What are the impurities in synthetic peptides? A COA map
Synthetic peptide impurities by class, from deletion sequences to TFA counterions, and which COA line, HPLC purity or MS mass, can reveal each one.
No. 01 Lead story
What is amino acid analysis of peptides? What it can count
Amino acid analysis hydrolyses a peptide and counts the residues. What that proves on a COA, what acid destroys, and how net peptide content is measured.
Story index
22 stories on file How long do lyophilized peptides last? Four makers' figures
Shelf-life figures for lyophilized peptides as sb-PEPTIDE, GenScript, peptide.com and JPT state them, by temperature, and why none is an expiry date.
Are peptides legal? FDA's own lists, peptide by peptide
Are peptides legal? The answer is in FDA documents. We read the category 2 list and the July 2026 advisory agenda and tabled each peptide's status.
How to store lyophilized peptides, per three manufacturers
Lyophilized peptide storage as GenScript, JPT and peptide.com publish it: cold, dry, dark, warmed before opening. Where the three pages disagree.
What Karl Fischer water content means on a peptide COA
Karl Fischer water content on a peptide COA is the water share of the powder by mass. How USP authors subtract it, and what vendor ranges rest on.
How to read a peptide COA: each line, and what it ties to
How to read a peptide COA line by line: what identity, purity, quantity and endotoxin results show, and what a vendor or anonymised COA ties them to.
How to verify a peptide COA is real, and what it leaves open
Four checks the category uses to verify a peptide COA, set against the two conditions 21 CFR 211.84(d)(2) puts on relying on a supplier's analysis.
What MS confirms on a peptide COA that HPLC purity cannot
MS on a peptide COA confirms the observed mass matches the intended molecule. HPLC purity is a peak-area share; it proves neither identity nor mass.
TFA salt vs acetate salt on a peptide COA, assessed
What 'TFA salt' or 'acetate salt' on a peptide COA records, why vials arrive as TFA salts, and how residual TFA is measured, per a 2025 ETH Zurich paper.
Does 99% purity on a peptide COA mean 99% peptide by weight?
No. HPLC purity is a peak-area fraction; net peptide content is a mass fraction. Six sequences show what a TFA counterion alone can take from a 10 mg vial.
Accreditation marks on a peptide test report: A2LA, ANAB and the ILAC/IAF merger, assessed
A logo on a certificate of analysis is not a purity grade. Assessed: what an ISO/IEC 17025 accreditation attests, why scope is the whole of it, and why the mutual-recognition line printed on reports is mid-rename.
Smithers enters peptide testing by buying ACS Laboratory
A testing group founded in 1925 has bought the Florida lab now trading as ACS Peptide Testing Labs. The release is worth reading for what it does not name.
Bacterial endotoxin testing, assessed as documentation a purity figure cannot supply
A percentage by HPLC is a chemical result. Endotoxin is a microbiological one, with its own method, its own calculated limit and its own report. Assessed on what a bacterial endotoxins test records and what it leaves open.
A 70-month sentence puts forged laboratory certificates on the record
The operator of a research-chemical seller was sentenced in late July after admitting the business forged laboratory certificates. For a market that runs on seller-hosted PDFs, that admission is the part worth reading.
'Research use only' is a use statement, not a quality grade
The most-printed phrase in research supply carries no method, no measurement and no issuing body. Assessed on what it commits a seller to, how regulators have read it, and which fields on a label do the work instead.
FDA's 503B Bulks List, assessed as a document rather than a verdict
A public, dated, numbered federal docket that circulates as though it were a register of approved substances. Assessed on what the notices record, how the process moves, and how little of it bears on a research-supply purchase.
The word 'peptide' is now doing two jobs on a label
Three August supplement launches print 'peptide' on the front of the container. The paperwork behind that word is a different kind of document from the one a research-supply buyer reads.
Lot traceability and vial labelling, assessed across the category
The label on a lyophilised vial is the only documentation that physically travels with the material. Assessed on what the category prints, what it omits, and what that costs a buyer.
Cold-chain claims outrun cold-chain evidence in peptide shipping
Suppliers increasingly advertise temperature-controlled shipping. Far fewer publish anything that would let a buyer verify the chain held.
The vendor-published certificate of analysis, assessed as evidence
The COA is the central document in research supply and the least examined. Assessed on what it actually establishes, what it leaves open, and how far a buyer can rely on it.
Third-party assay reports become a competition point in research supply
Vendors of research peptides spent years competing on price per milligram. A growing number now compete on whose laboratory signed the report.
About Labcoat Ledger
Labcoat Ledger — Research peptides, documented not prescribed. Every story indexed, numbered, and timestamped.
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