What is a Certificate of Analysis (COA) and why batch verification matters in peptide research

A Certificate of Analysis (COA) is the single most important document that accompanies any research peptide. It is the record that links a specific vial — identified by its batch number — to the analytical results obtained from an independent third-party laboratory. Without a COA tied to that exact batch, researchers cannot confirm the identity, purity or stability of the material they are about to introduce into an experiment.

What a research peptide COA contains

A complete COA will typically include:

• Product identity — the peptide name, sequence (where relevant) and molecular weight.
• Batch / lot number — a unique alphanumeric identifier traceable to the production run.
• Net peptide content — measured in milligrams, accounting for counter-ions and residual moisture.
• Purity percentage — measured by Reversed-Phase HPLC with UV detection, typically at 214 nm or 220 nm.
• Mass identification — confirmed by LC-MS / MS, matching the theoretical mass within instrument tolerance.
• Appearance — for lyophilised peptides, this is usually described as a white or off-white powder.
• Test date and report date — when the analytical work was performed.
• Signature of the principal chemist and the laboratory contact details.

How purity is determined

Purity is established by HPLC. A sample is dissolved in a buffer, injected into a column and separated by hydrophobicity. The detector records every species that elutes, integrates the resulting peaks and reports the target peptide as a percentage of the total area under the chromatogram. A clean single peak above 99 % is the expectation for a high-quality research peptide.

Identity is then confirmed by mass spectrometry. The instrument ionises the sample and measures the mass-to-charge ratio of the resulting fragments. Multiply-charged species — for example [M+2H]²⁺ or [M+5H]⁵⁺ — produce a characteristic fingerprint that should match the theoretical mass of the target sequence.

Why batch traceability matters

Two vials sharing the same product name but originating from different production runs are not interchangeable. Synthesis conditions, lyophilisation cycles and even ambient humidity during fill-finish can shift residual moisture, salt content and degradation products. A research team that does not pin its experimental record to a specific batch loses the ability to reproduce its own results or to trace anomalies back to a material origin.

Verifying a batch before laboratory use

Before opening a vial, three checks should always be performed:

1. Read the batch number printed on the side label and cross-reference it against the COA you have on file.
2. Match the appearance described on the COA against what is in the vial — for example, a blue lyophilised powder for GHK-Cu, white for most other peptides.
3. Note the test date and expiry date to confirm the analytical data is still in scope for your intended storage period.

Every Spheres Peptides vial carries a batch number on the label. The matching COA is retrievable in seconds via the COA Verification page — enter the batch number and the platform returns the purity, test date, lab name and a downloadable PDF.

For research use only. Not for human consumption. No medical, diagnostic, therapeutic, weight-loss or performance claims are made on this site. Prescription-only medicines are not advertised here.