One COA proves a batch; consistency is about the next ten
A single Certificate of Analysis shows one lot passed. The real repeat-order risk is variation across the lots you will receive over a year. Buyers reduce that risk by locking the active marker, the assay method and an acceptable range up front, then checking each incoming COA against that range rather than treating every lot as a fresh pass/fail.
Lock the marker, the method and the range
A standardized extract is defined by its active marker, a target range and the assay method. For example, green tea extract is offered at Tea Polyphenols 98% / EGCG 50% and a Tea Polyphenols 60% / EGCG 30% grade, both reported by UV plus HPLC; curcumin is supplied at 95% curcuminoids by HPLC; and nattokinase is graded by activity units (20,000 FU/g) rather than a percentage. Without the method and the range stated, a bare '95%' is not comparable from one lot to the next.
Ask for batch COA history, not a single sheet
Request recent batch records that show the marker value sitting inside the declared range across several production dates. As an example from a real recent run, green tea extract batches included HS-BE-GTE-98-2506 (2025-06) at Tea Polyphenols 98.2% / EGCG 50.4% (UV/HPLC), HS-BE-GTE-60-2503 (2025-03) at 60.5% / 30.8%, and HS-BE-GTE-50-2412 (2024-12) at 50.3% — each within its declared grade. A useful COA references batch number, assay result, test method, production date and the relevant contaminant checks.
Write a re-order spec, not a catalog line
Put the marker, method, acceptable range, packaging and document scope into the re-order RFQ, and confirm supplier route and stock before price. HerbalSourcing states its role as a supplier and exporter of botanical extracts and confirms document availability by product, grade, supplier route, stock status and destination market — so a re-order matches the batch your team already qualified.