Abstract: A portable (handheld) volatile organic compound monitoring system for monitoring, for fugitive emissions, a device that includes a coded identification tag. The system includes a housing, a tag reader, analysis chamber structure, a sample probe coupled to the analysis chamber, and pump structure for drawing a gas sample to be analyzed through the sample probe into the analysis chamber. Ionization apparatus is coupled to the analysis chamber for ionizing a gas sample drawn into the analysis chamber from the device being monitored, and a sensor responsive to ionized gas in the chamber produces an output signal as a function of an ionization characteristic of the ionized gas. First storage stores a plurality of response factors as a function of various types of volatile organic compounds to be monitored, second storage stores tag information read by the tag reader, and circuitry responsive to tag information stored in the second storage selects a response factor from the first storage.