Guide · Review practice
An out-of-specification CoA result: what reviewers typically do next
- Short answer
- An out-of-specification (OOS) CoA result is a reported value outside the acceptance limit it is measured against. Reviewers typically do not accept or reject on sight. They confirm the result was read correctly, check the limit, units and basis, hold the lot and ask the supplier, then follow their procedure. This guide is descriptive; your quality system decides.
Descriptive only: what reviewers commonly do. It is not regulatory, GMP or legal advice, and it does not tell you whether to release, reject or return a lot.
A supplier's OOS is not your laboratory's OOS
Formal laboratory OOS investigation procedures usually describe results produced in your own laboratory, where the analyst, the instrument and the raw data are yours to inspect. A failing result printed on a supplier's CoA is different: you see the number but not the raw data. It is typically handled under your incoming-material or supplier-quality procedure.
That is why the first steps concern the document, not the chemistry. Many apparent failures turn out to be a misread digit, a unit difference or the wrong specification.
The usual sequence
Steps reviewers commonly take, roughly in this order. Your procedure may differ.
Keep the lot on hold
If the material is already received, keep it segregated under your procedure while the question is open. See the review checklist.
Re-read the result
Confirm it is a real number outside the limit, not a transcription slip, a decimal comma or an OCR error on a scan. Compare with the other pages and with the original file.
Check which limit applies
Is it the supplier's limit, yours or an older revision? Note whether the limit is inclusive and whether your specification applies a rounding rule near the limit. See NMT, NLT and other abbreviations.
Check units and basis
A ppm result against a percent limit, or a dried-basis result against an as-is limit, can look like a failure. See ppm, mg/kg and percent conversions.
Confirm the document
Lot number, dates and certificate number match the delivery, and the result belongs to this lot.
Query the supplier with specifics
Send the lot, test, result, limit, method and certificate reference, and ask for an explanation and any investigation. Keep the exchange in writing.
Record the event
Log the lot, parameter, result, limit and who was told, in the system your procedures designate. A layout is on the batch release log template page.
Leave the disposition to its owner
Reject, return, test on receipt, use under a documented concession or another outcome is decided by the person your quality system names, not by the reviewer or a tool.
Where an apparent failure often comes from
Rule these out before treating a result as a genuine failure.
| Source | How it shows on the CoA | Quick check |
|---|---|---|
| Misread digit or decimal | A result off by a factor of 10 or 1,000 | Compare with the original file and other pages |
| Unit or basis difference | ppm against %, or as is against dried | Convert, then compare; read the basis |
| Wrong limit | A limit from an older revision or another grade | Check the specification reference and revision |
| Rounding rule | A result just above the limit | Apply the rule your specification names, if any |
| Another lot's data | Dates or values copied from an earlier certificate | Check lot, dates and certificate number |
| Below-detection value | '< 0.01 %' against NMT 0.005 % | Ask for a lower reporting level |
| Method difference | A result from a method the limit was not written for | Ask which method was used and whether the limit applies |
| A genuine failure | A clear result outside the limit, all else consistent | Follow your procedure and query the supplier |
What goes wrong
- Treating a '<' value above the limit as a pass. It cannot show compliance. It is simply not evidence.
- Retesting until a result passes. Many quality systems restrict retesting and require the original result to be explained. Follow yours.
- Releasing on the supplier's Pass column. The conclusion can disagree with the numbers.
- Letting the hold lapse under production pressure. An open question is not a pass.
- Accepting a corrected certificate without asking what changed. A re-issued CoA with different numbers needs a reason and a reference to the original.
- No record of the conversation. Without one, the next reviewer repeats the same questions.
How CertiClean helps
CertiClean marks a row red when the printed result is outside the printed limit, and writes the number, the limit and any unit conversion beside it. When a failure would disappear under pharmacopoeial rounding, the reason says so and the row stays a fail, because it does not apply that rule. Rows it cannot judge are amber with the reason and are not counted as passes, and the log line lists failed parameters. It does not investigate or decide. See CoA to Excel and pricing.
Free allowance: 1 file per day, up to 10 pages, no account.
Questions people ask
What does out of specification mean?
A result that falls outside the acceptance criterion it is measured against, such as a value above NMT 0.5 % or below NLT 98.0 %. A result equal to an inclusive limit is not out of specification.
Is an OOS on a supplier's CoA the same as one in my own lab?
Not exactly. Formal laboratory OOS procedures usually cover results from your own laboratory. A failing supplier result is typically handled under incoming-material or supplier-quality procedures. Check which applies.
Can I retest the material myself?
Many sites run confirmatory tests on receipt, under their sampling plans. Whether and how a retest is allowed after a failure is set by your procedures. Retesting repeatedly until a result passes is widely discouraged.
Does a result equal to the limit fail?
Not for NMT, NLT, ≤ or ≥, which include the limit. It fails < or >, which exclude it. Check the symbol and any rounding rule in your specification.
What if the supplier's conclusion says Pass but the number is outside the limit?
Treat the disagreement as a query. Ask whether the printed limit or the printed result is wrong, and ask for a corrected certificate if so.
Should I reject the lot?
That is a disposition decision for the person your quality system names. Options typically include rejection, return, testing on receipt or use under a documented concession.
What should I tell the supplier?
Give the lot, certificate number, test, result, limit and method, say what you need back, and put it in writing. Ask for an explanation and any investigation report.
How do I record an OOS result from a CoA?
Record the lot, supplier, parameter, result, limit, date, who was told and the outcome. Keep the certificate with the record.