[题名] 特氟龙管和仪器中的气壁分配对气相有机化合物时间分辨测量的影响

[作者] Demetrios Pagonis, Jordan E. Krechmer1 , Joost de Gouw, Jose L. Jimenez , and Paul J. Ziemann

[摘要] 这段文章是关于有机化合物在特氟龙管道和质子转移反应质谱仪（PTR-MS）内部的气-壁分配的研究。研究结果显示，对于饱和浓度在3×104至1×107µg m−3范围内的C8-C14 2-酮和C11-C16 1-烯烃，其快速分配会导致仪器响应延迟，延迟时间与管道长度、直径、流速和饱和浓度成比例。这种气-壁分配过程在管道中类似于气相色谱柱中的情况，测得的延迟时间（类似于保留时间）可以用线性色谱模型准确描述，其中壁被视为等效吸收质量，这与在特氟龙环境室中测定的值一致。此外，还量化了PTR-MS表面引起的延迟时间，并将其纳入模型中。该模型预测，对于半挥发性化合物，在常用条件下测量时，延迟时间可能长达一小时或更长时间。这些结果和模型有助于更好地设计采样系统，特别是在需要快速响应的情况下，如快速瞬态、飞机或涡旋协方差测量。它们还可以用于估计通过质谱检测未鉴定的有机化合物的饱和浓度值，并可用于引入化合物时间序列的差异以用于因子分析方法。最后，还为通过特氟龙管道采样有机化合物提出了最佳实践建议。

[关键词] 管道、特氟龙、特氟龙管

[Title] Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

[Author] Demetrios Pagonis, Jordan E. Krechmer1 , Joost de Gouw, Jose L. Jimenez , and Paul J. Ziemann

[Abstract] Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas–wall partitioning of organic compounds in Teflon tubing and inside a protontransfer-reaction mass spectrometer (PTR-MS) used to monitor compound concentrations. Rapid partitioning of C8–C14 2-ketones and C11–C16 1-alkenes was observed for compounds with saturation concentrations (c*) in the range of 3 × 104 to 1 × 107 µg m−3 , causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c* . The gas–wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times) were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. These results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c* values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.

[Keywords] tube、Teflon、Teflon tubing