Description
Headspace sampling is a type of sample introduction technique for gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). For headspace techniques, the gas layer, or the headspace above the sample in a vial, is analyzed as opposed to withdrawing a volume from within the sample layer (Figure 1). Headspace analysis requires that the compounds of interest have high volatility, while the rest of the sample is much less or non-volatile. The technique lends itself nicely as a substitute for labor-intensive extractions when the sample types are solids, viscous liquids, blood, or medications, as examples.
Headspace sampling offers several benefits for GC analysis.
- Compatible with virtually any matrix. The sample itself does not have to be volatile or soluble in a liquid appropriate for GC.
- Little or no sample preparation. This can lead to more reproducible results because sample prep may introduce errors into the overall workflow.
- Smaller solvent peak. In many applications, the amount of solvent introduced into the gas chromatograph is significantly less than the solvent in a liquid injection. In these cases, the solvent peak is smaller and less likely to interfere with the analytes of interest.
- Higher instrument uptime. Cleaner samples result in less maintenance to the GC inlet, column, detector, or mass spectrometer source.
- Often higher sensitivity with good precision and linearity.
