ASTM D6059-96

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
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Replaced By: ASTM D6059-96(2001) - 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
• 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 discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6059 – 96
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 bility of regulatory limitations prior to use.
1.1 This test method covers the sampling methods and
2. Referenced Documents
analysis techniques used to assess the airborne concentration
2.1 ASTM Standards:
and size distribution of single-crystal ceramic whiskers
D 1193 Specification for Reagent Water
(SCCW), such as silicon carbide and silicon nitride, which may
D 1356 Terminology Relating to Sampling and Analysis of
occur in and around the workplace where these materials are
Atmospheres
manufactured, processed, transported, or used. This test
D 4532 Test Method for Respirable Dust in Workplace
method is based on the collection of fibers by filtration of a
Atmospheres
known quantity of air through a filter. The filter is subsequently
D 6056 Test Method for Determining Concentration of
evaluated with a scanning electron microscope (SEM) for the
Airborne Single-Crystal Ceramic Whiskers in the Work-
number of fibers meeting appropriately selected morphological
place Environment by Transmission Electron Microscopy
and compositional criteria. This test method has the ability to
D 6057 Test Method for Determining Concentration of
distinguish among many different types of fibers based on
Airborne Single-Crystal Ceramic Whiskers in the Work-
energy dispersive X-ray spectroscopy (EDS) analysis. This test
place Environment by Phase Contrast Microscopy
method may be appropriate for other man-made mineral fibers
D 6058 Practice for Determining Concentration of Airborne
(MMMF).
Single-Crystal Ceramic Whiskers in the Workplace Envi-
1.2 This test method is applicable to the quantitation of
ronment
fibers on a collection filter that are greater than 5 μm in length,
E 691 Practice for Conducting Interlaboratory Study to
less than 3 μm in width, and have an aspect ratio equal to or
Determine the Precision of a Test Method
greater than 5:1. The data are directly convertible to a
E 766 Practice for Calibrating the Magnification of SEM
statement of concentration per unit volume of air sampled. This
Using NBS SRM 484
test method is limited by the diameter of the fibers visible by
SEM (typically greater than 0.10 to 0.25 μm in width as
3. Terminology
determined in 12.1.5) and the amount of coincident interfer-
3.1 Definitions:
ence particles.
3.1.1 analytical sensitivity, n—airborne fiber concentration
1.3 A more definitive analysis may be necessary to confirm
represented by a single fiber counted in the SEM.
the presence of fibers with diameters #0.10 to 0.25 μm in
3.1.1.1 Discussion—Although the terms fiber and whisker
width. For this purpose, a transmission electron microscope
are, for convenience, used interchangeably in this test method,
(TEM) is appropriate. The use of the TEM method for the
whisker is correctly applied only to single-crystal fibers
identification and size measurement of SCCW is described in
whereas a 88fiber” may be single- or poly-crystalline or may be
Practice D 6058 and Test Method D 6056.
noncrystalline.
1.4 The values stated in SI units are to be regarded as the
3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
standard. The values given in parentheses are for information
width.
only.
3.1.3 fiber, n—for the purpose of this test method,an
1.5 This standard does not purport to address all of the
elongated particle having a length greater than 5 μm, a width
safety concerns, if any, associated with its use. It is the
less than 3 μm, and an aspect ratio equal to or greater than 5:1.
responsibility of the user of this standard to establish appro-
3.1.4 fibrous, adj—composed of parallel, radiating, or inter-
priate safety and health practices and determine the applica-
laced aggregates of fibers, from which the fibers are sometimes
1 2
This test method is under the jurisdiction of ASTM Committee D-22 on Annual Book of ASTM Standards, Vol 11.01.
Sampling and Analysis and is the direct responsibility of Subcommittee D22.04 on Annual Book of ASTM Standards, Vol 11.03.
Analysis of Workplace Atmospheres. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved Dec. 10, 1996. Published February 1997. Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 6059
separable. That is, the aggregate may be referred to as fibrous This situation can be managed by regulating the air volume
even if it is not composed of separable fibers, but has that sampled and thus the filter loading. Fibers should appear
distinct appearance. The term fibrous is used in a general separated from other particles to ensure an adequate opportu-
mineralogical way to describe aggregates. nity for their recognition as separate entities in the SEM and
3.1.5 man-made mineral fiber, n—any inorganic fibrous accurate counting. Some coincident particle agglomeration
material produced by chemical or physical processes. does occur even with these guidelines. Analyze an alternate
3.1.6 single-crystal ceramic whiskers, n— a man-made filter with a reduced loading if the obscuring condition appears
mineral fiber that has a single-crystal structure. to exceed 15 % of the filter area (5). Redeposition of a portion
3.2 For definitions of other terms used in this test method, of an overloaded filter is permitted only in circumstances
see Terminology D 1356. where an alternate filter is not available and cannot be obtained
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
(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). A section 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 ).
must be free from pulsation. All pumps shall be calibrated prior
to use (6).
5. Significance and Use
7.3 Area Sampling Pump—Use a personal sampling pump
5.1 The SCCW may be present in the workplace atmosphere
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
airborne concentrations of SCCW fibers in these environments.
(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
element X-ray analyzer capable of detecting carbon, nitrogen,
NOTE 1—This test method assumes that the analyst is familiar with the
and oxygen is recommended.
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
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.
used to provide additional size information of SCCW if needed
7.7 SEM Sample Preparation Stubs—Stubs made of carbon
(see Practice D 6058 for additional information on the use of
are suitable. (A carbon planchet disk glued to a metal holder is
this test method).
also acceptable.)
5.4 Results from the use of this test method shall be reported
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 NIST SEM Magnification Standard, SRM 484 (see Prac-
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.
6. Interferences
7.11 Specification D 1193 Type II Water, (particle-free).
6.1 This test method has been designed to filter air for the
7.12 Tweezers.
determination of SCCW concentration. However, filtration of
7.13 Scalpel Blades.
air also involves collection of extraneous particles and other
7.14 MCE Filters, 25 mm, 0.45 and 0.22-μm.
fibers that may not be of interest. Extraneous particles may
7.15 Funnel/Filter Assembly, 25-mm.
obscure the fibers by overlay or by overloading of the filter.
7.16 Miscellaneous Supplies.
NOTE 3—If the alternate sample preparation method discussed in 10.4
is utilized, the following additional apparatus and reagents will be
The boldface numbers in parentheses refer to a list of references at the end of
this test method. necessary:
D 6059
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 F = fiber loading, f/mm ,
L
Q = sampling flow rate, L/min,
100-W unit is suitable.
C = estimated concentration of SCCW, f/mL, and
7.16.3 Oxygen, used as a bleed gas in the plasma asher.
e
10 = conversion factor.
7.16.4 Micro-syringe or Pipette, a device capable of consis-
8.5.4 At a minimum, check the flow rate before and after
tently delivering a solution volume of 100 μL is required.
sampling. If the difference is greater than 10 % from the initial
7.16.5 Dimethyl Formamide (DMF).
flow rate, the sample shall be rejected. Also see Test Method
7.16.6 Glacial Acetic Acid.
D 4532.
7.16.7 Purity of Reagents—Reagent grade chemicals shall
8.6 Carefully remove the cassette from the tubing at the end
be used in all tests. Unless otherwise indicated, it is intended
of the sampling period (ensure that the cassette is positioned
that all reagents conform to the specifications of the Committee
upright before interrupting pump flow). Replace the inlet cap
on Analytical Reagents of the American Chemical Society
,
7 8
and inlet and outlet plugs, and store the cassette.
where such specifications are available. Other grades may be
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
10 % of the total samples, whichever is greater) for each set of
8. Sample Collection
samples. Remove the cap of the field blank briefly (approxi-
8.1 Collect samples of airborne SCCW on MCE filters using
mately 30 s) at the sampling site, then replace it. The field
sampling cassettes and pumps as noted in Section 7.
blank is used to monitor field sampling procedures. Field
8.2 Remove the outlet plug from the sampling cassette and
blanks shall be representative of filters used in sample collec-
connect it to a sampling pump by means of flexible,
tion (for example, same filter lot number).
constriction-proof tubing.
8.8 Submit at least one unused and unopened sealed blank
8.3 Perform a leak check of the sampling system by
which is used to monitor the supplies purchased as well as
activating the pump with the closed cassette and rotameter (or
procedures used in the laboratory. The sealed blank shall be
other flow measurement device) in line. Any flow indicates a
representative of filters used in sample collection (for example,
leak that must be eliminated before starting the sampling
same filter lot number).
operation.
9. Transport of Samples
8.4 Remove the inlet plug from the sampling cassette to
eliminate any vacuum that may have accumulated during the
9.1 Ship the samples in a rigid container with sufficient
leak test, then remove the entire inlet cap. packing material to prevent jostling or damage. Care shall be
8.5 Conduct personal and area sampling as follows:
taken to minimize vibrations and cassette movement.
8.5.1 For personal sampling, fasten the sampling cassette to
NOTE 5—Do not use shipping material that may develop electrostatic
the worker’s lapel in the worker’s breathing zone and orient it
forces or generate dust.
face down. Adjust the calibrated flow rate to a value between
NOTE 6—Shipping containers for 25-mm sampling cassettes are com-
0.5 and 4 L/min (1). Typically, a sampling rate between 0.5 and
mercially available and their use is recommended.
2.5 L/min is selected (2-4,6,7). Also see Test Method D 4532.
9.2 Include in the container a list of samples, their descrip-
8.5.2 Place area samples on an extension rod facing down at
tions, and all other pertinent information.
a 45° angle. Adjust the calibrated flow rate to a value between
10. Specimen Preparation
0.5 and 16 L/min (1). Typically, a sampling rate between 1 and
10 L/min is selected (8).
10.1 The objective of the specimen preparation technique is
8.5.3 Set the sampling flow rate and time to
...