How do I interpret the COA (HPLC/MS)?
A Certificate of Analysis (COA) ties your vial to specific QC data. Here’s how to read it quickly and correctly.
1) Match identifiers
- Product name/SKU
- Fill amount
If any identifier doesn’t match your vial, contact support before use.
2) Understand HPLC purity (area %)
- What it is: % of the main peak’s area relative to all integrated peaks.
- What it means: Higher % ⇒ fewer related peptide species (e.g., truncations, oxidations, epimers).
- Typical details on COA: column type (often C18), gradient/solvents, flow, detection wavelength (commonly 214–220 nm), retention time, and purity (area %).
Key notes
- HPLC area % ≠ weight %. Water, counter-ions (TFA/acetate), and volatiles aren’t reflected in area %.
- Minor peaks are usually closely related variants, not fillers.
- Because methods vary, don’t over-compare purity % across different labs/conditions.
3) Read the MS section (identity confirmation)
- Calc. mass (M) vs. Found/Observed mass should align within instrument tolerance.
- You may see charge states (e.g., [M+H]+, [M+2H]2+) or MALDI/ESI annotations.
- A matching mass supports sequence identity; MS does not measure purity.
4) Quick troubleshooting guide
| COA shows… | What it implies | What to do |
|---|---|---|
| Purity high (≥98%) but vial looks “small” | Appearance varies with lyophilization density | Go by weight/COA, not cake size |
| Extra peaks in HPLC | Typical related species | Ensure your method tolerates them; contact us if your assay is highly sensitive |
| Observed mass off | Potential ID issue | Re-check units/charge; if still off, contact support with the COA and vial photo |
Takeaways
- HPLC = purity of peptide portion; MS = identity
RUO reminder: All products are for laboratory research use only—not for human or veterinary consumption.