Quantification of pentane in exhaled breath, a potential biomarker of bowel disease, using selected ion flow tube mass spectrometry.
BACKGROUND
Inflammatory bowel disease has a relatively large incidence in modern populations and the current diagnostic methods are either invasive or have limited sensitivity or specificity. Thus, there is a need for new non-invasive methods for its diagnosis and therapeutic monitoring, and breath analysis represents a promising direction in this area of research. Specifically, a method is needed for the absolute quantification of pentane in human breath.


METHODS
Selected ion flow tube mass spectrometry (SIFT-MS) has been used to study the kinetics of the O2(+) reaction with pentane. Product ions at m/z 42 and 72 were chosen as characteristic ions useful for the quantification of pentane and the reactivity of these ions with water vapour was characterized. A pilot study has been carried out of pentane in the exhaled breath of patients with Crohn's disease (CD) and ulcerative colitis (UC) and of healthy volunteers.


RESULTS
Accurate data on the kinetics of the gas phase reaction of the O2(+•) ions with pentane have been obtained: rate coefficient 8 × 10(-10) cm(3) s(-1) (±5%) and branching ratios into the following product ions C5H12(+•) (m/z 72, 31%); C4H9(+) (m/z 57, 8%); C3H7(+) (m/z 43, 40%), C3H6(+•) (m/z 42, 21%). A method of calculation of absolute pentane concentration in exhaled breath was formulated using the count rates of the ions at m/z 32, 42, 55 and 72. Pentane was found to be significantly elevated in the breath of both the CD (mean 114 ppbv) and the UC patients (mean 84 ppbv) relative to the healthy controls (mean 40 ppbv).


CONCLUSIONS
SIFT-MS can be used to quantify pentane in human breath in real time avoiding sample storage. This method of analysis can ultimately form the basis of non-invasive screening of inflammatory processes, including inflammatory bowel disease.
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic.
Kseniya
K
Dryahina
Patrik
P
Španěl
Veronika
V
Pospíšilová
Kristýna
K
Sovová
Luděk
L
Hrdlička
Naděžda
N
Machková
Milan
M
Lukáš
David
D
Smith
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D001944:Breath Tests; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008875:Middle Aged; D010420:Pentanes / Q000032:analysis*; D055815:Young Adult
D015415:Biomarkers; D010420:Pentanes; C033353:pentane