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SEMI F48-0600 © SEMI 2000 6 11.3.8 Set the parameters of the diges t i o n device to manufacturer’ s reco mm endations. NOTE 10: If the pressure exceed s the pressu re limits of the vessel, the pressure w ill be reduced …

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SEMI F48-0600 © SEMI 20005
11 Sampling
11.1 Sampling of Test Specimens
11.1.1 Test specimens shall be representative of the
polymer material being tested and shall be free of
embedded particles and extraneous surface
contamination when visually inspected.
11.1.2 Two samples of each material shall be prepared
per SEMI F40. This test is performed in duplicate.
More samples may be analyzed if desired.
NOTE 5: The samples are cleaned and weighed according to
SEMI F40. The sample preparation described in this
document begins with either the ashing (DDA) or digestion
under pressure (DCV) of the polymer material.
11.2 Sample Preparation – Digestion by Dry Ashing
(DDA)
NOTE 6: Digestion by ashing using an oxygen plasma asher
differs considerably from the described procedures that refer
to ashing in open crucibles. Specific instructions are available
from the instrument manufacturers.
11.2.1 Clean the digestion container and cover using
appropriate methods for the vessel materials and
procedures being employed.
11.2.2 Place the sample into a cleaned crucible. For at
least two additional samples, add the recovery spike as
discussed in Section 12.
11.2.3 Use a propane torch or other appropriate heat-
ing source to carefully flame the outside of the crucible
until the polymer inside the crucible is completely
charred. Do not flame exceedingly, i.e., do not allow a
platinum crucible, for example, to become red hot, as
excessive heat will allow some metals to volatilize.
NOTE 7: This step must be carried out in a well-ventilated
fume hood.
11.2.4 Prepare at least three procedural blanks by
flaming three or more empty crucibles using the method
discussed in Section 11.2.3. The results from these
blanks will be used to determine the metallic
contribution from the crucibles themselves, from the
reagents and from the test procedure. These procedural
blanks should be treated like any other sample.
Crucibles should be rotated in and out of service so that
the same crucibles are not always used for blanks.
11.2.5 Place the charred sample crucibles and blank
crucibles in a muffle furnace, cover the crucibles with
the cleaned covers, and continue to char at 500 to
650°C until all the carbon is removed (usually over a
period of 6–18 hrs). The removal of all carbon is indi-
cated by the absence of black material in the sample.
NOTE 8: Some oxides (such as SnO
2
) are black and may
confound this determination. If a sample is still black after 18
hours, assume that it is an oxide and continue with the
procedure.
11.2.6 Allow the crucibles to cool.
11.2.7 Add the appropriate amount (1–2 mL) of
concentrated ultrapure hydrochloric acid to each
crucible.
11.2.8 Evaporate the hydrochloric acid to dryness in a
chemical hood at less than 100°C if necessary to permit
instrumental compatibility.
NOTE 9: The presence of chloride in the sample can result in
interferences for the determination of arsenic and vanadium
by ICP-MS.
11.2.9 Continue preparing the sample as described in
Section 11.4.
11.3 Sample Preparation – Digestion in Closed Vessel
(DCV)
11.3.1 Clean the digestion container and cover using
appropriate methods for the vessel materials and
procedures being employed.
11.3.2 Place the sample into a cleaned digestion
container. For at least two additional samples, add the
recovery spike as discussed in Section 12.
11.3.3 Add the reagents needed for the digestion.
11.3.4 Prepare at least three procedural blanks by
adding the same amount of all reagents, but no sample,
to three or more additional containers. The results from
these blanks will be used to determine the metallic
contribution from the containers themselves, from the
reagents and from the test procedure. These procedural
blanks should be treated like any other sample.
Containers should be rotated in and out of service so
that the same containers are not always used for blanks.
11.3.5 The analyst should be aware of the potential for
a vigorous reaction. If a vigorous reaction occurs upon
the initial addition of reagent or the sample is suspected
of containing easily oxidizable materials, allow the
sample to predigest in the uncapped digestion vessel.
Heat may be added in this step for safety considerations
(for example the rapid release of carbon dioxide from
easily oxidized polymeric material). Once the initial
reaction has ceased, the sample may continue through
the digestion procedure.
11.3.6 Seal the vessel according to the manufacturer’s
directions.
11.3.7 Properly place the vessel in the digestion
system according to the manufacturer’s recommended
specifications and connect appropriate temperature and
pressure sensors to vessels according to manufacturer’s
specifications.
SEMI F48-0600 © SEMI 2000 6
11.3.8 Set the parameters of the digestion device to
manufacturer’s recommendations.
NOTE 10: If the pressure exceeds the pressure limits of the
vessel, the pressure will be reduced by the relief mechanism
of the vessel.
NOTE 11: Pressure control for a specific matrix is applicable
if instrument conditions are established using temperature
control. Because each matrix will have a different reaction
profile, performance using temperature control must be
developed for every specific matrix type prior to use of the
pressure control system.
11.3.9 At the end of the digestion program, allow the
vessels to cool for an appropriate period of time before
removing them from the system. When the vessels
have cooled to near room temperature, determine if the
microwave vessels have maintained a seal throughout
the digestion. Due to the wide variability of vessel
designs, a single procedure is not appropriate. The use
of a spiked control sample is appropriate to ensure that
analyte loss has not occurred due to vessel venting. For
vessels with burst disks, a careful visual inspection of
the disk may identify compromised sample digestions.
11.3.10 Complete the preparation of the sample by
carefully uncapping and venting each vessel in a fume
hood. Vent the vessels using the procedure
recommended by the vessel manufacturer. Transfer the
sample to an appropriate acid cleaned container.
11.3.11 If the digested sample contains particulates,
which may clog nebulizers or interfere with injection of
the sample into the instrument, the sample may be
centrifuged, allowed to settle, or filtered.
11.3.11.1 If necessary, centrifugation at 2,000–3,000
rpm for 10 minutes is usually sufficient to clear the
supernatant.
11.3.11.2 Settling –– If undissolved material remains
such as TiO, or other refractory oxides, allow the
sample to stand until the supernatant is clear. Allowing
a sample to stand overnight will usually accomplish
this.
11.3.11.3 Filtering –– If necessary, the filtering
apparatus must be thoroughly cleaned and pre-rinsed
with dilute (approximately 10% V/V) nitric acid. Filter
the sample through qualitative filter paper into a second
acid-cleaned container.
11.3.12 Continue preparing the sample as described in
Section 11.4.
11.4 Preparation of the Sample for Analysis
11.4.1 If the sample was obtained from the DDA
method, add 0.5 mL concentrated nitric acid to each
crucible.
11.4.2 For samples obtained from the DCV method,
transfer or decant the sample into volumetric ware.
11.4.3 Dilute either obtained sample to a required
volume with ultrapure water (usually 20 mL).
Alternatively, a gravimetric dilution of the samples is
also appropriate. The samples are now ready for
analysis. See Related Documents, Section 16 for
applicable trace inorganics test methods.
12 Recovery Preparation and Percentage
Recovery Rate Determination
12.1 Metal recovery percentage must be determined
for all instruments by the individual laboratory. This is
accomplished via spiking a crucible or digestion vessel
containing a polymer sample with a known
concentration of metals. Then, determining the
percentage of each metal recovered after the
decomposition process or acid digestion. The following
provides the recommended method for spiking:
12.1.1 Add a known volume of a standard to a crucible
or digestion container containing a polymer sample.
12.1.2 For DDA –– Gently evaporate the standard
solution to dryness.
12.1.3 Digest the dried standard and dried polymer
using the same procedure as for the samples. Typical
recovery rates are 70–110% for the alkali, alkaline
earths, and most transition metals.
13 Data Analysis
13.1 Calculations
13.1.1 The concentration of trace metals in the
solution must be calculated to determine the
concentration in µg/g (ppm) of the polymeric material
using the following equation:
polymer concentration (µg/g ) =
= solution concentration
(µg/L) × solution volume (L) / mass of the polymer(g)
13.1.2 Since the procedural blank does not contain a
weighed sample, the results must be transformed to
solid concentrations (in µg/g) by using the average
weight of the samples (see Section 11.1.2 and
corresponding NOTE).
14 Data Presentation
NOTE 12: Use the Report Form provided in Section 17 of this
document.
14.1 Sample Information
14.1.1 Provide the date(s) of the test, the person and/or
company requesting the analysis, the method in which
the sample was obtained (e.g., if it was separated from a
SEMI F48-0600 © SEMI 20007
larger component and delivered to the laboratory),
operator and laboratory performing the test, type of
material (e.g., PFA pellets, injection molded PVDF
valve, perfluoroelastomer O-ring), material supplier,
material model and lot number(s), date sample was
obtained and if the sample is a prototype or production
material.
14.2 Methods
14.2.1 Provide the method of cleaning the sample as
well as indicating if the sample arrived pre-cleaned
from the requester or if it was cleaned in the laboratory
performing the test.
14.2.2 Check the applicable box for the type of
digestion. Complete as well the information regarding
the conditions.
14.3 Results
14.3.1 Use Table 1, Trace Metals in Bulk Polymer
Worksheet in Section 17.3 to report the results of the
analysis along with detection limits and recovery rates
for all elements required in the samples.
NOTE 13: For this document, the detection limit is defined as
the concentration equivalent to three standard deviations of
the results of the procedural blanks (see Section 13.1.2).
NOTE 14: The procedural blanks should be averaged and
then subtracted from each sample (see Columns 3 and 4 of
Table 1).
NOTE 15: If multiple samples of the same polymer material
are evaluated, an average and standard deviation must be
reported.
15 Precision and Bias
15.1 Expected variations in the blank are due to
environmental and instrument variation.
15.2 Expected variation in the samples is 20–30% and
is due to environmental, instrumental, and ashing or
digestion variations.
15.3 This test does not give an indication of the
variations found in the polymer sample material.
15.3.1 Analyze multiple samples of the same polymer
material to determine the variation.
15.3.2 Refer to ASTM D4375 for information
regarding sample populations to determine differences
between materials.
16 Related Documents
16.1 References Pertaining to ICP–MS
Dams, R. F. J., Goossens, J., Moens, L. “Spectral and
Non-Spectral Interferences in Inductively Coupled
Plasma Mass Spectrometry” Microchim. Acta 119
(1995):277-286.
Evans, E. H., Giglio, J. J., “Interferences in Inductively
Coupled Plasma Mass Spectrometry” J Anal. Atom.
Spectrom. 8 (1993):1-18.
Jarvis, K. E., Gray, A. L., Houk, R. S. “Handbook of
Inductively Coupled Plasma mass Spectrometry”
Blackie, Glasgow 1992 (USA: Chapman and Hall, New
York).
Shao, Y. and G. Horlick. “Recognition of Mass Spectral
Interferences in Inductively Coupled Plasma–Mass
Spectrometry.” Applied Spectroscopy 45 (1991):143.
16.2 References Pertaining to ICP–AES
Garbarino, J.R., B.E. Jones, G.P. Stein, W.T. Belser,
and H.E. Taylor. “Statistical Evaluation of an ICP–AES
Method for Routine Water Quality Testing.” Applied
Spectroscopy 39 (1985):535.
Winge, R.K., V.S.Fassel, R.N. Kniseley, E. De Kalb,
and W.J. Haas Jr. “ICP as an Analytical Source.”
Spectrochimica Acta 32B (1977):327
16.3 References Pertaining to Microwave Digestion
Kingston, H. M. Skip and Haswell, Steve, Eds.,
Microwave Enhanced Chemistry: Fundamentals,
Sample Preparation, and Applications, ACS
Professional Reference Book Series, American
Chemical Society, Washington, DC, 1997.
16.4 U.S. EPA Documents
3
U.S. EPA Method 3052 –– Microwave Assisted Acid
Digestion of Siliceous and Organically Based Matrices
U.S. EPA RCRA SW-846 –– Chapter 3, sections on
clean chemistry and microwave decomposition.
16.5 SEMATECH Documents
4
SEMASPEC #92010956B–STD –– SEMATECH
Provisional Test Method for Analyzing the Plastic
Surface Composition and Chemical Bonding of
Components of UPW Distribution Systems (ESCA
Method)
SEMASPEC #92010936B–STD –– SEMATECH
Provisional Test Method for the Determination of
Leachable Trace Inorganics from UPW Distribution
System Components
3 Environmental Protection Agency, 401 M St., SW, Washington, DC
20460, USA
4 SEMATECH, 2706 Montopolis Dr., Austin TX 78741