Short answer: A Certificate of Analysis (COA) is a lab report for one batch. HPLC tells you how pure the sample is; mass spectrometry tells you what it is. You need both, from a named independent lab, with a lot number that matches your vial. Bloodwork then tells you how your body responds.
What a COA is
A COA reports tests on a specific lot. It is the only outside check that the powder matches the label. A purity claim on a product page with no report behind it tells you nothing. A report from the seller's own lab counts for less than one from an independent lab.
HPLC: how pure
High-performance liquid chromatography pushes the sample through a packed column. Different compounds come out at different times and show up as peaks on a chart (the chromatogram).
- Purity = the area of the main peak ÷ the area of all peaks.
- The main peak should dominate and come out at the expected time.
- Small extra peaks are other things: breakdown products, shortened chains or leftovers from making it.
- Look at the chart itself, not only the number. Big side peaks with a high headline number do not add up.
HPLC does not tell you what the main peak is.
Mass spectrometry: what it is
Mass spectrometry measures the mass of the molecule. Every peptide has a known expected mass: BPC-157 is 1419.5 g/mol and semaglutide about 4114 g/mol, per PubChem. A match confirms identity; a mismatch means the wrong compound, a labeling error, or a failed synthesis.
HPLC alone could show 99% purity of the wrong molecule. Mass spec alone says nothing about impurities. You need both. A combined LC-MS report covers both at once.
Other tests
- Endotoxin (LAL test): finds bacterial toxins that cause fever and inflammation. Important for anything injected. Acceptable limits depend on the dose and route.
- Sterility: checks for live bacteria and fungi.
- Residual solvents: chemicals such as acetonitrile and DMF used in making peptides. The ICH Q3C guideline sets limits for drugs. TFA left over from purification is also common.
- Heavy metals: more relevant for plant-based supplements than for made peptides.
Green flags and red flags
Scanning a COA
| Green flag | Red flag |
|---|
| Named independent lab you can find | "In-house" or no lab named |
| Lot number matches your vial | No lot number, or it does not match |
| Recent test date for this lot | No date, or very old |
| Exact purity with the method | "High purity" or ">95%" only |
| HPLC and mass spec, with charts | Only one of the two |
| Clean, readable report from the lab | Blurry, edited-looking PDF; same report reused across lots |
Pair it with bloodwork
A COA checks the product. Bloodwork checks your response.
- Growth hormone peptides: IGF-1 is the main marker. If the COA looks clean but IGF-1 does not move after a few weeks at a steady dose, the cause may be the dose, storage, or a vial that does not match its report.
- GLP-1 drugs: fasting glucose, HbA1c, lipids and liver enzymes.
- Repair peptides: blood tests say less; inflammation markers like hs-CRP are sometimes followed.
Get a baseline before starting and recheck with your clinician. Trends say more than one result. You can keep results in Dose Track; see upload labs and lab targets.
Key points
- HPLC shows purity; mass spectrometry shows identity. You need both.
- The lab should be named and independent, and the lot number should match your vial.
- For injected products, look for endotoxin testing.
- Bloodwork shows whether the product is doing what it should in you.
See also: Upload labs in Dose Track · Lab targets
This guide is general education, not medical advice. Follow your medicine's label and your prescriber.
What is the difference between HPLC and mass spec?+
HPLC measures how pure a sample is. Mass spectrometry measures the molecule's mass to confirm what it is. A trustworthy report has both.
What is the molecular weight of BPC-157?+
About 1419.5 g/mol, per PubChem. A mass spec result should match it.
How recent should a COA be?+
It should be for the exact lot you received. A report reused across lots or with no date is a warning sign.