Why We Offer a 99% Purity Guarantee

For laboratory and research use only. Not for human consumption.

Most Vendors Will Not Guarantee Purity. We Do.

Go to most peptide vendor websites and look for a purity guarantee. You will find vague language — “high purity,” “lab tested,” “premium grade.” What you will not find is a specific number with a specific promise attached to it.

There is a reason for that. Guaranteeing purity means putting money behind the claim. It means that if the product does not meet the standard, the vendor eats the cost. Most vendors are not confident enough in their supply chain to make that bet.

We are. Every peptide we sell comes with a 99% purity guarantee. If independent testing shows it falls below that threshold, you get a full refund. No arguments, no fine print.

The Purity Problem in the Peptide Industry

The peptide market has a quality problem, and it is getting worse.

A 2008 study in Clinical and Vaccine Immunology found that commercial synthetic peptides from established suppliers contained contaminating peptides — even at low levels, these contaminants were enough to produce false results in sensitive research assays (PMC2238048). That was from reputable suppliers with quality control programs in place.

Now consider the current market. The explosion in demand for GLP-1 peptides like semaglutide and tirzepatide has attracted a flood of new vendors — many with no quality infrastructure at all. A 2024 analysis of online “research” semaglutide found products with purity levels as low as 7-14%, far below anything that should be sold to researchers.

The Obesity Medicine Association published a position statement in 2024 raising serious concerns about compounded peptides, noting the higher risks that come with products that have not undergone FDA review for safety, effectiveness, or quality (PMC11369382).

In this environment, “trust us” is not good enough. You need a guarantee.

What Low Purity Actually Means for Your Research

When a peptide is 80% pure instead of 99%, three things happen:

• Less active peptide per vial. If you ordered 10mg of BPC-157 and the purity is 80%, you actually have 8mg of BPC-157 and 2mg of something else. Your dosing calculations are off from the start.
• Unknown impurities. That other 20%? It could be truncated peptide fragments, residual synthesis chemicals, or even a completely different peptide. In research settings, unknown variables introduce noise. Your results become harder to interpret and harder to reproduce.
• Inconsistent results between batches. If one batch is 90% pure and the next is 75%, your experiments will produce different outcomes even with the same protocol. Batch-to-batch consistency requires high purity at every step.

Our Guarantee: 99% Purity or Full Refund

Here is our promise in plain language:

If any peptide you purchase from NorthPeptide tests below 99% purity through independent third-party analysis, we will issue a full refund for that product.

No questions. No hoops to jump through. No “store credit only.” A full refund.

Why We Can Make This Promise

We can offer this guarantee because we have built our entire supply chain around quality. Specifically:

• We work with a small number of vetted manufacturers. We do not buy from whoever offers the lowest price. We source from manufacturers with documented quality systems and consistent track records.
• We test every single batch. Not a sample from a large order — every batch. HPLC for purity, mass spectrometry for identity, and third-party lab verification for independence. (Read the full breakdown: How We Test Our Peptides.)
• We reject batches that fall below standard. If a batch does not meet 99%, we send it back. We would rather be out of stock than sell a product we cannot stand behind.
• We provide a COA for every product. You can see the test results yourself. (Learn how to read one: How to Read a COA Without a Science Degree.)

The guarantee is not a marketing gimmick. It is a natural consequence of doing the work right.

The Cost of Quality

Let us be honest: our peptides are not the cheapest on the market. They never will be.

Here is why. Achieving and maintaining 99% purity is expensive. Proper purification takes time and specialized equipment. Third-party testing costs money — real money, for every batch. Working with quality manufacturers costs more than working with the cheapest option in a catalog.

We could sell cheaper peptides. We could skip the third-party testing. We could buy from the lowest-cost manufacturer and hope for the best. Our margins would be better. Our prices would be lower.

But our products would not be worth the label on the vial.

A review of reference standards for peptide therapeutics noted that quality assessment depends on well-characterized reference standards and rigorous analytical testing — none of which is free (PMC10338602). The cost of quality is built into the price because the cost of low quality is built into bad results.

When you buy from NorthPeptide, you are not just buying a peptide. You are buying the testing, the verification, and the guarantee that comes with it.

How to Make a Claim

If you believe a product you received falls below our 99% purity standard:

1. Contact our support team with your order number and a description of your concern.
2. Provide independent test results from a recognized third-party laboratory showing purity below 99%. We will work with you to identify a suitable lab if needed.
3. We review and process your refund. If the third-party results confirm purity below 99%, you receive a full refund. We also pull and re-test the batch in question to determine if it is an isolated issue or a broader problem.

We have never had to process a purity claim. We intend to keep it that way — not by making claims hard to file, but by making products that never fail the test.

Full details on all our guarantees — including our customs guarantee and arrival guarantee — are on our guarantees page.

Summary of Key Research References

Topic	Reference	PMC ID
Peptide impurities in commercial products	Currier et al., Clinical and Vaccine Immunology, 2008	PMC2238048
Compounded peptide safety concerns	Obesity Medicine Association, Obesity Pillars, 2024	PMC11369382
Reference standards for peptide therapeutics	Bak et al., Journal of Pharmaceutical Sciences, 2023	PMC10338602

Written by NorthPeptide Research Team

For laboratory and research use only. Not for human consumption.