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TNI Standards Guidance

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Module: Quality Systems

Subject: Switched Samples

Question 1

Your client says recently reported results for 2 samples do not match historical values. During your investigation, you determine the analyst inadvertently switched the labels on these 2 containers. What now?

Initiate a complaint or corrective action report process. Involve sample receiving staff, QAO, analysis staff and supervisors.  Investigate further to inspect sample containers (if still in storage) and the chain of custody to see whether the label matches the contents and establish how it was logged into LIMS.  Perform secondary review of receipt and log-in.  Reanalyze samples (if possible) to confirm hypothesis of switched labels.  Review historical results from the client. Re-train all involved staff. Notify client of results of investigation. Issue amended report (if possible).


2009 TNI V1M2 and 2016 TNI Rev. 2.1 V1M2

4.2.1,, and

4.8 Complaints (ISO/IEC 17025:2005, Clause 4.8)

4.9 Control of Nonconforming Environmental Testing Work (ISO/IEC 17025:2005(E), Clause 4.9)

4.11 Corrective Action (ISO/IEC 17025:2005(E), Clause 4.11), §4.11.1 – 4.11.4

4.13 Control of Records, §

4.13.3 Additional Requirements
a) The laboratory shall establish a record keeping system that allows the history of the sample and associated data to be readily understood through the documentation….

5.2 Personnel (ISO/IEC 17025:2005, Clause 5.2), §5.2.1

5.8 Handling Samples and Test Items (ISO/IEC 17025:2005(E), Clause 5.8)

5.8.6 Additional Requirements – Sample Acceptance Policy
The laboratory shall have a written sample acceptance policy that includes the following:
b) proper sample labeling to include unique identification and a labeling system ….

5.10 Reporting the Results, §5.10.9