Free checklist
Twelve things to check before you trust a certificate of analysis.
Most certificates are read for one number and then filed. The other eleven checks below are where the actual information is, and where a decorative PDF separates from a laboratory report. Nothing here is for sale and nothing on this page will try to sell you a vial.
- 01
The batch number on the document matches the vial
Does the lot or batch identifier on the certificate appear on the physical label?
If it is missing: A certificate for a different run tells you nothing about what you are holding. This is the most common substitution and the easiest to catch.
- 02
The laboratory is named, and it is not the seller
Is there a laboratory name, address, and report number on the document?
If it is missing: An unbranded template with no laboratory identity is a self-test. Independence is the entire point of third-party analysis.
- 03
The report carries a date, and the date is recent
When was the analysis run, relative to when the batch was produced?
If it is missing: An undated report cannot be tied to a production run. A years-old report attached to current stock is a report about different material.
- 04
The HPLC chromatogram is shown, not just the percentage
Can you see the trace, the retention time, and the integration?
If it is missing: A bare 99.4% is unverifiable. The trace is where a wide peak concealing shoulder impurities becomes visible.
- 05
The chromatogram has one dominant peak
Is there a single sharp principal peak, or several competing ones?
If it is missing: Multiple significant peaks mean multiple species. Integration choices can make that look clean in the summary figure.
- 06
Mass spec confirms identity, not just purity
Is there an ESI-MS result with observed against theoretical molecular weight?
If it is missing: Purity answers how much of one thing is present. Without mass spec, nothing establishes that the one thing is the sequence you ordered.
- 07
The observed mass sits inside instrument tolerance
Does the observed figure match theoretical within the stated tolerance?
If it is missing: A mass off by a residue or a common adduct is a different molecule. The number is printed; it is rarely checked.
- 08
Endotoxin is reported in EU/mg
Is there an LAL result with an actual number and a unit?
If it is missing: This is the most-skipped panel in the market, because it is the one most likely to fail. Absence is a result.
- 09
Residual solvents were screened
Is there a GC screen covering acetonitrile and TFA?
If it is missing: Residual solvent displaces peptide mass and can interfere with sensitive assays. Unscreened means unknown, not zero.
- 10
Net peptide content is stated separately from vial weight
Does the document distinguish peptide mass from total lyophilised mass?
If it is missing: Water and counter-ion salt count toward the labelled milligrams. Two vials at identical purity can differ materially in actual content.
- 11
The sequence is printed and matches the compound named
Is the amino acid sequence on the document, and does it correspond?
If it is missing: Naming errors and near-sequence substitutions are caught here and essentially nowhere else.
- 12
The document is a report, not an image of a report
Is it a laboratory-generated PDF with selectable text and intact metadata?
If it is missing: A flattened screenshot removes every trace of provenance and is trivially editable before flattening.
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