Abstract: Methods of sampling substances such as subsurface contaminants, a transfer line for use in a system for such sampling, a sampling system and methods of manufacture and use of the system are described. The transfer line used in a probe system for subsurface chemical sampling connects a detection apparatus with a probe, the transfer line including a first flexible tube for carrying fluid to the probe; and a second flexible tube for carrying sample-loaded fluid from the probe; wherein second flexible or both first and second flexible tubes comprise a barrier tube surrounded by a metal coating. The metal coating is a continuous cladding deposited with structural integrity, and the metal coating is surrounded by an insulating layer, so that one or both of the flexible tubes can be heated by applying a voltage on the metal coating.