4.6. Instruments
4.6.1. Gas collection
Generally, gas samples can be collected from a chamber with a syringe or with a pump
(Figure 4.5). The instrument chosen depends partly on the storage container used. A plastic
syringe (e.g., 25–50 mL) should be used if the samples are to be stored in (evacuated) glass
vials (e.g., 10–30 mL). If the storage container will be a plastic bag, it is necessary to collect a
relatively large volume (e.g., >0.5 L) to minimize gas contamination. In this case, a
battery-operated pump is helpful, although use of a plastic syringe is also possible. To avoid
a drastic change in air pressure inside the chamber, collecting a smaller gas volume is
recommended.