Understanding Independent Laboratory Testing

A report from an independent laboratory is evidence a buyer can check, where a supplier's own statement is not. This guide explains what independence means, what accreditation adds, and how to confirm that a report is genuine.

First, second and third party

Quality professionals describe testing by who carries it out.

• First-party testing is done by the supplier or manufacturer itself.
• Second-party testing is done by, or on behalf of, the customer.
• Third-party testing is done by a laboratory independent of both.

Independence matters because the laboratory has no stake in whether a sample passes.

What a laboratory report contains

ISO/IEC 17025, the international standard for the competence of testing and calibration laboratories, sets out what a test report should include. Among other things:

• a title and a unique identification of the report,
• the name and address of the laboratory,
• the method used,
• a description and unambiguous identification of the item tested,
• the date the item was received and the date or dates of testing,
• the measured values, with their units,
• a statement that the findings relate only to the items tested,
• identification of the person or people who authorized the report.

A report missing these is harder to rely on, whoever issued it.

Accreditation

Accreditation is formal recognition, by an accreditation body, that a laboratory is competent to carry out specific tests. It is granted for a defined scope: particular methods on particular kinds of sample. A laboratory accredited for one test is not thereby accredited for another, and a report is not covered by accreditation simply because the laboratory holds some. Where it matters, check the laboratory's scope with the body that granted it. Accreditation bodies that have signed the ILAC Mutual Recognition Arrangement recognize one another's accreditations.

Competence also rests on the methods themselves. A laboratory is expected to use methods that are validated, or verified, as fit for the purpose they serve, which is the subject of the Eurachem guide listed below.

Independence is not infallibility

An independent report is evidence about one sample, measured by one method, on one date. It can still be affected by sampling, by the limits of the method, or by error. Its value is that it can be checked: through the method details it prints, and by confirming it with the laboratory.

Checking a report with the laboratory

• Look for a report number and any verification code printed on it.
• Where the laboratory offers a verification service, confirm the report there rather than relying on a copy.
• Compare the product, batch number, vial size and dates with the vial and document you hold.
• If anything does not match, contact the laboratory directly, using contact details from its own website rather than from the report.

Where this site fits

Where a batch report is published, it is reproduced in full in the COA Library, with the report number and access code the laboratory printed, so it can be checked with the laboratory itself. How the reports on this site are produced and shown is described on Testing & quality. Purity & Third-Party Testing, Explained explains what the measurements on them show, Why Batch-Level Testing Matters why each report covers one batch, and How to Read a Certificate of Analysis where the report number and laboratory details sit on a report.

Sources and references

• ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories. International Organization for Standardization and International Electrotechnical Commission.
• ILAC, the International Laboratory Accreditation Cooperation, and its Mutual Recognition Arrangement.
• Eurachem, The Fitness for Purpose of Analytical Methods: A Laboratory Guide to Method Validation and Related Topics, 2nd edition. Eurachem, 2014.
• ICH Q2(R2), Validation of Analytical Procedures, International Council for Harmonisation, 2023.

Research use

All materials on this site are supplied for laboratory research use only. They are not for human or veterinary use, and this guide gives no instructions for preparing or using them.