Topic / Certificate interpretation
Read each line of a peptide certificate of analysis: HPLC purity, mass spec identity, net content, water, salt form, endotoxin and residual solvents.
A certificate of analysis answers several separate questions, and each test line answers only one of them. First confirm identity with the mass spectrometry line, then read HPLC purity, then work out how much of the powder is actually peptide using the purity versus content, water content and salt form guides. Readers who skip the content step often misread a high purity figure as the amount of peptide in the vial.
Once those core lines make sense, check the supporting results your work depends on: endotoxin units and limits, residual solvents and elemental impurities, and the retest or expiry date. If a line is missing, record it as missing rather than assuming it passed.
Finish with the authenticity checks. The fake or reused COA and third-party tested guides explain how to tie a certificate to a real lot and a real laboratory, and the 98% versus 99% guide shows why a small purity difference should not decide a purchase on its own.
Certificate interpretation
Separate chromatographic purity, gross mass, and net peptide content using a hypothetical mass example and a laboratory report worksheet.
7 min read · Research guide
Certificate interpretation
Use ICH Q7 definitions to read retest, expiry and certificate dates correctly, ask what stability data supports them, and avoid extending a date by assumption.
6 min read · Research guide
Certificate interpretation
Interpret solvent classes, ppm limits, loss-on-drying statements and Class 1 elements on a certificate using ICH Q3C(R9) and Q3D(R2), without treating them as a research-grade requirement.
7 min read · Research guide
Certificate interpretation
Record the counter-ion of a peptide lot, understand why TFA salts can confound cell assays, and see why regulators list salt forms as distinct substances.
6 min read · Research guide
Certificate interpretation
What "third-party tested" should mean on a research peptide listing: an independent laboratory, a named lot, a stated method and verifiable competence. Includes a five-question check and real examples, dated 29 October 2026, of claims that fall short.
8 min read · Research guide
Certificate interpretation
An annotated walkthrough of the chromatogram on a peptide certificate: retention time, peak area percent, integration, detection wavelength, co-elution and detection limits, plus what it means when the trace is missing or shows only a mass-filtered peak.
9 min read · Research guide
Certificate interpretation
Compute the expected mass from a sequence, match it to the observed ion and charge state, check the error in ppm, and record what a mass result cannot tell you.
8 min read · Research guide
Certificate interpretation
Spot reused chromatograms, lot and date mismatches, unverifiable laboratories and edited PDFs, then confirm a certificate with the issuing lab and handle a vial whose lot does not match.
8 min read · Research guide
Certificate interpretation
What EU and EU/mg mean, the gel-clot, turbidimetric and chromogenic methods in the harmonized pharmacopoeial chapter, why research certificates often show no endotoxin line, and how to record it.
8 min read · Research guide
Certificate interpretation
How water and counter-ions reduce the net peptide in a weighed sample, a worked mass-balance calculation from a fictional certificate, and when to ask a supplier for a Karl Fischer result.
7 min read · Research guide
Certificate interpretation
How much impurity a 98% or 99% HPLC purity figure leaves in a weighed sample, why the number depends on the method that produced it, and why a percentage without a chromatogram is weak evidence.
7 min read · Research guide
Certificate interpretation
A glossary of process- and degradation-related peptide impurities with the mass shift each produces, the regulatory reporting thresholds that frame them, and a fictional certificate decoded line by line.
9 min read · Research guide
Certificate interpretation
Where D-amino acid impurities come from in synthetic peptides, why RP-HPLC purity and intact mass can miss them, which methods measure them, and how to ask a supplier when the certificate is silent.
8 min read · Research guide
Certificate interpretation
What a compendial sterility test, a bioburden count and a bacterial endotoxin (LAL) test each measure, what a certificate must show before the word sterile means anything, and a checklist for sterile and sterile-filtered marketing.
9 min read · Research guide
Certificate interpretation
The main chemical degradation pathways for stored peptides, which residues are vulnerable, what each change looks like on a repeat HPLC or mass spectrum, and how ICH Q1A stability studies underpin retest dates.
10 min read · Research guide