Significance and Use
5.1 TDI is used mostly in the preparation of rigid and semi-rigid foams and adhesives.
5.2 Diisocyanates and polyisocyanates are irritants to skin, eyes, and mucous membranes. They are recognized to cause respiratory allergic sensitization, asthmatic bronchitis, and acute respiratory intoxication (6-9).
5.3 The American Conference of Governmental Industrial Hygienists (ACGIH) has adopted a Threshold Limit Value–Time Weighted Average (TLV-TWA) of 0.001 ppm of 0.007 mg/m3 with 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). The Occupational Safety and Health Administration of the U.S. Department of Labor (OSHA) has a permissible exposure limit of 0.02 ppm(V) or 0.14 mg/m3 of 2,4-TDI as a ceiling limit and 0.005 ppm (V) or 0.036 mg/m3 as a time-weighted average (11).
5.4 Monitoring of respiratory and other problems related to diisocyanates and polyisocyanates is aided through the utilization of this test method, due to its sensitivity and low volume requirements (15 L). Its short sampling times are compatible with the duration of many industrial processes and its low quantification limit also suits the concentrations often found in the working area.
5.5 The segregating sampling device pertaining to this proposed test method physically separates gas and aerosol allowing isocyanate concentrations in both physical states to be obtained, thus helping in the selection of ventilation systems and personal protection.
5.6 This test method is used to measure gaseous concentrations of 2,4- and 2,6-TDI in air for workplace and ambient atmospheres.
Scope
1.1 This test method covers the determination of gaseous 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI) in air samples collected from workplace and ambient atmospheres.
1.2 Differential air sampling is performed with a segregating device.2 The gaseous fraction is collected on a glass fiber filter (GFF) impregnated with 9-(N-methylaminomethyl) anthracene (MAMA).
1.3 The analysis of the gaseous fraction is performed with a high performance liquid chromatograph (HPLC) equipped with ultraviolet (UV) and fluorescence detectors. An ultra high performance liquid chromatograph (UPLC) can also be used, provided that its performance is equivalent to what is stated in this standard.
1.4 The analysis of the aerosol fraction is performed separately as described in Ref (1).3
1.5 The range of application of this test method, utilizing UV and a fluorescence detector, is validated for 0.014 to 1.16 μg of monomer 2,4- and 2,6-TDI/2.0 mL of desorption solution, which corresponds to concentrations of 0.001 to 0.077 mg/m3 of TDI based on a 15-L air sample. This corresponds to 0.0.14 to 11 ppb(V) and brackets the established TLV value of 1 ppb(v).
1.6 A field blank sampling system is used to check the possibility of contamination during the entire sampling and analysis.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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 additional hazards.
1.9 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.
