Purity and contamination on a peptide lot

Research-use notice: This article is laboratory and educational information only. It is not medical or legal advice, and it does not include how-to-use instructions. BlueNex Labs materials are research use only and are not intended for human or veterinary use. Research-use-only labelling is not a Health Canada authorization.

Publication status: Prepared for the BlueNex Labs Research Knowledge Centre. Literature and library notes checked September 24, 2026. Primary papers and the public COA library can change; verify the lot report in hand before an assay.

Purity, identity, and contamination are three different laboratory questions. A single percentage cannot answer all three, and a missing line is not a passing line. This page sorts those questions so a receiving file does not collapse them into one adjective. The method arithmetic stays in HPLC versus LC-MS. The line-by-line PDF reading stays in how to read a peptide COA. The endotoxin number stays in endotoxin testing on peptide COAs. The document definition stays in what a peptide COA records. This page is the map between them.

Three lines, three outcomes

A usable lot report lets you answer yes, no, or not reported for each question separately. Identity: does the observed mass match the named sequence, including the salt or adduct the report names? Purity: what fraction of the integrated ultraviolet area sat in the assigned peak, under the method that was printed? Contamination, as this catalogue uses the word: what else did the laboratory report, or explicitly decline to report? An impurity peak, a mismatched mass, an endotoxin value, and a blank where sterility would be are four different sentences. They do not average.

Older marketing copy treated "quality" as a mood. A receiving log cannot file a mood. It can file the sample name, the task ID, the area percent, the mass, and the words not reported next to every test the PDF omits. If those fields are missing, the lot is undocumented on that point. It is not clean by default.

What an area percent does not see

Reversed-phase HPLC at 214 or 220 nanometres sees compounds that absorb there. A deletion peptide or a truncation often does, which is why secondary peaks matter and why the integration cutoff matters. Several other things do not absorb, or do not absorb in proportion to their mass. Trifluoroacetate and acetate counter-ions can dominate the weight of a synthetic peptide and still be invisible on that chromatogram. Residual solvent can be invisible. Lipopolysaccharide is invisible. A sharp main peak therefore rules out neither salt, nor solvent, nor endotoxin.

Net peptide content, when a laboratory reports it, is the assay that speaks to how much of the weighed solid is the peptide rather than counter-ion. If the COA does not print net content, do not derive it from the area percent. Amino-acid analysis, described in how peptides are made, checks composition after hydrolysis. It will not catch a sequence swap that preserves the residue counts. Label each method as itself.

Co-elution is the other hole in an area percent. Two species under one peak look like one species. The mass under that peak is what splits them, and only when the spectrometer was aimed at that peak and the report shows the result. A total-ion trace is not a substitute you invent after the fact. The LC-MS section is the place to read that distinction. This page only insists that the receiving file keep the ultraviolet percentage and the mass on separate lines.

A missing test is its own result

Write the absence down. "Endotoxin not on this report" is a complete sentence. "Sterility not on this report" is another. "Residual solvent not on this report" is a third. None of them may be upgraded to a pass because a neighbouring lot passed, or because the area percent was high, or because the vial arrived cold and dry. Cold and dry is a storage observation. It is recorded in peptide storage for Canadian laboratories. It is not an analytical result.

The same rule stops a blend chromatogram from covering a single-peptide vial, and a missing solvent report from being filled with a peptide PDF. For the match between cap, library row, and PDF, see verify a peptide lot against its COA. Quarantine means the vial stays out of the working stock until the three records agree or the desk supplies the missing file. It does not mean the peptide has failed a test you do not have.

Published rows that show the split

The certificates library, reviewed September 26, 2026, already illustrates the split. Retatrutide 30 mg, pink cap, has a purity link and an endotoxin link at the Retatrutide 30 mg certificate row. Read the endotoxin number from that second file. GHK-Cu 50 mg, batch HF1F6C9, has both a mass/purity link and an endotoxin link at the GHK-Cu 50 mg certificate row. Copy the endotoxin number and its unit from that second link. The GHK-Cu endotoxin number does not apply to the pink-cap vial.

Retatrutide is three fills on three shop URLs. The 10 mg blue cap, the 20 mg purple cap, and the 30 mg pink cap each have mass/purity and endotoxin links at the Retatrutide 10 mg certificate row, the Retatrutide 20 mg certificate row, and the Retatrutide 30 mg certificate row. A passing endotoxin line on the blue cap says nothing about the pink cap. TB-500 10 mg has its own purity anchor. The 5 mg/5mg blend report is contamination of the file if someone attaches it to the single-peptide vial: the document is real, and it is the wrong document. Hospira bacteriostatic water 30 mL has no published row. The honest log records that absence. It does not borrow a peptide PDF to match the shop title.

What this page does not add

It does not set a house purity cutoff or an endotoxin limit. It does not claim a synthesis plant, because this catalogue does not publish factory identities. It does not convert research-use-only labelling into a Health Canada authorization. That category is are research peptides legal in Canada?. It does not rank suppliers. A purchaser compares documents that can be opened, on the lot in hand, and stops there.

If an independent laboratory later reports an identity mismatch or a purity figure below the figure printed on that lot's Certificate of Analysis, the commercial consequence on this site is the one stated on the certificates page: the vial is replaced and the original payment is refunded. That remedy is for the lot. It is not a sitewide purity or identity guarantee, it is not a method, and it is not a reason to skip reading the original PDF. File the original task ID first.

Frequently asked questions

Does a high area percent rule out contamination?

No. Area percent describes the ultraviolet peaks that were integrated. It does not measure endotoxin, residual solvent, or a salt counter-ion that lacks a chromophore. Read each line on its own.

Where are the live lot reports?

In the certificates library, one row per published lot. Open the Janoshik link from that row rather than a cropped image.

What should a receiver write when a test is missing?

Write not reported, and name the test. Do not copy a result from a different cap colour, a blend, or a neighbouring peptide.

What does research use only mean here?

Laboratory and in-vitro work. The label is not a drug authorization and this note is not a protocol for people or animals.

Catalogue cross-reference

This URL only sorts the questions. The PDFs stay in the certificates library. Shop examples: BPC-157 10 mg, GHK-Cu 50 mg, TB-500 10 mg, retatrutide, and Hospira bacteriostatic water.

Orders ship inside Canada only after Interac e-Transfer checkout. Sold-out SKUs remain listed and cannot be added to the cart. Match each vial to its own Certificate of Analysis when a lot is published. Research use only. Not for human or veterinary use.