Institute for Science and Technology in Medicine, School of Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB, UK.
J Breath Res. 2008 Dec;2(4):046004. doi: 10.1088/1752-7155/2/4/046004. Epub 2008 Sep 16.
We have carried out a selected ion flow tube mass spectrometry (SIFT-MS) study of the concentrations of the sulfur-containing compounds H(2)S (using H(3)O(+) precursor ions), CH(3)SH (H(3)O(+)), (CH(3))(2)S (O(2)(+)), (CH(3))(2)S(2) (NO(+)) and CS(2) (O(2)(+)) in single exhalations of mouth-exhaled breath and nose-exhaled breath and in the static gas in the oral cavity for two healthy volunteers. The primary purpose of the study was to show how compounds present in breath at levels as low as a part per billion (ppb) can be identified and quantified if the overlap of 'impurity' isobaric ions with the analytical product ions for each trace compound is identified and accounted for. The H(2)S measurements are straightforward using H(3)O(+) precursor ions, since no overlapping ions are recognized and its breath concentration is relatively high at typically 20-70 ppb. Thus, its concentration distribution for two healthy volunteers has been obtained over a period of a few weeks. The situation is very similar for CH(3)SH, but to analyse this compound we had to study the kinetics of its reactions with the SIFT-MS reagent ions H(3)O(+), NO(+) and O(2)(+) in order to provide the required kinetics library data for this compound. It is seen that CH(3)SH, (CH(3))(2)S and (CH(3))(2)S(2) are present in the mouth breath/cavity at lower levels of <10 ppb. The measurements of the levels of H(2)S and these compounds in the nose-exhaled breath and the closed mouth indicate that they are largely produced in the oral cavity, although there is some indication that (CH(3))(2)S is partially systemic in these two volunteers. It was not possible to quantify CS(2) in the breath because of serious interference (overlapping ions) due to the presence of carbon dioxide and acetone that inevitably occur in exhaled breath. This study paves the way for the accurate analysis of these sulfur compounds in halitosis and potentially for probing the diseased state, especially liver disease, by breath analysis. To demonstrate the simplicity of measuring these compounds when they are present at levels of about 100 ppb and greater, data are presented on the emissions of these sulfur-containing compounds from Pseudomonas bacterial cultures in vitro.
我们利用选择离子流管质谱（SIFT-MS）对 2 位健康志愿者的口腔呼出气、鼻腔呼出气和口腔静态气体中的含硫化合物 H(2)S（使用 H(3)O(+)前体离子）、CH(3)SH（H(3)O(+)）、(CH(3))(2)S（O(2)(+)）、(CH(3))(2)S(2)（NO(+)）和 CS(2)（O(2)(+)）的浓度进行了研究。本研究的主要目的是展示如果识别并解释每种痕量化合物的分析产物离子与杂质同量异位离子的重叠，那么在痕量水平（如十亿分之一（ppb））下存在于呼气中的化合物如何被识别和定量。使用 H(3)O(+)前体离子测量 H(2)S 非常简单，因为没有识别到重叠离子，而且其呼气浓度相对较高，通常为 20-70 ppb。因此，在数周内获得了 2 位健康志愿者的 H(2)S 浓度分布情况。CH(3)SH 的情况非常相似，但为了分析这种化合物，我们必须研究其与 SIFT-MS 试剂离子 H(3)O(+)、NO(+)和 O(2)(+)的反应动力学，以便为这种化合物提供所需的动力学库数据。结果表明，CH(3)SH、(CH(3))(2)S 和 (CH(3))(2)S(2)在口腔呼出气和口腔中的浓度较低，<10 ppb。H(2)S 和这些化合物在鼻腔呼出气和闭口呼吸中的测量值表明，它们主要在口腔中产生，尽管有迹象表明，在这两名志愿者中，(CH(3))(2)S 部分来自全身。由于呼出气体中不可避免地存在二氧化碳和丙酮，因此 CS(2)在呼气中的严重干扰（重叠离子）使其无法定量。本研究为准确分析口臭中的这些硫化合物以及通过呼吸分析探测疾病状态（特别是肝病）铺平了道路。为了证明当这些化合物的浓度约为 100 ppb 及以上时进行测量的简单性，本文还提供了体外培养的假单胞菌产生这些含硫化合物的排放数据。
