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A frozen specimen may have undergone more than one storage episode. Previous analyses and aliquot preparation can introduce different thaw histories. Explain their relevance to the investigated analyte and method.
Define the assessment
Define recorded freezing and thawing events, relationships between aliquots and unknown history separately. Do not assume a common cycle limit fits every assay. Assess suitability against supported device conditions and study evidence; absent handling records should not automatically mean acceptable handling.
Worked example
For example, three tubes from one person enter an archive study. One was previously analysed, while the others were unopened. The database assigns all three the same history. The team compares aliquot and processing records and corrects verifiable information. It retains uncertainty for unknown histories rather than treating similar results as proof of identical handling.
Practical checks
- Preserve identity and processing links between the original specimen and aliquots.
- Distinguish known, estimated and unknown handling histories.
- Justify analytical and reporting treatment of specimens outside supported conditions.
Decision and limitations
Acceptance depends on understanding the conditions represented by each specimen. Unknown history does not necessarily make all data worthless, but it limits claims that conditions were met. Consider further technical assessment and show how specimen exclusions affect performance findings.
Frequently asked questions
- Can one cycle limit be used for every assay?
- No. Evidence should fit specimen, analyte and method conditions.
- Do similar results establish identical history?
- No. Measurement similarity cannot create missing evidence about handling.