Can a PDF’s properties prove it was edited?

No. Properties such as the producer, creation date and modification date can hint at how a file was made, but they can be changed or stripped, and plenty of legitimate laboratory PDFs come from ordinary word processors. They are clues to follow up, not proof either way.

Does a clean PDF mean the report is genuine?

No. A document can be perfectly formatted and still be a copy or a fabrication. The only check that settles authenticity is confirming the report with the laboratory that issued it.

Why might a laboratory PDF show a word processor as its producer?

Many laboratories build reports from templates in common office software or from information systems that export through generic PDF tools, so an ordinary producer string is not suspicious on its own.

Was this COA PDF edited? What file properties can and can’t show

By PeptideProof · Updated 13 October 2026 · 5 min read

When a COA arrives as a PDF, people ask whether it was edited. A file’s hidden properties can offer a few clues, but they are weaker evidence than they sound. Here is what they can hint at, and what actually settles the question.

The properties people look at

Producer and creator. The software that made the file. A report claiming to come from a laboratory information system but produced by a consumer image editor is worth a question.
Creation and modification dates. When the file was made and last saved. A modification date well after the date on the report suggests it was saved again later.
Text layer. Whether the text can be selected, or the page is a flat image. A flat image hides whether the text was typed or pasted.
Fonts and layout. Different fonts, misaligned figures, or numbers that sit slightly off the baseline of the rest of the line.
Embedded scripts. PDFs can carry JavaScript. A laboratory report has no reason to.

Why they can’t settle it

The properties are easy to change or remove.
Legitimate reports are often edited, merged or re-saved before they’re sent — adding a cover page, for instance.
Generic producers are common in real laboratory workflows.
A forger can match all of it.

What actually settles it

Confirming the report with the issuing laboratory, through the verification key, QR code or lookup it provides. If the laboratory confirms the same report number and results, the file’s history matters far less; if it can’t, a clean file doesn’t help.

A sensible way to use the clues

Note anything odd: dates out of order, a producer that doesn’t fit, mixed fonts, scripts.
Ask the seller for the original file as the laboratory sent it.
Confirm the report with the laboratory (an example of how one laboratory’s check works).
Treat a report you couldn’t confirm as an unverified claim.

What PeptideProof checks

When you upload a PDF, PeptideProof reads the producer and dates, flags embedded scripts, compares report numbers across pages, checks that dates run in a sensible order, and looks for the same or near-identical document already on record. These are shown as observations in the report — see the example report — never as a finding that anyone did anything wrong.

Frequently asked questions

Can a PDF’s properties prove it was edited?: No. Properties such as the producer, creation date and modification date can hint at how a file was made, but they can be changed or stripped, and plenty of legitimate laboratory PDFs come from ordinary word processors. They are clues to follow up, not proof either way.
Does a clean PDF mean the report is genuine?: No. A document can be perfectly formatted and still be a copy or a fabrication. The only check that settles authenticity is confirming the report with the laboratory that issued it.
Why might a laboratory PDF show a word processor as its producer?: Many laboratories build reports from templates in common office software or from information systems that export through generic PDF tools, so an ordinary producer string is not suspicious on its own.

See it on a real document

PeptideProof reads a COA for you and shows what is only reported, what has no evidence and what looks inconsistent. See an example first, or check your own — new accounts include free analyses.

See an example report Verify a COA

More guides

Educational information about reading laboratory documents. It is not medical, dosing or purchasing advice, and it doesn’t say that any product is safe, legal or suitable for any use. See the medical and research-use disclaimer.