Corning Caps used Red High temp with sealing inserts as seen in the pictures. These are meant to seal bottles to keep anything precious inside and minimize any evaporation. These are either new or come off solvent bottles.
By solvent bottles I mean they came off new bottle of reagents which could contain acetonitrile or other organic solvents.
These have been rinsed the organic solvents are water soluble and would have minimal exposure to the caps.