ShiLai Healthcare research peptides, supplied from the UK.

A certificate of analysis (COA) is issued for one specific batch. It lists each test performed, the method used, the acceptance criteria and the measured result.

For a peptide, a COA usually reports identity (does the molecule have the expected mass) and purity (what share of the material is the target peptide). It may also report appearance, water content or counter-ion content.

• The batch or lot number on the COA should match the number on the vial or box.
• Each result should name its test method, such as HPLC for purity or mass spectrometry for identity.
• The document should state who performed the analysis and when.

High-performance liquid chromatography (HPLC) separates the components of a sample as they pass through a column. The target peptide produces a main peak, and impurities such as truncated sequences appear as smaller peaks.

Purity is the area of the main peak divided by the total area of all peaks. The figure depends on the method conditions, which is why the method should always be stated next to the result.

HPLC tells you how much of a sample is the main component, but not what that component is. Liquid chromatography with mass spectrometry (LC-MS) adds a mass detector, so each peak can be matched to an expected molecular weight.

HPLC answers “how pure is it?” and mass spectrometry answers “is it the right molecule?”. A complete analytical record for a peptide batch normally covers both questions.

Good Manufacturing Practice (GMP) covers how a manufacturer controls its facility, equipment, raw materials, records, staff training and batch release, so that every batch is made consistently and can be audited.

Whether a facility holds GMP certification, and from which authority, can only be confirmed by the certificate or inspection record issued to that facility. Ask for that document rather than relying on a label.

Traceability links the product in your hands to the batch it came from. The batch or lot number on the packaging connects the product to its test results and manufacturing records.

Record the batch number with your own notes. It lets you request documentation later and match it to the material you used.

The most useful signals are documents you can check, not badges on a website.

• Can the supplier provide documentation for the exact batch you receive?
• Does that documentation name the test methods, such as HPLC and LC-MS?
• Is a batch number printed on the product, and does it match the documents?
• Is the product stored and shipped according to the manufacturer’s instructions?
• Is there a named contact who answers questions before and after you order?

Peptides can be sensitive to heat, light and moisture. Storage conditions differ by product and format, such as powder, solution or pre-filled pen.

Use the storage temperature and shelf life printed on the packaging. If anything is unclear for a product, contact RPS before ordering.