A portable sampling system includes a heated probe, an input/output (“I/O”) system, and one membrane dryer in the form of a conduit that couples the probe to the I/O system. The dryer has purge gas flowing over the drying membrane and a gas sample flowing through the drying membrane, which is in the form of tubes of a perfluorosulfonic acid material, and wherein the dryer is operated in some embodiments under deep vacuum and with the purge gas flowing at a rate that is typically less than that of the gas sample being dried.