VOCs emitted by living organisms
It is not widely appreciated that the VOCs emitted by plants, moulds, animals and other life-forms – so-called ‘biogenic’ emissions – outweigh global anthropogenic VOC emissions by a factor of 10.
Biogenic VOCs are of current interest to atmospheric chemists dealing with the impact of airborne VOCs on air quality and atmospheric processes in general. However, they are also of interest from a biological perspective, as profiles of compounds such as monoterpenes can help to identify the species emitting them (and their phase of growth).
Biogenic VOCs also have an impact on local and regional atmospheric chemistry, and there are wide differences depending on land use. For example, biogenic emissions in the densely forested Nordic regions of Europe can play an important role in the regional oxidant budget.
In addition, in the marine environment a number of volatile halogenated hydrocarbons are produced by phytoplankton, bacteria and macroalgae, as well as by photochemical processes. These compounds eventually migrate to the atmosphere, where they can influence ozone levels and global climate. As a result, this is a topic of particular interest to atmospheric researchers.
What Markes can offer
The fact that studies of biogenic VOCs are carried out at particular times of the year, and in remote locations, makes sampling costly to repeat – as a result, sample security is paramount.
Sorbent sampling tubes incorporating diffusion-locking technology are a useful innovation in this respect, as they prevent ingress of contaminants or escape of analytes during transport to and from the field. Thermal desorbers that allow re-collection (collecting the split portion of the sample on to a clean tube), such as Markes’ TD100-xr, provide valuable ‘insurance’ against sample loss, should the analytical system fail mid-run.
Another advanced feature specific to sorbent tube sampling is TubeTAG tube-tagging technology, which allows individual samples to be automatically tracked, significantly reducing the time spent in sample logging.
- For the use of pumped-tube sampling with Markes’ UNITY-ULTRA automated thermal desorption system to detect for the first time the production of monoterpenes from marine algae, see: N. Yassaa et al., Evidence for marine production of monoterpenes, Environmental Chemistry, 2008, 5: 391–401.
- For an example of purge-and-trap sampling in conjunction with Markes’ UNITY thermal desorber to help understand the production and cycling of biogenic halocarbons in Arctic seawater, see: F.E. Hopkins et al., Response of halocarbons to ocean acidification in the Arctic, Biogeosciences, 2013, 10: 2331–2345.
- For an example of the use of Markes’ VOC-Mole soil sampler and UNITY thermal desorber to detect anti-insect chemicals released from compost, see: A. Papadopoulos and P. Alderson, A new method for collecting isothiocyanates released from plant residues incorporated in soil, Annals of Applied Biology, 2007, 151: 61–65.
- For a paper describing the development of a compact TD–GC×GC system for the detection of biogenic VOCs, see: S.J. Edwards, A.C. Lewis, S.J. Andrews, R.T. Lidster, J.F. Hamilton and C.N. Rhodes, A compact comprehensive two-dimensional gas chromatography (GC×GC) approach for the analysis of biogenic VOCs, Analytical Methods, 2013, 5: 141–150.
- For a description of the use of Markes’ UNITY–CIA system in a round-robin study for the detection of halocarbons in modified standard atmosphere, see: C.E. Jones et al., Results from the first national UK inter-laboratory calibration for very short-lived halocarbons, Atmospheric Measurement Techniques, 2011, 4: 865–874.