Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Environ Sci Technol. 2010 Jul 1;44(13):5074-8. doi: 10.1021/es100727v.
Laboratory chambers used to study atmospheric chemistry and aerosol formation are subject to wall loss of vapors and particles that must be accounted for in calculating aerosol yields. While particle wall loss in chambers is relatively well-understood and routinely accounted for, that of vapor is less so. Here we address experimental measurement and modeling of vapor losses in environmental chambers. We identify two compounds that exhibit wall loss: 2,3-epoxy-1,4-butanediol (BEPOX), an analog of an important isoprene oxidation product; and glyoxal, a common volatile organic compound oxidation product. Dilution experiments show that BEPOX wall loss is irreversible on short time scales but is reversible on long time scales, and glyoxal wall loss is reversible for all time scales. BEPOX exhibits minimal uptake onto clean chamber walls under dry conditions, with increasing rates of uptake over the life of an in-use chamber. By performing periodic BEPOX wall loss experiments, it is possible to assess quantitatively the aging of chamber walls.
实验室腔室用于研究大气化学和气溶胶形成，会受到蒸气和粒子的壁损失的影响，在计算气溶胶产率时必须考虑到这一点。虽然腔室内的粒子壁损失已经得到了相对较好的理解和常规的解释，但蒸气的损失则不然。在这里，我们研究了环境腔室中蒸气损失的实验测量和建模。我们确定了两种表现出壁损失的化合物：2,3-环氧-1,4-丁二醇（BEPOX），它是一种重要的异戊二烯氧化产物的类似物；以及乙二醛，一种常见的挥发性有机化合物氧化产物。稀释实验表明，BEPOX 的壁损失在短时间尺度上是不可逆的，但在长时间尺度上是可逆的，而乙二醛的壁损失在所有时间尺度上都是可逆的。BEPOX 在干燥条件下对清洁腔室壁的吸收最小，随着使用腔室寿命的延长，吸收速率逐渐增加。通过定期进行 BEPOX 壁损失实验，可以定量评估腔室壁的老化程度。
