ND denotes the nominal diameter. ND 18 designates a headspace vial with fine thread. The vials fit into standard autosamplers.

Fine thread vials ND18 are intended for headspace analysis. To eliminate the difficulties and risks of crimping and to reproducibly increase the tightness of the sample bottles, instrument manufacturers strive to keep the capping process as simple as possible, hence the long thread.

The headspace is the gas space above the sample in a chromatography vessel.
Volatile sample components diffuse into the gas phase and form the headspace gas.
Headspace analysis is therefore the analysis of the components present in this gas.
It places special demands on the vials and especially on the caps.
LABC offers a comprehensive range of headspace vials and closures for your analyses.
ND18 fine thread designates a magnetic high-density screw cap.
ND20 includes vials in various lengths and base shapes.
The bottle head always has a crimp to crimp the caps cleanly and tightly.