Tube filled with charcoal typically used to adsorb analytes from the gas or liquid phase.
Note: Activated charcoal was used in early applications, but a wider selection of carbon materials are currently used, with properties tailored to each application.
Source:
PAC, 2016, 88, 517. 'Glossary of terms used in extraction (IUPAC Recommendations 2016)' on page 521 (https://doi.org/10.1515/pac-2015-0903)