Abstract
A COA and supporting laboratory report are comparable only when their identity, measurement basis and applicable requirements can be reconciled. Use this workflow for HA, β-TCP and 45S5 to identify missing evidence before accepting a sample or lot. Keep unresolved differences visible rather than selecting the more favorable result.
1. Establish the document chain
Record the supplier, grade, material form, lot, sample identifier and test date from each document. Link the COA to the agreed specification revision and the supporting report number. If a report describes a development sample or another lot, label it as reference evidence rather than evidence for the delivered lot.
Ask which COA entries are measured on the lot, calculated, based on periodic testing or reported as typical values. Do not silently treat all four as equivalent. Record the responsible laboratory and any subcontracted work where relevant to the requested evidence.
2. Compare one requirement at a time
Copy the requirement, limit, result, unit and method into one comparison row. Also record sample preparation and the reporting basis. A difference in units, dry versus as-received basis, or phase normalization can prevent a valid comparison even when the numbers look similar.
Check whether the supporting method is suitable for the requested property. ISO 13779-3 covers HA-based material characterization [1]; it should not be assumed to define a 45S5 specification. Use the material-specific method and the applicable revision agreed for the order.
3. Separate results from a pass decision
A result below the quantification limit does not establish zero concentration. If the reporting limit cannot resolve the agreed acceptance limit, request an appropriate method or additional evidence. Keep the original report and the clarification together.
If a conformity statement is requested, identify the specification and decision rule, including how measurement uncertainty is handled. ILAC G8 explains that the rule should be agreed with the customer unless it is already inherent in the requested specification or standard [2]. There is no universal guard band for these materials.
4. Close or hold the discrepancy
For a mismatch, request a written explanation, a corrected record where justified, or a planned investigation. Do not average incompatible methods or replace an unfavorable result with an unexplained repeat. Record who resolves the issue and what evidence permits closure.
If accredited testing is needed, verify the laboratory and relevant accreditation scope. ISO/IEC 17025 concerns laboratory competence and operation [3]; accreditation is not product certification. A COA alone does not qualify the material for a finished medical device.
Table 1. A reconciliation record for each acceptance requirement.
| Check | Compare or record | Disposition if unresolved |
|---|---|---|
| Identity | Grade, lot, sample and report identifiers | Request a traceable document link |
| Measurement | Method, preparation, units and basis | Clarify comparability before judging |
| Conformity | Limit, reporting limit and decision rule | Hold the acceptance decision |
| Resolution | Explanation, revision and accountable owner | Retain the issue and closure evidence |
References
[1] ISO. ISO 13779-3:2018. Implants for surgery — Hydroxyapatite — Part 3: Chemical analysis and characterization of crystallinity ratio and phase purity. With Amd 1:2021. Geneva: ISO; 2018.
https://www.iso.org/standard/64618.html
[2] ILAC. ILAC-G8:09/2019. Guidelines on decision rules and statements of conformity. Silverwater: ILAC; 2019.
https://ilac.org/publications-and-resources/ilac-guidance-series/
[3] ISO, IEC. ISO/IEC 17025:2017. General requirements for the competence of testing and calibration laboratories. Geneva: ISO; 2017.
https://www.iso.org/standard/66912.html