Real-Time Analysis of Exhaled Breath via Resonance-Enhanced Multiphoton Ionization-Mass Spectrometry with a Medium Pressure Laser Ionization Source: Observed Nitric Oxide Profile

Abstract

An elevated concentration of nitric oxide (NO) in alveolar ventilation is indicative of inflammatory stress within the lung. We present here the first description of time-resolved measurement of NO in breath using photoionization mass spectrometry, providing new capabilities for the medical investigator, such as isotopic tracing. Here we use resonance-enhanced multiphoton ionization (REMPI) with time-of-flight mass spectrometry (TOF-MS) coupled with a medium pressure laser ionization (MPLI) source for the selective detection of NO in breath. To demonstrate this technology, a single male subject breathes NO-free air for several minutes, and then the exhaled breath is monitored. The ability of REMPI to differentiate among three different isotopomers of NO is demonstrated, and then the concentration profile of NO in exhaled breath is measured. A similar time-dependence concentration is found as observed by previous techniques. The advantages of this approach compared to other techniques are: (1) parts-per-billion by volume (ppbV) mixing ratios of NO can be measured on a sub-second time scale, (2) since the technique operates optically as well as mass-resolved, isotopomers of NO are discernable, permitting the use of isotopic tracing, and (3) other biologically significant gas molecules can be measured via REMPI.

Volatile compounds characteristic of sinus-related bacteria and infected sinus mucus: Analysis by solid-phase microextraction and gas chromatography–mass spectrometry

“…A number of investigations have focused on human breath analysis for volatile compounds indicative of oral [19][20][21] and systemic [18,[22][23][24][25][26][27][28][29][30][31] pathologies. Exhaled air may be collected in a relatively non-invasive manner, with minimal inconvenience for the patient [32][33][34].…”

Экспериментальная установка на базе перестраиваемого в диапазоне волн 5.3-12.8 μm квантово-каскадного лазера для спектрального анализа выдыхаемого человеком воздуха

“…Основными методами исследования выдыхаемого человеком воздуха являются масс-спектрометрия [16], электрохимические сенсоры [17], газовая хроматография [18], xромато-масс-спектрометрия, лазерная абсорбционная спектроскопия [19]. Установки, основанные на таких методах анализа пробы, могут занимать целые помещения, а время одного исследования существенно ограничивает возможности использования таких систем [20]. Метод спектроскопии ионной подвижности обладает высокой чувствительностью и способен регистрировать концентрации от долей до сотен ppb.…”

Investigation of the Photoionization Properties of Pharmaceutically Relevant Substances by Resonance-Enhanced Multiphoton Ionization Spectroscopy and Single-Photon Ionization Spectroscopy Using Synchrotron Radiation

“…13 With resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) it was possible, for example, to measure aromatic substances online in the mouth space of smokers and detect nitric oxide in breath gas. 14,15…”