Analysis of Flame Ionization Detector Oxygen Effects Using Blended Cylinders

Recent papers have investigated the influence of sample composition on Flame Ionization Detector (FID) instrumentation used to measure total hydrocarbon content in exhaust emission samples. In this paper we describe experiments and results that further define these effects. Specially blended propane in air cylinders were crafted to provide a nominal 3 ppmC propane concentration with an oxygen content ranging from 17.5 vol % to 21 vol%. These cylinders were evaluated on multiple FID designs and then used to evaluate a strategy to correct the effects of the interaction. The study shows that, in general, most FID's behave similarly in response to changing oxygen content in the presence of hydrocarbon. Anomalies are discussed. The cylinders are then used to demonstrate that a proposed method for correcting the oxygen and hydrocarbon interaction is successful in reducing the effects.