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Experimentally validated mathematical model of analyte uptake by permeation passive samplers
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2017-09-14 00:00:00 , DOI: 10.1039/c7em00315c F. Salim 1, 2, 3, 4 , M. Ioannidis 1, 3, 4, 5 , T. Górecki 1, 2, 3, 4
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2017-09-14 00:00:00 , DOI: 10.1039/c7em00315c F. Salim 1, 2, 3, 4 , M. Ioannidis 1, 3, 4, 5 , T. Górecki 1, 2, 3, 4
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A mathematical model describing the sampling process in a permeation-based passive sampler was developed and evaluated numerically. The model was applied to the Waterloo Membrane Sampler (WMS), which employs a polydimethylsiloxane (PDMS) membrane as a permeation barrier, and an adsorbent as a receiving phase. Samplers of this kind are used for sampling volatile organic compounds (VOC) from air and soil gas. The model predicts the spatio-temporal variation of sorbed and free analyte concentrations within the sampler components (membrane, sorbent bed and dead volume), from which the uptake rate throughout the sampling process can be determined. A gradual decline in the uptake rate during the sampling process is predicted, which is more pronounced when sampling higher concentrations. Decline of the uptake rate can be attributed to diminishing analyte concentration gradient within the membrane, which results from resistance to mass transfer and the development of analyte concentration gradients within the sorbent bed. The effects of changing the sampler component dimensions on the rate of this decline in the uptake rate can be predicted from the model. Performance of the model was evaluated experimentally for sampling of toluene vapors under controlled conditions. The model predictions proved close to the experimental values. The model provides a valuable tool to predict changes in the uptake rate during sampling, to assign suitable exposure times at different analyte concentration levels, and to optimize the dimensions of the sampler in a manner that minimizes these changes during the sampling period.
中文翻译：
经过实验验证的渗透无源采样器吸收分析物的数学模型
建立了描述基于渗透的无源采样器中采样过程的数学模型，并对其进行了数值评估。该模型已应用于滑铁卢膜采样器（WMS），该采样器使用聚二甲基硅氧烷（PDMS）膜作为渗透屏障，并使用吸附剂作为接收相。这种采样器用于从空气和土壤气体中采样挥发性有机化合物（VOC）。该模型预测采样器组件（膜，吸附剂床和死体积）内吸附和自由分析物浓度的时空变化，从中可以确定整个采样过程中的吸收率。预计在采样过程中摄取率会逐渐下降，这在采样更高浓度时会更加明显。吸收速率的下降可归因于膜内分析物浓度梯度的降低，这是由于对传质的阻力以及吸附剂床内分析物浓度梯度的发展所致。可以从模型中预测改变采样器组件尺寸对吸收率下降速率的影响。通过实验评估了模型的性能，以在受控条件下对甲苯蒸气进行采样。模型预测证明接近于实验值。该模型提供了一种有价值的工具，可预测采样期间的摄取率变化，在不同分析物浓度水平下分配合适的暴露时间，并以最小化采样期间这些变化的方式优化采样器的尺寸。
更新日期：2017-11-15
中文翻译：
经过实验验证的渗透无源采样器吸收分析物的数学模型
建立了描述基于渗透的无源采样器中采样过程的数学模型，并对其进行了数值评估。该模型已应用于滑铁卢膜采样器（WMS），该采样器使用聚二甲基硅氧烷（PDMS）膜作为渗透屏障，并使用吸附剂作为接收相。这种采样器用于从空气和土壤气体中采样挥发性有机化合物（VOC）。该模型预测采样器组件（膜，吸附剂床和死体积）内吸附和自由分析物浓度的时空变化，从中可以确定整个采样过程中的吸收率。预计在采样过程中摄取率会逐渐下降，这在采样更高浓度时会更加明显。吸收速率的下降可归因于膜内分析物浓度梯度的降低，这是由于对传质的阻力以及吸附剂床内分析物浓度梯度的发展所致。可以从模型中预测改变采样器组件尺寸对吸收率下降速率的影响。通过实验评估了模型的性能，以在受控条件下对甲苯蒸气进行采样。模型预测证明接近于实验值。该模型提供了一种有价值的工具，可预测采样期间的摄取率变化，在不同分析物浓度水平下分配合适的暴露时间，并以最小化采样期间这些变化的方式优化采样器的尺寸。
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