Columns | Column: GC Connections

In this article, we discuss the fundamentals of headspace extraction, including static versus dynamic extraction, establishing equilibrium in the vial, consequences of the partition coefficient, temperature, pressure, and transfer to the gas chromatograph.

Roy Lautamo was a genius in the gas chromatography (GC) industry, responsible for numerous technical advancements. Here, we remember his storied career and accomplishments.

In this installment, we examine several of the common parameters that can affect automated peak integration and the resulting peak areas. We will consider how the data system detects the beginning and end of the peak, how it determines the peak maximum, how real peaks are differentiated from noise, and how signals at individual time intervals are summed to generate the peak area.

A recent sample preparation survey explored the critical role of sample preparation in gas chromatographic analysis.

Gas chromatography can be used in combination with molecular spectroscopy to provide structural and quantitative information on a variety of sample types.

Comprehensive two-dimensional GC×GC has made great strides in the past 20 years. The author discusses advances in instrumentation, column sets, data analysis, and the range and types of samples amenable to this method.

We offer troubleshooting tips for various gas chromatography (GC) detectors, as well as provide an overview of the different options chromatographers have when using a GC detector.

Everyone is talking about sustainability, and organizations are creating sustainability programs. But what does green chemistry really mean, and how does it apply to gas chromatography?

We assess the landscape of new gas chromatography (GC) instrumentation, supplies, and accessories introduced over the past 12 months.

Understanding the relationship between selectivity and retention is key to realizing excellent gas chromatographic separations.

By reviewing the basic thermodynamics underlying GC separations, we see how it impacts retention and method development in GC analysis.

The common measures of stationary phase polarity—McReynolds constants and the polarity scale—are not always accurate predictors of retentiveness or selectivity in GC.

The electron capture detector (ECD) for GC is still used relatively unmodified today. But using it effectively means understanding the tradeoffs between selectivity, ease of use, and sensitivity.

We pass on valuable lessons shared by the six GC speakers at ChromTalks 2022.

Hidden uncertainties in quantitative methods may make data look more precise and accurate than they really are. Take particular care when using dilution, which can increase experimental uncertainty.

Our annual review of new gas chromatography products.

The glass inlet liner is one of the most important, yet least understood and most often ignored, components of a gas chromatographic experiment.

When applying Golay’s equation for height equivalent of a theoretical plate (HETP) to capillary GC, you should ask three key questions.

We are all familiar with Golay’s equation relating to height equivalent to a theoretical plate (HETP) in GC. But do we understand it correctly?

Gas chromatographers may not have the latest equipment they need. Here, we give a list of tools and consumables that can help make workflows more efficient, detection limits lower, and GC instruments cleaner.

The late Harold McNair had a remarkable 60-year career as a chromatographer. He taught us many valuable lessons, three of which we discuss here.

How far can you get on optimizing a GC separation without changing the column? Pretty far, in fact.

At ChromTalks, experienced speakers shared mistakes made during their careers.

The limit of detection (LOD) of an analytical method may be defined as the smallest concentration of analyte that has a signal significantly greater than that of a blank sample signal. We explore the sources of experimental uncertainty and variability in LOD determinations.

We present our annual review of new products in gas chromatography, introduced between spring 2020 and spring 2021.

Capillary GC has been miniaturized, while maintaining some performance aspects of full-size laboratory systems. The benefits and challenges involved with considering these newer, smaller gas chromatographs for typical analytical problems are discussed.

By moving from GC–MS to GC–MS/MS, you can have both universal and selective detection along with low detection limits. Here’s how it works.

For GC, how do data systems both assist and hinder us in obtaining maximum information from chromatograms? We explain how a chromatogram can provide a wealth of information about an individual analyte in a sample, about the sample itself, and about how well a GC instrument is performing.

Computers control all aspects of modern GC instrument operation, from temperature to valve actuation. We look under the hood to see how this works.

Using the flame ionization detector (FID) as an example, we explain how the detector in a GC system generates a signal and how it is processed into chromatograms, and explore modern aspects of storing and processing digital data.

In gas chromatography, heating the sample in the inlet can lead to sample losses and loss of quantitative reproducibility, but these problems can be avoided using cold sample introduction. Here, we explain the various types of cold injection and why you should consider it in your next instrument purchase or upgrade.

Our annual review of new gas chromatography (GC) products introduced in the past 12 months.

Successful GC analysis requires careful control of carrier gas. Here, we explain how to measure and control flow rate, use constant pressure vs. constant flow, and more.

After 32 years as a columnist, John Hinshaw writes his final “GC Connections” article, examining how GC has changed over the years and considering where it might go in the future.

Multidimensional chromatography combining HPLC and GC, or LC–GC, sounds simple, but several factors complicate this combination, including solvent compatibility, separation time, and sample concentration.

Although manufacturers ship gas chromatographs with a collection of consumable parts and accessories, a number of other essential items should be on hand in every GC laboratory. What items are needed and how can they be used most effectively?

Temperature programming is used in most capillary GC separations, but many analysts lack a good understanding of the principles behind this approach.

Two-dimensional gas chromatography (GCxGC) is becoming the technique of choice for analysis of highly complex samples such as petroleum, pharmaceuticals, biological materials, food, flavors, and fragrances. Here, we explain how GCxGC works and provide examples that illustrate its advantages.

By taking simple proactive troubleshooting steps, GC users can ensure that instruments will operate correctly over time, thus avoiding workflow disruptions.

Here, we focus on selectivity: its definition, its importance for generating separations and resolution; and its role in column polarity.

The recent relocation of a laboratory yielded a number of insights as to how to ensure a quality environment to deliver quality gas separation and detection within a safe working atmosphere.

We discuss the challenges of split and splitless injections, ideas for mitigating them, and the case for renewed exploration of cool inlets and injection techniques.

We present our annual review of new developments in the field of gas chromatography, which this year includes eight new GC and GC–MS laboratory benchtop systems as well as numerous new columns and accessories.

In last month's installment of "GC Connections," John Hinshaw discussed how peak retention times depend upon relationships between pressure, flow rate, oven temperature, column dimensions, and stationary phase. This concluding installment of a two-part series discusses the effects that column variability has on isothermal capillary gas chromatography and explores instrument calibration with the goal of maximizing instrument-to-instrument similarity of retention times.

Thermal desorption sampling often provides a means for bringing otherwise intractable samples to a gas chromatography (GC) column for separation and detection.

In this month's "GC Connections," John Hinshaw examines optimization strategies for gas chromatography columns in the second installment of a multipart series. He starts with a question from a reader and then discusses broader column issues.

John Hinshaw reviews the new gas chromatography instrumentation and accessories introduced at Pittcon this year.

This month's column reviews some basic GC measurements and calculations that can be applied to questions of column quality. By understanding the analytical process, chromatographers can improve the quality of their results.

This report describes five small and very useful accessories developed 40 years ago to adapt gas chromatographs for special tasks.

This month's "GC Connections" begins a multipart series about gas chromatograph performance optimization. In this first part, John Hinshaw addresses questions of instrument capabilities and chromatographers' expectations, as well as manual–hardware optimization strategies and software-separation strategies.

In the first of two "GC Connections" columns, Hinshaw responds to reader questions about the signal-to-noise ratio and what it means in practical terms.

A second installment of "GC Connections" answers a reader's question about dual-column gas chromatography systems and their proper maintenance.

In part I, Hinshaw described a simple experiment with coins to explain the statistical nature of separations and to impart a better understanding of the physical processes inside the column. In part II, he compares this coin-toss simulation with chromatographic columns and describes differences between the analogy and real-world situations.

Analysts can optimize their separations by using combinations of two columns connected in series. This type of coupled column system produces peak separations that are a combination of separations obtained on each column.