Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2003
Publication Date: 2/1/2004
Citation: Roberge, M.T., Finley, J.W., Lukaski, H.C., Borgerding, A.J. 2004. Evaluation of the pulsed discharge helium ionization detector for the analysis of hydrogen and methane in breath. Journal of Chromatography A. 1027:19-23. Interpretive Summary: Gas Chromatography is a technique that is used to separate compounds in the gas phase. Once compounds are separated they must be detected. The Pulsed Discharge Helium Ionization Detector (PDHID) can detect small amounts of chemicals in the gas phase. However, very few researchers take advantage of this detector because they are unfamiliar with its operation. We compared the PDHID to other commonly used detectors such as the Flame Ionization Detector (FID) and the Thermal Conductivity Detector (TCD) in a number of situations. With the PDHID we were able to determine the amount of hydrogen and methane in human breath at concentrations that were significantly lower than previously possible using the FID and TCD. Using the FID and TCD only about half of the human population could be monitored. This is important because hydrogen and methane levels in breath are used to monitor the metabolism of bacteria in the large intestine. A field portable gas chromatograph was constructed equipped with a PDHID because such an instrument would allow for measurement to be taken in the field, however the PDHID needs a helium purifier that requires too much power to be truly field portable. For now the PDHID is best suited for detecting separations where a power outlet is available.
Technical Abstract: The Pulsed Discharge Helium Ionization Detector (PDHID) was compared to the Flame Ionization Detector (FID) and the Thermal Conductivity Detector (TCD) in regard to selectivity, sensitivity and reproducibility under high speed separation conditions. It was shown that the PDHID is as sensitive as the FID but can be less reproducible because of its unselective detection mechanism.Moreover, the PDHID is more sensitive and more universal than the TCD. Under the appropriate separation conditions the PDHID was used to detect hydrogen and methane separated from the matrix components of breath samples with over an order of magnitude better sensitivity than methods using an FID or TCD. The prospect of a portable PDHID was explored because the detector requires little power and a single cylinder for operation. Because of the power necessary to operate the required helium purifier the PDHID is better suited for benchtop operation at this time.