Guide · Methods
Pharmacopoeial methods on a CoA: USP, EP, JP and in-house
- Short answer
- A method reference on a CoA names the procedure behind a result. USP, EP (Ph. Eur.) and JP are the United States, European and Japanese pharmacopoeias; a reference such as USP <731> points to a numbered chapter. In-house means the supplier's own procedure, not published in a pharmacopoeia. Neither is automatically better, so check the edition and what was run.
General background, not regulatory or GMP advice. Which methods and editions your specification requires, and whether another procedure is acceptable, is for your quality system and the pharmacopoeia itself to say.
What a method reference does and does not tell you
A pharmacopoeia is a published set of standards for medicines and their ingredients: monographs that list tests and limits for a named substance, and general chapters that describe how a test is performed. The USP–NF, the European Pharmacopoeia (Ph. Eur. or EP) and the Japanese Pharmacopoeia (JP) are commonly cited on a CoA; British, Indian and Chinese pharmacopoeias also exist. Food ingredient certificates tend to cite the Food Chemicals Codex, ISO, AOAC International or ASTM instead: see food ingredient vs pharma CoAs.
A method column records what the supplier states it ran. It does not show that the test was run correctly, that the laboratory is accredited for it, or that the method suits your material. Compendial procedures are generally regarded as validated, though a laboratory using one is typically expected to confirm it works under its own conditions (USP <1226> covers this). In-house procedures are typically validated by the supplier, for example following ICH Q2, though a certificate rarely shows it. Treat the column as a source of questions, not assurance.
Reading the method column, row by row
Six checks that apply to any certificate.
Find the method column
If there is none, or it says 'per supplier', treat the methods as unknown and ask for references. Without them you cannot compare lots or suppliers.
Decode the reference
Pharmacopoeial references carry a name and a number: USP <731>, Ph. Eur. 2.2.32, or a monograph title. A bare 'USP' or 'EP' names the book but not the test.
Find the edition
Monographs and chapters are revised. A reference with an edition, supplement or year can be pinned down; one without can only be checked against the current text. Ask which edition applied.
Compare with your specification
If your specification names a compendial method and the certificate shows another, the results may not be directly comparable. Ask whether the two are equivalent and record the answer.
Treat in-house as a question, not a verdict
Ask for a short description or validation summary, under confidentiality if needed, and watch for the method changing between lots. See how buyers verify supplier certificates.
Record the method with the result
Keep the method text beside each result as printed, so a later change shows when you line lots up. Limits themselves are decoded in NMT, NLT and other abbreviations.
Common method references and what they point to
Examples of how references are written. Chapter numbers are illustrative; check the current text.
| Written as | What it points to | Check or ask |
|---|---|---|
| USP <731> | A numbered USP–NF general chapter, here loss on drying | The edition; that your monograph cites it |
| USP, 'per USP monograph' | The monograph's own procedure | Which test within the monograph, and which edition |
| Ph. Eur. 2.2.32, EP 2.2.32 | A Ph. Eur. general method, here loss on drying | The edition; the EP monograph |
| JP general test | A Japanese Pharmacopoeia general test, cited by number | The edition and any supplement |
| FCC | Food Chemicals Codex standards for food ingredients | The edition; specification or only method |
| ISO 6579-1, AOAC, ASTM | A standards-body or consensus method, with a number | The year or version of the standard |
| In-house, IH, internal, SOP number | The supplier's own procedure | A summary or validation evidence; change between lots |
| Blank, 'per supplier' | Nothing you can check | Ask for references; record the gap |
What goes wrong with method references
- 'USP' with no chapter or edition. It names a book, not a test.
- A pharmacopoeial name with a short test list. A certificate that claims a pharmacopoeial grade should show the tests its monograph requires. A shorter list is a reason to ask.
- In-house taken as inferior, or as equivalent. Neither follows automatically. A well-validated in-house method can suit a product better than a general chapter.
- A method changed between lots. Results can shift for method reasons alone. Look for the change before you look for a trend.
- An old edition cited. A test or limit may have changed since the edition printed on the certificate.
- A reference read as proof of competence. A method code says what was meant to be run, not who ran it or how well.
How CertiClean helps
CertiClean carries the method column through as printed, one entry per test, into the results table and the parameter CSV, so methods can be sorted and compared across lots in a spreadsheet. It does not interpret method references, check an edition or judge whether a method suits the material. If a certificate has no method column, the method field is left empty. See CoA to Excel and pricing.
Free allowance: 1 file per day, up to 10 pages, no account.
Questions people ask
What do USP, EP and JP stand for?
USP is the United States Pharmacopeia, published with the National Formulary as USP–NF. EP, or Ph. Eur., is the European Pharmacopoeia. JP is the Japanese Pharmacopoeia. Other national pharmacopoeias exist, including British, Indian and Chinese ones.
What does in-house method mean?
A procedure developed and validated by the supplier or its laboratory rather than taken from a pharmacopoeia or standards body. It can be entirely appropriate, particularly for proprietary products. You can ask the supplier for a description or validation summary.
Is a pharmacopoeial method better than an in-house method?
Not automatically. A pharmacopoeial method is public, so you can read it and compare suppliers. An in-house method may fit a material better. What matters is that it is appropriate, validated and stable between lots.
Does complies with USP mean every monograph test was run?
It should, but the CoA is the evidence. Compare its test list with the monograph for the grade you ordered. If tests are missing, ask whether they were run and where the results are.
Why does the edition matter?
Pharmacopoeias are revised, and tests or limits can change between editions. A certificate that names the edition lets you check the exact text that applied; one that does not leaves you using the current version.
What if the CoA method differs from my specification?
The results may not be directly comparable. Ask the supplier whether the methods are equivalent, record the answer and follow your procedure, which may include testing a sample.
Are USP, EP and JP chapters interchangeable?
Some general chapters are harmonised through the Pharmacopoeial Discussion Group, but harmonisation is partial and regional differences remain. Check the text of the chapter your specification names.
Does a method reference mean the laboratory is accredited?
No. A method reference says what the supplier states it ran. Accreditation, for example to ISO/IEC 17025, is a separate matter that you can ask the supplier about.