How to Interpret Peptide Purity

In order to be sure that your peptide products are accurately labeled to actually contain the compound on the label, and also have the accurate amount of active compound in the vial, laboratory testing is required. To determine these two variables, two different tests are needed. These tests are explained below.

A warning from the team – there are many common labs used to test research chemicals such as peptides. We investigated this and unfortunately found that they are not real laboratories. Thus, you can rest assured that the laboratory tests that appear across the internet, all of which come from one of three common “labs” are fake. Even if they were real, most vendors just Photoshop the lab tests published by other vendors.

At, we found a real and verified laboratory (we did a site visit) that would agree to test peptide products for us. At this time, this is the only laboratory that we can recommend. A great thing about this lab – Verve Laboratories – is that they enable the public to search for archived lab tests using a LOT number.

Disclaimer: We are a user funded community and we do not make any commissions from tests purchased from Verve Laboratories.

HPLC and Mass Spectrometry

HPLC stands for high performance liquid chromatography. This is a widely used testing methodology that separates, identifies, and quantifies each component in a solution. The only way that the test can identify each component of a solution is by using a reference standard. This is a critical variable to understand. Without a reference standard, the test is not useful. 

For peptides, almost all peptides have readily available reference standards available that licensed and legitimate laboratories can acquire. In fact, some of the largest peptide vendors online sell their products B2B (business to business) to academic laboratories and testing companies. Unfortunately, there are about as many legitimate vendors as there are fingers on one of your hands. That’s not to say you won’t receive “something” in the mail when you pay for an order with xyz vendor, but you’re 90% likely to receive a bottle of nothing.

Mass spectrometry (MS) is a methodology that can measure the weights (more accurately, the masses) in a sample by a process that involves ionizing chemicals and differentiating the ions depending on their mass to ionic charge (a ratio). We know this sounds technical, but it is a widely used methodology.

Purity Ratings and What They Mean

Highly Pure (>98% Peptide Purity)

This level of purity (98%+) is used in the following applications:

• In vitro and in vivo studies.
• Clinical trials.
• Drug studies in which peptides are used as pharmaceuticals.
• Cosmetic peptides for cosmeceuticals.
• Crystallography.
• Monoclonal antibody production.
• Quantitative protease studies and enzyme studies.
• Quantitative receptor – ligand interaction studies.
• Quantitative blocking and competitive inhibition studies.
• Quantitative ELISA and RIA protocol standard.
• Chromatography standard.

Mid-range Peptide Purity (>85%)

This level of purity (98%+) is used in the following applications:

• Peptide blocking studies (Western blot).
• Phosphorylation studies.
• NMR studies.
• Cell attachment studies.
• Phosphorylation studies.
• Semi-quantitative studies of enzyme-substrate interactions.
• Epitope mapping tests.
• Biological activity testing.

Lower Peptide Purity (>70%)

This level of purity (98%+) is used in the following applications:

• Peptide arrays.
• Performing an ELISA standard for measuring titers of antibodies.
• Antigens for polyclonal antibody production or affinity purification.