1、Designation: D6281 09D6281 15Standard Test Method forAirborne Asbestos Concentration in Ambient and IndoorAtmospheres as Determined by Transmission ElectronMicroscopy Direct Transfer (TEM)1This standard is issued under the fixed designation D6281; the number immediately following the designation ind
2、icates the 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method2 is an analytical proced
3、ure using transmission electron microscopy (TEM) for the determination of theconcentration of asbestos structures in ambient atmospheres and includes measurement of the dimension of structures and of theasbestos fibers found in the structures from which aspect ratios are calculated.1.1.1 This test m
4、ethod allows determination of the type(s) of asbestos fibers present.1.1.2 This test method cannot always discriminate between individual fibers of the asbestos and non-asbestos analogues of thesame amphibole mineral.1.2 This test method is suitable for determination of asbestos in both ambient (out
5、door) and building atmospheres.1.2.1 This test method is defined for polycarbonate capillary-pore filters or cellulose ester (either mixed esters of cellulose orcellulose nitrate) filters through which a known volume of air has been drawn and for blank filters.1.3 The upper range of concentrations t
6、hat can be determined by this test method is 7000 s/mm2. The air concentrationrepresented by this value is a function of the volume of air sampled.1.3.1 There is no lower limit to the dimensions of asbestos fibers that can be detected. In practice, microscopists vary in theirability to detect very s
7、mall asbestos fibers. Therefore, a minimum length of 0.5 m has been defined as the shortest fiber to beincorporated in the reported results.1.4 The direct analytical method cannot be used if the general particulate matter loading of the sample collection filter asanalyzed exceeds approximately 10 %
8、coverage of the collection filter by particulate matter.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability
9、 of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis of AtmospheresD1357 Practice for Planning the Sampling of the Ambient AtmosphereD4483 Practice for Evaluating Precision for Test
10、Method Standards in the Rubber and Carbon Black Manufacturing IndustriesD6620 Practice for Asbestos Detection Limit Based on CountsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Meth
11、od2.2 ISO Standard:4ISO 10312 Ambient air - Determination of asbestos fibres - Direct-transfer transmission electron microscopy method1 This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.07 on Sampling and Analysisof A
12、sbestos.Current edition approved Dec. 1, 2009Dec. 1, 2015. Published December 2009January 2016. Originally approved in 1998. Last previous edition approved in 20062009as D6281 06.D6281 09. DOI: 10.1520/D6281-09.10.1520/D6281-16.2 This test method was adapted from International Standard ISO 10312 “Ai
13、r qualityDetermination of asbestos fibresDirect transfer transmission electron microscopymethod.”3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Docume
14、nt Summary page on the ASTM website.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have b
15、een made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official docume
16、nt.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 For definitions of general terms used in this test method, refer to Terminology D1356 (see 2.1).3.2 Definitions of Terms Specific to This Standard:3.2.1 acicularthe
17、shape shown by an extremely slender crystal with cross-sectional dimensions that are small relative to itslength, that is, needle-like.3.2.2 amphibolea group of more than 60 different silicate minerals with similar crystal structures and complex compositionsthat conform to the nominal formula:A021B2
18、C5T8O22OH,F,Cl!2 (1)where:A = K, Na, Ca,B = Fe2+, Mn, Mg, Ca, Na,C = Al, Cr, Ti, Fe3+, Mg, Fe2+, Mn, andT = Si, Al, Cr, Fe3+, Ti.In some varieties of amphibole, these elements can be partially substituted by Li, Pb, Zn, Be, Ba, or Ni. Amphiboles arecharacterized by a complex monoclinic or orthorhomb
19、ic structure that includes a double chain of T-O tetrahedra with a T:O ratioof approximately 4:11; a variable morphology that ranges from columnar to prismatic to acicular to fibrous; and good prismaticcleavage at angles of about 56 and 124. The cleavage may not be readily exhibited by small crystal
20、s that are bound by irregulargrowth and fracture surfaces (1).53.2.3 amphibole asbestosamphibole in an asbestiform habit.3.2.4 analytical sensitivitythe calculated airborne asbestos structure concentration in asbestos structures/L, equivalent to thecounting of one asbestos structure in the analysis.
21、3.2.5 asbestiforma specific type of fibrous habit in which the fibers are separable into thinner fibers and ultimately into fibrils.This habit accounts for greater flexibility and higher tensile strength than other habits of the same mineral.3.2.6 asbestosa collective term that describes a group of
22、naturally occurring, inorganic, highly-fibrous, silicate minerals thatare easily separated into long, thin, flexible, strong fibers when crushed or processed.3.2.6.1 DiscussionIncluded in the definition are the asbestiform varieties of serpentine (chrysotile); riebeckite (crocidolite); grunerite (gr
23、uneriteasbestos Amosite); anthophyllite (anthophyllite asbestos); tremolite (tremolite asbestos); and actinolite (actinolite asbestos). Theamphibole mineral compositions are defined according to the nomenclature of the International Mineralogical Association.Asbestos Chemical Abstracts Service Regis
24、try No.6Chrysotile 12001-29-5Crocidolite 12001-28-4Grunerite Asbestos Amosite 12172-73-5Anthophyllite Asbestos 77536-67-5Tremolite Asbestos 77536-68-6Actinolite Asbestos 77536-66-43.2.7 asbestos structurea term applied to isolated fibers or to any connected or overlapping grouping of asbestos fibers
25、 orbundles, with or without other nonasbestos particles.3.2.8 aspect ratiothe ratio of length to width of a particle.3.2.9 blanka structure count made on TEM specimens prepared from an unused filter to determine the backgroundmeasurement.3.2.10 camera lengththe equivalent projection length between t
26、he specimen and its electron diffraction pattern, in the absenceof lens action.3.2.11 chrysotilea group of fibrous minerals of the serpentine group that have the nominal composition Mg3Si2O5(OH)4 andhave the crystal structure of either clinochrysotile, orthochrysotile, or parachrysotile. Most natura
27、l chrysotile deviates little fromthis nominal composition. Chrysotile may be partially dehydrated or magnesium-leached, both in nature and in building materials.In some varieties of chrysotile, minor substitution of silicon by Al3+ may occur. Chrysotile is the most prevalent type of asbestos.3.2.12
28、cleavagethe breaking of a mineral along one of its crystallographic directions.5 The boldface numbers in parentheses refer to the list of references at the end of this standard.6 The non-asbestiform variations of the minerals indicated in 5.2.6 have different Chemical Abstracts Service (CAS) numbers
29、.D6281 1523.2.13 cleavage fragmenta fragment of a crystal that is bounded in whole or in part by cleavage faces. Some cleavagefragments would be included in the fiber definition used in this method.3.2.14 clustera structure in which two or more fibers or fiber bundles are randomly oriented in a conn
30、ected grouping.3.2.15 d-value or interplanar spacingthe perpendicular distance between identical adjacent and parallel planes of atoms in acrystal.3.2.16 decision value, nthe structure count that must be exceeded to claim that a measurement represents a population ofairborne structures that is diffe
31、rent than the background population, which is established by analyzing blanks (see 3.2.9 andPractice D6620).3.2.17 electron diffractiontechniques in electron microscopy, including selected area electron diffraction (SAED) andmicrodiffraction, by which the crystal structure of a specimen is examined.
32、3.2.18 electron scattering powerthe extent to which a substance scatters electrons from their original courses.3.2.19 energy dispersive X-ray analysismeasurement of the energies and intensities of X-rays by use of a solid state detectorand multichannel analyzer system.3.2.20 eucentricthe condition w
33、hen the area of interest of an object is placed on a tilting axis at the intersection of the electronbeam with that axis and is in the plane of focus.3.2.21 field blanka filter cassette that has been taken to the sampling site, opened, and then closed. Such a filter is used todetermine the backgroun
34、d structure count for the measurement.3.2.22 fibrila single fiber of chrysotile that cannot be further separated longitudinally into smaller components without losingits fibrous properties or appearances.3.2.23 fiberan elongated particle that has parallel or stepped sides. For the purposes of this t
35、est method, a fiber is defined ashaving an aspect ratio equal to or greater than 5:1 and a minimum length of 0.5 m.3.2.24 fiber bundlea structure composed of parallel, smaller-diameter fibers attached along its length. A fiber bundle mayexhibit diverging fibers at one or both ends.3.2.25 fibrous str
36、ucturea fiber or connected grouping of fibers with or without other particles.3.2.26 habitthe characteristic crystal growth form or combination of these forms of a mineral, including characteristicirregularities.3.2.27 limit of detectionthe calculated airborne asbestos structure concentration in str
37、uctures/L, equivalent to counting 2.99asbestos structures in the analysis. The mean count for a population of structures that detection limithas been set at 2.99 structurescounted in any area of any filter because of concerns that false positives (counting a structure when none exists) may occur in
38、bothblanks and sample filters. Based on the assumption of a Poisson distribution of false positives, the detection limit of 2.99 wouldprotect against a false positive rate as high as 5 % (5 false positive structures per 100 blank filters counted). This level is veryconservative, since the actual fal
39、se positive rate is believed to be 2 % or lower. Thus, many of the samples reported as being belowthe determined, based on a measurement or average of measurements, to be different than the background population of detectionlimit (less than three structures counted) willstructures (see 3.2.16 actual
40、ly containand Practice D6620true positives. Note thatconcentration values are included in the test report, even if they are below the limit of detection.). The limit of detection may berestated in units of structures/L by multiplying the mean count by analytical sensitivity (see 3.2.4).3.2.28 matrix
41、a structure in which one or more fibers or fiber bundles touch, are attached to, or partially concealed by a singleparticle or connected group of nonfibrous particles.3.2.29 miller indexa set of three integer numbers used to specify the orientation of a crystallographic plane in relation to thecryst
42、al axes.3.2.30 PCM equivalent fibera particle of aspect ratio that is greater than or equal to 3:1, is longer than 5 m, and that has adiameter between 0.2 and 3.0 m3.2.31 PCM equivalent structurea fibrous structure of aspect ratio that is greater than or equal to 3:1, is longer than 5 m, andhas a di
43、ameter between 0.2 and 3.0 m.3.2.32 primary structurea fibrous structure that is a separate entity in the TEM image.3.2.33 replicationa procedure in electron microscopy specimen preparation in which a thin copy, or replica, of a surface ismade.3.2.34 residual structurematrix or cluster material cont
44、aining asbestos fibers that remains after accounting for the prominentcomponent fibers or bundles, or both.3.2.35 serpentinea group of common rock-forming minerals having the nominal formula: Mg3Si2O5(OH)4.3.2.36 structurea single fiber, fiber bundle, cluster, or matrix.D6281 1533.2.37 twinningthe o
45、ccurrence of crystals of the same species joined together at a particular mutual orientation, and such thatthe relative orientations are related by a definite law.3.2.38 unopened fiber bundlea large-diameter asbestos fiber bundle that has not been separated into its constituent fibrils orfibers.3.2.
46、39 zone-axisthe crystallographic direction parallel to the intersection edges of the crystal faces defining the crystal zone.3.3 Symbols:eV = electron voltkV = kilovoltL/min = liters per minuteg = micrograms (106 g)m = micrometer (106 m)nm = nanometer (109 m)W = wattPa = Pascals3.4 Abbreviations:DMF
47、 = dimethyl formamideED = electron diffractionEDXA = energy dispersive X-ray analysisFWHM = full width, half maximumHEPA = high-efficiency particle absoluteMCE = mixed cellulose ester; also refers to pure cellulose nitrate filtersPC = polycarbonatePCM = phase contrast optical microscopyED = selected
48、 area electron diffractionSEM = scanning electron microscopeSTEM = scanning transmission electron microscopeTEM = transmission electron microscopeUICC = Union Internationale Contre le Cancer4. Summary of Test Method4.1 A sample of airborne particulate matter is collected by drawing a measured volume
49、 of air through either a capillary-porepolycarbonate membrane filter of maximum pore size 0.4 m or a cellulose ester (either mixed esters of cellulose or cellulosenitrate) membrane filter of maximum pore size 0.45 m by means of a battery-powered or mains-powered pump. TEM specimensare prepared from polycarbonate filters by applying a thin film of carbon to the filter surface by vacuum evaporation. Small areasare cut from the carbon-coated filter, supported on TEM specimen grids, and the filter medium is dissolved aw
