ASTM F1926/F1926M-14(2021)

Standard Test Method for Dissolution Testing of Calcium Phosphate Granules, Fabricated Forms, and Coatings

SIGNIFICANCE AND USE
4.1 Aspects of the biological response to calcium phosphate materials in soft tissue and bone have been reported from laboratory studies and clinical use (1-11).3  
4.2 The requirements of this test method apply to calcium phosphate materials such as calcium hydroxyapatite (see Specification F1185), beta-tricalcium phosphate (see Specification F1088), and biphasic mixtures thereof with or without intentional addition of other minor (  
4.3 This test method is limited to the laboratory evaluation of the dissolution rate of a calcium phosphate material. No correlation of the results to in-vivo performance is implied. Therefore, it is recommended that a control material be included in the evaluation. The control material can be a standardized material such as NIST SRM 2910 or a historical control.
SCOPE
1.1 This test method covers calcium phosphate materials intended for use in surgical implant applications.  
1.2 The material(s) shall be representative of that produced for sale. It shall have been produced and processed under standard manufacturing conditions.  
1.3 The materials may be in the form of powders, granules, spall material, fabricated forms, or coatings; and may be porous, nonporous, textured, and other implantable topographical substrate form representative of the end-use product.  
1.4 The calcium phosphate material may constitute the only material in a substrate or it may be one of multiple materials so long as all other materials present do not dissolve under the test conditions described in this test method.  
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2021
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.13 - Ceramic Materials

Relations

• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM F1088-04a(2010) - Standard Specification for Beta-Tricalcium Phosphate for Surgical Implantation
• Effective Date: 01-Sep-2010
• Refers: ASTM F1185-03(2009) - Standard Specification for Composition of Hydroxylapatite for Surgical Implants
• Effective Date: 15-Jun-2009
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM F1088-04a - Standard Specification for Beta-Tricalcium Phosphate for Surgical Implantation
• Effective Date: 01-May-2004
• Refers: ASTM F1088-04ae1 - Standard Specification for Beta-Tricalcium Phosphate for Surgical Implantation
• Effective Date: 01-May-2004
• Refers: ASTM F1088-04 - Standard Specification for Beta-Tricalcium Phosphate for Surgical Implantation
• Effective Date: 01-Jan-2004
• Refers: ASTM F1185-03 - Standard Specification for Composition of Hydroxylapatite for Surgical Implants
• Effective Date: 10-Apr-2003
• Refers: ASTM E691-99 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 10-May-1999
• Refers: ASTM F1088-87(1992)e1 - Standard Specification for Beta-Tricalcium Phosphate for Surgical Implantation
• Effective Date: 01-Jan-1992

Overview

ASTM F1926/F1926M-14(2021), titled Standard Test Method for Dissolution Testing of Calcium Phosphate Granules, Fabricated Forms, and Coatings, is a key international standard developed by ASTM International. This test method defines procedures for the laboratory assessment of dissolution rates of various forms of calcium phosphate materials used in surgical implant applications. Calcium phosphate biomaterials, including hydroxyapatite and beta-tricalcium phosphate, are widely used for their biocompatibility in contact with bone and soft tissue. This standard provides a framework for conducting dissolution testing under reproducible laboratory conditions, helping manufacturers and researchers evaluate the stability and performance characteristics of these materials before clinical use.

Key Topics

• Scope of the Standard

  • Addresses calcium phosphate materials intended for surgical implants.
  • Includes granules, powders, fabricated forms, spalls, and surface coatings in both porous and nonporous configurations.
  • Applicable to calcium hydroxyapatite, beta-tricalcium phosphate, biphasic mixtures, and materials that do not interact negatively under test conditions.

• Test Method Significance

  • Enables laboratory-based comparison of dissolution rates of different calcium phosphate materials.
  • Focuses exclusively on in vitro evaluation, with no direct correlation to in vivo (clinical) performance implied.
  • Recommends use of control materials (such as NIST SRM 2910) for comparative purposes.

• Testing Protocols

  • Utilizes standardized dissolution media and pH control to mirror physiological conditions.
  • Requires precise temperature control and agitation to ensure consistent and reliable measurements.
  • Supports use of various analytical techniques to quantify calcium ion concentration and monitor pH changes over time.

• Reporting and Precision

  • Outlines strict criteria for documenting dissolution rates, pH changes, test specimen preparation, and any deviations from standard procedures.
  • Emphasizes the importance of consistent laboratory practices for reproducibility.

Applications

The ASTM F1926/F1926M-14(2021) standard is pivotal for industries and laboratories engaged in:

• Medical Device Manufacturing

  • Assists in the preclinical evaluation of calcium phosphate coatings and materials used in orthopedic, dental, and other surgical implants.
  • Provides quality assurance benchmarks for material consistency, dissolution characteristics, and safety.

• Biomaterials Research and Development

  • Facilitates the comparison of new formulations, surface treatments, or fabrication technologies for calcium phosphate biomaterials.
  • Enables screening for bioresorption rates, predictive of long-term material performance and integration.

• Regulatory Compliance

  • Demonstrates adherence to globally accepted laboratory test methods for dissolution testing in submissions to regulatory bodies.
  • Supports the risk assessment processes required by health authorities and notified bodies.

• Academic and Industrial Research

  • Standardizes testing protocols across research institutions, allowing meaningful data comparison and sharing.

Related Standards

Several related ASTM standards complement or are referenced within ASTM F1926/F1926M-14(2021):

• ASTM F1088: Specification for Beta-Tricalcium Phosphate for Surgical Implantation.
• ASTM F1185: Specification for Composition of Hydroxylapatite for Surgical Implants.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.

These standards collectively support the safe and effective development of bioceramic materials for use in medical and dental implants.

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Keywords: ASTM F1926/F1926M-14, dissolution testing, calcium phosphate, hydroxyapatite, tricalcium phosphate, medical implants, biomaterials, laboratory test methods, surgical applications, coatings, bioceramics.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1926/F1926M − 14 (Reapproved 2021)
Standard Test Method for
Dissolution Testing of Calcium Phosphate Granules,
Fabricated Forms, and Coatings
ThisstandardisissuedunderthefixeddesignationF1926/F1926M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers calcium phosphate materials
E691Practice for Conducting an Interlaboratory Study to
intended for use in surgical implant applications.
Determine the Precision of a Test Method
1.2 The material(s) shall be representative of that produced
F1088Specification for Beta-Tricalcium Phosphate for Sur-
for sale. It shall have been produced and processed under
gical Implantation
standard manufacturing conditions.
F1185Specification for Composition of Hydroxylapatite for
Surgical Implants
1.3 The materials may be in the form of powders, granules,
spall material, fabricated forms, or coatings; and may be
3. Terminology
porous,nonporous,textured,andotherimplantabletopographi-
3.1 Definitions of Terms Specific to This Standard:
cal substrate form representative of the end-use product.
3.1.1 calcium phosphate, n—any one of a number of inor-
1.4 The calcium phosphate material may constitute the only
ganic chemical compounds containing calcium and phosphate
materialinasubstrateoritmaybeoneofmultiplematerialsso
ions as its principal constituents.
longasallothermaterialspresentdonotdissolveunderthetest
3.1.2 coating, n—layer of material mechanically or chemi-
conditions described in this test method.
cally adhering to the surface of a substrate.
1.5 The values stated in either SI units or inch-pound units
4. Significance and Use
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each
4.1 Aspectsofthebiologicalresponsetocalciumphosphate
system shall be used independently of the other. Combining
materials in soft tissue and bone have been reported from
values from the two systems may result in nonconformance
laboratory studies and clinical use (1-11).
with the standard.
4.2 The requirements of this test method apply to calcium
1.6 This standard does not purport to address all of the
phosphate materials such as calcium hydroxyapatite (see
safety concerns, if any, associated with its use. It is the
Specification F1185), beta-tricalcium phosphate (see Specifi-
responsibility of the user of this standard to establish appro-
cation F1088), and biphasic mixtures thereof with or without
priate safety, health, and environmental practices and deter- intentional addition of other minor (<10 %) components.
mine the applicability of regulatory limitations prior to use.
4.3 This test method is limited to the laboratory evaluation
1.7 This international standard was developed in accor-
of the dissolution rate of a calcium phosphate material. No
dance with internationally recognized principles on standard-
correlation of the results to in-vivo performance is implied.
ization established in the Decision on Principles for the
Therefore, it is recommended that a control material be
Development of International Standards, Guides and Recom-
included in the evaluation. The control material can be a
mendations issued by the World Trade Organization Technical
standardized material such as NIST SRM 2910 or a historical
Barriers to Trade (TBT) Committee. control.
1 2
ThistestmethodisunderthejurisdictionofASTMCommitteeF04onMedical For referenced ASTM standards, visit the ASTM website, www.astm.org, or
andSurgicalMaterialsandDevicesandisthedirectresponsibilityofSubcommittee contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
F04.13 on Ceramic Materials. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved June 1, 2021. Published June 2021. Originally the ASTM website.
published in 1998. Last previous edition approved in 2014 as F1926/F1926M–14. Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
DOI: 10.1520/F1926_F1926M-14R21. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1926/F1926M − 14 (2021)
++
5. Dissolution Media 6.1.2 The dissolved Ca concentration (61 ppm) shall be
measured as soon as practical after the start of the experiment
5.1 Water used for preparing reagents or dissolution media
and at appropriate time intervals thereafter to allow determi-
shall be degassed carbon dioxide free deionized or distilled
++ nation of changes with time.
water and have less than 0.1 ppm of residual Ca ion.
Optionally, the water can be degassed in situ.
7. Analytical Procedures
5.2 Unbuffered Water Media—Deionized or distilled water
–5 –5 –5
7.1 Make pH measurements with an appropriately cali-
containing8×10 M NaCl,8×10 M CaCl,and5×10
brated pH meter and probe.
MK (PO ).
3 4
++
7.2 Measure the Ca concentrations potentiometrically.
5.3 pH 5.5 MES Buffer Media—1.0 M MES, [2-(N-
Ionic strength adjuster (ISA) shall be added as required by the
morphplino)ethanesulfonic acid] having a pH of 5.5 at 37 6
–5 –5
electrode manufacturer. Other methods (for example,
0.5°Candcontaining8×10 MNaCl,8×10 MCaCl ,and
–5
colorimetrically, atomic absorption (AA), inductively coupled
5×10 MK (PO ).
3 4
plasma (ICP) spectroscopy, or inductively coupled plasma
5.3.1 A buffer concentration of 1.0 M will usually provide
mass spectroscopy (ICP/MS)) may be used if equivalency can
sufficient buffer capacity to keep the solution within 60.1 pH
be demonstrated.
units of the initial value. If this is not the case, the buffer
capacity should be adjusted accordingly.
7.3 An appropriate bacteriostat (for example, 0.1 v/v %
5.3.2 The pH shall be adjusted to 5.5 at 37 6 0.5°C using
Hibiclens or 0.1 w/v % sodium azide) may be added to the
HCl or NaOH solutions.
dissolution media before the start of an experiment.
5.4 pH 7.4 TRIS Buffer Media—1.0 M TRIS, [Tris(hy-
droxymethyl)aminomethane] having a pH of 7.4 at 37 6 8. Dissolution Apparatus
–5 –5
0.5°Candcontaining8×10 MNaCl,8×10 MCaCl ,and
8.1 The dissolution vessel shall be of such design as to
–5
5×10 MK (PO ).
3 4
easily accommodate the test specimen, the stirrer, and the
5.4.1 A buffer concentration of 1.0 M will usually provide
specific ion-electrode and reference electrode assemblies. It
sufficient buffer capacity to keep the solution within 60.1 pH
shall also be isolated from the atmosphere by an oxygen- and
units of the initial value. If this is not the case, the buffer
carbon dioxide-free inert gas purge.
capacity should be adjusted accordingly.
8.1.1 A convenient apparatus (see Fig. 1) is a 100-mL
5.4.2 The pH shall be adjusted to 7.4 at 37 6 0.5°C using
jacketed beaker with circulating water from a thermostatically
HCl or NaOH solutions.
controlled vessel. A flat piece of polyethylene or other inert
plastic with appropriate holes drilled to accommodate the
6. Analytical Parameters
probes, sample holder, and purge gas tube can serve as a lid.
6.1 Thefollowingprocedureshouldbeperformedwitheach
8.2 Thevesselshallbeofappropriatedimensionstocontain
of the media listed:
the required volume of dissolution media at a level to keep the
6.1.1 The dissolution rate shall be measured under the
test material completely submerged during the test and facili-
conditions of a constant ratio of initial material mass (mg) to
tate sufficient stirring action from the magnetic stirrer bar.
total dissolution media volume (mL).The ratio of test material
mass to dissolution media shall typically be between 1 to 4 8.3 The stirrer assembly shall be capable of maintaining a
mg/mL. constant stirring rate of 100 6 20 rpm.
FIG. 1 Dissolution Apparatus
F1926/F1926M − 14 (2021)
8.3.1 Magnetic Stirrer Bar—Approximately 8-mm [0.31-
in.] diameter, 28-mm [1.125-in.] length, polytetrafluoroethyl-
ene (PTFE)-coated.
8.3.2 Overhead Stirrer—An overhead stirrer is preferred
especially when testing granulate, forms, or plates so as to
avoid degradation of the materials by the stirring bar.
8.3.3 Adifferent type of stirrer design and stirring rate may
be used provided equivalence in experimental results can be
demonstrated.
8.4 The dissolution vessel shall be thermostatically con-
trolled at 37 6 0.5°C.
8.5 The dissolution apparatus may include various data
recordingandstoragedevices,stripchartrecorders,computers,
FIG. 3 Test Specimen and Coating
and so forth to facilitate continuous monitoring throughout the
duration of the experiment.
9. Preparation of Test Specimens
9.2 Fabricated Forms—Afabricated form shall be tested in
9.1 Coatings:
the form it is provided as a product. The form shall be placed
9.1.1 The test specimen shall be manufactured from the
onapolymericscreenoverthestirbarorunderastirrersothat
same materials and processes as substrates produced f
...