Gas Chromatography (GC)

In this extended special feature to celebrate the 30th anniversary edition of LCGC Europe, leading figures from the separation science community explore contemporary trends in separation science and identify possible future developments. We asked key opinion leaders in the field to discuss the current state of the art in gas chromatography instruments.

In this study, an empirical assessment of summation integration (using the lowest baseline point in user-defined tR windows) was conducted involving 490 low-pressure GC–MS/MS analyses of 70 pesticides in 10 common fruits and vegetables over the course of 10 days.

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.

Leading separation scientists share their perspectives on current challenges in separation science and where the field is heading.

A quick step-by-step guide for optimizing GC temperature programming.

If you understand how your system is affected by outside influences, you can take control of the variables.

A method was developed to address the constraints encountered when measuring methane levels during the degassing process.

Some 50 years after Giddings’s iconic comparison of the separation speed of gas chromatography (GC) and liquid chromatography (LC), the authors revisit this comparison using kinetic plots of the current state‑of‑the-art systems in LC, supercritical fluid chromatography (SFC), and GC. It is found that, despite the major progress LC has made in the past decade (sub-2-µm particles, pressures up to 1500 bar, core–shell particles), a fully optimized ultrahigh-pressure liquid chromatography (UHPLC) separation is still at least one order of magnitude slower than capillary GC. The speed limits of packed bed SFC are situated in between.

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.

Recent advances in vacuum ultraviolet (VUV) spectroscopy have allowed for the application of this technology as a chemical detection platform for gas chromatography (GC). This technique is known as GC–VUV. A GC–VUV detector can produce highly characteristic absorbance spectra for nearly all chemical species in the wavelength region of 125–240 nm. This enables not only identification but also robust quantitation of a variety of compounds separable by gas chromatography, including water. This article describes the results of a pilot study focused on trace water determination in common organic solvents using an ionic liquid stationary phase GC column in a GC–VUV platform.

The most prominent advantage of using nitrogen as a carrier gas is that it is the most efficient one when used at its optimum linear velocity.

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.

This month's “GC Connections” continues the discussion of procedures for safe setup, use, and disposal of compressed gas cylinders in the chromatographic lab.

Many gas chromatographers are not fully aware of safe practices for handling high-pressure gas cylinders. GC operators should be trained to properly transport, install, connect, and maintain their gas supplies, as well to deal with emergencies. In the first of a two-part series, this month’s GC Connections examines the principal hazards and safety issues surrounding the compressed gas cylinder. Next month’s installment will present safe procedures for routine cylinder use.

While gas chromatographers may take their septa for granted, in fact these small and seemingly unremarkable polymer discs keep air out of the carrier gas stream when used in an inlet and keep sample intact and uncontaminated when used in a sample vial. Choosing the wrong septa can compromise method accuracy and repeatability as well as reduce column lifetime in extreme cases. This installment addresses septa for inlets and sample vials.

Chromatography connected with ion mobility spectrometry (IMS) is not commonly used, but is being investigated more. IMS is an independent analytical technique with very good detectability and a rather small separation ability. One favourable property of IMS is that it can work with ambient pressure and can be easily connected to a gas chromatograph. Analytical applications of GC–MS are very different and encompass investigations into food, medical science, environment, drugs of abuse, chemical warfare agents, and explosives.

Put yourself in their spot: How would you tackle analyzing a bag of gummy bears that showed up on your lab bench? Here, we offer some insights from the very capable finalists at The Conference on Small Molecule Science (CoSMoS), which was held in August 2015 in San Diego, California.

John Hinshaw presents his annual review of new developments in the field of gas chromatography seen at Pittcon and other venues in the past 12 months.

Incognito shares his thoughts on the importance of specifications for method transfer in gas chromatography (GC).

Jack Cochran’s new column “Practical GC” provides readers with practical advice and new experimental evidence for how to get the best results from their gas chromatography (GC) systems. This instalment looks at understanding and using split ratio for “shoot and dilute” GC.

Gas chromatography (GC) is an established and well-understood technique. As the cannabis industry grows, demand for analytical robustness is increasing for analytes such as pesticides, residual solvents, and terpenes. GC and GC coupled to mass spectrometry (GC–MS) are effective tools to address the demands of laboratories, growers, manufacturers, and consumers. This article provides an overview of the types of compounds that can be analyzed by GC, reviews the strengths and weaknesses of the analytical methods, and discusses areas of opportunity for chromatography.

This article describes the use of a headspace thermal desorption–gas chromatography–time-of-flight mass spectrometry (headspace TD–GC–TOF-MS) method to analyze complex aroma profiles from hops, and highlights how it can provide a rapid yet robust approach when comparing similar samples. The article also examines the potential of “soft” electron ionization at 12 eV for distinguishing between structurally similar monoterpenoids and sesquiterpenoids to provide better characterization of the often subtle differences in headspace profiles between different hop varieties.

This study describes the need to recover compounds above the boiling point of naphthalene by optimizing the thermal desorption chemistry for the determination of VOCs from C3 to C26 in soil gas samples using Method TO-17. Figures of merit, such as breakthrough, precision, linearity and detection capability will be presented, in addition to evaluating its real-world capability at sites with moderate diesel and semi-volatile polynuclear aromatic hydrocarbon (up to pyrene) contamination, in the presence of high humidity.

Chromatographers often use the term carrier-gas flow and velocity interchangeably when discussing column parameters. In LC, the two terms scale together, but in GC they do not: Doubling the flow does not double the velocity. This month's “GC Connections” investigates the reasons for this non-intuitive behavior and how it affects best practices for gas chromatographers.