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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.

Dolan answers readers' questions about a variety of topics, including life-spans of cyano columns, successfully transferring and running a method, why chromatographers water-saturate solvents such as chloroform or methylene chloride, and suggested buffers for high-pH analyses.

Here's what's available this month.

Guest authors Thompson and Morris summarize the problems and progress in establishing regulated analytical methods for dietary supplements.

Products, literature, application notes, etc.

Guest author Greg LeBlanc reviews techniques for preparing non- and semivolatile compounds from environmental samples for analysis under the Environmental Protection Agency's SW-846 guidelines.

Dolan examines some options for increasing the retention of polar compounds, which is a goal when using gradient elution scouting runs to screen the retention characteristics of compounds for separation by reversed-phase liquid chromatography.

Hinshaw examines the effects of system time constants and sampling rates upon apparent peak shapes and areas when performing fast gas chromatography.

Hinshaw looks at how carrier-gas choices influence gas chromatograms and provides some guidelines for choosing the right one.

This month's installment presents a systematic approach for dealing with a common chromatographic headache -- carryover.

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

Sometimes you must sacrifice chromatographic performance to obtain analytical results.

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

Ron Majors describes solid-phase extraction devices that provide new levels of convenience, improved performance.

The authors trace the evolution of TLC, which replaced paper chromatography as one of the most popular chromatographic techniques.

The authors describe how they separated and collected milligram quantities of six pyrethrin esters in pyrethrum extract and used them to create analytical reference standards for these insecticide compounds.

This installment surveys the evolution of thin-layer chromatography...

Krull and Swartz describe how chromatographers can determine peak purity and identity using new software programs.

Hinshaw looks at causes and modes of premature column failure and at practices that ensure the longest possible column life.

The authors descibe the use of CE with condensation nucleation light-scattering detection to analyze three pharmaceutical analytes. Because the compounds lack adequate UV chromophores, they require a more sensitive means of detection.

The authors compare the chromatographic properties of embedded-carbamate-group bonded phases with those of their purely alkyl counterparts.

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

The author presents an approach to screen resins for chromatographic optimization in the purification process of a protein drug substance.

This month's "LC Troubleshooting" focuses on the baseline characteristics of several common LC buffers and methods to minimize drift.

On the occasion of the 60-year anniversary of the invention of partition chromatography and the 50-year anniversary of the introduction of gas-liquid partition chromatography, this installment of Milestones in Chromatography discusses the circumstances that led to these developments...

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.

Hinshaw explains how combining certain column dimensions and electronic pneumatic settings can produce unexpected results.

This article describes the determination of D/L-amino acid residues in peptides at microgram levels.

The first of a two-part series about LC autosamplers.

Scored layers, sequential development, modifications of the development chamber, and a careful choice of standards produce better reliability in thin-layer chromatography analysis of urine for the diagnosis of mucopolysaccharidoses. In equivocal cases, repeating the procedure and varying the solvents will improve results.