A certificate of analysis (COA) is easier to use when you read it as a record of specific tests on a specific sample. Start with what was measured, then check how the result connects to the material in question. This guide gives you a repeatable way to organise that review.
Start with the sample, not the headline
Write down the report identifier, sample or batch code, compound name, test date and issuing laboratory. Check that these details are consistent across the pages and any supporting chromatograms or spectra. If a field is missing, record a question rather than filling the gap with an assumption.
A useful first question is: Which sample does this report describe, and how was it identified? Keep the original report alongside your notes so the source remains traceable.
Separate identity, purity and quantity
Different analytical methods answer different questions. Mass-spectrometry data can support molecular identification, while chromatographic data describe separation under the reported conditions. Amino acid analysis can contribute to peptide quantification. A methods paper by Hoofnagle and colleagues discusses why characterisation data and documented procedures matter in peptide-based analytical assays. Read the methods paper.
For reference standards, researchers use complementary methods and account for components such as counterions and residual solvents when assigning values. A review of synthetic peptide reference standards explains this approach. Read the reference-standard review.
The BIPM’s peptide and protein measurement programme also distinguishes purity characterisation from assigning values to calibration materials. See the BIPM overview.
A checklist you can reuse
- Match: record the sample code, report number and date.
- Identify the method: note which test supports each result.
- Keep the units: copy the unit and reporting basis, not just the number.
- Check the supporting data: look for the relevant chromatogram, spectrum or method reference.
- Record open questions: ask the issuer about unclear identifiers, abbreviations or missing pages.
- Keep the version: retain the original document and any corrected report together.
Make your review easy to revisit
Use a short note with four headings: sample, method, result and unanswered question. This keeps an impressive-looking document from becoming a substitute for a clear record. When comparing reports, compare matching tests and reporting bases; label anything that is not directly comparable.
For the next step, read our guide to reading a peptide research paper. For questions about documentation associated with an item, contact MEDLABS with the item reference.
Sources and further reading
- Hoofnagle AN et al. Recommendations for the generation, quantification, storage and handling of peptides used for mass spectrometry-based assays. Clinical Chemistry (2016). doi:10.1373/clinchem.2015.250563.
- Reference Standards to Support Quality of Synthetic Peptide Therapeutics. Pharmaceutical Research (2023). doi:10.1007/s11095-023-03493-1.
- BIPM. Peptides / Proteins measurement programme.