TFA vs Acetate: Why Peptide Counter-Ions Change the Numbers
The counter-ion on a synthetic peptide is not a footnote. It contributes mass, it can affect assays, and it belongs in your notes alongside the sequence.
Why Two Suppliers Report Different Purity for the Same Peptide
Two honest laboratories can analyse the same peptide and publish different numbers. The gap is usually method rather than misconduct.
Mass Spectrometry for Peptide Identity: What It Proves
A matching mass is strong evidence of identity and weak evidence of purity. Knowing the difference stops a mass spectrum doing the wrong job.
Common Peptide Synthesis Impurities and How to Spot Them
Synthetic peptides do not fail cleanly. The characteristic by-products of SPPS are near-relatives of the target, which is exactly why they are hard to see.
Reverse-Phase HPLC for Peptide Purity: How It Works
Why RP-HPLC became the default method for assessing synthetic peptide purity, where the method is strong, and where it is genuinely blind.
What Should a Peptide Certificate of Analysis Contain?
Most documents sold as a COA are a purity number on letterhead. Here is what a genuinely useful analytical record contains, and what its absence tells you.
Peptide Purity vs Net Peptide Content: What Is the Difference?
A vial labelled 5 mg at 99% purity does not contain 4.95 mg of peptide. Here is why, and what it does to your molarity calculation.
How to Read an HPLC Chromatogram for a Research Peptide
A chromatogram is the most informative document a peptide supplier can publish. How to read one properly, and what a clean-looking trace can still hide.