title: Concentrating breath samples using liquid nitrogen: a reliable method for the simultaneous determination of ethane and pentane.
abstract: The measurement of ethane and pentane in breath offers a sensitive and noninvasive means to assess in vivo lipid peroxidation in animals and humans. However, numerous technical obstacles inherent in collecting and concentrating air-breath samples have limited the wider application of these measurements for the assessment of in vivo lipid peroxidation. We have developed a relatively simple, inexpensive, rapid, and reliable method to collect, concentrate, and measure breath ethane and total-body pentane from rats. This method, which concentrates alkanes from 4 liters of collected air-breath on adsorbant cooled to -174 degrees C, was found to be superior to similar cryofocusing techniques at -130 degrees C, which fail to effectively trap highly volatile ethane from large volumes of air. We found ethane evolves predominantly through breath, whereas a significant amount of pentane evolves from sources other than breath. Mean evolution rate for ethane was 1.08 pmol/100 g body wt/min. Pentane evolution rates displayed more inter-rat and day-to-day variability with a mean of 0.52 pmol/100 g body wt/min. We also found that excreted rat feces exude large amounts of ethane and pentane.
authors.affiliation: Department of Nutritional Sciences, University of California, Berkeley 94720, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Knutson
authors.forename: F E
authors.initials: FE
authors.lastname: Viteri
mesh_terms: D000828:Animal Population Groups; D000818:Animals; D001944:Breath Tests / Q000295:instrumentation / Q000379:methods*; D002849:Chromatography, Gas; D003080:Cold Temperature; D004980:Ethane / Q000032:analysis*; D008297:Male; D009584:Nitrogen; D010420:Pentanes / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010420:Pentanes; C033353:pentane; D004980:Ethane; D009584:Nitrogen