The HPLC chromatogram
High-performance liquid chromatography separates the sample by hydrophobicity. The target peptide elutes as a dominant peak; impurities from incomplete coupling, deletion sequences or oxidation appear as smaller peaks. Purity is the area of the main peak as a percentage of total peak area.
Look for a clean baseline, a single dominant peak, and a stated gradient and column. A percentage with no chromatogram is an unverifiable claim.
Mass-spectrometry identity
HPLC tells you the sample is pure; mass spectrometry tells you it is pure of the right thing. The observed molecular weight should match the theoretical mass calculated from the sequence, typically within a fraction of a dalton for ESI-MS.
If the observed mass is off by a residue's worth, you have a deletion sequence — pure, and wrong.
Peptide content, water and counter-ions
Synthesised peptides are supplied as salts, usually acetate or trifluoroacetate, and lyophilised powder retains bound water. Net peptide content is therefore below the gross vial weight. Reputable suppliers state the counter-ion and, where relevant, the peptide content by nitrogen analysis or amino-acid analysis.
Red flags
Certain omissions are decisive. If any of these apply, treat the material as unverified.
- No batch/lot number, or a lot number that does not match the vial
- No named testing laboratory, or testing performed in-house only
- A stated purity figure with no chromatogram attached
- No analysis date, or a COA dated years before your batch
- Refusal to supply the COA before purchase
Buying in the UK: what to expect from UK Peptide
Every vial is held in UK stock at -20°C in our Central London facility, so there are no customs delays, no overseas drop-shipping and no month-long waits. Orders placed before 2pm Monday to Friday are dispatched the same working day.
Express overnight delivery is £9.99 nationwide and free on orders over £200. Parcels are vacuum-sealed, gel-cooled, insulated and discreet.
- 99%+ minimum purity by HPLC, identity confirmed by mass spectrometry
- Independent third-party UK laboratory testing — never in-house self-certification
- Visa & Mastercard accepted (no American Express)
- Research use only — not for human or veterinary use. Purchasers must be 18+
Frequently asked questions
- What is a peptide Certificate of Analysis?
- A document from an analytical laboratory recording the purity and identity of a specific batch, normally via HPLC purity analysis and mass-spectrometry identity confirmation.
- Does UK Peptide provide a COA with every order?
- Contact hello@globalbioresearch.co to request available analytical documentation before purchase.
Related guides
All products referenced are laboratory reagents supplied for in-vitro research use only. They are not medicines, supplements or cosmetics, are not licensed for human or veterinary use, and no dosing guidance is provided. Purchasers must be 18 or over.
