1.1 本试验方法描述了从工作场所大气中采集的空气样品中2,4-甲苯二异氰酸酯（2,4-TDI）和2,6-甲苯二异氰酸酯（2,6-TDI）的测定，样品盒中含有浸渍有1-（2-吡啶基）哌嗪（1-2 PP）的玻璃纤维过滤器。该程序对测定大气中的蒸汽含量有效。建议对含有气溶胶的大气进行现场提取，以避免低估的可能性。 1.2 本试验方法使用配备荧光或紫外线检测器的高效液相色谱仪（HPLC） ( 1- 4. ) . 2. , 3. 也可以使用超高效液相色谱仪（UPLC），前提是其性能等同于本标准中的规定。 1.3 如文所述，测试方法的验证范围为1。 4至5.6μg 2,4-TDI和2,6-TDI，相当于基于20升空气样品的2,4-TDI和2,6-TDI的约9.8至39 ppb。使用紫外线检测器的高效液相色谱法能够在4.0毫升溶剂体积中检测0.078μg 2,4-TDI和0.068μg 2,6-TDI，相当于基于20升空气样品的2,4-TDI的0.55 ppb和2,6-TDI的0.48 ppb。 1.4 2,4-TDI和2,6-TDI的异构体可以使用反相柱进行HPLC法分离。由于工业应用使用2,4-和2,6-TDI的异构混合物，因此实现这种分离的能力很重要。 1.5 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 参见第节 9 具体预防措施。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 二异氰酸酯用于生产聚氨酯泡沫、塑料、弹性体、表面涂层和粘合剂 ( 5. , 6. ) . 据估计，TDI的产量将在未来几年稳步增长。 5.2 二异氰酸酯对眼睛、皮肤和粘膜有刺激性，是呼吸道致敏剂。长期接触低浓度的二异氰酸酯会产生过敏性致敏反应，可能发展为哮喘性支气管炎 ( 7. , 8. ) . 5.3 美国职业安全与健康管理局（OSHA）对2,4-TDI的允许暴露极限（PEL）为0.02 ppm或0.14 mg/m 3. 作为上限。2,6-TDI没有OSHA PEL ( 9 ) . 美国政府工业卫生学家会议（ACGIH）的时间加权平均阈值（TWA）为0.001 ppm或0.007 mg/m 3. 短期暴露极限（STEL）为0.005 ppm或0.036 mg/m 3. 对于2,4-TDI或2,6-TDI，或2,4-和2,6-TDI的混合物 ( 10 ) .

1.1 This test method describes the determination of 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI) in air samples collected from workplace atmospheres in a cassette containing a glass-fiber filter impregnated with 1-(2-pyridyl)piperazine (1-2 PP). This procedure is effective for determining the vapor content of atmospheres. It is advisable to perform a field extraction for atmospheres containing aerosols to avoid the possibility of an underestimation. 1.2 This test method uses a high-performance liquid chromatograph (HPLC) equipped with a fluorescence or an ultraviolet (UV) detector ( 1- 4 ) . 2 , 3 An ultra high performance liquid chromatograph (UPLC) can also be used, provided that its performance is equivalent to what is stated in this standard. 1.3 The validated range of the test method, as written, is from 1.4 to 5.6 μg of 2,4-TDI and 2,6-TDI which is equivalent to approximately 9.8 to 39 ppb for 2,4-TDI and 2,6-TDI based on a 20-L air sample. The HPLC method using an UV detector is capable of detecting 0.078 μg of 2,4-TDI and 0.068 μg of 2,6-TDI in a 4.0-mL solvent volume, which is equivalent to 0.55 ppb for 2,4-TDI and 0.48 ppb for 2,6-TDI based on a 20-L air sample. 1.4 The isomers of 2,4-TDI and 2,6-TDI can be separated utilizing a reversed phase column for the HPLC method. Because industrial applications employ an isomeric mixture of 2,4- and 2,6-TDI, the ability to achieve this separation is important. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See Section 9 for specific precautions. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Diisocyanates are used in the production of polyurethane foams, plastics, elastomers, surface coatings, and adhesives ( 5 , 6 ) . It has been estimated that the production of TDI will steadily increase during the future years. 5.2 Diisocyanates are irritants to eyes, skin, and mucous membrane and are respiratory sensitizers. Chronic exposure to low concentrations of diisocyanates produces an allergic sensitization which may progress into asthmatic bronchitis ( 7 , 8 ) . 5.3 The United States Occupational Safety and Health Administration (OSHA) has a permissible exposure limit (PEL) for 2,4-TDI of 0.02 ppm or 0.14 mg/m 3 as a ceiling limit. There is no OSHA PEL for 2,6-TDI ( 9 ) . The American Conference of Governmental Industrial Hygienists (ACGIH) has a time–weighted average (TWA) Threshold Limit Value (TLV) of 0.001 ppm or 0.007 mg/m 3 and a short-term exposure limit (STEL) of 0.005 ppm or 0.036 mg/m 3 for either 2,4-TDI, or 2,6-TDI, or for a mixture of 2,4- and 2,6-TDI ( 10 ) .