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.
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Assay
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.
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.
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.
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.
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.
