Liu L J, Dills R L, Paulsen M, Kalman D A
Department of Environmental Health, University of Washington, Box 357234, Seattle, Washington 98195-7234, USA.
Environ Sci Technol. 2001 Jun 1;35(11):2301-8. doi: 10.1021/es001795c.
We evaluated the GMD passive sampler for its suitability to measure six aldehydes over a 7-d period in population exposure studies. The six target aldehydes were formaldehyde, acetaldehyde, acrolein, crotonaldehyde, glyoxal, and methylglyoxal. The GMD sampler contains a silica gel-impregnated cellulose pad coated with 2,4-dinitrophenylhydrazine (DNPH) hydrochloride. This agent reacts with formaldehyde to form a hydrazone that is quantified with a high-performance liquid chromatograph. The GMD sampler was tested for background contamination and aldehyde recoveries after 0, 1, and 7 d of storage. Results indicated that the GMD monitor, as currently manufactured, is suitable for shorter-term sampling (up to 24 h) of formaldehyde and acetaldehyde. It is however not acceptable for sampling of acetaldehyde, acrolein, crotonaldehyde, glyoxal, and methylglyoxal over a 7-d exposure period due to the chemical reactions on the silica gel-impregnated cellulose pad. Glyoxal- and methylglyoxal-DNPH derivatives formed on the cellulose and Teflon-coated glass fiber pads that had been prepared with glycerol under acidic and oxidative conditions. Acrolein- and crotonaldehyde-DNPH derivatives diminish through the reverse reaction of the DNPH derivatives to form free aldehydes under acidic conditions. We showed that the unknown reaction products of acrolein and crotonaldehyde derivatives were not pyrazolines but probably resulted from E/Zisomerization. These conversion reactions are favored in acidic conditions present in either the derivatization solution or the collection medium. The most consistent recovery was obtained on glass fiber pads. In particular, recoveries of crotonaldehyde- and acrolein-DNPH derivatives were increased through the use of a pH 4 buffered derivatization solution. These chemical instability problems were overcome by using a pH 4 buffer (citric acid/sodium citrate) and an alternative hygroscopic agent (1,3-butanediol) in the DNPH derivatization solution. Results with DNPH derivatives from these spiking experiments were further confirmed with gas-phase spiking experiments. We determined the optimal acidity, buffer solution, and concentrations of the buffer solution and 1,3-butanediol for the DNPH derivatization solution. This new formulation of the DNPH derivatization solution can be used for collection of the six target aldehydes over a 7-d sampling period.
我们评估了GMD被动采样器在人群暴露研究中测量六种醛类物质7天的适用性。六种目标醛类物质为甲醛、乙醛、丙烯醛、巴豆醛、乙二醛和甲基乙二醛。GMD采样器包含一个涂有盐酸2,4 - 二硝基苯肼（DNPH）的硅胶浸渍纤维素垫。该试剂与甲醛反应形成腙，然后用高效液相色谱仪进行定量分析。对GMD采样器进行了背景污染测试以及储存0、1和7天后醛类物质回收率的测试。结果表明，目前生产的GMD监测仪适用于甲醛和乙醛的短期采样（长达24小时）。然而，由于硅胶浸渍纤维素垫上的化学反应，在7天暴露期内对乙醛、丙烯醛、巴豆醛、乙二醛和甲基乙二醛进行采样是不可接受的。在酸性和氧化条件下用甘油制备的纤维素和聚四氟乙烯涂层玻璃纤维垫上形成了乙二醛和甲基乙二醛 - DNPH衍生物。在酸性条件下，丙烯醛和巴豆醛 - DNPH衍生物会通过DNPH衍生物的逆反应形成游离醛而减少。我们表明，丙烯醛和巴豆醛衍生物的未知反应产物不是吡唑啉，而是可能由E/Z异构化导致。这些转化反应在衍生化溶液或收集介质中存在的酸性条件下较为有利。在玻璃纤维垫上获得的回收率最为一致。特别是，通过使用pH 4缓冲衍生化溶液，巴豆醛和丙烯醛 - DNPH衍生物的回收率有所提高。通过在DNPH衍生化溶液中使用pH 4缓冲液（柠檬酸/柠檬酸钠）和替代吸湿剂（1,3 - 丁二醇）克服了这些化学稳定性问题。这些加标实验中DNPH衍生物的结果通过气相加标实验进一步得到证实。我们确定了DNPH衍生化溶液的最佳酸度、缓冲溶液以及缓冲溶液和1,3 - 丁二醇的浓度。这种新配方的DNPH衍生化溶液可用于在7天采样期内收集六种目标醛类物质。
