sample injector

in chromatography
https://doi.org/10.1351/goldbook.S05458
A device by which a liquid or gaseous sample is introduced into the apparatus. The sample can be introduced directly into the carrier-gas stream, or into a chamber temporarily isolated from the system by values which can be changed so as to make an instantaneous switch of the gas stream through the chamber. The latter is a by-pass injector.
Source:
Orange Book, 2nd ed., p. 98 (https://media.iupac.org/publications/analytical_compendium/)