How to read a Certificate of Analysis before you approve a shipment

Every reputable supplier sends a Certificate of Analysis. Far fewer buyers read it closely — and a COA you did not check is documentation, not assurance.

Match the document to the shipment

Start with identity. The batch or lot number on the COA must match the number on the bags you received. A generic COA, or one from a previous lot, tells you nothing about the material in your warehouse.

Check the date of analysis too. A certificate issued long before the shipment date may describe material that has since been reprocessed or reblended.

Read the method, not just the result

A result without a method is an opinion. For standardized extracts, the assay method matters enormously: withanolide content by HPLC and by gravimetric methods can produce very different numbers from the same material.

Ask that the method be stated on the certificate — HPLC, UV, gravimetric — and keep it consistent across suppliers when you compare.

The sections worth scrutinising

• Identity and actives — the botanical name, plant part, and the assay for the active you are paying for.
• Heavy metals — lead, arsenic, cadmium and mercury, with limits appropriate to your destination market.
• Pesticide residues — which panel was run, and whether it covers the residues relevant to that crop.
• Microbiology — total plate count, yeast and mould, E. coli, Salmonella.
• Physical parameters — moisture, mesh, ash, bulk density.

Who did the testing

In-house results from a supplier's own lab are useful for process control. For release testing, third-party results from an accredited laboratory carry more weight — and many buyers require them contractually.

Build it into your process

Decide in advance which parameters are release-critical for your product, write them into your purchase specification, and treat the COA as the document that proves conformance. Anything you did not specify is not something you can reject a lot for later.