Gas Chromatography (GC)

Direct coupling of SFE with GC has advantages over the off-line alternative.

Flame ionization detection (FID) is the most commonly used gas chromatography (GC) detection method. Flame ionization detectors respond to a wide assortment of hydrocarbons, have a large dynamic range, are...

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."

In January 2004, LCGC Europe published an article on methods for selecting pure gases for analytical applications. 1 Here, the authors expand on this topic by addressing questions regarding gas mixtures - defined simply as more than one gas in a cylinder.

Analytical chemists are concerned with the quality of their methods and results. An important question in this context is whether the precision of a newly developed and validated method is up to standard. In other words: is the precision of the newly developed method comparable to what could be expected? This article looks at how the Horwitz equation can answer this. It also describes the results of an extensive study involving 10000 laboratories which indicates that the relative reproducibility approximately doubles for every 100-fold decrease in concentration and that, surprisingly, it does not depend on the type of material or method.

In this installment of "GC Connections," the author reviews some of the developments infused-silica solumn technology and then takes a brief tour through the process of column manufacturing.

The implementation and validation of a new site-wide chromatography data system for a major active pharmaceutical ingredient custom manufacturer provided the opportunity to map and optimize the GMP and ISO business processes to use electronic signatures effectively. This article describes the process optimization and how it integrates with the validation activities of the system. This overall approach provides substantial business benefits from the use of electronic signatures as evidenced by the savings resulting from process improvement and by the fact that the non-GMP laboratories implemented a similar process to analyse and approve results electronically.

There is a great deal of confusion floating about when it comes to selecting gas mixtures for analytical applications. Questions such as "How is the gas certified?," "What standard should I use?," and "What level of uncertainty is acceptable?" are common concerns heard among those tasked with specifying and using mixtures. In addition, the uncertainty regarding terminology, measurement, safety, and storage can make specifying mixtures a true source of headaches and hassles for any lab manager. The following article provides answers to questions about gas mixtures.

The trend towards dedicated analytical solutions continues to gain momentum while what might have been considered high performance instrumentation a few years ago are increasingly being viewed as routine techniques.

The instrument is "a splendid example of automatic analysis."

As environmental legislation becomes more stringent, the need to deliver quantitative results in shorter times and greater volumes is necessary for routine environmental analysis. Most of the high-throughput screening methods used to analyze pharmaceutical compounds are, however, useless for environmental monitoring. This is because these methods primarily aim to retrieve as much information from a single sample using the broadest range of techniques. The chromatographic separation process is considered to be the bottleneck in the process. This is not the situation for environmental procedures, in which the bottleneck is the sample preparation step and is usually very tedious and time-consuming.

This article discusses utra fast gas chromatography as a suitable technique for determining the hydrocarbon oil index in water. The advantages of this technique over conventional GC technology are presented.

A review of the latest products and innovations in gas chromatography to come out of Pittcon 2005.

Bob McDowall stresses the importance of using accurate and precise time and date stamps to ensure the integrity of the data and results generated by computerized systems in any chromatography laboratory.

John Hinshaw asks what constitutes a chromatographic method and addresses some of the issues that method transfer raises for method documentation and validation.

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 this article, Jo Webber tackles the problem of ensuring data integrity in pharmaceutical manufacturing. She shows how, by using modern technology and well integrated systems, quality can be improved.

The authors explain how to construct box plots and how they can help you to learn more about your data.

Protease inhibitors are a class of anti-HIV drugs used in combination therapy to block replication of the HIV virus in a person's blood. It is important to monitor the levels of these drugs in the patient since resistance can develop at low levels and at high levels the drug can exhibit toxic effects.

Mini application notes summaries

In the concluding part of this series, the effects that column variability has on isothermal capillary gas chromatography is discussed and instrument calibration explored. The goal is to reduce the normal variability that occurs when working with multiple instruments and columns to ensure consistent results.

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.

The authors discuss the issue of meeting the demands of regulatory compliance whilst ensuring good scientific practice. A number of requirements from 21 CFR Part 11 are cited to demonstrate the importance of applying the principles of risk analysis.

This month's installment of "Milestones in Chromatography" pays tribute to a true milestone in the evolution of chromatography: the introduction of the first successful GC instruments.

In this first of a two-part series, John Hinshaw discusses the relative effects that inlet pressures and oven temperatures have on capillary gas chromatography.