Contamination Concerns

Use with caution:
PFA (light and dark)
PTFE parts (beware: emits COS in light conditions)
Stainless steel
Glass 
Synflex or Dekabon tubing if kept flushed
Stainless steel collar for soil chambers
Silonite treated tubing (Entech)
Silcotek or Sulfinert treated parts (Restek)   

Test for OCS production before using:
Gas regulators
Pumps
Sealants and O-rings

Avoid:
Rubber (especially in o-rings)
Neoprene
Most plastic tubing
Any surface with sulfate aerosol that can get wet (e.g. filter)
Rubber seals in pumps or other wetted parts
Black rubber stoppers. 
Blue bellco stoppers (non-neglible emissions) 
Plastic collars for soil chambers
Black walking mats
Paint coatings
PVC rubber and plastic
Nickel tubing (consumes OCS very quickly - possible "zero air" applications)