How to read a Certificate of Analysis.

A COA is a lab report from an outside lab. It should show the right molecule, 95% pure or better, and clean. Match the batch number.

What a real lab report shows

Certificate of Analysis (COA)

✓Identity: matches the molecule you ordered (a mass-spec weight match)
✓Purity: 95% or higher (a test called HPLC)
✓Endotoxin: under 0.5 EU/mg (a germ-junk test for shots)
✓Batch number: matches the number printed on your vial
✓Lab + date: an outside lab, signed, less than a year old

No batch number, or a lab owned by the seller? That is a red flag. Walk away.

A (people call it a ) is a test report. An outside lab, not the seller, runs the tests and writes it. A good says three things: the vial holds the right molecule, it is as pure as the label claims, and it has no harmful junk above safe limits. With no COA, you are guessing.

What a real shows.

identity (proof it is the right molecule). The lab weighs the molecule with a machine called a mass spec. The weight has to match what that should weigh.
purity (how clean it is). A test called should show 95% pure or higher (98% or more is pharmacy-grade).
(these are bits of dead germ that can make you sick). For shots, the level should be under 0.5 EU/mg.
moisture (how much water is trapped in the powder). Dry peptides should be under 8%.
the batch number (a code for that exact made batch). It must match the code on your vial exactly.
the lab name, a signature, and a date.

Red flags. These mean be careful:

no batch number at all
a batch number that does not match your vial
a lab that is the same company as the seller (then it is not really an outside check)
a "purity" number with no test method named ( is the one you want)
no test
a date more than 12 months old
a number that looks too perfect, like "99.9999%"

Even a clean COA can go bad later

A vial that sat too long, or got too warm, can break down. So look at the vial yourself. Throw it out if the powder changed color, bits float in it after you mix it, or it smells bad. When in doubt, throw it out.

One more thing

A seller who posts COAs is not always safer than one who does not. They are just more open about being checked. Ask for a before you buy. If they cannot show one, walk away.

More: How to source.