I get asked all the time, “How do I know if a peptide has actually been tested?” Seeing a COA is a good start, but simply having a piece of paper that says 99% purity is not enough. You need to know what you’re looking at, what was actually tested, and whether the report can be independently verified. Using the Tirzepatide COA below as an example, here are the important things I look for. 1. PRODUCT / IDENTITY — IS IT ACTUALLY TIRZ? Look for Product and Identity. In this example: Product: Tirzepatide 30 mg Identity: Confirmed The laboratory used LC-MS (liquid chromatography–mass spectrometry) for identity testing. This helps confirm that the material analyzed is consistent with the compound it is supposed to be. In other words: Did they actually send Tirzepatide to the lab? 2. NET CONTENT — HOW MANY MILLIGRAMS ARE ACTUALLY IN THE VIAL? This is one of the most important numbers people overlook. The vial may be labeled 30 mg, but the COA shows the laboratory's measured Net Content. On this report: Labeled: 30 mg Tested Net Content: 29.07 mg On the second sample we looked at, the measured content was 31.31 mg. This is why I want to see quantity testing, not just purity. A peptide can test extremely pure while still containing substantially less material than the label claims. Purity and quantity are two different measurements. 3. PURITY — HOW PURE IS THE MATERIAL? Look for Purity (HPLC-UV). On the first COA: Purity: 99.87% The second sample tested: Purity: 99.90% Purity tells you how much of the detected peptide material corresponds to the target compound relative to detectable impurities under that analytical method. 99.9% purity does NOT mean the vial contains 99.9% of the advertised milligrams. That is exactly why you need to look at both PURITY and NET CONTENT. 4. DATE REPORTED — HOW CURRENT IS THE TEST? Look near the top of the COA for: Received: When the laboratory received the sample Reported: When the laboratory issued the results This example was: