ASTM D6059-96(2006)
(Test Method)Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy
Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy
SIGNIFICANCE AND USE
The SCCW may be present in the workplace atmosphere where these materials are manufactured, processed, transported, or used. This test method can be used to monitor airborne concentrations of SCCW fibers in these environments. It may be employed as part of a personal or area monitoring strategy.
This test method is based on morphology and elemental composition. The analysis technique has the ability to identify SCCW.
Note 1—This test method assumes that the analyst is familiar with the operation of SEM/EDS instrumentation and the interpretation of data obtained using these techniques.
This test method is not appropriate for measurement of fibers with diameters ≤0.10 to 0.25 μm due to visibility limitations associated with SEM. The TEM method may be used to provide additional size information of SCCW if needed (see Practice D 6058 for additional information on the use of this test method).
Results from the use of this test method shall be reported along with 95 % confidence limits for the samples being studied. Individual laboratories shall determine their intralaboratory coefficient of variation and use it for reporting 95 % confidence limits (1,3,4).
SCOPE
1.1 This test method covers the sampling methods and analysis techniques used to assess the airborne concentration and size distribution of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used. This test method is based on the collection of fibers by filtration of a known quantity of air through a filter. The filter is subsequently evaluated with a scanning electron microscope (SEM) for the number of fibers meeting appropriately selected morphological and compositional criteria. This test method has the ability to distinguish among many different types of fibers based on energy dispersive X-ray spectroscopy (EDS) analysis. This test method may be appropriate for other man-made mineral fibers (MMMF).
1.2 This test method is applicable to the quantitation of fibers on a collection filter that are greater than 5 m in length, less than 3 m in width, and have an aspect ratio equal to or greater than 5:1. The data are directly convertible to a statement of concentration per unit volume of air sampled. This test method is limited by the diameter of the fibers visible by SEM (typically greater than 0.10 to 0.25 m in width as determined in 12.1.5) and the amount of coincident interference particles.
1.3 A more definitive analysis may be necessary to confirm the presence of fibers with diameters 0.10 to 0.25 m in width. For this purpose, a transmission electron microscope (TEM) is appropriate. The use of the TEM method for the identification and size measurement of SCCW is described in Practice D 6058 and Test Method D 6056.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6059–96 (Reapproved 2006)
Standard Test Method for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment by
Scanning Electron Microscopy
This standard is issued under the fixed designation D6059; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the sampling methods and
responsibility of the user of this standard to establish appro-
analysis techniques used to assess the airborne concentration
priate safety and health practices and determine the applica-
and size distribution of single-crystal ceramic whiskers
bility of regulatory limitations prior to use.
(SCCW),suchassiliconcarbideandsiliconnitride,whichmay
occur in and around the workplace where these materials are
2. Referenced Documents
manufactured, processed, transported, or used. This test
2.1 ASTM Standards:
method is based on the collection of fibers by filtration of a
D1193 Specification for Reagent Water
knownquantityofairthroughafilter.Thefilterissubsequently
D1356 Terminology Relating to Sampling and Analysis of
evaluated with a scanning electron microscope (SEM) for the
Atmospheres
number of fibers meeting appropriately selected morphological
D4532 Test Method for Respirable Dust in Workplace
and compositional criteria. This test method has the ability to
Atmospheres
distinguish among many different types of fibers based on
D6056 Test Method for Determining Concentration of Air-
energy dispersive X-ray spectroscopy (EDS) analysis.This test
borne Single-Crystal Ceramic Whiskers in the Workplace
method may be appropriate for other man-made mineral fibers
Environment by Transmission Electron Microscopy
(MMMF).
D6057 Test Method for Determining Concentration of Air-
1.2 This test method is applicable to the quantitation of
borne Single-Crystal Ceramic Whiskers in the Workplace
fibers on a collection filter that are greater than 5 µm in length,
Environment by Phase Contrast Microscopy
less than 3 µm in width, and have an aspect ratio equal to or
D6058 Practice for Determining Concentration of Airborne
greater than 5:1. The data are directly convertible to a
Single-Crystal Ceramic Whiskers in the Workplace Envi-
statementofconcentrationperunitvolumeofairsampled.This
ronment
test method is limited by the diameter of the fibers visible by
E691 Practice for Conducting an Interlaboratory Study to
SEM (typically greater than 0.10 to 0.25 µm in width as
Determine the Precision of a Test Method
determined in 12.1.5) and the amount of coincident interfer-
E766 Practice for Calibrating the Magnification of a Scan-
ence particles.
ning Electron Microscope
1.3 Amore definitive analysis may be necessary to confirm
the presence of fibers with diameters #0.10 to 0.25 µm in
3. Terminology
width. For this purpose, a transmission electron microscope
3.1 Definitions:
(TEM) is appropriate. The use of the TEM method for the
3.1.1 analytical sensitivity, n—airborne fiber concentration
identification and size measurement of SCCW is described in
represented by a single fiber counted in the SEM.
Practice D6058 and Test Method D6056.
3.1.1.1 Discussion—Although the terms fiber and whisker
1.4 The values stated in SI units are to be regarded as the
are, for convenience, used interchangeably in this test method,
standard. The values given in parentheses are for information
whisker is correctly applied only to single-crystal fibers
only.
whereas a “fiber” may be single- or poly-crystalline or may be
noncrystalline.
This test method is under the jurisdiction of ASTM Committee D22 on Air
Quality and is the direct responsibility of Subcommittee D22.04 on Workplace
Atmospheres. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2006. Published October 2006. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2001 as D6059 - 96 (2001). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6059-96R06. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6059–96 (2006)
3.1.2 aspect ratio, n—the ratio of the length of a fiber to its 6. Interferences
width.
6.1 This test method has been designed to filter air for the
3.1.3 fiber, n—for the purpose of this test method,an
determination of SCCW concentration. However, filtration of
elongated particle having a length greater than 5 µm, a width
air also involves collection of extraneous particles and other
less than 3 µm, and an aspect ratio equal to or greater than 5:1.
fibers that may not be of interest. Extraneous particles may
3.1.4 fibrous, adj—composed of parallel, radiating, or inter-
obscure the fibers by overlay or by overloading of the filter.
laced aggregates of fibers, from which the fibers are sometimes
This situation can be managed by regulating the air volume
separable. That is, the aggregate may be referred to as fibrous
sampled and thus the filter loading. Fibers should appear
even if it is not composed of separable fibers, but has that
separated from other particles to ensure an adequate opportu-
distinct appearance. The term fibrous is used in a general
nity for their recognition as separate entities in the SEM and
mineralogical way to describe aggregates.
accurate counting. Some coincident particle agglomeration
3.1.5 man-made mineral fiber, n—any inorganic fibrous
does occur even with these guidelines. Analyze an alternate
material produced by chemical or physical processes.
filter with a reduced loading if the obscuring condition appears
3.1.6 single-crystal ceramic whiskers, n— a man-made
to exceed 15 % of the filter area (
5). Redeposition of a portion
mineral fiber that has a single-crystal structure.
of an overloaded filter is permitted only in circumstances
3.2 For definitions of other terms used in this test method,
where an alternate filter is not available and cannot be obtained
see Terminology D1356.
through resampling (see 10.1.5).
4. Summary of Test Method
7. Apparatus and Reagents
4.1 The sample is collected on a mixed cellulose ester
7.1 Sampling Cassette—Use a 25-mm electrically conduc-
(MCE) filter by drawing air, using a sampling pump, through
tive cassette assembly such as a three-piece cassette with an
an open-face 25-mm electrically conductive sampling cassette
extension cowl or retainer ring containing a 0.45-µm pore-size
assembly (1,2). Asection of the filter is transferred to an SEM
MCE filter and a support pad. Seal the cassette assembly with
stub and the fibers are identified, sized, and counted at a
shrink tape. Reloading of used cassettes is not permitted.
magnification of 20003 in the SEM using the criteria dis-
7.2 Personal Sampling Pump—Use a portable battery-
cussed in Section 11. Results are expressed as a fiber concen-
operated pump for personal sampling. Each pump must be
tration per unit volume of air and a fiber loading per unit area
capable of operating within the range from 0.5 to 4 L/min and
of filter. The airborne concentration is expressed as fiber per
continuously over the chosen sampling period (1). The flow
millilitre (f/mL) and fiber loading is expressed as fibers per
mustbefreefrompulsation.Allpumpsshallbecalibratedprior
square millimetre (f/mm ).
to use (6).
7.3 Area Sampling Pump—Use a personal sampling pump
5. Significance and Use
or a non-portable high-volume pump for area sampling. Each
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
pump shall be capable of operating within the range from 0.5
where these materials are manufactured, processed, trans-
to 16 L/min and continuously over the chosen sampling period
ported, or used. This test method can be used to monitor
(1). The flow shall be free from pulsation. All pumps shall be
airborneconcentrationsofSCCWfibersintheseenvironments.
calibrated prior to use (6).
It may be employed as part of a personal or area monitoring
7.4 Vinyl tubing or equivalent.
strategy.
7.5 Scanning Electron Microscope, a SEM capable of op-
5.2 This test method is based on morphology and elemental
erating using an accelerating voltage of at least 15 kV. The
composition. The analysis technique has the ability to identify
SEM must be capable of performing EDS analysis. A light
SCCW.
element X-ray analyzer capable of detecting carbon, nitrogen,
and oxygen is recommended.
NOTE 1—This test method assumes that the analyst is familiar with the
operation of SEM/EDS instrumentation and the interpretation of data 7.6 Vacuum Evaporator—For vapor deposition of conduc-
obtained using these techniques.
tive layers of carbon.
5.3 This test method is not appropriate for measurement of
NOTE 2—Sputter coaters and carbonaceous fiber coaters are not appro-
fibers with diameters #0.10 to 0.25 µm due to visibility
priate.
limitations associated with SEM. The TEM method may be
7.7 SEM Sample Preparation Stubs—Stubs made of carbon
usedtoprovideadditionalsizeinformationofSCCWifneeded
are suitable. (Acarbon planchet disk glued to a metal holder is
(see Practice D6058 for additional information on the use of
also acceptable.)
this test method).
7.8 Conducting DAG, (colloidal graphite) type adhesive
5.4 Resultsfromtheuseofthistestmethodshallbereported
paint or double-sided conductive carbon tape.
along with 95 % confidence limits for the samples being
7.9 NISTSEM Magnification Standard, SRM 484 (seePrac-
studied. Individual laboratories shall determine their intralabo-
tice E766).
ratory coefficient of variation and use it for reporting 95 %
7.10 Sample Preparation Area, consisting of either a clean
confidence limits (1,3,4).
room facility or a room containing a laminar flow hood.
7.11 Specification D1193 Type II Water, (particle-free).
7.12 Tweezers.
The boldface numbers in parentheses refer to a list of references at the end of
this test method. 7.13 Scalpel Blades.
D6059–96 (2006)
7.14 MCE Filters, 25 mm, 0.45 and 0.22-µm. 8.5.3 Set the sampling flow rate and time to produce an
7.15 Funnel/Filter Assembly, 25-mm. optimum fiber loading between 100 to 1300 f/mm (1,2). The
7.16 Miscellaneous Supplies. time of sampling can be estimated by using the following
equation:
NOTE 3—If the alternate sample preparation method discussed in 10.4
is utilized, the following additional apparatus and reagents will be ~A ! ~F !
c L
t 5 (1)
necessary:
~Q! ~C !10
e
7.16.1 Oven, capable of operating at 65°C is required to
where:
collapse the filter. A hot plate capable of maintaining the
A = active filter collection area (;385 mm for 25-mm
c
required temperature is an acceptable alternative to the oven.
filter),
7.16.2 Plasma Asher, a low-temperature asher (LTA) is
t = time, min,
required to plasma-etch the collapsed MCE filter. A nominal 2
F = fiber loading, f/mm ,
L
100-W unit is suitable.
Q = sampling flow rate, L/min,
7.16.3 Oxygen, used as a bleed gas in the plasma asher.
C = estimated concentration of SCCW, f/mL, and
e
7.16.4 Micro-syringe or Pipette, a device capable of consis-
10 = conversion factor.
tently delivering a solution volume of 100 µL is required.
8.5.4 At a minimum, check the flow rate before and after
7.16.5 Dimethyl Formamide (DMF).
sampling. If the difference is greater than 10 % from the initial
7.16.6 Glacial Acetic Acid.
flow rate, the sample shall be rejected. Also see Test Method
7.16.7 Purity of Reagents—Reagent grade chemicals shall
D4532.
be used in all tests. Unless otherwise indicated, it is intended
8.6 Carefully remove the cassette from the tubing at the end
thatallreagentsconformtothespecificationsoftheCommittee
of the sampling period (ensure that the cassette is positioned
on Analytical Reagents of the American Chemical Society
upright before interrupting pump flow). Replace the inlet cap
4,5
wheresuchspecificationsareavailable. Othergradesmaybe
and inlet and outlet plugs, and store the cassette.
used, provided it is first ascertained that the reagent is of
NOTE 4—Deactivate the sampling pump prior to disconnecting the
sufficiently high purity to permit its use without lessening the
cassette from the tubing.
accuracy of the determination.
8.7 Submit at least one field blank (or a number equal to
8. Sample Collection
10 % of the total samples, whichever is greater) for each set of
8.1 CollectsamplesofairborneSCCWonMCEfiltersusing samples. Remove the cap of the field blank briefly (approxi-
mately 30 s) at the sampling site, then replace it. The field
sampling cassettes and pumps as noted in Section 7.
8.2 Remove the outlet plug from the sampling cassette and blank is used to monitor field sampling procedures. Field
blanks shall be representative of filters used in sample collec-
connect it to a sampling pump by means of flexible,
constriction-proof tubing. tion (for example, same filter lot number).
8.8 Submit at least one unused and unopened sealed blank
8.3 Perform a leak check of the sampling system by
activating the pump with the closed cassette and rotameter (or which is used to monitor the supplies purchased as well as
procedures used in the laboratory. The sealed blank shall be
other flow measurement device) in line. Any flow indicates a
leak that must be eliminated before starting the sampling representative of filters used in sample collection (for example,
same filter lot number).
operation.
8.4 Remove the inlet plug from the sampling cassette to
eliminate any vacuum that may have accumulated during the
9. Transport of Samples
leak test, then remove the entire inlet cap.
9.1 Ship the samples in a rigid container with sufficient
8.5 Conduct personal and area sampling as follows:
packing material to prevent jostling or damage. Care shall be
8.5.1 For personal sampling, fasten the sampling cassette to
taken to minimize vibrations and cassette movement.
the worker’s lapel in the worker’s breathing zone and orient it
NOTE 5—Do not use shipping material that may develop electrostatic
face down. Adjust the calibrated flow rate to a value between
forces or generate dust.
0.5and4L/min (1).Typically,asamplingratebetween0.5and
NOTE 6—Shipping containers for 25-mm sampling cassettes are com-
2.5 L/min is selected (2-4,6,7). Also see Test Method D4532.
mercially available and their use is recommended.
8.5.2 Placeareasamplesonanextensionrodfacingdownat
9.2 Include in the container a list of samples, their descrip-
a 45° angle.Adjust the calibrat
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