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Recent studies have demonstrated that organic compounds can partition fromthe gas phase to the walls in Teflon environmental chambers and that theprocess can be modeled as absorptive partitioning. Here these studies wereextended to investigate gas–wall partitioning of organic compounds in Teflontubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS) usedto monitor compound concentrations. Rapid partitioning of C8–C142-ketones and C11–C16 1-alkenes was observed for compounds withsaturation concentrations (c∗) in the range of 3 × 104 to 1 × 107 µg m−3, causing delays in instrument responseto step-function changes in the concentration of compounds being measured.These delays vary proportionally with tubing length and diameter andinversely with flow rate and c∗. The gas–wall partitioning process thatoccurs in tubing is similar to what occurs in a gas chromatography column,and the measured delay times (analogous to retention times) were accuratelydescribed using a linear chromatography model where the walls were treated asan equivalent absorbing mass that is consistent with values determined forTeflon environmental chambers. The effect of PTR-MS surfaces on delay timeswas also quantified and incorporated into the model. The model predictsdelays of an hour or more for semivolatile compounds measured under commonlyemployed conditions. These results and the model can enable betterquantitative design of sampling systems, in particular when fast response isneeded, such as for rapid transients, aircraft, or eddy covariancemeasurements. They may also allow estimation of c∗ values for unidentifiedorganic compounds detected by mass spectrometry and could be employed tointroduce differences in time series of compounds for use with factoranalysis methods. Best practices are suggested for sampling organic compoundsthrough Teflon tubing

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