Basanta M, Koimtzis T, Singh D, Wilson I, Thomas C L P
The Centre for Instrumentation and Analytical Science at The School of Chemical Engineering and Analytical Science, The Faraday Tower, The University of Manchester, Sackville Street, Manchester, UK.
Analyst. 2007 Feb;132(2):153-63. doi: 10.1039/b608608j. Epub 2006 Nov 6.
An adaptive sampler for collecting 2.5 dm(3) samples of exhaled air from human subjects with an impaired respiratory function is described. Pressure in the upper respiratory tract is continuously monitored and the data used to control an automated system to collect select portions of the expired breathing cycle onto a mixed bed Tenax(trade mark) and Carbotrap(trade mark) adsorbent trap for analysis by GC-MS. The sampling approach is intended for use in metabolomic profiling of volatiles in human breath at concentrations greater than microg m(-3). The importance of experimental reproducibility in metabolomic data is emphasised and consequently a high purity air supply is used to maintain a stable exogenous volatile organic compound profile at concentrations in the range 5 to 30 microg m(-3). The results of a 90 day stability study showed that exogenous VOCs were maintained at significantly lower levels (40 times lower for isopropyl alcohol) and with significantly higher reproducibility (80 times lower standard deviation for isopropyl alcohol) than would have been be the case if ambient air had been used. The sampling system was evaluated with healthy controls alongside subjects with chronic obstructive pulmonary disease. Subjects were able to breathe normally with control subjects observed to breathe at a rate of 9 to 17 breaths per minute, compared to 16 to 30 breaths per minute for subjects with COPD. This study presents, for the first time, observations and estimates of intra-subject breath sample reproducibility from human subjects. These reproducibility studies indicated that VOCs in exhaled breath exhibit a variety of dynamic behaviours, with some species recovered with a RSD <30%, while other species were observed to have significantly more variable concentrations, 30 to 130% RSD. The approach was also demonstrated to reliably differentiate the differences in the VOC profiles between alveolar and dead space air.
描述了一种用于从呼吸功能受损的人体受试者收集2.5立方分米呼出空气样本的自适应采样器。对上呼吸道压力进行连续监测，并将数据用于控制自动化系统，以将呼出呼吸周期的选定部分收集到混合床Tenax（商标）和Carbotrap（商标）吸附阱上，用于气相色谱-质谱分析。该采样方法旨在用于对浓度大于微克每立方米的人体呼出气体中的挥发性物质进行代谢组学分析。强调了代谢组学数据中实验可重复性的重要性，因此使用高纯度空气供应来维持浓度在5至30微克每立方米范围内的稳定外源挥发性有机化合物谱。一项90天稳定性研究的结果表明，与使用环境空气相比，外源挥发性有机化合物的维持水平显著更低（异丙醇低40倍），且具有显著更高的可重复性（异丙醇的标准偏差低80倍）。该采样系统在健康对照者和慢性阻塞性肺疾病患者中进行了评估。受试者能够正常呼吸，观察到对照者的呼吸频率为每分钟9至17次呼吸，而慢性阻塞性肺疾病患者为每分钟16至30次呼吸。本研究首次展示了对人体受试者体内呼吸样本可重复性的观察和估计。这些可重复性研究表明，呼出气体中的挥发性有机化合物表现出多种动态行为，一些物质的相对标准偏差（RSD）<30%，而其他物质的浓度变化明显更大，RSD为30%至130%。该方法还被证明能够可靠地区分肺泡气和死腔气中挥发性有机化合物谱的差异。
