Mass spectrometry is a well-established technique for gas composition analysis which can analyze any molecular or atomic species that can be brought to gas phase with very low detection limits, often in the parts-per-billion (ppb) range. However, due to mass coincidence and fragmentation in the mass spectrometer, the quantitative analysis of combinations of certain molecular species can be difficult and sometimes impossible. Once of these cases presents itself in the analysis of parts-per-million (ppm)-level Carbon Monoxide in the presence of percent-level Nitrogen, Oxygen and Carbon Dioxide. Representative scenarios would be the analysis of Carbon Monoxide in air or in the industrially-important Flue Gas whereby the parent peak of Carbon Monoxide at 28 amu and its fragments at 16 and 12 amu will be completely obscured by the parent peak of Nitrogen and the fragments of Oxygen and Carbon Dioxide. To get around this issue in the analysis of Flue Gas, we utilized an external detector to monitor the Carbon Monoxide concentration while analyzing the other components of the Flue Gas with the mass spectrometer. The Ultima XE Carbon Monoxide detector made by MSA Safety, Inc. employs electrochemical cell technology and outputs 4 to 20 mA signal which can be read by Extrel’s Questor5 software and can be plotted and analyzed alongside the concentration signals coming from the mass spectrometer. We used an Extrel CMS, LLC MAX300-LG mass spectrometer, but the external Carbon Monoxide detector can be seamlessly integrated with any of our products. In addition to analyzing a blend which mimics the composition of Flue Gas, we also performed a series of dilutions with dry air which yielded measured Carbon Monoxide concentrations within 1 ppm of the expected values. The concentrations of the other Flue Gas components analyzed by the mass spectrometer were also very close to the expected values.<br/>

Flue gas analysis by mass spectrometry with carbon monoxide monitoring via an external detector

2019 Fall National Meeting

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