Question

could there be impurities in gases?

Answer 1

yes obviously it may contain impurities

Answer 2

 Best Answer

Yes. It is impossible (w/ our current technology) to get a 100% pure sample of a gas (or any other material - assuming you want more than one or two atoms worth). Inert gasses like N2, Ar, He often contain water vapor, oxygen, and organic compounds as impurities. Organic gases like acetylene, ethylene, ethane, propane, butane will often contain other similar organic compounds as impurities. 

Keep in mind though that purity is a relative term. If the gas is "pure enough" for your application, then a certain level of impurities is acceptable.

Hope it'll help u