1、Designation: F2102 13F2102 17Standard Guide forEvaluating the Extent of Oxidation in PolyethyleneFabricated Forms Intended for Surgical Implants1This standard is issued under the fixed designation F2102; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers a method for the measurement of the relative extent of oxidation pr
3、esent in HDPE homopolymers andultra-high-molecular-weight polyethylene (UHMWPE) intended for use in medical implants. The material is analyzed by infraredspectroscopy. The intensity (area) of the carbonyl absorptions (C=O) centered near 1720 cm-1 is related to the amount ofchemically bound oxygen pr
4、esent in the material. Other forms of chemically bound oxygen (C-O-C, C-O-O-C, C-O-H, and soforth) are not captured by this guide.1.2 Although this guide may give the investigator a means to compare the relative extent of carbonyl oxidation present invarious UHMWPE samples, it is recognized that oth
5、er forms of chemically bound oxygen may be important contributors to thesematerials characteristics.1.3 The applicability of the infrared method has been demonstrated by many literature reports. This particular method, usingthe intensity (area) of the C-H absorption centered near 1370 cm-1 to normal
6、ize for the samples thickness, has been validated byan Interlaboratory Study (ILS) conducted according to Practice E691.1.4 The following precautionary caveat pertains only to the test method portion, Section 5, of this specification: This standardmay involve hazardous materials, operations, and equ
7、ipment. 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 practicesand determine the applicability of regulatory requirements prior to use.1.5 This int
8、ernational standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Co
9、mmittee.2. Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE2857 Guide for Validating Analytical Methods3. Terminology3.1 Definitions:3.1.1 bulk oxidation index (BOI)a samples bulk oxidation index (BOI) is the a
10、verage of the oxidation indices collected overa 500-m section at the center of the sample.3.1.1.1 DiscussionTypically, this is a plateau region with the smallest oxidation indices.3.1.1.2 Discussion1 This guide is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Dev
11、ices and is the direct responsibility of Subcommittee F04.15on Material Test Methods.Current edition approved Nov. 1, 2013Sept. 1, 2017. Published December 2013September 2017. Originally approved in 2001. Last previous edition approved in 20062013as F2102 06F2102 13.1. DOI: 10.1520/F2102-13.10.1520/
12、F2102-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intende
13、d only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current
14、versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1For samples less than about 8 to 10 mm thick, this central region may display the samples highest ox
15、idation indices, dependingon its state of oxidation.3.1.2 depth locator (DL)a measurement of the distance from the articular surface, or surface of interest, that a spectrum wascollected and a corresponding OI calculated.3.1.3 oxidation index (OI)an oxidation index (OI) is defined as the ratio of th
16、e area of the carbonyl absorption peak(s) centerednear 1720 cm-1 to the area of the absorption peak(s) centered near 1370 cm-1, as shown in Fig. 1. Note that the peak areas arecomputed after subtracting out the appropriate baseline, as further discussed in Section 6.3.1.4 oxidation index profilean o
17、xidation index profile is the graphical representation of variation of the samples oxidationindex with distance from its articular surface or the surface of interest. This is a plot of an OI versus DL. Typically, the graph willshow the profile through the entire thickness of the sample.3.1.5 surface
18、 oxidation index (SOI)a samples surface oxidation index (SOI) is the average of the oxidation indices from thesamples articular surface, or the surface of interest, to a depth of 3-mm subsurface.4. Apparatus4.1 Infrared Spectrometer:4.1.1 A calibrated infrared spectrometer capable of recording a tra
19、nsmission absorption spectrum over the range of about 1200to about 2000 cm-1 using about 200-sm-thick films at a resolution of 4 cm-1 and an aperture of about 200 by 200 m.FIG. 1 Typical FTIR Spectra of Oxidized UHMWPE, Showing the Definition of an Area-Based Oxidation Index Based on NormalizationUs
20、ing the 1370-cm-1 PeakFIG. 2 FTIR Spectra Showing the Carbonyl Absorption BandsNOTE 1Note that both reagents effectively extracted the lipids (the lipid absorption peak is centered at approximately 1740 cm-1). The tibial insertwas fabricated from highly crosslinked and remelted UHMWPE followed by te
21、rminal sterilization in EtO gas (Ref. 1).F2102 1724.1.1.1 Other modes of collection (that is, percent reflection, attenuated total reflection (ATR), and so forth) and aperture andincrement sizes may be used to generate the samples absorption spectrum provided they can be demonstrated to produceequiv
22、alent results. Too large an aperture can result in a loss of profile accuracy.4.1.1.2 When a Fourier Transform Infrared (FTIR) spectrometer is used, a minimum of 32 scans shall be collected perspectrum.spectrum as a default. A fewer number of scans may be performed if a user can verify that their FT
23、IR spectrometer canreproducibly measure the OI with less than 0.03 difference in OI compared with the result obtained using the default number ofscans. In no case shall an OI be reported based on fewer than 8 scans per spectrum. Guide E2857 provides guidance on how tovalidate analytical methods, whi
24、ch the user may use to determine the appropriate number of scans for their laboratory. Dependingon the level of oxidation in the tested samples, the user may elect to establish a lower threshold value of OI (nominally 0.01),particularly for UHMWPE samples that exhibit little to no detectable oxidati
25、on.4.1.1.3 The FTIR instrument and sample compartment may be purged with a moisture-free inert gas (for example, nitrogen,helium, or argon) to minimize spectral interference from these components.4.2 Specimen HolderEquipment capable of accurately positioning the sample under the orifice in increment
26、s at the scale ofthe aperture dimensions.4.3 MicrotomeEquipment capable of producing about 200-m-thick slices (films) of a sample perpendicular to the articularsurface or the surface of interest.5. Procedure5.1 Preparation of the Infrared Spectrometer:5.1.1 Prepare the infrared spectrometer for coll
27、ection of a transmission absorption spectrum from a thin film of the UHMWPEsample according to the manufacturers recommendations and the conditions described in Section 4 above.5.1.2 Collect the sequence of spectra per 5.2 and 5.3.5.2 Preparation of the Test Specimen:5.2.1 Using a microtome, or othe
28、r appropriate device, prepare a thin slice of the sample about 200 m thick.5.2.2 The slice shall be taken near the center of the samples articular surface or the surface of interest.5.2.3 The orientation of the slice shall typically be perpendicular to the articular surface or the surface of interes
29、t.5.2.4 For explanted components retrieved after in vivo use or in vitro samples that have been exposed to lipids (for example,simulator specimens exposed to lubricants containing serum), the film should be submerged in a reagent (heptane or hexane) toextract lipids from the polymer that interfere w
30、ith the carbonyl peak absorptions. The extraction technique should be verified toconfirm that the oxidation level has stabilized.5.3 Configuration of the Test Specimen in the Spectrometer:5.3.1 The test film (slice) shall be first configured in the spectrometer (after an appropriate background spect
31、rum has beencollected) such that the aperture is positioned over the first 200 m of the film starting at the surface of interest.5.3.2 Subsequent spectra shall be collected sequentially at increments matching the aperture size (that is, about 200 m) fromthe articular surface, or surface of interest,
32、 across the width of the film to the opposite surface.5.3.2.1 Larger increments may be used; however, too large an increment size may result in a loss of profile accuracy.6. Calculations6.1 Oxidation Peak Area (OA):6.1.1 For each absorbance spectrum, calculate the total area of the carbonyl peak abs
33、orptions centered near 1720 cm-1 (Fig. 1).6.1.1.1 This is the area below the samples carbonyl absorption curve and above the straight line baseline drawn between thestarting and ending points.6.2 Normalization Peak Area (ON):6.2.1 For each absorbance spectrum, calculate the total area of the peak ab
34、sorptions centered near 1370 cm-1 (Fig. 1).6.2.1.1 This is the area below the samples absorption curve and above the straight line baseline drawn between the samestarting and ending points.6.3 Oxidation Index (OI):6.3.1 For each absorbance spectrum, calculate its OI by dividing the area of its oxida
35、tion peak (6.1) by the area of itsnormalization peak (6.2), as shown in Fig. 1.6.4 Oxidation Index Depth Locator (DL):6.4.1 Calculate the distance from the articular surface, or surface of interest (DL), for each spectrum and its corresponding OIfrom the following equation.DL50.5A!1nS!where:A = the
36、size of the aperture in micrometres in the step direction,F2102 173n = the number of steps (increments) the aperture had been moved from its initial location at the articular surface or surface ofinterest, andS = the step (increment) size in micrometres.6.5 Samples Oxidation Index ProfileConstruct a
37、 plot of a samples oxidation indices (OI) versus the corresponding depthlocators (DLs).6.6 Surface Oxidation Index (SOI)Calculate a samples SOI by calculating the average of the samples oxidation indices (OI)with depth locator (DL) values between 0 and 3000.6.7 Bulk Oxidation Index (BOI)Calculate a
38、samples BOI by calculating the average of the samples oxidation indices (OIs)corresponding to the center 500 mm of material.6.8 Maximum Oxidation Index (MOI)Calculate the samples MOI index observed between depth locator (DL) values of 0 and3000.7. Report7.1 The report shall contain at least the foll
39、owing experimental details and results:7.1.1 Material Information:7.1.1.1 Resin type and resin lot number.7.1.1.2 Consolidation method and manufacturer and manufacturer lot number.7.1.1.3 Any special post-consolidation treatments, for example, shot isostatic pressing (HIPing), annealing, sterilizati
40、on,cross-linking, stabilization, accelerated aging, and storage conditions.7.1.2 Sample Information:7.1.2.1 Orthopedic implant or laboratory test specimen.7.1.2.2 Time elapsed between sample preparation and testing in the FTIR.7.1.2.3 Articular surface or non-articulator surface.7.1.2.4 Test samples
41、 original dimensions.7.1.2.5 Any special post-treatments of the original test sample, for example, annealing, sterilization, cross-linking, stabilization,accelerated aging, and storage conditions.7.1.2.6 Test film thickness and total width.7.1.2.7 Any special post-treatments of the test films, for e
42、xample, annealing, sterilization, cross-linking, stabilization,accelerated aging, and storage condition.7.1.2.8 Describe sample fixturing (for example, pressed between KBr plates).7.1.3 Spectrometer Information:7.1.3.1 Manufacturer and model number.7.1.3.2 Analogue or Fourier Transform spectrometer.
43、7.1.3.3 Aperture dimensions, profile step size, spectral resolution, and number of scans per spectrum.7.1.4 Data Analysis Information:7.1.4.1 Manual or by spectrometers software algorithms.7.1.4.2 Calculated SOI, BOI, and MOI.7.1.4.3 Calculated SOI, BOI, and MOI values of less than 0 reflect noise o
44、r uncertainty in the baseline and shall be assigneda value of 0. The rationale for this interpretation of very low oxidation values is discussed in X1.10.8. Precision and Bias8.1 PrecisionThe data in Table 1 is based on a series of international interlaboratory studies using this method which wereco
45、nducted in 1999 and 2000, in accordance with Practice E691, involving up to twelve institutions across the United States andEurope. Metrics of repeatability and reproducibility between different institutions were calculated as outlined in Practice E691 andnormalized with respect to the mean oxidatio
46、n index to estimate relative uncertainty. The data for the GUR 4150 HProd stock wereTABLE 1 International Interlaboratory Study Test ResultsUHMWPE Resin,Component Type Shelf Age,Average OxidationIndex (OI), Absolute UncertaintyStandardRelative Uncertaintyyears x sx sr sR sr, % sR, %GUR 4150 HP, rods
47、tock0.0 0.232 0.077 0.017 0.078 7.2 33.8GUR 1120, tibialinsert5.3 1.28 0.138 0.040 0.142 3.1 11.1GUR 1120, tibialinsert7.5 4.51 0.823 0.168 0.834 3.7 18.5GUR 1120, tibialinsert11.5 4.53 0.823 0.483 0.912 10.7 20.2F2102 174collected on as-irradiated microtomed samples. For the long-term shelf-aged ti
48、bial implants, the data were collected below thesurface at the location of maximum oxidation. All samples were 200-m-thick microtomed films gamma irradiated in air.8.2 BiasNo statement may be made about the bias of this test method, as there is no standard reference material or referencetest method
49、that is applicable.9. Keywords9.1 FTIR; implant; oxidation; oxidation index; UHMWPEAPPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 The extent of overall oxidation and specifically certain oxidation index profiles present in orthopaedic implant componentsmade of UHMWPE have been shown to degrade their mechanical properties and thus potentially adversely affect their in vivoperformance. It is, therefore, important to have standard methods for assessing the oxidative characteristics of such materials.X1.2 The method described
