Rando R J, Poovey H G
Section of Environmental Medicine, Tulane University Medical Center, New Orleans, LA 70112.
Am Ind Hyg Assoc J. 1994 Aug;55(8):716-21. doi: 10.1080/15428119491018600.
A dichotomous sampler was developed for speciation of airborne methylene-bis-(phenylisocyanate) (MDI) into vapor and aerosol fractions. The sampler consisted of an impactor inlet and two sections of annular diffusional denuder, in series with a glass fiber filter. The denuders and filter were coated with N-4-nitrobenzyl-N-1-propylamine for collection and derivatization of MDI followed by high performance liquid chromatography analysis. The sampler was evaluated in the laboratory with test atmospheres of MDI over a range of 24 to 355 micrograms/m3 at an average temperature of 26 degrees C. The total amounts of MDI collected by the dichotomous sampler were not significantly different from a reference sampler over the entire range of MDI concentrations. The first denuder collected MDI vapor with an average efficiency of 91.6 +/- 5.2%, in comparison to a theoretical efficiency of 94.1%. MDI existed solely in the vapor state up to approximately 75 micrograms/m3 and was collected on the denuders. Above this, MDI partitioned into vapor and aerosol, and the device efficiently separated the sample into the vapor fraction, found on the denuders, and the aerosol fraction, which penetrated to the filter. While this work was done with condensation aerosol, appropriate modification of the sampler inlet should allow use of the device for sampling atmospheres containing larger aerosols.
开发了一种二分采样器，用于将空气中的亚甲基双（苯基异氰酸酯）（MDI）分为蒸汽和气溶胶部分进行形态分析。该采样器由一个冲击式入口和两段环形扩散式除雾器组成，与玻璃纤维过滤器串联。除雾器和过滤器涂有N-4-硝基苄基-N-1-丙胺，用于收集和衍生MDI，随后进行高效液相色谱分析。该采样器在实验室中于平均温度26℃、MDI测试气氛浓度范围为24至355微克/立方米的条件下进行评估。在整个MDI浓度范围内，二分采样器收集的MDI总量与参考采样器没有显著差异。第一个除雾器收集MDI蒸汽的平均效率为91.6±5.2%，而理论效率为94.1%。在约75微克/立方米以下，MDI仅以蒸汽状态存在，并被收集在除雾器上。高于此浓度，MDI会分配到蒸汽和气溶胶中，该装置能有效地将样品分离为在除雾器上发现的蒸汽部分和穿透到过滤器上的气溶胶部分。虽然这项工作是针对冷凝气溶胶进行的，但对采样器入口进行适当修改后，该装置应可用于对含有较大气溶胶的大气进行采样。
