Columns | Column: GC Connections

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.

Our annual review of new developments in the field of gas chromatography, as seen at Pittcon and other venues

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.

Gas chromatography makes use of a wide variety of detection methods, which really shine when deployed properly. Here’s guidance for how to choose the right one for your analysis.

Fast gas chromatography (GC) has received new attention recently in the form of available enhanced instrument capabilities. What can fast GC do for separations, and how can laboratories take advantage of enhanced separation speeds?

When data change over time, you may be able to tease out the causes by conducting a time-series analysis or by looking at various forms of correlation.

Annual review of new developments in the field of GC

Gas chromatographers can control several variables that affect their separations: carrier-gas flow, column temperature, column dimensions, and stationary phase chemistry. When faced with less than optimum resolution or separation speed, a strategy of changing just one variable at a time can be more productive than trying to hit the goal in one attempt. This month's GC Connections examines how to use such a plan to obtain better GC results.

Separation scientists may seek an optimum spot between chromatographic performance required to obtain sufficient results quality, and the time and resources needed to do so. This installment of GC Connections examines the factors that control peak resolution - one of the main drivers of separation quality - and how chromatographers can use this to find an optimum between time, cost, and performance.

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.