Everyone Claims Their Peptides Are Tested. But What Does That Really Mean?
Many companies boast that their peptides undergo rigorous testing to ensure they’re safe for research. Most people know purity is important—but fewer realize how critical sterility and endotoxin testing are, too. This article breaks down what each test does and why all three are essential for safety.
Understanding the Tests
1. Purity Testing: What’s in the Mix?
Purity testing measures how much of the substance is the actual peptide versus other related compounds. One common method is High-Performance Liquid Chromatography (HPLC), which shows the “peak area percentage” of the main ingredient.
For example, if a peptide has 99% purity, that means 99% of it is the desired compound and 1% is made up of other related substances. Anything over 95% is generally considered pharmaceutical grade.
2. Assay Testing: Is the Dosage Right?
While purity tells you what’s in the sample, assay testing tells you how much. It measures the actual quantity of the active ingredient by comparing it to a reference standard. This ensures that your research peptide has the correct dosage and will work as intended.
3. USP <71>: Sterility Testing
Sterility testing follows the USP <71> standard and confirms that no living microorganisms are present. Labs use methods like membrane filtration or direct inoculation to detect bacteria, fungi, or other contaminants in products labeled as “sterile.”
4. USP <85>: Endotoxin (Pyrogen) Testing
Even if all bacteria are killed during manufacturing, they can leave behind harmful fragments known as endotoxins. These can trigger serious immune reactions, even in sterile products. The USP <85> test checks for these toxic residues to make sure they’re below safe limits.
Why Purity Alone Isn’t Enough
High purity doesn’t guarantee safety. A product that’s 99.9% pure can still be dangerous if the remaining 0.1% includes harmful contaminants. Here’s what purity testing can’t catch:
- Live microorganisms that could cause infections
- Endotoxins that can trigger severe immune reactions, even if the product is sterile
Why Sterility and Endotoxin Testing Matter
Sterility Testing (USP <71>):
Without it, products could be contaminated with live bacteria or fungi. This can lead to:
- Mild to severe infections
- Life-threatening complications in immunocompromised patients
- In extreme cases, multiple organ failure
Endotoxin Testing (USP <85>):
Skipping this test can allow toxic residues to go undetected. Even tiny amounts (as low as 0.5 EU/mL) can cause:
- Fever and inflammation
- Septic shock in severe cases
- Increased risk to children, the elderly, and the immunocompromised
Sterile doesn’t always mean safe—endotoxins can still be present.
The Complete Safety Picture
To truly ensure a peptide is safe for research use, all of the following must be tested:
- Purity – Confirms the substance is the right one
- Assay – Confirms the dosage is accurate
- Sterility – Confirms there are no live organisms such as fungus and viruses
- Endotoxins – Confirms no toxic bacterial fragments remain
Only when a product passes all of these tests can it be considered safe. This multi-layered approach protects researchers from both obvious and hidden dangers.