Additivity of detector responses of a portable direct-reading 10.2 eV photoionization detector and a flame ionization gas chromatograph for atmospheres of multicomponent organics: use of PID/FID ratios.

The H-Nu PI-101 with a photoionization detector (PID) of 10.2 eV and the Century OVA-128 equipped with a flame ionization detector (FID) were evaluated for the additivity of their responses to a defined mixture of dissimilar organic vapors at a 0 and 90% relative humidity (RH). The responses of both instruments were additive as long as the effect of RH was accounted for with the PID. The PI-101 was not as precise as the Century OVA-128 for 90% RH atmospheres. PID/FID ratios did not change in the presence of 90% RH as long as the effect of RH also was accounted for in the PID reading.