How to read a certificate of analysis without a chemistry degree

Four lines tell you almost everything

A certificate of analysis is not written for consumers, which makes it more trustworthy, not less. Find four things: the assay result for each active, the heavy-metal panel, the microbiological panel, and the batch and date. Everything else is administrative.

If a brand cannot produce one for the batch number on your box, that is the answer to the question you were asking.

The assay

This is the measured amount of each active, usually by HPLC, expressed against the label claim. Anything between 90 and 110 percent of claim is normal and expected — overages are built in because some actives degrade across shelf life.

What matters is that the actives you are paying for appear here at all. Ingredients present at trace amounts often do not.

Heavy metals

Lead, arsenic, cadmium and mercury, measured by ICP-MS in parts per million, against a stated limit. Botanical and marine ingredients concentrate these from soil and water, so this panel matters most for greens, algae and mushroom products.

A result of "not detected" is good. A result under the limit is acceptable. A blank field is not a pass.

Microbiology and what failing looks like

Total plate count, yeast and mould, and specific screens for E. coli, salmonella and S. aureus. Pathogen screens should read absent, not a number.

A failing batch does not usually reach you — it is quarantined and either reworked or destroyed. The reason to read a COA is not to catch a failure. It is to confirm that someone is looking.