ASTM F1877-16

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Designation: F1877 − 05 (Reapproved 2010) F1877 − 16
Standard Practice for
Characterization of Particles
This standard is issued under the fixed designation F1877; 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
1.1 This practice covers a series of procedures for characterization of the morphology, number, size, and size distribution of
particles. The methods utilized include sieves, optical, SEM, scanning electron microscopy (SEM), transmission electron
microscopy (TEM), and electrooptical.
1.2 These methods are appropriate for particles produced by a number of different methods. These include wear test machines
(Test Method F732), total joint simulation systems (Guides F1714 and F1715), abrasion testing, methods for producing
particulates, such as shatter boxes or pulverizors,pulverizers, commercially available particles, and particles harvested from tissues
in animal or clinical studies.
1.3 The debris may include metallic, polymeric, ceramic, or any combination of these.
1.4 The digestion procedures to be used and issues of sterilization of retrieved particles are not the subject of this practice.
1.5 A classification scheme for description of particle morphology is included in Appendix X3Appendix X3.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 As a precautionary measure, removed debris from implant tissues should be sterilized or minimally disinfected by an
appropriate means that does not adversely affect the particulate material.
1.8 As a precautionary measure, removed debris from implant tissues should be sterilized or minimally disinfected by an
appropriate means that does not adversely affect the particulate material.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.
2. Referenced Documents
2.1 ASTM Standards:
C242 Terminology of Ceramic Whitewares and Related Products
C678 Test Method for Determination of Particle Size Distribution of Alumina or Quartz Using Centrifugal Sedimentation
(Withdrawn 1995)
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
E161 Specification for Precision Electroformed Sieves
E766 Practice for Calibrating the Magnification of a Scanning Electron Microscope
E1617 Practice for Reporting Particle Size Characterization Data
F561 Practice for Retrieval and Analysis of Medical Devices, and Associated Tissues and Fluids
F660 Practice for Comparing Particle Size in the Use of Alternative Types of Particle Counters
F661 Practice for Particle Count and Size Distribution Measurement in Batch Samples for Filter Evaluation Using an Optical
Particle Counter (Discontinued 2000) (Withdrawn 2000)
F662 Test Method for Measurement of Particle Count and Size Distribution in Batch Samples for Filter Evaluation Using an
Electrical Resistance Particle Counter (Discontinued 2002) (Withdrawn 2002)
F732 Test Method for Wear Testing of Polymeric Materials Used in Total Joint Prostheses
This practice is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.16
on Biocompatibility Test Methods.
Current edition approved June 1, 2010Oct. 1, 2016. Published September 2010October 2016. Originally approved in 1998. Last previous edition approved in 20052010
ε1
as F1877 – 05 (2010). . DOI: 10.1520/F1877-05R10. 10.1520/F1877-16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
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F1877 − 16
F1714 Guide for Gravimetric Wear Assessment of Prosthetic Hip Designs in Simulator Devices
F1715 Guide for Wear Assessment of Prosthetic Knee Designs in Simulator Devices (Withdrawn 2006)
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 agglomerate, n—a jumbled mass or collection of two or more particles or aggregates, or a combination thereof, held
together by relatively weak cohesive forces caused by weak chemical bonding or an electrostatic surface charge generated by
handling or processing.
3.1.2 aggregate, n—a dense mass of particles held together by strong intermolecular or atomic cohesive forces that is stable
towith normal mixing techniques, including high-speed stirring and ultrasonics.
3.1.3 flocculate, n—a group of two or more attached particles held together by physical forces, such as surface tension,
adsorption, or similar forces.
3.1.4 aspect ratio (AR), n—a ratio of the major to the minor diameter of a particle, which can be used when the major axis does
not cross a particle outline (see 11.3.3).
3.1.5 elongation (E), n—ratio of the particle length to the average particle width (see 11.3.4).
3.1.6 equivalent circle diameter (ECD), n—a measure of the size of a particle (see 11.3.2 and Appendix X1).
3.1.7 Feret diameter, n—the mean value of the distance between pairs of parallel tangents to a projected outline of a particle.
3.1.7 flocculate, n—a group of two or more attached particles held together by physical forces, such as surface tension,
adsorption, or similar forces.
3.1.8 form factor (FF), n—a dimensionless number relating area and perimeter of a particle, as determined in 11.3.6.
3.1.9 irregular, adj—referring to a particle that cannot be described as round or spherical. A set of standard nomenclature and
reference figures are given in Appendix X2.
3.1.10 particle, n—the smallest discrete unit detectable as determined in test methods. A nanoparticle has at least one dimension
less than 100 nm.
3.1.11 particle breadth, n—distance between touch points of the shortest Feret pair, orthogonal to length.
3.1.12 particle length, n—distance between the touch points of maximum Feret pair. This value will be greater than or equal
to the maximum Feret diameter.
3.1.13 rectangular, adj—referring to a particle that approximates a square or rectangle in shape.
3.1.14 roundness (R), n—a measure of how closely an object represents a circle as determined in 11.3.5.
3.1.15 spherical, adj—referring to a particle with a generally spherical shape that appears round in a photograph.
4. Summary of Practice
4.1 Particles produced by implant wear in vivo in animal or clinical studies are harvested from tissues after digestion utilizing
methods, such as those in Practice F561. Particles generated in vitro, or obtained from commercial sources, are used as received,
or after digestion, if they were generated in protein solutions, and further separation if there are signs of aggregation. A two level
analysis is provided. For routine analysis, the particles are characterized by the terms of morphology and by size using Feret
diameters. For more detailed studies, several methods are described that may be utilized for numerically characterizing their
dimensions, size distribution, and number.number are described.
5. Significance and Use
5.1 The biological response to materials in the form of small particles, as from wear debris, often is significantly different from
that to the same materials as larger implant components. The size and shape (morphology) of the particles may have a major effect
on the biological response; therefore, this practice provides a standardized nomenclature for describing particles. Such a unified
nomenclature will be of value in interpretation of biological tests of responses to particles, in that it will facilitate separation of
biological responses associated with shape from those associated with the chemical composition of debris.
5.2 The quantity, size, and morphology of particles released as wear debris from implants in vivo may produce an adverse
biological response which will affect the long term survival of the device. Characterization of such debris will provide valuable
information regarding the effectiveness of device designs or methods of processing components and the mechanisms of wear.
5.3 The morphology of particles produced in laboratory tests of wear and abrasion often is affected by the test conditions, such
as the magnitude and rate of load application, device configuration, and test environment. Comparison of the morphology and size
of particles produced in vitro with those produced in vivo will provide valuable information regarding the degree to which the
method simulates the in vivo condition being modeled.
F1877 − 16
6. Interferences
6.1 Particles may form aggregates or agglomerates during preparation and storage. These wouldcould result in an increase in
measured particle size and decrease in particle number. It is essential that care be taken to resuspend particles prior to analysis and
to note any effects of the dispersant used.
6.2 Debris from wear tests or harvested from tissues may contain a mixture of materials. Care should be taken to separate the
particles and methods utilized to determine the chemical composition of the particles.
6.3 Many automated particle counters operate on the assumption that the particles are spherical. These methods may not be
appropriate for nonspherical debris. Additional methods should be used to verify size using methods that take aspect ratio into
consideration, for example, SEM or TEM image analysis.
7. Apparatus
7.1 Scanning Electron Microscope (SEM) (see Practice E766):
7.1.1 Standard SEM equipment can be utilized for many studies. In special instances, such as with polymeric particles, a low
acceleration voltage (1-2 kV) machine with a high brightness electron source, such as a field emission tip, may be utilized.
7.1.2 Elemental analysis may be accomplished with an energy dispersive spectrometer (EDS) for energy dispersive X-ray
analysis (EDXA).
7.2 Transmission Electron Microscopy (TEM):
7.2.1 TEM equipment can be used for the analysis of nanoparticles, although SEM with a field emission tip has also been
successfully used to characterize particles as small as 50 to 100 nm.
7.2.2 Elemental analysis may be accomplished with an energy dispersive spectrometer (EDS) for energy dispersive X-ray
analysis (EDXA).
7.3 Optical Microscope—An optical microscope operating in the transmission mode may be utilized. Dark field illumination
may enhance visualization of some particles. Polarized light will facilitate identification of semicrystalline polymeric materials.
7.4 Automatic Particle Counters (see Practice F660):
7.4.1 Image Analyzer—This instrument counts particles by size as those particles lie on a microscope slide.
7.4.2 Optical Counter—This instrument measures the area of a shadow cast by a particle as it passes a window. From this area
the instrument reports the diameter of a circle of equal area.
7.4.3 Electrical Resistance Counter—This instrument measures the volume of an individual particle. From that volume the
instrument reports the diameter of a sphere of equal volume (see Test Methods C678).
8. Reagents
8.1 Particle-Free (0.2 μm Filtered) Deionized Water, for nonpolymeric particles.
8.2 Particle-Free (0.2 μm Filtered) Methanol or Ethanol, for polymeric or mixed debris.
8.3 Ultra-Cleaning Reagent, for apparatus or labware cleaning.
9. Specimen Preparation
9.1 Specimens from explanted tissues from animal or clinical studies may need to be harvested and digested using methods,
such as those described in Practice F561.
9.2 Particles from in vitro cell culture tests also may need to be diges
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