40 CFR Part 763 (EPA AHERA) Part 8.5 PDF

Pt. 763, Subpt. E, App. E 40 CFR Ch. I (7–1–07 Edition) of 500 °C or lower. Temperatures of 550 °C or higher will cause dehydroxylation of the asbestos minerals, resulting in changes of the refractive index and other key parameters. If a muffle furnace is to be used, the furnace thermostat should b...

Pt. 763, Subpt. E, App. E 40 CFR Ch. I (7–1–07 Edition) of 500 °C or lower. Temperatures of 550 °C or higher will cause dehydroxylation of the asbestos minerals, resulting in changes of the refractive index and other key parameters. If a muffle furnace is to be used, the furnace thermostat should be checked and calibrated to ensure that samples will not be heated at temperatures greater than 550 °C. Ashing and acid treatment of samples should not be used as standard procedures. In order to monitor possible changes in fiber characteristics, the material should be viewed microscopically before and after any sample preparation procedure. Use of these procedures on samples to be used for quantitation requires a correction for percent weight loss. vermiculite. Grinding of amphiboles may result in the separation of fiber bundles or the production of cleavage fragments with aspect ratios greater than 3:1. Grinding of vermiculite may also produce fragments with aspect ratios greater than 3:1. Acid treatment may occasionally be required to eliminate interferences. Calcium carbonate, gypsum, and bassanite (plaster) are frequently present in sprayed or trowelled insulations. These materials may be removed by treatment with warm dilute acetic acid. Warm dilute hydrochloric acid may also be used to remove the above materials. If acid treatment is required, wash the sample at least twice with distilled water, being careful not to lose the particulates during decanting steps. Centrifugation or filtration of the suspension will prevent significant fiber loss. The pore size of the filter should be 0.45 micron or less. Caution: prolonged acid contact with the sample may alter the optical characteristics of chrysotile fibers and should be avoided. Coatings and binding materials adhering to fiber surfaces may also be removed by treatment with sodium metaphosphate.7 Add 10 mL of 10g/L sodium metaphosphate solution to a small (0.1 to 0.5 mL) sample of bulk material in a 15-mL glass centrifuge tube. For approximately 15 seconds each, stir the mixture on a vortex mixer, place in an ultrasonic bath and then shake by hand. Repeat the series. Collect the dispersed solids by centrifugation at 1000 rpm for 5 minutes. Wash the sample three times by suspending in 10 mL distilled water and recentrifuging. After washing, resuspend the pellet in 5 mL distilled water, place a drop of the suspension on a microscope slide, and dry the slide at 110 °C. In samples with a large portion of cellulosic or other organic fibers, it may be useful to ash part of the sample and view the residue. Ashing should be performed in a low temperature asher. Ashing may also be performed in a muffle furnace at temperatures 1.7.2.3 Fiber Identification Positive identification of asbestos requires the determination of the following optical properties. • Morphology • Color and pleochroism • Refractive indices • Birefringence • Extinction characteristics • Sign of elongation Table 1–1 lists the above properties for commercial asbestos fibers. Figure 1–1 presents a flow diagram of the examination procedure. Natural variations in the conditions under which deposits of asbestiform minerals are formed will occasionally produce exceptions to the published values and differences from the UICC standards. The sign of elongation is determined by use of the compensator plate and crossed polars. Refractive indices may be determined by the Becke line test. Alternatively, dispersion staining may be used. Inexperienced operators may find that the dispersion staining technique is more easily learned, and should consult Reference 9 for guidance. Central stop dispersion staining colors are presented in Table 1–2. Available high-dispersion (HD) liquids should be used. TABLE 1–1—OPTICAL PROPERTIES OF ASBESTOC FIBERS Refrac- tive indices b Morphology, color a Mineral rfrederick on PROD1PC67 with CFR a g Chrysotile (asbestiform serpentine). Wavy fibers. Fiber bundles have splayed ends and ‘‘kinks’’. Aspect ratio typically >10:1. Colorless 3, nonpleochroic. 1.493–1.560 Amosite (asbestiform grunerite). Straight, rigid fibers. Aspect ratio typically >10:1. Colorless to brown, nonpleochroic or weakly so. Opaque inclusions may be present. 1.635–1.696 1.517– 1.562f (normally 1.556). 1.655– 1.729 f (normally 1.696– 1.710. Birefringence Extinction .008 | to fiber length. + (length slow) .020–.033 | to fiber length. + (length slow) 836 VerDate Aug<31>2005 14:36 Aug 06, 2007 Jkt 211171 PO 00000 Frm 00846 Fmt 8010 Sfmt 8002 Sign of elonation Y:\SGML\211171.XXX 211171 Environmental Protection Agency Pt. 763, Subpt. E, App. E TABLE 1–1—OPTICAL PROPERTIES OF ASBESTOC FIBERS—Continued Refrac- tive indices b Morphology, color a Mineral Extinction 1.668– 1.7173e (normally close to 1.700). 1.615– 1.676 f. .014–.016 | to fiber length. ¥ (length fast) .019–.024 | to fiber length. + (length slow) 1.622– 1.688 f. .023–.020 Oblique extinction, 10– 20° for fragments. Composite fibers show | extinction. + (length slow) Straight, rigid fibers. Thick fibers and bundles common, blue to purpleblue in color. Pleochroic. Birefringence is generally masked by blue color. 1.654–1.701 Anthophylliteasbestos. Straight fibers and acicular cleavage fragments.d Some composite fibers. Aspect ratio <10:1. Colorless to light brown. Normally present as acicular or prismatic cleavage fragments.d Single crystals predominate, aspect ratio <10:1. Colorless to pale green. 1.596–1.652 1.599–1.668 a From reference 5; colors cited are seen by observation with plane polarized light. references 5 and 8. subjected to heating may be brownish. d Fibers defined as having aspect ratio >3:1. e to fiber length. f |To fiber length. b From rfrederick on PROD1PC67 with CFR c Fibers 837 VerDate Aug<31>2005 14:36 Aug 06, 2007 Jkt 211171 PO 00000 Frm 00847 Fmt 8010 Sign of elonation g Crocidolite (asbestiform Riebeckite). Tremolite-actinolite-asbestos. Birefringence a Sfmt 8002 Y:\SGML\211171.XXX 211171 40 CFR Ch. I (7–1–07 Edition) 838 VerDate Aug<31>2005 14:36 Aug 06, 2007 Jkt 211171 PO 00000 Frm 00848 Fmt 8010 Sfmt 8006 Y:\SGML\211171.XXX 211171 EC01AP92.017</GPH> rfrederick on PROD1PC67 with CFR Pt. 763, Subpt. E, App. E Environmental Protection Agency Pt. 763, Subpt. E, App. E TABLE 1–2—CENTRAL STOP DISPERSION STAINING COLORS A h Mineral RI Liquid Chrysotile ..... 1.550 HD Blue ............. Amosite ........ 1.680 Blue-magenta to pale blue. Yellow to white. Red magenta 1.550HD Crocidolite b .. 1.700 1.550HD Anthophyllite 1.605HD Tremolite ...... Actinolite ...... 1.605HD c 1.605HD 1.630HD c a From b Blue Yellow to white. Blue ............. Pale blue ..... Gold-magenta to blue. Magenta ...... h| Blue-magenta Golden-yellow Yellow to white Blue-magenta Yellow to white Gold to goldmagenta Gold Gold Golden-yellow reference 9. absorption color. extinction view. c Oblique rfrederick on PROD1PC67 with CFR 1.7.2.4 Quantitation of Asbestos Content Asbestos quantitation is performed by a point-counting procedure or an equivalent estimation method. An ocular reticle (crosshair or point array) is used to visually superimpose a point or points on the microscope field of view. Record the number of points positioned directly above each kind of particle or fiber of interest. Score only points directly over asbestos fibers or nonasbestos matrix material. Do not score empty points for the closest particle. If an asbestos fiber and a matrix particle overlap so that a point is superimposed on their visual intersection, a point is scored for both categories. Point counting provides a determination of the area percent asbestos. Reliable conversion of area percent to percent of dry weight is not currently feasible unless the specific gravities and relative volumes of the materials are known. For the purpose of this method, ‘‘asbestos fibers’’ are defined as having an aspect ratio greater than 3:1 and being positively identified as one of the minerals in Table 1–1. A total of 400 points superimposed on either asbestos fibers or nonasbestos matrix material must be counted over at least eight different preparations of representative subsamples. Take eight forcep samples and mount each separately with the appropriate refractive index liquid. The preparation should not be heavily loaded. The sample should be uniformly dispersed to avoid overlapping particles and allow 25–50 percent empty area within the fields of view. Count 50 nonempty points on each preparation, using either • A cross-hair reticle and mechanical stage; or • A reticle with 25 points (Chalkley Point Array) and counting at least 2 randomly selected fields. For samples with mixtures of isotropic and anisotropic materials present, viewing the sample with slightly uncrossed polars or the addition of the compensator plate to the polarized light path will allow simultaneous discrimination of both particle types. Quantitation should be performed at 100X or at the lowest magnification of the polarized light microscope that can effectively distinguish the sample components. Confirmation of the quantitation result by a second analyst on some percentage of analyzed samples should be used as standard quality control procedure. The percent asbestos is calculated as follows: % asbestos=(a/n) 100% where a=number of asbestos counts, n=number of nonempty points counted (400). If a=0, report ‘‘No asbestos detected.’’ If 0< a≤3, report ‘‘<1% asbestos’’. The value reported should be rounded to the nearest percent. 1.8 References 1. Paul F. Kerr, Optical Mineralogy, 4th ed., New York, McGraw-Hill, 1977. 2. E. M. Chamot and C. W. Mason, Handbook of Chemical Microscopy, Volume One, 3rd ed., New York: John Wiley & Sons, 1958. 3. F. Chayes, Petrographic Modal Analysis: An Elementary Statistical Appraisal, New York: John Wiley & Sons, 1956. 4. E. P. Brantly, Jr., K. W. Gold, L. E. Myers, and D. E. Lentzen, Bulk Sample Analysis for Asbestos Content: Evaluation of the Tentative Method, U.S. Environmental Protection Agency, October 1981. 5. U.S. Environmental Protection Agency, Asbestos-Containing Materials in School Buildings: A Guidance Document, Parts 1 and 2, EPA/OPPT No. C00090, March 1979. 6. D. Lucas, T. Hartwell, and A. V. Rao, Asbestos-Containing Materials in School Buildings: Guidance for Asbestos Analytical Programs, EPA 560/13–80–017A, U.S. Environmental Protection Agency, December 1980, 96 pp. 7. D. H. Taylor and J. S. Bloom, Hexametaphosphate pretreatment of insulation samples for identification of fibrous constituents, Microscope, 28, 1980. 8. W. J. Campbell, R. L. Blake, L. L. Brown, E. E. Cather, and J. J. Sjoberg. Selected Silicate Minerals and Their Asbestiform Varieties: Mineralogical Definitions and Identification-Characterization, U.S. Bureau of Mines Information Circular 8751, 1977. 9. Walter C. McCrone, Asbestos Particle Atlas, Ann Arbor: Ann Arbor Science Publishers, June 1980. 839 VerDate Aug<31>2005 14:36 Aug 06, 2007 Jkt 211171 PO 00000 Frm 00849 Fmt 8010 Sfmt 8002 Y:\SGML\211171.XXX 211171 Pt. 763, Subpt. E, App. E 40 CFR Ch. I (7–1–07 Edition) SECTION 2. X-RAY POWDER DIFFRACTION 2.1 Principle and Applicability The principle of X-ray powder diffraction (XRD) analysis is well established. 1,2 Any solid, crystalline material will diffract an impingent beam of parallel, monochromatic X-rays whenever Bragg’s Law, λ = 2d sin q, is satisfied for a particular set of planes in the crystal lattice, where λ = the X-ray wavelength, Å; d = the interplanar spacing of the set of reflecting lattice planes, Å; and q = the angle of incidence between the X-ray beam and the reflecting lattice planes. By appropriate orientation of a sample relative to the incident X-ray beam, a diffraction pattern can be generated that, in most cases, will be uniquely characteristic of both the chemical composition and structure of the crystalline phases present. Unlike optical methods of analysis, however, XRD cannot determine crystal morphology. Therefore, in asbestos analysis, XRD does not distinguish between fibrous and nonfibrous forms of the serpentine and amphibole minerals (Table 2–1). However, when used in conjunction with optical methods such as polarized light microscopy (PLM), XRD techniques can provide a reliable analytical method for the identification and characterization of asbestiform minerals in bulk materials. For qualitative analysis by XRD methods, samples are initially scanned over limited diagnostic peak regions for the serpentine (∼7.4 Å) and amphibole (8.2–8.5 Å) minerals (Table 2–2). Standard slow-scanning methods for bulk sample analysis may be used for materials shown by PLM to contain significant amounts of asbestos (>5–10 percent). Detection of minor or trace amounts of asbestos may require special sample preparation and step-scanning analysis. All samples that exhibit diffraction peaks in the diagnostic regions for asbestiform minerals are submitted to a full (5°–60° 2q; 1° 2q/min) qualitative XRD scan, and their diffraction patterns are compared with standard reference powder diffraction patterns 3 to verify initial peak assignments and to identify possible matrix interferences when subsequent quantitative analysis will be performed. TABLE 2–1—THE ASBESTOS MINERALS AND THEIR NONASBESTIFORM ANALOGS Asbestiform SERPENTINE Chrysotile AMPHIBOLE Anthophyllite asbestos Cummingtonite-grunerite asbestos (‘‘Amosite’’) Crocidolite Tremolite asbestos Actinolite asbestos Nonasbestiform Antigorite, lizardite Anthophyllite Cummingtonite-grunerite Riebeckite Tremolite Actinolite TABLE 2–2—PRINCIPAL LATTICE SPACINGS OF ASBESTIFORM MINERALS a Minerals Chrysotile .................. ‘‘Amosite’’ .................. Anthophyllite .............. Anthophyllite .............. Crocidolite ................. Tremolite ................... Principal d-spacings (Å) and relative intensities 7.37100 7.36100 .. 7.10100 .. 8.33100 8.22100 .. 3.05100 3.06100 .. 2.72100 8.35100 8.38100 2.706100 3.13100 .. 3.6570 3.6680 2.3380 3.0670 3.06085 3.2460 8.3370 2.54100 3.1055 3.12100 3.1495 2.70660 4.5750 2.4565 3.5570 2.75670 3.2570 8.2655 3.2350 3.48080 2.72035 2.70590 8.4340 8.4440 JCPDS Powder diffraction file 3 number 21–543b 25–645 22–1162 (theoretical) 17–745 (nonfibrous) 27–1170 (UICC) 9–455 16–401 (synthetic) 25–157 27–1415 (UICC) 13–437b 20–1310b (synthetic) 23–666 (synthetic mixture with richterite) rfrederick on PROD1PC67 with CFR a This information is intended as a guide, only. Complete powder diffraction data, including mineral type and source, should be referred to, to ensure comparability of sample and reference materials where possible. Additional precision XRD data on amosite, crocidolite, tremolite, and chrysotile are available from the U.S. Bureaus of Mines.4 b Fibrosity questionable. Accurate quantitative analysis of asbestos in bulk samples by XRD is critically dependent on particle size distribution, crystallite size, preferred orientation and matrix absorption effects, and comparability of standard reference and sample materials. The most intense diffraction peak that has been shown to be free from interference by prior qualitative XRD analysis is selected for quantitation of each asbestiform mineral. A ‘‘thin-layer’’ method of analysis 5,6 is recommended in which, subsequent to comminution of the bulk material to ∼10 µm by suitable cryogenic milling techniques, an accurately known amount of the sample is deposited on a silver membrane filter. The 840 VerDate Aug<31>2005 14:36 Aug 06, 2007 Jkt 211171 PO 00000 Frm 00850 Fmt 8010 Sfmt 8002 Y:\SGML\211171.XXX 211171