Peptide Testing FAQ

What is peptide testing?

Peptide testing is the laboratory analysis of a peptide sample to verify its identity (is it the right peptide?), purity (how much is the target compound?), and fill weight (how much material is in the vial?). The most common methods are HPLC for purity and LC-MS for identity confirmation. Learn how testing works →

Why should I test my peptides?

Without independent testing, you are relying entirely on the vendor's claims. Independent HPLC and LC-MS analysis verifies that you received the correct peptide at the stated purity and quantity. This is especially important for research where results depend on peptide quality — impurities or incorrect peptides can invalidate experimental data.

What does a Certificate of Analysis (COA) include?

A COA includes: peptide identity confirmation (molecular weight match via mass spectrometry), purity percentage (from HPLC), fill weight (gravimetric), chromatograms (visual HPLC traces), mass spectra, and any additional test results such as endotoxin levels, heavy metals, or residual solvents. How to read a COA →

How much does peptide testing cost?

PepsReview offers free HPLC and LC-MS testing for peptide samples. Optional paid add-ons include endotoxin testing ($50), heavy metals analysis ($75), residual solvents ($60), and private/confidential testing ($100). At independent laboratories, HPLC typically costs $75-150 per sample, and LC-MS adds another $100-250.

How much peptide do I need to send?

Most HPLC and LC-MS analyses require only 0.5-1 mg of peptide. The test is minimally destructive — only a fraction of the sample is consumed, and the remaining material can be returned if you request it.

How long does testing take?

Standard HPLC and LC-MS testing takes 5-7 business days from when the laboratory receives your sample. Additional tests like endotoxin screening or heavy metals analysis may add 2-3 days.

Is the testing confidential?

Yes. PepsReview's testing service is 100% confidential. Your sample data, test results, and personal information are never shared with third parties, including vendors. Results are sent only to the email address you provide. For additional privacy, choose the private testing add-on ($100) which uses anonymous sample IDs with no personal data attached.

What purity level should I expect?

Research-grade peptides should be at least 98% pure. Premium research grade is 99% or higher. Purity below 95% indicates manufacturing issues (incomplete synthesis, poor purification) and may compromise research results. Learn about purity testing →

What does fill weight mean?

Fill weight is the actual mass of peptide material in the vial. If the label says "5 mg" but the fill weight is 3.8 mg, you received less than you paid for. Fill weight is measured by weighing the vial before and after removing the contents. Learn about fill weight →

What happens if my peptide fails testing?

You receive the full COA showing exactly what was found — incorrect identity, low purity, or short fill weight. You can use this independent report to request a refund, replacement, or quality investigation from your vendor. PepsReview does not intervene in vendor disputes but provides the data you need to make your case.

Can you tell me which vendor my peptide came from?

No. Peptide testing verifies the chemical properties of the sample (identity, purity, fill weight) but cannot identify the manufacturer or vendor. The test results are independent of the source and reflect only the physical and chemical properties of the material.

Do you test peptides for human consumption?

No. PepsReview testing is for research and educational purposes only. We do not test peptides intended for human consumption, and our results should not be used to make decisions about self-administration or medical treatment.

Can you test any type of peptide?

We can test most lyophilized (freeze-dried) peptide powders. We cannot test liquid solutions, peptides in oil-based carriers, or non-peptide compounds. If you are unsure whether your sample is testable, start the submission process and we will let you know.

What about endotoxins and heavy metals?

Endotoxin testing (LAL assay) and heavy metals analysis (ICP-MS) are available as optional paid add-ons. Endotoxins are bacterial lipopolysaccharides that can cause inflammatory reactions. Heavy metals (lead, arsenic, mercury, cadmium) can come from manufacturing contamination. These tests are recommended for peptides intended for sensitive biological assays.