Fernández Del Río R, O'Hara M E, Pemberton P, Whitehouse T, Mayhew C A
Molecular Physics Group, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
J Breath Res. 2016 Oct 12;10(4):046006. doi: 10.1088/1752-7155/10/4/046006.
Isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether), CHClFO, is a commonly used inhalation anaesthetic. Using a proton transfer reaction mass spectrometer (PTR-MS) we have detected isoflurane in the breath of patients several weeks following major surgery. That isoflurane is detected in the breath of patients so long after being anaesthetised raises questions about when cognitive function has fully returned to a patient. Temporal profiles of isoflurane concentrations in breath are presented for five patients (F/M 3/2, mean age 50 years, min-max 36-58 years) who had undergone liver transplant surgery. In addition, results from a headspace analysis of isoflurane are presented so that the product ions resulting from the reactions of HO with isoflurane in PTR-MS could be easily identified in the absence of the complex chemical environment of breath. Six product ions were identified. In order of increasing m/z (using the Cl isotope where appropriate) these are [Formula: see text] (m/z 51), CHFCl (m/z 67), CFCHCl (m/z 117), CFOCl (m/z 163), CHFOCl (m/z 165), and CFOCl HO (m/z 183). No protonated parent was detected. For the headspace study both clean air and CO enriched clean air (4% CO) were used as buffer gases in the drift tube of the PTR-MS. The CO enriched air was used to determine if exhaled breath would affect the product ion branching ratios. Importantly no significant differences were observed, and therefore for isoflurane the product ion distributions determined in a normal air mixture can be used for breath analysis. Given that PTR-MS can be operated under different reduced electric fields (E/N), the dependence of the product ion branching percentages for isoflurane on E/N (96-138 Td) are reported.
异氟烷（1-氯-2,2,2-三氟乙基二氟甲基醚），化学式为CHClFO，是一种常用的吸入式麻醉剂。我们使用质子转移反应质谱仪（PTR-MS）在大手术后数周的患者呼出气体中检测到了异氟烷。在麻醉后如此长的时间仍能在患者呼出气体中检测到异氟烷，这引发了关于患者认知功能何时完全恢复的疑问。文中给出了5例接受肝移植手术患者（男女比例3/2，平均年龄50岁，年龄范围36 - 58岁）呼出气体中异氟烷浓度随时间的变化情况。此外，还给出了异氟烷的顶空分析结果，以便在没有呼出气体复杂化学环境的情况下，能轻松识别PTR-MS中HO与异氟烷反应产生的产物离子。共识别出6种产物离子。按质荷比（m/z）从小到大（适当使用Cl同位素）依次为[化学式：见原文]（m/z 51）、CHFCl（m/z 67）、CFCHCl（m/z 117）、CFOCl（m/z 163）、CHFOCl（m/z 165）和CFOCl HO（m/z 183）。未检测到质子化母体。在顶空研究中，纯净空气和富CO纯净空气（4% CO）均被用作PTR-MS漂移管中的缓冲气体。使用富CO空气来确定呼出气体是否会影响产物离子分支比。重要的是，未观察到显著差异，因此对于异氟烷，在正常空气混合物中测定的产物离子分布可用于呼出气体分析。鉴于PTR-MS可在不同的折合电场（E/N）下运行，本文还报道了异氟烷产物离子分支百分比对E/N（96 - 138 Td）的依赖性。
