Columns | Column: Column Watch

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.