Organic or inorganic; abundant or in trace amounts; in solid, liquid, or gas form—most sample types and reasonably-volatile analytes can be analyzed using a choice of gas chromatography (GC) (link to GC overview page) approaches.
Outstanding results and flexibility do not require great expense or complexity. Today's GC provides a wide selection of technologies (link to product page), each suitable for a variety of analyte types, sample matrices, and workflows. Innovative equipment featuring instant-connect injectors and detectors (link to product page) makes it easy to tailor a cost-effective system for the methods you need, with the option to expand or reconfigure easily as your needs evolve.
What are the choices?
Gas chromatography setups differ in three areas:
Sample introduction: First, the chemical properties of your analytes—primarily volatility and fragility—along with the nature and complexity of the sample matrix will indicate the best means for getting the sample into the chromatograph.
Separation: Sample abundance, complexity, and analyte concentration and polarity help guide the choice of carrier gas, GC column(s), and single versus multi-dimensional separation.
Detection and analysis: Your analysis goals along with analyte characteristics like thermal conductivity and ionization will make some methods of detection preferable to others.
In Part One of this blog post we'll look at gas chromatography sample introduction approaches to address different sample types. Future posts will explore choices in separation columns, and delve into the many methods of GC detection.
Which Approach for Which Samples?
Packed versus Capillary Column Inlets
Many general GC applications can use regular columns packed with adsorbant media. Inlets for packed columns are fairly straightforward: they protect the column from nonvolatiles in the sample, and direct all sample flow to the column.
The picture is more nuanced for capillary GC inlets, due in part to the need to limit sample and analyte amounts, but also to support many varied and demanding applications. The list below compares five GC sample introduction approaches that address the most common analysis challenges.
Combination Split/Splitless Inlet Approach
Goal: General or trace GC analysis
Example Application: General and trace analyses
Rugged and easy-to-use
Good for high-concentration analytes (split) or trace levels (splitless)
Easy to automate
Not for heat-sensitive analytes
Best for samples with limited range of analyte boiling temperatures