Selected ion flow tube-mass spectrometry (SIFT-MS) can measure volatile compounds in breath on-line in real time and has the potential to provide accurate breath tests for a number of inflammatory, infectious and metabolic diseases, including diabetes. Breath concentrations of acetone in type 2 diabetic subjects undertaking a long-term dietary modification programme were studied. Acetone concentrations in the breath of 38 subjects with type 2 diabetes were determined by SIFT-MS. Anthropomorphic measurements, dietary intake and medication use were recorded. Blood was analysed for beta hydroxybutyrate (a ketone body), HbA1c (glycated haemoglobin) and glucose using point-of-care capillary (fingerprick) testing. All subjects were able to undertake breath manoeuvres suitable for analysis. Breath acetone varied between 160 and 862 ppb (median 337 ppb) and was significantly higher in men (median 480 ppb versus 296 ppb, p = 0.01). In this cross-sectional study, no association was observed between breath acetone and either dietary macronutrients or point-of-care capillary blood tests. Breath analysis by SIFT-MS offers a rapid, reproducible and easily performed measurement of acetone concentration in ambulatory patients with type 2 diabetes. The high inter-individual variability in breath acetone concentration may limit its usefulness in cross-sectional studies. Breath acetone may nevertheless be useful for monitoring metabolic changes in longitudinal metabolic studies, in a variety of clinical and research settings.
The haloamines, including the chloramines (H(2)NCl, HNCl(2)) and bromamine (H(2)NBr), are diffusible gases that are likely to be produced during inflammation and so may be present as markers of lung inflammation on breath. Although haloamines are quite reactive, it is possible to measure these compounds in humid samples using SIFT-MS. Until recently the quantification of haloamines in breath suffered from interference from other common breath compounds. This was overcome by heating the flow tube which removed major water cluster product ions. Despite the improvements to the method, previous attempts to measure the haloamines in breath samples from normal volunteers had found no evidence to support their presence. Since it is proposed that the haloamines may be present in higher concentrations during airways inflammation we have attempted to detect the compounds in the exhaled breath of patients with airways inflammatory conditions. On-line and off-line breath samples were analyzed; however, there was no discernable change to any of product ions when compared to ambient air or normal subjects. This suggests that despite sensitivity in the mid part per trillion range haloamines are not significantly raised in airways inflammation.
Selected ion flow tube mass spectrometry (SIFT-MS) is a sensitive technique capable of measuring volatile compounds (VCs) in complex gas mixtures in real time; it is now being applied to breath analysis. We investigated the effect of inhalers containing chlorofluorocarbons (CFCs) on the detection and measurement of haloamines in human breath. SIFT-MS mass scans (MS) and selected ion monitoring (SIM) scans were performed on three healthy non-smoking volunteers before and after inhalation of the following medications: Combiventtrade mark metered-dose inhaler (MDI) (CFC-containing); Ventolintrade mark MDI (CFC-free); Atroventtrade mark MDI (CFC-free), Beclazonetrade mark MDI (CFC-containing); Duolintrade mark nebuliser. In addition, the duration of the persistence of the mass/charge ratios was measured for 20 h. Inhalers containing CFCs generated large peaks at m/z 85, 87, 101, 103 and 105 in vitro and in vivo, consistent with the predicted product ions of CFCs 12, 114 and 11. No such peaks were seen with Duolintrade mark via nebuliser, or CFC-free MDIs. We conclude that measurement of VCs, such as haloamines, with product ions of similar m/z values to the ions found for CFCs would be significantly affected by the presence of CFCs in inhalers. This issue needs to be accounted for prior to the measurement of VCs in breath in people using inhalers containing CFCs.
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