【国外标准】 Standard Test Method for Determination of 2,4-Toluene Diisocyanate (2,4-TDI) and 2,6-Toluene Diisocyanate (2,6-TDI) in Workplace Atmospheres (1-2 PP Method)

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/m3 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/m3 and a short-term exposure limit (STEL) of 0.005 ppm or 0.036 mg/m3 for either 2,4-TDI, or 2,6-TDI, or for a mixture of 2,4- and 2,6-TDI (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.