Peptide Lab Testing & COA Guide

Identity: LC-MS

Identity testing checks whether the submitted material matches the named compound. LC-MS separates components and measures mass-to-charge signals that can be compared with the expected molecular mass.

What it does not establish: A matching mass supports identity, but mass alone may not distinguish compounds with the same mass or establish the full sequence. It does not establish purity, quantity or freedom from contamination.

Peptide Identity Testing Methods That Verify Claims · COA guide: identity

Purity: HPLC

HPLC separates the components detected under a stated method. A reported purity percentage commonly compares the target peak area with the total detected peak area.

What it does not establish: Peak-area purity is not the percentage of the vial's total weight that is peptide. It depends on the method and detector; it does not independently confirm identity, amount, sterility or endotoxin levels.

Peptide Purity Testing: What a COA Must Prove · COA guide: purity

Net content: Quantitative assay

Net content testing measures how much of the named compound is in the tested sample, usually reported in milligrams per vial. A quantitative assay needs a documented method and an appropriate calibration or reference.

What it does not establish: The powder's total weight and a high HPLC purity percentage are not substitutes for measured compound content. Water, counterions and other material can contribute to weight.

What Counts as Peptide Net Content Verification? · COA guide: net content

Sterility: Microbial growth testing

Sterility testing checks for viable microorganisms that grow under the test's specified conditions. The report should identify the method, sample and result.

What it does not establish: A pass applies to the tested sample and conditions, not an absolute guarantee for every vial or later handling. It does not establish a low endotoxin level or suitability for human use.

Sterility Testing for Research Peptides Explained · COA guide: sterility

Endotoxin: LAL or recombinant assay

Endotoxin testing measures bacterial endotoxins associated with gram-negative bacteria, using a method such as LAL or a validated recombinant assay. Check the reported units, detection limit and sample concentration.

What it does not establish: Endotoxin can remain after bacteria are no longer viable, so a sterility result cannot replace this test. A low result does not rule out all contaminants or establish safety for human use.

Endotoxin Testing for Peptide Products Explained · COA guide: endotoxin

Heavy metals: ICP-MS or another validated elemental assay

Elemental testing measures specified metals, often including lead, arsenic, cadmium and mercury. ICP-MS can detect trace concentrations when the sample preparation and method are appropriate.

What it does not establish: Only the listed elements and reported detection limits are covered. A pass does not mean every possible contaminant was tested, or that the compound is suitable for human use.

Heavy Metal Testing for Peptides Explained · COA guide: heavy metals

Read the report in context

How RUO Codes vets vendors explains our directory standards. The AI-Assisted COA Check can help review a document, but cannot authenticate a laboratory report or independently test a sample.

• What Conformity Testing for Peptides Can Verify
• Peptide quality testing: what labs actually find
• How to verify a peptide COA
• Bacteriostatic water: third-party testing findings

Testing glossary

Certificate of Analysis (COA) · HPLC · Mass spectrometry (LC-MS) · Endotoxin

Lab testing questions

What does a peptide identity test verify?

It provides evidence that the tested sample matches the named compound. LC-MS mass data can support identity, but matching mass alone does not establish the full sequence, purity or amount.

Does HPLC purity tell me how many milligrams are in a vial?

No. HPLC peak-area purity and net content answer different questions. A quantity claim needs a documented quantitative assay; total powder weight is not the same as measured peptide content.

Do sterility and endotoxin tests verify the same thing?

No. Sterility testing looks for viable microorganisms under specified conditions. Endotoxin testing measures bacterial endotoxins, which can remain even when bacteria are no longer viable.

What does a heavy metal test cover?

It covers the specific elements, sample and detection limits listed in the report. It does not rule out every possible contaminant.

Does a COA prove that every vial is identical or safe for human use?

No. A COA describes the sample and methods reported by the laboratory. Batch matching, representative sampling, report authenticity and handling all matter. Research-use-only material is not established as safe for human use by a COA.