1、Designation: D 5836 08Standard 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 cause TDI results to beunderestimated.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-TD
5、I and 2,6-TDI 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
6、for 2,6-TDI based 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 The values stated
7、 in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport 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 h
8、ealth practices and determine the applica-bility of regulatory limitations prior to use. See Section 9 forspecific precautions.2. Referenced Documents2.1 ASTM Standards:4D 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planni
9、ng the Sampling of the AmbientAtmosphereD 3686 Practice for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal Tube Ad-sorption Method)E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 For definitions of terms
10、 used in this test method, refer toTerminology D 1356.4. Summary of Test Method4.1 A known volume of air is drawn through a cassettecontaining 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
11、-fiber filter is extracted with acetonitrile(ACN) containing 10 % dimethyl sulfoxide (DMSO) and theextract is analyzed by HPLC. The eluent is monitored with afluorescence detector (240-nm excitation, 370-nm emissioncutoff filter) or a UV detector (254 nm).4.3 The amount of the urea derivative collec
12、ted is deter-mined by comparison of sample response (peak area integra-tions or peak heights) to a standard calibration curve for theurea derivative.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace Ai
13、rQuality.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 1995. Last previous edition approved in 2003 as D 5836 - 03.2Validation data and a preliminary draft of this test method were provided by theSalt Lake Technical Center of the U.S. Dept. of Labor, Occupational
14、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 vo
15、lume 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.4.4 The amount of diisocyanate is calculated from theamount of urea determined in the analysis.5. Signi
16、ficance and Use5.1 Diisocyanates are used in the production of polyure-thane foams, plastics, elastomers, 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 mucousme
17、mbrane and are respiratory sensitizers. Chronic exposure tolow concentrations of diisocyanates produces 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 (PEL) for 2,4-TDI of0.02
18、ppm or 0.14 mg/m3as a ceiling limit. There is no OSHAPEL for 2,6TDI (9). The American Conference of Govern-mental Industrial Hygienists (ACGIH) has a timeweightedaverage (TWA) Threshold Limit Value (TLV) of 0.005 ppm or0.036 mg/m3and a short-term exposure limit (STEL) of 0.02ppm or 0.14 mg/m3for eit
19、her 2,4TDI, or 2,6TDI, or for amixture of 2,4 and 2,6TDI(10).5.4 This proposed test method has been found satisfactoryfor measuring 2,4 and 2,6-TDI levels in the workplace.6. Interferences6.1 Any compound having the same retention time as thestandards is a possible interference. Generally, chromato-
20、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-taining the functional groups: amines, alcohols, anhydrides,phenols, and carboxylic acids.6.3 Strong oxidizing agents can
21、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, ratioing of wavelength response using two wave-lengths or types of detector, should be performed to confirmchemical identit
22、y.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 organic binder,impregnated with 1.0 mg of 1-(2-pyridyl)piperazine.5,67.1.3 Cassette, plastic holders of the three-piece perso
23、nalmonitor 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:7.2.1 Liquid Chromatograph, a high-performance liquidchromatograph (HPLC) equipped with a fluorescence detectorcapable
24、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 Column, an HPLC stainlesssteel column capable of separating the urea derivatives. Ana-lytical columns recommended in this te
25、st 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-isorb C610; 5-m Supelcosil LC-CN11; or an equivalent col-umn.7.2.3 Electronic Integrator, an electronic integrator or some
26、other 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 with a 4-mL volume and fitted withpolytetrafluoroethylene-lined caps used for extraction ofsamples.8. Reagents and Mater
27、ials8.1 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 Reagents ofthe American Chemical Society, where such specifications areavailable.12Other grades may be used provided it can
28、 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, referencewater shall be understood to mean Type II reagent waterconforming to Specification D 1193, HPLC grade.8.3 Acetonit
29、rile (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 sulfoxide in the percentage of 90 and 10 (v/v),respectively.8.7 Glacial Acetic Acid (CH3COOH)Reagent grade.8.8 Hexane (C6H
30、14)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.Add to the mobile phase enough ammonium acetate (8.4) (1.54to 7.7 g/L of solution or 0.02 to 0.1 N) to optimize the5ORBO-80
31、 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 beenfoun
32、d 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 PhaseSep,
33、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 tes
34、ting 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.D5836082chromatographic resolution. Add acetic
35、acid (8.7)tothemixture 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-piperazinecarboxamide (C27H32N8O2)(2,4-TDIP).148.13 N,N8-(2-Methyl-1,3-phenylene)bis 4-(2-pyridinyl)-1-piperazinecarboxamide (C27
36、H32N8O2)(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 potentially hazardous chemicalsand are extremely reactive. Avoid exposure to the diisocyanatestandards. Sample and standar
37、d 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 as necessary.10. Sampling10.1 Refer to Practices D 1357 and D 3686 for generalinformation on sampling.10.2 Equip the work
38、er, 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 zone of the worker and remove thetop for open-face sampling. Draw air through the filter at acalibrated rate of approximate
39、ly 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 in the same manner as samples. Openthem in the environment to be sampled and immediately closeand place with the samples
40、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 of samples.11. Preparation of Apparatus11.1 Glass-Fiber FilterPrepare a fresh solution of 2mg/mL of 1-(2-pyridyl)piperaz
41、ine (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 not contaminate the filters. Using a pipet thatwill deliver 0.5 mL, place 0.5 mL in the center of each filter.The liqui
42、d 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 in anunheated vacuum oven for 1 h (about 20-in. Hg vacuum) toremove residual methylene chloride. Install the top on the j
43、arand 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). The filters should not bestored at ambient temperature for more a day or two.11.2 CassetteAssemble the three-piece cassette, insertingthe
44、 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 and outlet openings of the cassette withpla
45、stic plugs.12. Calibration and Standardization12.1 Sample Pump CalibrationCalibrate the personalsampling pumps in accordance with Practice D 3686,attherecommended flow rate with an assembled cassette betweenthe pump and the flow-measuring device. Calibrate the pumpbefore and after the sampling. If t
46、he postcalibration flow ratevaries more than 65 % 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 TDI. Multiply the amount of TDIP by the corre
47、ctionfactor 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 concen-trations by diluting working standards w
48、ith 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 follows:Column temperature 25CFlow rate 1.0
49、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 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 p
