A selected ion flow tube study of the reactions of NO+ and O+2 ions with some organic molecules: The potential for trace gas analysis of air

Abstract

Ground and excited state adiabatic 2 A″ and 2 A′ potential energy surfaces of the (Kr-O2)+ cluster ion

Quantification of pentane in exhaled breath, a potential biomarker of bowel disease, using selected ion flow tube mass spectrometry

“…In agreement with previous work, it was observed that pentane does not react at a significant rate with H 3 O + or NO + under the thermalised conditions (300 K) of SIFT‐MS, but it does react with O 2 +• . The first SIFT study of this reaction was carried out in 1996 as part of the early exploration of the usefulness of the NO + and O 2 +• reagent ions for trace gas analysis . Thus, the rate coefficient for the O 2 +• /pentane reaction was measured as 8 × 10 ‐10 cm 3 s ‐1 at 300 K compared with the collisional rate coefficient of 1.6 × 10 –9 cm 3 s –1 .…”

“…The first SIFT study of this reaction was carried out in 1996 as part of the early exploration of the usefulness of the NO + and O 2 +• reagent ions for trace gas analysis. [46] Thus, the rate coefficient for the O 2 +• /pentane reaction was measured as 8 × 10 -10 cm 3 s -1 at 300 K compared with the collisional rate coefficient of 1.6 × 10 -9 cm 3 s -1 . This 300 K value is adopted in this study and, as we show later, it is confirmed by the present experimental validation using standard mixtures.…”

Potential applications of breath isoprene as a biomarker in modern medicine: a concise overview

“…Compared to gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS) methods [29], PTR-MS is sufficiently sensitive and specific that it doesn't require pre-concentration or separation of the sample and therefore the volatile organic compounds can be measured on line and breath isoprene levels can be obtained every few seconds [14]. In addition, SIFT-MS analyses breath for the major breath metabolites and provides a measure of their alveolar concentration, both simply and directly, from only a single exhalation in real time, without the need to collect large volumes of breath, which are sometimes difficult to acquire, and without preconcentration of the breath metabolites on some form of trap as is generally required for analysis by GC-MS, and also avoiding bag sampling [30][31][32][33]. Thus, SIFT-MS offers a rapid, on-line, non-invasive technique for breath analysis which is more likely to be accepted for clinical diagnosis and therapeutic monitoring [34].…”

The SIFT and FALP techniques; applications to ionic and electronic reactions studies and their evolution to the SIFT-MS and FA-MS analytical methods

“…Such a complication can be diminished using some form of extraction and gas chromatographic separation (GC-MS), but this cannot realise a real time analytical technique. Recognising a growing interest in breath analysis for clinical diagnosis and therapeutic monitoring, D. Smith and P. Spanel saw the potential value of CI and SIFT for the real time analysis of complex gaseous media; thus the unique new analytical technique called selected ion flow tube mass spectrometry, SIFT-MS, was born [30][31][32][33][34][35]. SIFT-MS is an ideal ambient analysis method that is utilised for the immediate real time analysis of humid air obviating sample collection and treatment, such as water vapour removal or pre-concentration of trace compounds that is usually required for GC-MS analysis and which can compromise the sample to be analysed.…”

“…The most analytically important development stemming from SIFT is that of selected ion flow tube mass spectrometry, SIFT-MS, by P. Spanel and D. Smith in 1995 [30][31][32][33][34][35]. This is a novel gas phase analysis method by which trace gases can be quantified in real time in dry air and, significantly, in humid air such as exhaled breath and the headspace of aqueous liquids.…”