ASTM D6059-96(2001)

Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy

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 μm in length, less than 3 μm 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 μm 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.
1.5 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.

General Information

• Status: Historical
• Publication Date: 09-Dec-1996
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Replaces: ASTM D6059-96 - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy
• Effective Date: 10-Dec-1996
• Replaced By: ASTM D6059-96(2006) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy
• Effective Date: 01-Oct-2006
• Referred By: ASTM D6058-96(2016) - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 10-Dec-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D6059–96 (Reapproved 2001)
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 D 6059; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method covers the sampling methods and
bility of regulatory limitations prior to use.
analysis techniques used to assess the airborne concentration
and size distribution of single-crystal ceramic whiskers
2. Referenced Documents
(SCCW),suchassiliconcarbideandsiliconnitride,whichmay
2.1 ASTM Standards:
occur in and around the workplace where these materials are
D 1193 Specification for Reagent Water
manufactured, processed, transported, or used. This test
D 1356 Terminology Relating to Sampling and Analysis of
method is based on the collection of fibers by filtration of a
Atmospheres
knownquantityofairthroughafilter.Thefilterissubsequently
D 4532 Test Method for Respirable Dust in Workplace
evaluated with a scanning electron microscope (SEM) for the
Atmospheres
number of fibers meeting appropriately selected morphological
D 6056 Test Method for Determining Concentration of
and compositional criteria. This test method has the ability to
Airborne Single-Crystal Ceramic Whiskers in the Work-
distinguish among many different types of fibers based on
place Environment by Transmission Electron Microscopy
energy dispersive X-ray spectroscopy (EDS) analysis.This test
D 6057 Test Method for Determining Concentration of
method may be appropriate for other man-made mineral fibers
Airborne Single-Crystal Ceramic Whiskers in the Work-
(MMMF).
place Environment by Phase Contrast Microscopy
1.2 This test method is applicable to the quantitation of
D 6058 Practice for Determining Concentration ofAirborne
fibers on a collection filter that are greater than 5 µm in length,
Single-Crystal Ceramic Whiskers in the Workplace Envi-
less than 3 µm in width, and have an aspect ratio equal to or
ronment
greater than 5:1. The data are directly convertible to a
E 691 Practice for Conducting Interlaboratory Study to
statementofconcentrationperunitvolumeofairsampled.This
Determine the Precision of a Test Method
test method is limited by the diameter of the fibers visible by
E 766 Practice for Calibrating the Magnification of SEM
SEM (typically greater than 0.10 to 0.25 µm in width as
Using NBS SRM 484
determined in 12.1.5) and the amount of coincident interfer-
ence particles.
3. Terminology
1.3 Amore definitive analysis may be necessary to confirm
3.1 Definitions:
the presence of fibers with diameters #0.10 to 0.25 µm in
3.1.1 analytical sensitivity, n—airborne fiber concentration
width. For this purpose, a transmission electron microscope
represented by a single fiber counted in the SEM.
(TEM) is appropriate. The use of the TEM method for the
3.1.1.1 Discussion—Although the terms fiber and whisker
identification and size measurement of SCCW is described in
are, for convenience, used interchangeably in this test method,
Practice D 6058 and Test Method D 6056.
whisker is correctly applied only to single-crystal fibers
1.4 The values stated in SI units are to be regarded as the
whereas a 88fiber” may be single- or poly-crystalline or may be
standard. The values given in parentheses are for information
noncrystalline.
only.
3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
1.5 This standard does not purport to address all of the
width.
safety concerns, if any, associated with its use. It is the
1 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D22 on
Sampling andAnalysis and is the direct responsibility of Subcommittee D22.04 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Workplace Atmospheres. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved December 10, 1996. Published February 1997. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6059–96 (2001)
3.1.3 fiber, n—for the purpose of this test method,an 6. Interferences
elongated particle having a length greater than 5 µm, a width
6.1 This test method has been designed to filter air for the
less than 3 µm, and an aspect ratio equal to or greater than 5:1.
determination of SCCW concentration. However, filtration of
3.1.4 fibrous, adj—composed of parallel, radiating, or inter-
air also involves collection of extraneous particles and other
laced aggregates of fibers, from which the fibers are sometimes
fibers that may not be of interest. Extraneous particles may
separable. That is, the aggregate may be referred to as fibrous
obscure the fibers by overlay or by overloading of the filter.
even if it is not composed of separable fibers, but has that
This situation can be managed by regulating the air volume
distinct appearance. The term fibrous is used in a general
sampled and thus the filter loading. Fibers should appear
mineralogical way to describe aggregates.
separated from other particles to ensure an adequate opportu-
3.1.5 man-made mineral fiber, n—any inorganic fibrous
nity for their recognition as separate entities in the SEM and
material produced by chemical or physical processes.
accurate counting. Some coincident particle agglomeration
3.1.6 single-crystal ceramic whiskers, n— a man-made
does occur even with these guidelines. Analyze an alternate
mineral fiber that has a single-crystal structure.
filter with a reduced loading if the obscuring condition appears
3.2 For definitions of other terms used in this test method,
to exceed 15 % of the filter area (
5). Redeposition of a portion
see Terminology D 1356.
of an overloaded filter is permitted only in circumstances
where an alternate filter is not available and cannot be obtained
4. Summary of Test Method
through resampling (see 10.1.5).
4.1 The sample is collected on a mixed cellulose ester
7. Apparatus and Reagents
(MCE) filter by drawing air, using a sampling pump, through
7.1 Sampling Cassette—Use a 25-mm electrically conduc-
an open-face 25-mm electrically conductive sampling cassette
tive cassette assembly such as a three-piece cassette with an
assembly (1,2). Asection of the filter is transferred to an SEM
extension cowl or retainer ring containing a 0.45-µm pore-size
stub and the fibers are identified, sized, and counted at a
MCE filter and a support pad. Seal the cassette assembly with
magnification of 20003 in the SEM using the criteria dis-
shrink tape. Reloading of used cassettes is not permitted.
cussed in Section 11. Results are expressed as a fiber concen-
7.2 Personal Sampling Pump—Use a portable battery-
tration per unit volume of air and a fiber loading per unit area
operated pump for personal sampling. Each pump must be
of filter. The airborne concentration is expressed as fiber per
capable of operating within the range from 0.5 to 4 L/min and
millilitre (f/mL) and fiber loading is expressed as fibers per
continuously over the chosen sampling period (1). The flow
square millimetre (f/mm ).
mustbefreefrompulsation.Allpumpsshallbecalibratedprior
to use (6).
5. Significance and Use
7.3 Area Sampling Pump—Use a personal sampling pump
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
or a non-portable high-volume pump for area sampling. Each
where these materials are manufactured, processed, trans-
pump shall be capable of operating within the range from 0.5
ported, or used. This test method can be used to monitor
to 16 L/min and continuously over the chosen sampling period
airborneconcentrationsofSCCWfibersintheseenvironments.
(1). The flow shall be free from pulsation. All pumps shall be
It may be employed as part of a personal or area monitoring
calibrated prior to use (6).
strategy.
7.4 Vinyl tubing or equivalent.
5.2 This test method is based on morphology and elemental
7.5 Scanning Electron Microscope, a SEM capable of op-
composition. The analysis technique has the ability to identify
erating using an accelerating voltage of at least 15 kV. The
SCCW.
SEM must be capable of performing EDS analysis. A light
NOTE 1—This test method assumes that the analyst is familiar with the
element X-ray analyzer capable of detecting carbon, nitrogen,
operation of SEM/EDS instrumentation and the interpretation of data
and oxygen is recommended.
obtained using these techniques.
7.6 Vacuum Evaporator—For vapor deposition of conduc-
tive layers of carbon.
5.3 This test method is not appropriate for measurement of
fibers with diameters #0.10 to 0.25 µm due to visibility
NOTE 2—Sputter coaters and carbonaceous fiber coaters are not appro-
limitations associated with SEM. The TEM method may be
priate.
usedtoprovideadditionalsizeinformationofSCCWifneeded
7.7 SEM Sample Preparation Stubs—Stubs made of carbon
(see Practice D 6058 for additional information on the use of
are suitable. (Acarbon planchet disk glued to a metal holder is
this test method).
also acceptable.)
5.4 Resultsfromtheuseofthistestmethodshallbereported
7.8 Conducting DAG, (colloidal graphite) type adhesive
along with 95 % confidence limits for the samples being
paint or double-sided conductive carbon tape.
studied. Individual laboratories shall determine their intralabo-
7.9 NISTSEM Magnification Standard, SRM 484 (seePrac-
ratory coefficient of variation and use it for reporting 95 %
tice E 766).
confidence limits (1,3,4).
7.10 Sample Preparation Area, consisting of either a clean
room facility or a room containing a laminar flow hood.
7.11 Specification D 1193 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 (2001)
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
D 4532.
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-
sampling cassettes and pumps as noted in Section 7. mately 30 s) at the sampling site, then replace it. The field
8.2 Remove the outlet plug from the sampling cassette and blank is used to monitor field sampling procedures. Field
connect it to a sampling pump by means of flexible, blanks shall be representative of filters used in sample collec-
constriction-proof tubing. tion (for example, same filter lot number).
8.3 Perform a leak check of the sampling system by 8.8 Submit at least one unused and unopened sealed blank
activating the pump with the closed cassette and rotameter (or which is used to monitor the supplies purchased as well as
other flow measurement device) in line. Any flow indicates a procedures used in the laboratory. The sealed blank shall be
leak that must be eliminated before starting the sampling representative of filters used in sample collection (for example,
operation. same filter lot number).
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 D 4532.
mercially available and their use is recommended.
8.5.2 Placeareasamplesonanextensionrodfacingdownat
a 45° angle.Adjust the calibrated flow rate to a value between 9.2 Include in the container a list of samples, their descrip-
0.5 and 16 L/min (1).Typically, a sampling rate between 1 and tions
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