What QC documents and data to request before buying research peptides
Learn which COA items, HPLC and MS details, and SDS information to request so you get the right peptide for your experiments.
Before you place a peptide order, asking for and reviewing quality control documents reduces surprises and costly delays. This post explains the specific data items to request, how to read them quickly, and what to do if information is missing.
Essential documents to request
Ask every supplier for these items with each lot you buy:
- Certificate of Analysis (COA): lot number, sequence, purity method, and measured purity percent.
- HPLC or UPLC chromatogram: retention time, solvent system, column type, and a clear dominant peak.
- Mass spectrometry spectrum: observed m/z values, charge states, and annotation of the expected monoisotopic mass.
- SDS or MSDS: safety, storage, and disposal instructions.
- Recommended storage conditions, solubility notes, and aliquot suggestions.
If the vendor offers downloadable PDFs or image files on the product page, save them alongside your experimental records.
How to interpret HPLC and MS quickly
You do not need to be an analytical chemist to spot red flags:
- HPLC: a single sharp peak covering most of the chromatogram area indicates a clean product. Multiple large peaks suggest impurities or incomplete synthesis.
- MS: confirm the dominant m/z matches the expected molecular weight or the expected charged species. Missing the target peak is a major concern.
- Purity: a COA purity of 95 percent or higher is typical for many applications. Lower purity may be acceptable for screening, but expect more purification work for sensitive assays.
If the vendor does not provide labeled chromatograms or spectra, request raw data or a higher resolution COA.
What to do if data is incomplete
If a supplier cannot provide full QC documentation, consider these steps:
- Request a recent COA for the actual lot you will receive, not a generic example.
- Ask for third party testing, or an independent analysis agreement for critical projects.
- Order a small test quantity before committing to larger batches.
Practical ordering checklist
Before hitting submit, confirm these items:
- Product page has sequence, molecular weight, COA link, and SDS link.
- Shipping and storage conditions are appropriate for your timeline.
- Purchase order terms and lead times meet your project schedule.
- Technical contact is available for follow up questions.
Requesting these QC documents will protect your experiments, speed troubleshooting, and make it easier to compare vendors objectively.