A Certificate of Analysis is only useful if you can read it. Here is line-by-line what a legitimate peptide COA reports and what each field means for New Zealand research labs.
A Certificate of Analysis (COA) is the primary document verifying that a peptide batch matches its declared identity and purity. This Kiwi Peps reference walks through each COA field a research lab evaluates before releasing the material into an experiment, and lists the most common red flags on inadequate COAs.
Peptide COA field-by-field reference
| Field | What it should report |
|---|---|
| Batch / lot identifier | Unique per production run, traceable to the lot record |
| Synthesis date | Anchors shelf-life and stability documentation |
| HPLC purity (%) | Typically ≥98% for research; ≥99% for peptides under ~30 residues |
| Analytical HPLC method | Column, mobile phase and gradient specified |
| LC-MS identity | Observed mass within ±0.5 Da of theoretical |
| Counterion identity | Acetate or TFA |
| Counterion content | Percent by mass |
| Water content | Karl Fischer or Medsafe result |
| Endotoxin | Where downstream cell culture is involved |
| RUO classification | Explicit statement on the COA |
Common peptide COA red flags
- Purity value reported without a supporting HPLC chromatogram image.
- Mass reported without a supporting LC-MS trace.
- No counterion or water-content data.
- Boilerplate batch numbers reused across shipments.
- Blend products with combined-mass-only purity figures.
How the Kiwi Peps COA is structured
- Every batch ships with a lot-specific COA that includes all fields above.
- HPLC chromatogram and LC-MS trace are included as visual verification.
- Third-party analytical verification is available on request.
- RUO classification is stated explicitly on both the COA and the vial.
Peptide purity testing FAQ
What HPLC purity value is standard for research-grade peptides?
Typically ≥98% for research use; peptides under ~30 residues are frequently specified at ≥99%.
What is a counterion on a peptide COA?
The counterion is the salt form of the peptide — typically acetate or TFA — and its percent by mass affects the true peptide content in the vial.
Where can New Zealand researchers buy peptides with a full COA?
Kiwi Peps supplies every peptide with a full lot-specific COA, HPLC and LC-MS data, third-party verification on request, and same-day domestic dispatch.
