Understand the source comparison
SS-LUP-332 COA: Data Field Comparison
HPLC Purity (%) Proportion of target peptide vs impurities ≥95% for research use, ≥98% for quantitative assays <90% or multiple peaks >3% HPLC purity alone isn't enough. You need MS confirmation to prove the primary peak is the correct compound. A 97% pure pep
No winner is assigned.
This page preserves a source comparison for education. It does not add a rating, recommendation or clinical judgment.
- HPLC Purity (%)
- Proportion of target peptide vs impurities
- ≥95% for research use, ≥98% for quantitative assays
- <90% or multiple peaks >3%
- HPLC purity alone isn't enough. You need MS confirmation to prove the primary peak is the correct compound. A 97% pure peptide with the wrong sequence is useless.
- Observed Mass (MS)
- Confirms peptide identity and sequence accuracy
- Within ±1 Da of calculated mass (ESI-MS)
- Off by >2 Da, or multiple peaks without explanation
- If observed mass doesn't match expected within 1 Da, stop. You either have the wrong peptide, a synthesis error, or significant degradation. Request MS/MS fragmentation data before using.
- Retention Time (HPLC)
- Indicates hydrophobicity and column interaction
- Consistent across batches (±0.5 min)
- Shifts >1 min between batches or split peaks
- Retention time should be reproducible. If it shifts significantly between batches, the peptide's hydrophobicity has changed. Possibly due to oxidation, acetylation, or incomplete deprotection during synthesis.
- Batch Number
- Traceability for cross-study comparison
- Unique alphanumeric code matching vial label
- Missing, illegible, or mismatched with label
- No batch number = no traceability. If results can't be replicated, you'll never know if it was biological variability or a bad peptide batch. Always log batch numbers in your lab notebook.
- Synthesis Date
- Indicates peptide age and potential degradation
- <12 months for oxidation-prone peptides
- >24 months without re-analysis
- Peptides don't last forever. If synthesis date is >18 months old and the COA doesn't include recent re-analysis data, request updated HPLC or order a fresh batch. Oxidation and aggregation increase over time even at −20°C.