Several compounds were previously identified as being present in modified concentrations in the breath of patients with inflammatory bowel diseases, IBD: 2-methylpentane, 1,3,5-triazine, trans-2-octene, cis-2-nonen-1-ol, 2'-methylacetophenone, 1-heptene and 2-hexanone. A selected ion flow tube, SIFT, study has thus been carried out of the reactions of H3O+, NO+ and O2(+ radical) with these volatile organic compounds.
The rate constants and product ion branching ratios of the primary reactions including three body association rate constants, describing the rate of hydration, were obtained. The results of this study allow accurate SIFT-MS quantification of concentrations of these compounds in exhaled breath of IBD patients with the ultimate aim of establishing their use as non-invasive biomarkers of the disease activity.