ASTM F2381-04
(Test Method)Standard Test Method for Evaluating Trans-Vinylene Yield in Irradiated Ultra-High-Molecular-Weight Polyethylene Fabricated Forms Intended for Surgical Implants by Infrared Spectroscopy
Standard Test Method for Evaluating Trans-Vinylene Yield in Irradiated Ultra-High-Molecular-Weight Polyethylene Fabricated Forms Intended for Surgical Implants by Infrared Spectroscopy
SIGNIFICANCE AND USE
Published literature shows that the yield of radiolytic reactions that occur during radiation treatment increases with radiation dose level. Measurement of the products of these reactions can be used as an internal dosimeter.
Trans-vinylene unsaturations are formed during ionization treatment by abstraction of a hydrogen molecule, and to a lesser extent by the recombination of two adjacent alkyl free radicals that reside on the same chain.
Previous work generated calibration curves of trans-vinylene absorption area as a function of absorbed radiation dose, yielding a linear relationship for both gamma- and electron beam-irradiated polyethylene.
This data can be used to determine received dose as a function of position, assuming a calibration curve (TVI versus radiation dose level) is known for the particular material and radiation conditions used, and can be used to determine uniformity of dose level in irradiated polyethylene.
SCOPE
1.1 This test method describes the measurement of the number of trans-vinylene groups in ultra-high molecular weight-weight polyethylene (UHMWPE) intended for use in medical implants. The material is analyzed by infrared spectroscopy.
1.2 This test method is based on Guide F 2102.
1.3 The applicability of the infrared method has been demonstrated in other literature reports. This particular method, using the intensity (area) of the C-H absorption centered at 1370 cm-1 to normalize for the samples thickness, will be validated by an Interlaboratory Study (ILS) conducted according to Practice E 691.
1.4 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
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Standards Content (Sample)
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Designation: F2381 – 04
Standard Test Method for
Evaluating Trans-Vinylene Yield in Irradiated Ultra-High-
Molecular-Weight Polyethylene Fabricated Forms Intended
for Surgical Implants by Infrared Spectroscopy
This standard is issued under the fixed designation F2381; 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 3.1.1 trans-vinylene index (TVI)—a trans-vinylene index is
defined as the ratio of the absorption peak area between 950
1.1 This test method describes the measurement of the
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and 980 cm to the absorption peak area between 1330 and
number of trans-vinylene groups in ultra-high molecular
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1396 cm .
weight-weight polyethylene (UHMWPE) intended for use in
3.1.2 depth locator (DL)—a measurement of the distance
medical implants. The material is analyzed by infrared spec-
fromthearticularsurface,orsurfaceofinterest,thataspectrum
troscopy.
was collected and a corresponding TVI calculated.
1.2 This test method is based on Guide F2102.
3.1.3 trans-vinylene index profile—a trans-vinylene index
1.3 The applicability of the infrared method has been
profile is defined as the graphical representation of variation of
demonstrated in other literature reports. This particular
the sample’s trans-vinylene index with distance from its
method, using the intensity (area) of the C-H absorption
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articular surface or the surface of interest.This is a plot ofTVI
centered at 1370 cm to normalize for the sample’s thickness,
versus DL. Typically, the graph will show the profile through
will be validated by an Interlaboratory Study (ILS) conducted
the entire thickness of the sample.
according to Practice E691.
1.4 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 Published literature shows that the yield of radiolytic
responsibility of the user of this standard to establish appro-
reactions that occur during radiation treatment increases with
priate safety and health practices and determine the applica-
radiation dose level. Measurement of the products of these
bility of regulatory limitations prior to use.
reactions can be used as an internal dosimeter.
2. Referenced Documents 4.2 Trans-vinylene unsaturations are formed during ioniza-
tion treatment by abstraction of a hydrogen molecule, and to a
2.1 ASTM Standards:
lesser extent by the recombination of two adjacent alkyl free
E691 Practice for Conducting an Interlaboratory Study to
radicals that reside on the same chain.
Determine the Precision of a Test Method
4.3 Previous work generated calibration curves of trans-
E1421 Practice for Describing and Measuring Performance
vinylene absorption area as a function of absorbed radiation
of Fourier Transform Mid-Infrared (FT-MIR) Spectrom-
dose, yielding a linear relationship for both gamma- and
eters: Level Zero and Level One Tests
electron beam-irradiated polyethylene.
F2102 Guide for Evaluating the Extent of Oxidation in
4.4 This data can be used to determine received dose as a
Ultra-High-Molecular-Weight Polyethylene Fabricated
function of position, assuming a calibration curve (TVI versus
Forms Intended for Surgical Implants
radiation dose level) is known for the particular material and
3. Terminology
radiation conditions used, and can be used to determine
uniformity of dose level in irradiated polyethylene.
3.1 Definitions:
5. Apparatus
This test method is under the jurisdiction ofASTM Committee F04 on Medical
5.1 Infrared Spectrometer:
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
5.1.1 A calibrated infrared spectrometer capable of record-
F04.15 on Materials Test Methods.
ing a transmission absorption spectrum over a minimum range
Current edition approved Apr. 1, 2004. Published April 2004. DOI: 10.1520/
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F2381-04.
of 900 to about 2000 cm using about 200 µm-thick films at a
For referenced ASTM standards, visit the ASTM website, www.astm.org, or -1
resolution of 4 cm and an aperture of approximately 200 by
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
200 µm for a rectangular aperture, or 200 µm diameter for a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. circular aperture.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2381 – 04
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5.1.1.1 Other modes of collection (that is, reflection, attenu- trans-vinylene absorbance at 965 cm . This rippling is caused
ated total reflection (ATR), and so forth) and aperture and by internal reflection of the infrared beam, and can be avoided
sampling step sizes may be used to generate the sample’s by lightly rubbing the sample film against 400 grit sandpaper
absorption spectrum provided they can be demonstrated to until the film becomes translucent. This roughening procedure
produce equivalent results. Too large an aperture can result in should be done slowly to avoid heating the film, and should be
a loss of profile accuracy. performed until the area under a single peak due to Fourier
5.1.1.2 When a Fourier Transform Infrared (FTIR) spec- rippling is less than 10 % of the area under the trans-vinylene
trometer is used, a minimum of 32 scans shall be collected per peak.
spectrum.
5.1.1.3 The FTIR instrument and sample compartment 7. Preparation of Apparatus
should be purged with a moisture- and carbon-dioxide-free
7.1 Prepare the infrared spectrometer for collection of a
inert gas (for example, nitrogen, helium, or argon) to minimize
transmission absorption spectrum from a thin film of the
spectral interference from these components.
UHMWPEsampleaccordingtothemanufacturer’srecommen-
5.2 Specimen Holder—Equipment, such as an x-y table,
dations, Practice E1421, and the conditions described in 5.1.
capable of accurately positioning the sample under the FTIR
aperture with a minimum resolution at the scale of the aperture
8. Procedure
dimensions.
8.1 The test film (slice) shall be first configured in the
5.3 Microtome—Equipment capable of producing films of
spectrometer (after an appropriate background spectrum has
thickness 200 µm or less of a sample perpendicular to the
been collected) such that the aperture is positioned over the
articular surface or the surface of interest.
first 200 µm of the film starting at the surface of interest.
8.2 Subsequent spectra shall be collected sequentially at
6. Sampling, Test Specimens, and Test Units
increments matching the aperture size (that is, about 200 µm)
6.1 Using a microtome, or other appropriate device, prepare
from the articular surface, or surface of interest, across the
a thin slice of the sample about 200 µm thick. If the detected
width of the film to the opposite surface.
signal from the FTIR is too weak with this thickness, a thicker
8.3 Larger increments may be used; however, too large an
sample may be used.
increment size may result in a loss of profile accuracy.
6.2 The slice shall typically be taken near the center of the
sample’s articular surface or the surface of interest.
9. Calculation of Results
6.3 The orientation of the slice shall typically be perpen-
dicular to the
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