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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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 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.
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.
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.
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.
