Which tubing material is appropriate for delivering acetylene to an atomic absorption spectrometer to avoid copper-related reactions?

• A. Copper tubing
• B. Plastic tubing
• C. Glass tubing
• D. Stainless steel tubing

Answer: (D)

Acetylene can react with copper to form copper acetylide, a very unstable and explosive compound. To prevent that hazardous reaction in the gas-delivery line to an atomic absorption spectrometer, the tubing material must be non-reactive with acetylene and mechanically robust. Stainless steel tubing fits this need: it is chemically resistant to acetylene, does not promote unwanted side reactions, and can handle the pressures and cleaning requirements of AA instrumentation. It also avoids the permeability and degradation risks that plastics can have with acetylene, and it isn’t as fragile or break-prone as glass. Copper tubing would cause the dangerous copper acetylide formation, while plastic and glass have practical drawbacks for routine lab gas delivery.