1、Designation: D 5836 03Standard Test Method forDetermination of 2,4-Toluene Diisocyanate (2,4-TDI) and 2,6-Toluene Diisocyanate (2,6-TDI) in Workplace Atmospheres(1-2 PP Method)1This standard is issued under the fixed designation D 5836; the number immediately following the designation indicates the
2、year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the determination of 2,4
3、-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate(2,6-TDI) in air samples collected from workplace atmo-spheres in a cassette containing a glass-fiber filter impregnatedwith 1-(2-pyridyl)piperazine (1-2 PP). This procedure is veryeffective for determining the vapor content of atmospheres.
4、Atmospheres containing aerosols may produce low results.1.2 This test method uses a high-performance liquid chro-matograph (HPLC) equipped with a fluorescence or an ultra-violet (UV) detector (1-4).2,31.3 The validated range of the test method, as written, isfrom 1.4 to 5.6 g of 2,4-TDI and 2,6-TDI
5、which is equivalentto approximately 9.8 to 39 ppb for 2,4-TDI and 2,6-TDI basedon a 20-L air sample. The HPLC method using an UV detectoris capable of detecting 0.078 g of 2,4-TDI and 0.068 g of2,6-TDI in a 4.0-mL solvent volume, which is equivalent to0.55 ppb for 2,4-TDI and 0.48 ppb for 2,6-TDI ba
6、sed on a 20-Lair sample.1.4 The isomers of 2,4-TDI, and 2,6-TDI, can be separatedutilizing a reversed phase column for the HPLC method.Because industrial applications employ an isomeric mixture of2,4- and 2,6-TDI, the ability to achieve this separation isimportant.1.5 This standard does not purport
7、to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. See Section 9 forspecific precautions.2. Referenc
8、ed Documents2.1 ASTM Standards:4D 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning the Sampling of the AmbientAtmosphereD 3686 Practice for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal T
9、ube Ad-sorption Method)E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D 1356.4. Summary of Test Method4.1 A known volume of air is drawn through a cassettecontai
10、ning a glass-fiber filter impregnated with 1-(2-pyridyl)piperazine. The diisocyanate reacts with the secondaryamine to form a urea derivative.4.2 The coated glass-fiber filter is extracted with acetonitrile(ACN) containing 10 % dimethyl sulfoxide (DMSO) and theextract is analyzed by HPLC. The eluent
11、 is monitored with afluorescence detector (240-nm excitation, 370-nm emissioncutoff filter) or a UV detector (254 nm).1This test method is under the jurisdiction of ASTM Committee D22 onSampling and Analysis of Atmospheres and is the direct responsibility of Subcom-mittee D22.04 on Workplace Atmosph
12、eres.Current edition approved October 1, 2003. Published December 2003. Originallyapproved in 1995. Last previous edition approved in 1995 as D 5836 - 95.2Validation data and a preliminary draft of this test method were provided by theSalt Lake Technical Center of the U.S. Dept. of Labor, Occupation
13、al Safety andHealth Administration, Salt Lake City, UT.3The boldface numbers in parentheses refer to the references at the end of thistest method.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
14、 volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 The amount of the urea derivative collected is deter-mined by comparison of sample response (pea
15、k area integra-tions or peak heights) to a standard calibration curve for theurea derivative.4.4 The amount of diisocyanate is calculated from theamount of urea determined in the analysis.5. Significance and Use5.1 Diisocyanates are used in the production of polyure-thane foams, plastics, elastomers
16、, surface coatings, and adhe-sives (5,6). It has been estimated that the production of TDIwill steadily increase during the future years.5.2 Diisocyanates are irritants to eyes, skin, and mucousmembrane and are respiratory sensitizers. Chronic exposure tolow concentrations of diisocyanates produces
17、an allergic sen-sitization which may progress into asthmatic bronchitis (7,8).5.3 The Occupational Safety and Health Administration(OSHA) has a permissible exposure limit for 2,4-TDI of 0.02ppm or 0.14 mg/m3as a ceiling limit (9). The AmericanConference of Governmental Industrial Hygienists (ACGIH)h
18、as a Threshold Limit Value (TLV) of 0.005 ppm or 0.036mg/m3and a short-term exposure limit (STEL) of 0.02 ppm or0.14 mg/m3(10). No exposure limits have been established for2,6-TDI.5.4 This proposed test method has been found satisfactoryfor measuring 2,4 and 2,6-TDI levels in the workplace.6. Interf
19、erences6.1 Any compound having the same retention time as thestandards is a possible interference. Generally, chromato-graphic conditions can be altered to resolve an interference.6.2 Compounds that can react with an isocyanate representa potential interference. These would include molecules con-tai
20、ning the functional groups: amines, alcohols, anhydrides,phenols, and carboxylic acids.6.3 Strong oxidizing agents can potentially react with the1-(2-pyridyl)piperazine.6.4 Retention time data on a single column is not definitiveproof of chemical identity. Analysis by an alternate columnsystem, rati
21、oing of wavelength response using two wave-lengths or types of detector, should be performed to confirmchemical identity.7. Apparatus7.1 Sampling Equipment:7.1.1 Personal Sampling Pumps, any pump capable ofsampling at a rate of about 1.0 L/min for 8 h.7.1.2 Glass-Fiber Filters, 37 mm, free of organi
22、c binder,impregnated with 1.0 mg of 1-(2-pyridyl)piperazine.5,67.1.3 Cassette, plastic holders of the three-piece personalmonitor type, that accept filters of 37-mm diameter. Numberthe cassette for identification.7.1.4 Cellulose Backup Pad, sized to fit the cassette (7.1.3).7.2 Analytical Equipment:
23、7.2.1 Liquid Chromatograph, a high-performance liquidchromatograph (HPLC) equipped with a fluorescence detectorcapable of monitoring 240-nm excitation and 370-nm cutoff ora UV detector capable of monitoring 254-nm wavelength anda manual or automatic sample injector.7.2.2 Liquid Chromatographic Colum
24、n, an HPLC stainlesssteel column capable of separating the urea derivatives. Ana-lytical columns recommended in this test method are thefollowing: a 25-cm by 4.6-mm inside diameter stainless steelcolumn packed with 10-m Alltech C87; 6-m Zorbax CN8;5-m Zorbax TMS; 5-m Chromegabond TMS9; 5-m Spher-iso
25、rb C610; 5-m Supelcosil LC-CN11; or an equivalent col-umn.7.2.3 Electronic Integrator, an electronic integrator or someother suitable method of determining peak areas or heights.7.2.4 Pipets and Volumetrics, various sizes of volumetricpipets and flasks to prepare standards.7.2.5 Vials, glass vials w
26、ith a 4-mL volume and fitted withpolytetrafluoroethylene-lined caps used for extraction ofsamples.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. It is intended that all reagents shall conform tothe specifications of the Committees on Analytical Reag
27、ents ofthe American Chemical Society, where such specifications areavailable.12Other grades may be used provided it can bedemonstrated that they are of sufficiently high purity to permittheir use without decreasing the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, refe
28、rencewater shall be understood to mean Type II reagent waterconforming to Specification D 1193, HPLC grade.8.3 Acetonitrile (CH3CN)HPLC grade.8.4 Ammonium Acetate (CH3COONH4)HPLC grade.8.5 Dimethyl Sulfoxide (CH3)2SO)HPLC grade.8.6 Extracting SolutionA solvent mixture of acetonitrileand dimethyl sul
29、foxide in the percentage of 90 and 10 (v/v),respectively.8.7 Glacial Acetic Acid (CH3COOH)Reagent grade.8.8 Hexane (C6H14)HPLC grade.8.9 Methylene Chloride (CH2Cl2)HPLC grade.8.10 Mobile PhaseA solvent mixture of acetonitrile (8.3)and water in the percentage of 37.5 and 62.5 (v/v), respectively.5ORB
30、O-80 filters supplied by Supelco, Inc., Bellefonte, PA have been foundsatisfactory for this purpose.6Isocyanate glass fiber filters supplied by Forest Biomedical, Salt Lake City, UT,have been found satisfactory for this purpose.710-m ALLTECH C8 supplied by Alltech Associates, Deerfield, IL, has been
31、found satisfactory for this purpose.86-m ZORBAX CN and 5-m ZORBAX TMS supplied by E.I. DuPont,Wilmington, DE, have been found satisfactory for this purpose.95-m Chromegabond TMS supplied by ES Industries, Marlton, NJ, has beenfound satisfactory for this purpose.105-m Spherisorb C6 supplied by PhaseS
32、ep, Hauppauge, NY, has been foundsatisfactory for this purpose.115-m Supelcosil LC-CN supplied by Supelco, Inc., Belleforte, PA has beenfound satisfactory for this purpose.12Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the
33、testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5836032Add to the mobile phase enough ammon
34、ium acetate (8.4) (1.54to 7.7 g/L of solution or 0.02 to 0.1 N) to optimize thechromatographic resolution. Add acetic acid (8.7) to themixture to lower the pH to 6.0 to 6.2.8.11 1-(2-Pyridyl)piperazine (1-2 PP) (C9H13N3)Reagentgrade.138.12 N,N8-(4-Methyl-1,3-phenylene)bis 4-(2-pyridinyl)-1-piperazin
35、ecarboxamide (C27H32N8O2)(2,4-TDIP).148.13 N,N8-(2-Methyl-1,3-phenylene)bis 4-(2-pyridinyl)-1-piperazinecarboxamide (C27H32N8O2)(2,6-TDIP).158.14 2,4-Toluene Diisocyanate (C9H6N2O2)Reagentgrade.168.15 2,6-Toluene Diisocyanate (C9H6N2O2)Reagentgrade.179. Safety Precautions9.1 The diisocyanates are po
36、tentially hazardous chemicalsand are extremely reactive. Avoid exposure to the diisocyanatestandards. Sample and standard preparations should be done inan efficient operating hood.9.2 Avoid skin contact with all solvents.9.3 Wear safety glasses at all times and other laboratoryprotective equipment a
37、s necessary.10. Sampling10.1 Refer to Practices D 1357 and D 3686 for generalinformation on sampling.10.2 Equip the worker, whose exposure is to be evaluated,with a filter holder connected to a belt-supported samplingpump. Collect personal samples by pointing the samplerdownward in the breathing zon
38、e of the worker and remove thetop for open-face sampling. Draw air through the filter at acalibrated rate of approximately 1.0 L/min and collect amaximum air sample of 15 L. Use a tripod or other support tolocate the sampler in the general room area for stationarymonitoring.10.3 Treat field blanks i
39、n the same manner as samples. Openthem in the environment to be sampled and immediately closeand place with the samples to be sent to the laboratory foranalysis. Provide an unopened, unused cassette assembly as alaboratory blank. Submit at least one laboratory blank and onefield blank with each set
40、of samples.11. Preparation of Apparatus11.1 Glass-Fiber FilterPrepare a fresh solution of 2mg/mL of 1-(2-pyridyl)piperazine (8.11) in methylene chlorideevery time a batch of filters is to be coated. In an exhaust hood,set several glass-fiber filters on an appropriate holder, one thatwill support and
41、 not contaminate the filters. Using a pipet thatwill deliver 0.5 mL, place 0.5 mL in the center of each filter.The liquid will just wet the filter; allow the filters to air-dry inthe hood for several minutes. Place the filters in a jar that islarge enough for the filters to lie flat. Place the jar i
42、n anunheated vacuum oven for 1 h (about 20-in. Hg vacuum) toremove residual methylene chloride. Install the top on the jarand store in a refrigerator until ready for use. Coated filtersmay be stored for up to six months if they are stored in smallsealed jars in a refrigerator (4C).11.2 CassetteAssem
43、ble the three-piece cassette, insertingthe cellulose backup pad into the bottom, adding an impreg-nated filter, and installing the ring and top. Seal the assemblyagainst air leakage by a wrap of masking tape or celluloseshrink bands, covering the crevice between the ring andbottom. Close the inlet a
44、nd outlet openings of the cassette withplastic plugs.12. Calibration and Standardization12.1 Sample Pump CalibrationCalibrate the personalsampling pumps in accordance with Practice D 3686, at therecommended flow rate with an assembled cassette betweenthe pump and the flow-measuring device. Calibrate
45、 the pumpbefore and after the sampling. If the postcalibration flow ratevaries more than 610 % from the precalibration flow rate,invalidate the sample.12.2 Standardization:12.2.1 Prepare a stock standard solution as micrograms ofTDIP per millilitre of dimethyl sulfoxide. Express the TDIP asthe free
46、TDI. Multiply the amount of TDIP by the correctionfactor derived from the ratios of the respective molecularweights of the TDI and TDIP. The factor is 0.3479 for TDI.12.2.2 Prepare working standards by diluting the stockstandard with acetonitrile.12.2.3 Prepare dilution standards at the necessary co
47、ncen-trations by diluting working standards with acetonitrile togenerate a full calibration curve that brackets the sampleconcentrations.12.2.4 Analyze by high-performance liquid chromatogra-phy using a suitable column and the mobile phase as describedin 8.10. The typical operating conditions are as
48、 follows:Column temperature 25CFlow rate 1.0 mL/minUltraviolet 254 nmFluorescence 240 nm, excitation370 nm or none, emissioncutoff filterInjection size 525 LAnalytical conditions serve as a guideline and may need tobe modified depending upon the specific samples, columncondition, detector, and other
49、 parameters.12.2.5 Analyze each diisocyanate standard solution in du-plicate and utilize peak area integration if possible. Peak areasshould agree within 65 % per standard solution.12.2.6 Prepare a calibration curve by plotting microgramsper millilitre of diisocyanate versus peak area or peak heightvalues.12.2.7 Periodically prepare quality control samples by spik-ing the underivatized TDI onto impregnated glass-fiber filtersto verify the correctness of the calibration curve.131-(2-Pyridyl)piperazine supplied by Aldrich Chemical, Milwaukee, WI,
