4 research outputs found
Isoprene and acetone concentration profiles during exercise on an ergometer
A real-time recording setup combining exhaled breath VOC measurements by
proton transfer reaction mass spectrometry (PTR-MS) with hemodynamic and
respiratory data is presented. Continuous automatic sampling of exhaled breath
is implemented on the basis of measured respiratory flow: a flow-controlled
shutter mechanism guarantees that only end-tidal exhalation segments are drawn
into the mass spectrometer for analysis.
Exhaled breath concentration profiles of two prototypic compounds, isoprene
and acetone, during several exercise regimes were acquired, reaffirming and
complementing earlier experimental findings regarding the dynamic response of
these compounds reported by Senthilmohan et al. [1] and Karl et al. [2]. While
isoprene tends to react very sensitively to changes in pulmonary ventilation
and perfusion due to its lipophilic behavior and low Henry constant,
hydrophilic acetone shows a rather stable behavior. Characteristic (median)
values for breath isoprene concentration and molar flow, i.e., the amount of
isoprene exhaled per minute are 100 ppb and 29 nmol/min, respectively, with
some intra-individual day-to-day variation. At the onset of exercise breath
isoprene concentration increases drastically, usually by a factor of ~3-4
within about one minute. Due to a simultaneous increase in ventilation, the
associated rise in molar flow is even more pronounced, leading to a ratio
between peak molar flow and molar flow at rest of ~11.
Our setup holds great potential in capturing continuous dynamics of
non-polar, low-soluble VOCs over a wide measurement range with simultaneous
appraisal of decisive physiological factors affecting exhalation kinetics.Comment: 35 page
Analiza wydechu - oznaczanie zawartości związków lipofilowych w organizmie człowieka
Real-time analysis of exhaled breath is a promising new method to get quantitative information on lipophilic compounds stored in the human body. Some pilot results are presented on isoprene, which is produced as a by-product of the cholesterol synthesis and appears in exhaled breath at concentrations of about 100 parts-per-billion (ppb). The results have been obtained using proton transfer reaction mass spectrometry (PTR-MS) from healthy volunteers undergoing an ergometer challenge test (with 75 W). Peak exhalation flow of isoprene is about 400 nmol/min shortly after start of the challenge. The setup holds great potential in capturing continuous dynamics of non-polar, low-soluble VOCs over a wide measurement range with simultaneous recording of physiological parameters affecting exhalation kinetics.Przedstawiono wstępne wyniki oznaczenia stężenia izoprenu w wydechu zdrowego człowieka. Izopren jest produktem ubocznym reakcji syntezy cholesterolu. Do oznaczenia zastosowano metodę reakcji przeniesienia protonu przy wykorzystaniu spektrometrii mas (PTR-MS)