Streicher R P, Arnold J E, Cooper C V, Fischbach T J
Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, OH 45226, USA.
Am Ind Hyg Assoc J. 1995 May;56(5):437-42. doi: 10.1080/15428119591016854.
Method 25 for the Determination of Hazardous Substances (MDHS 25) of the Health and Safety Executive of the United Kingdom attempts to identify and quantify all isocyanate species in an air sample. Isocyanate species are derivatized with 1-(2-methoxyphenyl)piperazine (MOPP) and analyzed by high-performance liquid chromatography (HPLC) with tandem ultraviolet/electrochemical (UV/EC) detection. The method identifies peaks as being isocyanate-derived if the EC/UV detector response ratio is between 0.75 and 1.5 times that of the derivatized monomer. This investigation sought to determine if the method correctly identifies and accurately quantifies intermediates created during polyurethane formation that possess free isocyanate groups. Model compounds derived from 2,4-toluene diisocyanate (2,4-TDI) and ethylene glycol were prepared. These urethane species contained two ("dimer") and three ("trimer") TDI units and terminal MOPP-derivatized isocyanate groups. Like monomeric 2,4-TDI/MOPP urea, each contained two derivatized isocyanate groups per molecule. This investigation found that neither the UV nor the EC response is proportional to the number of isocyanate groups present in the model compounds. Therefore, it is concluded that MDHS 25 is neither capable of correctly identifying TDI-urethane intermediates possessing MOPP-derivatized isocyanate groups nor is it capable of accurately quantifying these isocyanate groups. The proposed solution to this problem is the utilization of a derivatizing reagent that yields derivatized isocyanate species whose detector responses come more exclusively from the derivatized isocyanate moiety and, therefore, are more proportional to the number of derivatized isocyanate groups.
英国健康与安全执行局的《有害物质测定方法25》（MDHS 25）试图识别并量化空气样本中的所有异氰酸酯种类。异氰酸酯种类用1-(2-甲氧基苯基)哌嗪（MOPP）进行衍生化，并通过配备串联紫外/电化学（UV/EC）检测的高效液相色谱（HPLC）进行分析。如果EC/UV检测器的响应比在衍生化单体响应比的0.75至1.5倍之间，则该方法将峰识别为异氰酸酯衍生峰。本研究旨在确定该方法能否正确识别并准确量化聚氨酯形成过程中产生的具有游离异氰酸酯基团的中间体。制备了由2,4-甲苯二异氰酸酯（2,4-TDI）和乙二醇衍生而来的模型化合物。这些聚氨酯种类包含两个（“二聚体”）和三个（“三聚体”）TDI单元以及末端MOPP衍生化的异氰酸酯基团。与单体2,4-TDI/MOPP脲一样，每个分子均含有两个衍生化的异氰酸酯基团。本研究发现，UV响应和EC响应均与模型化合物中存在的异氰酸酯基团数量不成正比。因此，得出结论：MDHS 25既无法正确识别具有MOPP衍生化异氰酸酯基团的TDI-聚氨酯中间体，也无法准确量化这些异氰酸酯基团。针对该问题提出的解决方案是使用一种衍生化试剂，该试剂产生的衍生化异氰酸酯种类的检测器响应更专门地来自衍生化的异氰酸酯部分，因此与衍生化异氰酸酯基团的数量更成正比。
