By Matthew Klee
This month we continue last month’s discussion of ferrules used in gas chromatography. We discuss ferrules of graphite, Vespel® (polyimide), Vespel®- graphite mixtures, and Teflon® (polytetrafluoroethlyene, PTFE). Attributes of these ferrule materials are summarized in Table 1.
GC Ferrules – Metal Ferrules
By Matthew Klee
Gas chromatography would not be a practical routine technique without ferrules – those necessary consumables that provide a pressure seal between the atmosphere and the gas flow path. Ferrules are used in junctions that can be disconnected and remade. Proper selection and use of ferrules ensures a reliable installation. Incorrect selection and/or implementation can cause enumerable problems and can affect the quality of analytical results.
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Uncoated Pre-Column Backflush Configuration
By Matthew Klee
This month we discuss one of the newer approaches to capillary column backflush: the uncoated pre-column configuration.
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Coated Pre-Column Backflush Configuration
By Matthew Klee
Continuing our discussion of the three configurations of capillary column backflush, this month we cover the coated pre-column configuration.
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Post-Column Backflush
By Matthew Klee
We continue last month’s backflush discussion with a description of the most common form of backflush: post-column backflush.
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Capillary Column Backflush
By Matthew Klee
This month we introduce the concepts of back flushing capillary columns. The technique of reversing the flow in GC columns to remove highly retained components from the front of the column has been used for decades with packed columns in valved configurations. Packed columns are usually used in isothermal analyses that require the use of several different columns in order to cover the boiling point range of a sample.
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The Flame Ionization Detector – Part 2
By Matthew Klee
Continuing last month’s discussion of the most popular GC detector, the FID, this month we cover deviations from typical unit carbon response, optimization and troubleshooting.
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The Flame Ionization Detector – Part 1
By Matthew Klee
This month we initiate a discussion on the workhorse detector of gas chromatography: the fl ame ionization detector. The flame ionization detector (FID) is the premier detector in gas chromatography. It has unique properties and performance that puts it above and beyond all other general-use detectors in gas chromatography (or any other form of chromatography, for that matter).
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Basis of Interactions in Gas Chromatography – Part 3: Stationary Phase Selectivity, Glass Half Full?
By Matthew Klee
In Part 3 we bring together the retention mechanism concepts discussed earlier to form a simple view of the nature of selectivity in liquid stationary phases used in gas chromatography.
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Basis of Interactions in Gas Chromatography – Part 2: Polar Interactions
By Matthew Klee
To fully grasp the concepts of retention and selectivity of GC stationary phases, one must fi rst understand the fundamental intermolecular interactions that lead to retention. This month we discuss polar interactions; the interactions responsible for any observed selectivity in GC.
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Basis of Interactions in Gas Chromatography, Part 1 – Non-Polar Interactions
By Matthew Klee
To fully grasp the concepts of retention and selectivity of GC stationary phases, one must first understand the fundamental intermolecular interactions that lead to retention. This month we discuss the most dominant of those interactions – dispersive, non-polar interactions.
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Hot Split Injections, Part 3 – Decomposition
By Matthew Klee
This month, we tackle another potential problem of hot split injection: sample decomposition. Decomposition changes the nature of components in the original sample, aff ecting the “recovery” of target compounds. This in turn introduces errors in analytical results. We will look at common forms of decomposition and the clues your chromatograms might be presenting you that decomposition is happening.
Hot Split Injections – Part 1
By Matthew Klee
This month’s article will discuss split injections with a hot split/splitless inlet. This is the most popular inlet and sampling mode for capillary GC. The focus will be on the basic concepts and flow paths. Later articles will cover liner choice, optimization and other practical Matthew Klee considerations.
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GC Detectors
By Matthew Klee
In my opinion, there are three major strengths of gas chromatography over other common analytical separation techniques. The fi rst is the total separation power aff orded by long wall-coated open tubular columns. The second...
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The Function of GC Columns
By Matthew Klee
Hello chromatographers, welcome back. This month I present a general overview of the purpose of GC columns, key processes involved and high-level description of differences between them.
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The Function of GC Inlets
By Matthew Klee
Welcome back. This month I will cover the general function of GC inlets. I will describe some common attributes, diff erences and provide a context for future articles covering inlets in more detail.
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Helping you get the most out of GC analysis
By Matthew Klee
First I would like to thank you for your interest in GC Solutions and for spending your valuable time checking us out. I know how hard it is to find the time. In the monthly series of articles that will follow in GC Solutions I aspire to make the time you spend as rewarding as possible by presenting concise, clear, straightforward and practical articles on gas chromatographic (GC) analysis. Click here for the full article >>