface chemistry often makes it possible to separate compounds not well resolved by C18 or phenyl phases.

Our annual review of new liquid chromatography (LC) columns and accessories introduced at Pittcon and throughout the previous year.

The carotenoid test allows one to build a simple classification map of stationary phases used in reversed-phase liquid chromatography, on the basis of the shape recognition(plotted on the x axis) the polar surface activity(plotted on the y axis) and the phase hydrophobicity (related by the bubble size).

Interest in chromatography using hydrophilic interaction liquid chromatography (HILIC) has continued to build in recent years. Adoption of the technique has been slowed by experiences of poor reproducibility. In particular, re-equilibration times in HILIC have been reported as being exceptionally long as compared to reversed-phase chromatography. In this study, re-equilibration times in HILIC, for both aqueous–organic gradients and buffer gradients are systematically explored. The results not only promise to improve method development practices, but also provide insight into HILIC retention mechanisms across mechanistically differing polar stationary phases.

Cartenoid compounds can be used as probes for studying the stationary bonded phases devoted for reversed-phase liquid chromatography, that is, C18, phenyl-hexyl, and cholester. From one analysis achieved in supercritical fluid chromatography (SFC) that favors the chromatographic behaviors due to the stationary phase properties, bonding density, ligand type (monomeric or polymeric), and endcapping treatment, two separation factors are calculated allowing us to build a bi-dimentional map. These two axes are related either to the shape selectivity or the polar surface activity (residual silalnos). Each point on the map corresponds to a column. The retention factor of beta-carotene, which describes the phase hydrophobicity, is indicated by the size of the point. More than 200 stationary phases were studied, including small particle sizes and superficially porous ones. Moreover, the results are now available on a website, allowing you to check and compare, by selecting the required tabs, columns, manufacturer brands, and ligand nature.

HPLC 2016, chaired by Professor Robert Kennedy, was held June 19–24 in San Francisco, California, at the Marriott San Francisco Marquis. This installment of "Column Watch" covers some of the highlights observed at the symposium including stationary-phase developments, particle technology, and areas of growing application of HPLC. In addition, trends and perspectives on future developments in HPLC noted from the conference are presented.

Microflow LC–MS-MS has seen a surge of attention, development, and popularity among research scientists and bioanalysts over the last few years. The potential of this technology to provide better sensitivity, less solvent waste, near-zero dead volume, and high through-put are a big part of this renewed interest. However, microflow LC techniques are hardly a new idea. More than 40 years ago, in 1974, a group at Nagoya University in Japan first developed a microcolumn liquid chromatography system, elements of which can be found in today’s commercial products. With the advances in technology over the last several years, development and implementation of this technique have been kicked into high gear. In this article, we discuss the history of microflow LC–MS-MS, the current state of the art, and where the future might lead for this rapidly growing technology.

In recent years industry has been moving to columns with smaller and smaller inner diameters-moving from 4.6 and 3.0 mm i.d. columns to 2.1 mm, 1.0 mm, and even smaller. While small inner diameter columns have some clear advantages, they also bring challenges. Reduction of extracolumn volumes must be given greater consideration by both customers and manufacturers. Additionally, experimental evidence suggests that the very narrow confinement of chromatographic particles can result in packed bed structures that promote increased dispersion and reduced efficiency. This article focuses on the sources of band broadening within high performance liquid chromatography (HPLC) columns with particular emphasis on eddy dispersion. The physical mechanisms of dispersion are discussed and a review of the current literature as it pertains to small inner diameter columns is presented.

Our annual review of new LC columns and accessories introduced at Pittcon and through the previous year.

In his final “Column Watch” article, Ron Majors looks into his crystal ball and discusses future needs in the area of HPLC/UHPLC column technology and related instrumentation. He looks at where current technology may be heading and makes a prediction that monolith-based columns may still have a rightful place in the HPLC/UHPLC laboratory .This article concludes his duration as a monthly columnist for LCGC.

During the course of my scientific career beginning in the 1960s, I have grown up with the birth of modern LC column technology, the refinements of the instrumentation, and the development of widespread application of this most powerful separation and analysis technique. In this installment, I would like to share with you some of my observations and experiences with the beginning, the growth period, and the maturation of HPLC columns, where I have focused nearly 33 years of writing for this magazine. I will explore some of the early column breakthroughs beginning with the development of large superficially porous particles (SPP), the porous irregular and spherical microparticulate particles, inorganic and organic polymeric monoliths and the rebirth of the current generation of SPP. In next month’s installment I will look into my crystal ball and see what the future of HPLC and UHPLC holds.

HPLC 2015, chaired by Gérard Hopfgartner was held in Geneva, Switzerland, from June 21–25. This installment covers some of the highlights observed at the symposium including stationary phase developments, particle technology, and areas of growing application of HPLC. In addition, trends and perspectives on future developments in HPLC culled from the conference are presented.

The use of superficially porous particles in the manufacture of high performance liquid chromatography (HPLC) columns has become prominent in recent years. Over the course of the past decade most major manufacturers have built column lines around the technology.

 Volume 33 Number 4Pages 234-247This is our annual review of new liquid chromatography (LC) columns and accessories introduced at Pittcon and throughout the previous year. This year, Michael Swartz, former author of our "Innovations in HPLC" and "Validation Viewpoint" columns, steps in as a guest columnist to write the review.

 There has been a revival of supercritical fluid chromatography (SFC) in recent years, especially in the chiral preparative field, but also more recently in the analytical area. However, SFC is considerably more complex than liquid chromatography (LC), mainly because of the compressibility of the mobile phase. One can say that SFC is a "rubber variant" of LC where everything considered constant in LC varies in SFC. In this review, we go through advances in theory, instrumentation, and novel applications.

Understanding the interactions that stationary-phase chemistries provide will help you choose the most appropriate blend of interactions to address a given separation challenge.

To obtain the best performance from your UHPLC system, you need the right tubing and fittings. Here is what you need to know.

Understanding the chemistry of embedded polar group and perfluorophenyl phases leads to better decisions during method developement

Mechanical strength, acid and alkaline durability, loadability, and overload characteristics are a few of the parameters evaluated.

Highlights of the discussions on column-technology topics - such as monoliths, high-pH columns, SPPs, and HILIC - and an analysis of the larger trends observed at the conference.

New GC columns, SFC columns, and products for sample preparation, including small benchtop instruments

New product introductions in the areas of HPLC columns for reversed-phase LC, HILIC, ion-exchange and ion chromatography, SEC, and specialty columns for specific types of analyses are covered.

Stacking and sweeping injection methods are compared and practical suggestions are provided about how to enhance sensitivity for charged and neutral compounds.

Highlights of the column technology observed at the symposium

A review of the advances and trends in technology and applications discussed at the HPLC 2013 conference, including a summary of the awards presented.

A summary of the results from a survey of 14 leading HPLC–UHPLC column experts is presented, covering the state of sub-2-?m porous particles, superficially porous (core–shell) particles, silica monoliths, and polymeric monoliths.

Evidence to demystify HPLC and UHPLC column myths

For the next improvements, we must look beyond the column.

This month's installment of "Column Watch" comprises Part II of our yearly report on new products introduced at Pittcon. Gas chromatography columns, sample preparation products, and hardware, accessories, and small tabletop instruments mainly for sample preparation are covered.

Part I of our yearly report, covering columns for all modes of HPLC, UHPLC, and liquid-phase separations.

A look at what influences the use of CE in the pharma industry.

Professor Mary Wirth and graduate students Bingchuan Wei and Benjamin Rogers from Purdue University demonstrate a quantum leap in protein column efficiency. Using colloidal silica particles of submicrometer diameters (470 nm), they obtained plate heights that were as much as 15-fold lower than the theoretical limit for Hagen-Poiseuille flow.

A review of the trends at this year&s symposium, including discussions of column technology, sample preparation, and detector usage.

A comprehensive review of standard and specialty SEC columns, including up-to-date charts and advice on how to choose

Advantages of the planar, off-line format of TLC relative to on-line column HPLC, the steps in TLC analyses, and future prospects of TLC are discussed.

What you need to know about gas chromatography columns, thin-layer chromatography plates, sample preparation products, as well as chromatography and sample preparation accessories (including small benchtop instruments) unveiled at Pittcon this year

A review of columns unveiled at Pittcon this year, including all modes of HPLC, UHPLC, and liquid-phase separations.

Learn how to use selectivity throughout the sample analysis cycle, from the sampling stage through data analysis and report generation.

The results of a recent survey on high performance liquid chromatography (HPLC) columns shows some interesting changes.

A limited set of stationary phases can separate a wide variety of molecules and maintain good peak shape without mobile-phase additives.

A presentation of the overall trends in liquid-phase chromatography observed at the symposium, as well as the awards presented and the opening plenary session

A brief history of phase development is presented, along with a comparison of gas chromatography and high performance liquid chromatography chiral separations

The advantages of using software to optimize GC methods with practical examples for pesticide analysis are described.

Method translation software enables conversion and improvement of GC methods.

Converting a method from conventional HPLC to high-throughput HPLC or UHPLC is easy with a method translation calculator. Here's how to use them and where to find them, for free.

Nanomaterials offer exciting possibilities for improving separations with techniques such as TLC, SPME, and CE.

A review of the gas chromatography columns, sample preparation, and chromatographic and sample preparation accessories that were presented at Pittcon 2011.

A review of the liquid chromatography columns and accessories for analytical and preparative chromatography to be unveiled at Pittcon 2011

This installment will trace the development of SPP supports to the present-day versions that rival UHPLC supports.

The guest authors describe an optimization procedure to achieve the highest plate count in a given analysis time.

GC expert Jaap de Zeeuw explores the historical development of PLOT columns, covers details of the most popular stationary phases, and provides practical hints.

Ron Majors presents his yearly review of the HPLC Conference.

Monolith pioneer, Frantisek Svec, brings readers up to date on the latest developments in monolith technology.

We focus on the characterization of reversed-phase columns with particular emphasis on the hydrophobic-subtraction model

The coauthors discuss the various attributes of and approaches to reversed-phase chromatography.

The authors review the requirements for columns specifically designed and manufactured for SFC.

Monolith pioneer, Frantisek Svec, brings readers up to date on the latest developments in monoliths for use in chromatography

Ron Majors presents the second part of his yearly review of all that was new and innovative at Pittcon 2010, held this year in Orlando, Florida.

This month's installment of "Column Watch" features Ron Majors' yearly report on new products introduced at Pittcon 2010.

Hydrogen carrier gas can be an effective replacement for helium in many gas chromatography (GC) and GC–mass spectrometry (MS) applications.

In this installment, columnist Ron Majors and guest columnist Frantisek Svec address the current status of CEC, once the hottest topic in the field.

In this installment of "Column Watch," Ron Majors looks at the results of a recent HPLC column survey conducted by LCGC North America.

To meet system suitability requirements, chromatographers might need to make adjustments to the high performance liquid chromatography (HPLC) operating conditions.

Ron Majors provides first-hand coverage of some of the technology and application advances reported at HPLC 2009.

Guest columnists explore how ionic liquids can be tweaked to mimic the popular stationary phases of today.

Ron Majors provides an unbiased look at this present crisis and gives alternative solutions.

Ron Majors brings readers the second part of his yearly review of all that was new and innovative at the annual Pittsburgh Conference.

Ron Majors brings readers his yearly review of all that was new and innovative at the annual Pittsburgh Conference.

Guest authors show how mixed modes can be used successfully in the optimization of protein purification, and discuss how various experimental parameters can be used to regulate the binding of proteins to mixed-mode sorbents.

A variety of chromatographic sorbents are commercially available for reversed-phase liquid chromatography (RPLC) and while many of these columns are nominally similar, in practice the columns may provide significantly different separations.

Ron Majors continues his summary of the technical highlights of HPLC 2008, discussing more hot topics from the show.

HPLC 2008 was held in Baltimore in May. Columnist Ron Majors covers the highlights of this major symposium, held in the U.S. every two years.

Guest Editor Peter Schoenmakers provides an introduction to LCxLC, and then goes on to talk about peak capacity, sample dimensionality, phase orthogonality, and some of the successes of the technique and the obstacles yet to be overcome.

Guest columnsist and LCGC Emerging Leader award recipient Gert Desmet considers the different methods that can be used to compare the performance of LC columns.

In this instalment of "Column Watch", columnist Ron Majors examines the role of pressure in high performance liquid chromatography (HPLC) from two viewpoints: the impact of the ultrahigh pressures encountered in ultrahigh-pressure liquid chromatography (UHPLC) on chromatographic parameters and increases in column pressure encountered in normal daily use. The latter is of more practical consequence to HPLC users because increased back pressure usually implies that something has gone wrong with the column. Pressure increases as a result of physical and chemical contamination are explored and practical approaches to solve these problems are suggested.

This month's installment of "Column Watch" is the second part of a two-part series in which columnist Ron Majors examines the trends and highlights in columns and consumables at Pittcon 2008.

This month's installment of "Column Watch" is the first of a two-part series in which columnist Ron Majors examines the trends and highlights in columns and consumables at Pittcon 2008.

In 2001, the second glossary of common and not-so-common terms and "buzz words" for reference to HPLC columns and column technology was published. It is time for an update since new terms have arisen or, in some cases, their original meanings have expanded or changed.

In this installment of "Column Watch," Ron Majors examines the various approaches to increasing the speed of high performance liquid chromatography (HPLC) separations.

In this installment of "Column Watch," columnist Ron Majors examines the role of pressure in high performance liquid chromatography (HPLC) from two viewpoints: the impact of the ultrahigh pressures encountered in ultrahigh-pressure liquid chromatography (UHPLC) on chromatographic parameters and increases in column pressure encountered in normal daily use. The latter is of more practical consequence to HPLC users since increased back pressure usually implies that something has gone wrong with the column. Pressure increases due to physical and chemical contamination are explored and practical approaches to solve these problems are suggested.

HPLC 2007 was held in Ghent, Belgium in June. Last month, columnist Ron Majors summarized some the important column developments as well as other Symposium highlights. This month, he winds up coverage with additional highlights in the areas of technology and applications. Among the topics covered are stationary phase preparation and characterization, multi-dimensional and comprehensive LC, temperature studies, detectors and an application overview.

Columnist Ron Majors covers some of the highlights of HPLC 2007 including honorary sessions, best poster awards, and the latest developments in HPLC column technology.

In this installment of "Column Watch" columnist Ron Majors revisits expert predictions from a survey conducted in 1987. A cross section of column experts of the time were asked a series of questions on the future directions in high performance liquid chromatography (HPLC) column technology. Now, 20 years later, these predictions are contrasted against current column technology. In many cases, the experts were entirely correct, while in other cases, they were dead wrong. Some current trends were not even considered 20 years ago. The author backs up his analysis with current survey information.

Modern gas chromatography (GC) capillary columns are rugged and forgiving but some care should be taken when handling and using these high-efficiency columns. In this instalment of "Column Watch", the authors discuss the issues surrounding avoiding column breakage, stationary phase damage and column contamination. Prolonging the life of a column by keeping an oxygen-free system, providing a cleaner sample and not exceeding the upper temperature limit of the stationary phase are highlighted in this practical discussion.

In this month's issue, columnist Ron Majors and coauthors discuss the important steps in the successful production of fused-silica gas chromatography (GC) capillary columns.

In early 2007, a web-based HPLC columns survey was conducted. Current usage was compared to a 1997 survey.

In 1983, the brainchild of Ed Aster, President of Aster Publishing, and Tom Hager, an editor, a publication called LC-Liquid Chromatography and HPLC Magazine was christened.

This month's installment of "Column Watch" is the conclusion of a two-part series in which columnist Ron Majors examines trends in column and sample prep introductions at Pittcon 2007.

This month's installment of "Column Watch" is the first of a two-part series in which Ron Majors examines the trends and highlights in columns and consumables at Pittcon 2007.

In any field there are often "misconceptions" or "myths" that are perpetuated and passed on to the next generation. These myths are often driven by a lack of understanding by practitioners of the real issues. In this instalment of "Column Watch", the 10 most popular myths around high performance liquid chromatography (HPLC) column technology will be demystified by discussing the issues at hand. Among some of the popular myths that will be dispelled are that "All C18 (L1) columns are the same", "You can't reverse an HPLC column", "High temperature always leads to better separations" and "The higher the carbon load the better the reversed-phase column".

In any field there are often "misconceptions" or "myths" that are perpetuated and passed on to the next generation.

October 2006. This brief review introduces the GCxGC technique and its advantages, hich primarily lie in the area of ncreased separation power for volatile chemical analysis.

The popular HPLC 2006 Symposium was held in June in San Francisco, California. It is the premier annual meeting in liquid phase separations technology.

In this installment of "Column Watch," Ron Majors traces the developments in modern column design in analytical and preparative configurations and speculates on future directions.

Guest columnist Walter Jennings reflects on the early days of capillary gas chromatography (GC) and how chromatographers become experts in the technology by constructing their own columns, thereby achieving a more thorough understanding of the chromatographic process.

This month's installment of "Column Watch" is the conclusion of a two part series in which Ron Majors examines the trends in columns and sample preparation at Pittcon 2006.

This month's installment of "Column Watch" is the first of a two-part series in which Ron Majors examines the trends and highlights in columns and consumables at Pittcon 2006.

Capillary gas chromatography (GC) is a well-established separation technique. Rick Parmely reviews some of the capillary column basics by investigating a standard test mixture and observing some of the chromatographic effects that can affect peak response, peak shape and column bleed. He provides guidelines for obtaining the best performance from a capillary column. He discusses peak tailing, column overload, ghost peaks and column bleed and speculates on "when to give up." He concludes with a set of fundamental steps to be used in achieving better GC analyses.

Liquid-liquid extraction (LLE) is among the most widely used sample preparation methods. In this month's installment of "Sample Prep Perspectives," Ron Majors discusses newer LLE approaches that offer significant advantages over classical methods. The miniaturization of LLE has resulted in solvent and time savings, improved automation possibilities, and faster sample preparation. The techniques of single-drop microextraction, extraction in levitated droplets, flow injection-, membrane-based-, and solid-supported extractions are reviewed. Often, these techniques use the same immiscible solvent pairs of conventional LLE.

Higher productivity and faster analyses are two of the driving forces for continued improvement in high performance liquid chromatography (HPLC) column technology.

guest Columnist Rick Parmely takes a look at some capillary column basics of a well-established separation technique. He discusses peak tailing, column overload, ghost peaks, and column bleed, and speculates on "when to give up."

Ron Majors discusses advances in multidimensional chromatography and comprehensive multidimensional chromatography.

HPLC 2005 was held in Stockholm, Sweden, June 26-30. In this month's installment of "Column Watch," Ron Majors covers this year's hot topics including proteomics, column technology - especially monoliths - microfluidics, and multidimensional and high-throughput separations.

In the last part of this series, the authors provide a technical review of the means for method adjustment and the pertinent regulations concerning the required validation of adjusted methods.

Guest columnist Matt Przybyciel reviews the structure, behavior, and applications of both alkyl- and phenyl-fluorinated phases in HPLC.

This month&#146;s column provides an overview of green chemistry issues relating to preparative chiral SFC chromatography in support of preclinical development in the pharmaceutical industry.

The authors provide the latest information on new stationary phases for modern TLC and high performance TLC (HPTLC), along with helpful hints on how to get the most out of this flexible form of chromatography.

This month's installment of "Column Watch" is the conclusion of a two-part series in which Ron Majors examines the trends in column introductions at Pittcon 2005. Here, he discusses gas chromatography columns, sample preparation products, hardware, and accessories.

In the first part of this series, the authors look at method modification from a scientific and regulatory standpoint with regard to changing a column and the operating parameters.

Pittcon 2005 - the 56th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy - returned to the Orange County Convention Center, Orlando, Florida, 27 February-4 March 2005. This year's event hosted more than 900 instrument manufacturers and 1aboratory suppliers in more than 2300 booths. In addition to attending the exposition, the conferees were able to listen to numerous oral presentations, view more than 900 posters, check out 38 seminar rooms, or attend one of 150 short courses.

When a column is replaced with a new or "equivalent" column, sometimes the chromatogram can change so much that it is no longer suitable for its intended use. In such cases, method adjustment is necessary to correct the change. How much can the chromatographic variables be changed before revalidation is required? What do the regulatory agencies have to say about method adjustment? The authors discuss these issues and propose a technique that can be used to speed selection of new operating conditions.

This column focuses on some of the latest developments in preparative-scale columns, bulk packing materials and column hardware designs. Silica, polymeric and other packings are discussed together with the newest monolithic columns.

The authors look at two types of method modification from a scientific and regulatory standpoint: a change of column and a change in the operating system. Both are difficult to avoid if a method is used for several years.

The author focuses on some key considerations in the manufacture and use of microplates, particularly the 96-well plate.

Column Editor Ron Majors turns his attention to preparative chromatography. He focuses on the columns used in preparative chromatography, including how to select the appropriate mode, mobile-phase system and operating conditions.

A look at the latest developments in preparative-scale columns, bulk packing materials, and column hardware designs.

In the final of this two-part series examining trends in column introductions at the recent Pittcon 2004, Ron Majors looks at gas chromatography columns, sample preparation products, hardware, accessories and kits for chromatography and sample preparation.

The second part of a two-part series examining new column introductions at Pittcon 2004.

In the first of a two-part series, Ron Majors examines new column introductions at Pittcon with special attention to high performance liquid chromatography columns and packings for reversed-, normal- and bonded-phase; ion exchange; ion and size-exclusion chromatography. He also considers speciality HPLC columns.

This month'ss "Column Watch" is the first of a two-part series that examines new column introductions at Pittcon 2004.

Majors discusses low-dispersion columns, describes how to modify HPLC systems to work with the small-volume columns, and provides guidance about obtaining the optimum capabilities from these columns.

Majors analyzes results from LCGC's GC user survey, which was conducted in January 2003.

Majors discusses highlights from HPLC 2003, held June 2003 in Nice, France.

The guest authors describe capillary columns for ultrahigh pressure liquid chromatography.

The conclusion of a two-part series in which Ron Majors examines the trends in column introduction at Pittcon 2003.

The first of two columns about new chromatography columns, accessories, and sample preparation products introduced at Pittcon 2003.

Ron Majors looks at practical ways to return a contaminated column to its original state.

Ron Majors analyzes results from LCGC's recent sample prep user survey.

Guest authors Lloyd Snyder and John Dolan describe a method for determining reversed-phase column selectivity.

Guest author Steve Griffin identifies the fundamental problems in capillary manufacturing techniques that cause capillary defects and suggests some corrective actions.

Ron Majors describes developments reported at HPLC 2002.

Continued from last month, this month's column discusses specially designed columns for use in highly aqueous environments. Many of these columns also can be used as regular reversed-phase columns for a range of mobile phases.

The authors suggest ways to avoid phase collapse and regenerate collapsed phases.

Second of a two-part series in which Ron Majors examines the trends in column introductions at Pittcon 2002.

The first of two columns on new chromatography columns, accessories, and sample preparation products, including solid-phase extraction, introduced at Pittcon 2002 will feature families/series of HPLC columns new to the marketplace along with detailed coverage of reversed-phase, normal-phase, ion-exchange, and size-exclusion HPLC columns.

This month's installment discusses the practical aspects of the scale-up process and the problems and costs of preparative separations within a mid-sized pharmaceutical company.

The guest authors discuss the use of monolithic silica columns in high-throughput HPLC, including developments and applications in combinatorial chemistry. They also explain performance characteristics for these columns and provide caveats about their effective usage.

Majors gives the details of this year's 25th International Symposium on High Performance Liquid-Phase Separations and Related Techniques in Maastricht, The Netherlands.

Majors looks at solid-phase extraction devices that provide new levels of convenience, improved performance, and automation possibilities.

Guest author Cameron George discusses recent advances in purge-and-trap systems that enable considerable reduction in analysis times.

Second column of a two-part series in which Ron Majors examines trends in column introductions at Pittcon 2001. He describes GC and SFC columns, sample preparation products, and accessories.

The first of a two-part series in which Majors examines the trends in column introductions at Pittcon 2001. He describes HPLC columns and packings for reversed-, normal-, and bonded-phase; ion-exchange; ion; size-exclusion; and large- and preparative-scale chromatography. He also looks at specialty HPLC columns.

A single-source reference for key chromatography terms.

Ron Majors discusses stationary-phase developments such as molecular-imprint polymers and monolithic phases. He also examines column stability, temperature as a separation variable, ultrahigh-pressure LC, and retention mechanisms.

Ron Majors highlights presentation from the 24th International Symposium on High Performance Liquid Phase Separations and Related Techniques.

By calculating optimal stationary-phase composition and physical parameters, column developers can construct columns that provide the exact separation requirements desired by analysis or current methods.

This month's "Column Watch" describes moving bed chromatography and how the concept is realized in the form of simulated moving bed chromatography. Also included is an inside look at instrumentation, method development, and applications for industrial purifications.

This month's "Column Watch" examines developments in column packings. Ron Majors looks at the physical design of packing materials from a performance standpoint and discusses some new packing materials that have unique characteristics.

Concluding a two-part series, Ron Majors looks at the trends in the introduction of columns and column-related products at Pittcon 2000. In this second part, he describes gas chromatography and supercritical fluid chromatography columns, CE capillaries, thin-layer chromatography products, sample preparation products, and accessories for chromatography and sample preparation.

This month's column begins our annual roundup of new column technologies shown at the Pittsburgh Conference. In part I, we'll look at HPLC columns and packings for reversed-, normal-, and bonded-phase; ion-exchange; ion; size-exclusion; and large- and preparative-scale chromatography as well as specialty columns.

The efficiencies of microbore-2 columns, which are prepared from blanks that have a wide variety of inner surface roughness, drop sharply when the size of individual surface roughness features approaches the particle size of the packing material. The results suggest that two categories of packed column structure relate to the surface features and yield high and low efficiency columns. This installment of "Column Watch" discusses this conclusion in terms of the stability of an agglomerated layer of packing particles on the blank wall when subjected to shear forces during column packing.

Guest author Paul Ross explains why porous graphite carbon may provide a solution to certain specific challenges in the retention and separation of very polar analytes and structurally similar compounds.

Monoliths are chromatography sorbents cast into columns as a single continuous piece in contrast with regular chromatographic sorbents, which are packed as individual particles. The guest authors compare three such novel sorbents with a conventional particle-packed column.

In this month's "Column Watch," Majors recounts some of the more interesting paper and poster presentations given at HPLC '99, held May 30–June 4, in Grenada, Spain.