Atmosphere generation system for the preparation of ambient air volatile organic compound standard mixtures

A dynamic generation system based on permeation for the preparation of vola tile organic compounds at ambient air concentration levels is described her ein. The performance of the equipment, sources of uncertainties, and overal l uncertainty value are also evaluated. The system is capable of generating multicomponent mixtures at ppb levels and simulating different atmospheric conditions by changing the humidity, concentration level, temperature, and wind velocity. A minimized value for the overall uncertainty in the concen tration generated by the system was determined to be +/-1.9% for higher wei ghing time intervals of 4 weeks.