Capillary method of gas sampling under constant flow rate for the measurement of time average concentration of hydrocarbons in the atmosphere

Steady flow rate of air through a capillary of proper diameter and length was observed, when one end of a capillary was exposed to air while another end was connected to the vessel kept at the pressure ranging from 0 to 0.3 atm. Time average concentration of the substance in air can be obtained by measuring concentrations of the substance collected. To confirm this point the concentrations of ethane and benzene collected through a capillary under time-dependent concentrations were analyzed. The measured average concentration agreed well with calculated one. Such a sampling method of air may be effectively applied to obtain time average concentrations of the gaseous substances in the atmosphere. A chromatogram of actual atmospheric sample was shown as an example.