Real-time optical sensing of exhaled acetone concentration utilizing non-Fickian Nafion diffusion inside a flow-through sample chamber
Real-time optical sensing of exhaled acetone concentration utilizing non-Fickian Nafion diffusion inside a flow-through sample chamber
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DOI：
10.1016/j.sbsr.2020.100373
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发表时间：
2020-08-01
影响因子：
5.3
通讯作者：
Angelopoulos, Anastasios P.
中科院分区：
文献类型：
--
作者：
Badmaarag, Ulzii-Orshikh;Bernstein, Jonathan A.;Angelopoulos, Anastasios P.
流动气体流的快速原位化学分析在广泛的应用中是令人感兴趣的，但是需要与分析物源浓度、其在采样室内的积累以及其通过传感器的检测相关联的时间尺度的去卷积。一个数学分析上的使用的流通样品室的快速，原位呼吸分析，利用分析物扩散通过Nafion膜光电二极管。我们表明，这种方法产生明显的非Fickian（异常或情况II）的传输，从t（1/2）到t变化的t -> 0与恒定的入口浓度。这种行为的出现是由于从膜限制到样品室限制的传输动力学的转变，这取决于测试条件。该模型进行了验证，利用从与Friedel-Craft酰化丙酮蒸气与间苯二酚试剂固定在Nafion膜固态催化剂的颜色响应的实验数据。光极膜厚度的减小和膜增湿的增加产生仅受样品室材料积累限制的光学响应。在此极限下，发现从健康个体获得的丙酮呼出气信号随t（2）变化（显然是超级情况II转运）。利用人肺上的简化物质平衡，该观察结果归因于恒定的丙酮呼气速率，而不是恒定的呼出丙酮浓度。这一结论显示出对使用呼出气生物标志物进行医学诊断具有广泛的影响，特别是肺生理学和渗透性。
Rapid in-situ chemical analysis of flowing gas streams is of interest in a wide range of applications but requires deconvolution of the time-scales associated with the analyte source concentration, its accumulation within a sampling chamber, and its detection by a sensor. A mathematical analysis is presented on the use of a flow-through sample chamber for rapid, in-situ breath analysis utilizing analyte diffusion through a Nafion membrane optode. We show that this approach yields apparently non-Fickian (anomalous or Case II) transport that varies from t(1/2) to t as t -> 0 with constant inlet concentration. Such behavior arises due to the transition from membrane-limited to sample chamber-limited transport dynamics depending on test conditions. The model is validated utilizing experimental data obtained from the color response associated with the Friedel-Craft acylation of acetone vapor with resorcinol reagent immobilized in Nafion membrane solid-state catalyst. Reduction of optode membrane thickness and increase in membrane humidification yield an optical response limited only by sample chamber material accumulation. At this limit, the exhaled breath signal for acetone obtained from a healthy individual is found to vary as t(2) (apparently Super Case II transport). Utilizing a simplified material balance on the human lung, this observation is ascribed to a constant acetone exhalation rate as opposed to a constant exhaled acetone concentration. This conclusion is shown to have broad implications on the use of exhaled breath biomarkers for medical diagnosis, in particular, lung physiology and permeability.