In short: A COA you can rely on has five verifiable blocks — batch identity, physical & chemical data, assay with a named method, contaminants with numbers, and microbiological results with methods. Before you compare prices, check three things: the batch number matches your shipment, the assay method is stated (HPLC vs UV changes the number), and no required section is blank. A COA missing a batch number cannot be tied to any shipment you receive — treat it as a template, not evidence.
Why a COA is a specification check, not a certificate
A Certificate of Analysis documents what was tested on one specific batch of material. It is not a certification of your supplier’s system (that is FSSC 22000, ISO 22000 or cGMP), and it is not a guarantee that the next batch will match. Read it as an evidence record you can audit — each number should be traceable to a method, a batch and a signature.
The five sections every COA should have
Each block answers a different question. If any one is missing, the COA is incomplete for regulated-market purchasing.
| Section | What it must contain | What it proves | Red flag if… |
|---|---|---|---|
| 1. Product identity & batch block | Product name, batch/lot number, botanical name (Latin), manufacture / analysis / expiry dates | This document belongs to the material you are buying | No batch number, or dates that do not match your shipment |
| 2. Physical & chemical data | Appearance, colour, odour, loss on drying, ash, particle size, bulk density | The powder you receive matches the material that was tested | Values identical across unrelated batches (template reuse) |
| 3. Analytical quality — the assay | Active marker, method (HPLC / UV / TLC / GC), specification limit, measured result | The material actually meets the grade you paid for | No method named; result exactly equal to the minimum spec |
| 4. Contaminants | Heavy metals (Pb, As, Cd, Hg), residual solvents, pesticides, with methods | The batch is safe for your target market’s limits | Section blank, “not tested”, or only the words “meets EU” |
| 5. Microbiological data | TPC, yeast & mould, E. coli, Salmonella — with methods (USP <61>, <62>) | Microbial load is within specification for food/supplement use | Blank cells, or “negative” with no method reference |
Reading the assay column: minimum spec vs result
Most botanical extract specifications are written as a minimum (for example, “ginsenosides ≥ 30% by UV”). Two checks matter:
- Is the method stated? Withanolides measured by UV can read materially higher than by HPLC on the same material. If your purchase agreement says HPLC, a UV result does not satisfy it.
- Is the result above the minimum? A batch at 30.0% against a ≥30% minimum is technically compliant but leaves no margin for blending or storage drift. Representative results in the 30.1–30.5% range are normal for a well-controlled process.
Typical limits buyers should expect to see
The table below shows limits commonly applied to botanical extract powders for food and supplement use. Confirm the exact values against your target market’s pharmacopoeia or your own specification before ordering.
| Parameter | Typical limit | Method |
|---|---|---|
| Lead (Pb) | ≤ 3 ppm | ICP-MS |
| Arsenic (As) | ≤ 2 ppm | ICP-MS |
| Cadmium (Cd) | ≤ 1 ppm | ICP-MS |
| Mercury (Hg) | ≤ 0.1 ppm | ICP-MS |
| Total plate count | ≤ 10⁴ cfu/g | USP <61> |
| Yeast & mould | ≤ 10² cfu/g | USP <61> |
| E. coli | Absent | USP <62> |
| Salmonella | Absent | USP <62> |
| Residual solvents | Per ICH Q3C / USP <467> | GC |
| Pesticides | Per EU MRL or USP <561> | LC-MS/MS |
Red flags: six patterns that repeat across rejected batches
| Red flag | What a compliant COA shows instead |
|---|---|
| No batch number or no dates | Batch code plus manufacture, analysis and expiry dates |
| Identical values across unrelated batches | Small natural variation between batches (e.g. 30.2% vs 30.4%) |
| Assay result exactly on the minimum spec | Result with margin above the stated minimum |
| Contaminants blank or “not tested” | Per-batch numbers with ICP-MS / GC methods |
| No method references anywhere | HPLC, UV, GC, ICP-MS, USP chapter numbers stated |
| No QC signatures | Named analyst, reviewer and approver |
Comparing a COA against your own lab result
Method mismatch is the single most common cause of “failed” incoming QC that is not actually a quality failure. Before disputing a batch, confirm that both labs used the same method, the same reference standard and the same calculation basis (for example, on an anhydrous basis vs as-is). Where methods differ — UV versus HPLC for the same marker — agree the method in the purchase agreement, not after delivery.
FAQ
Can I trust a supplier COA without third-party testing?
Use it for screening, not as final evidence. For first orders, high-value lots or regulated markets, commission an independent lab on a retained sample. Ask the supplier to hold a sealed retention sample of the same batch.
What if the COA uses a different method than my lab?
State the method in your purchase agreement before ordering (for example “withanolides 7.0% minimum, HPLC”). Method differences such as UV versus HPLC can move a result by several percentage points without any quality defect.
The assay result exactly equals the minimum spec — is that a problem?
It is compliant but worth questioning. A result sitting exactly on the limit usually signals either a specification written from a template or a batch blended to the edge of the range. Ask for the value with decimals and the method.
How recent should a COA be?
The COA must belong to your batch, so its analysis date normally falls within weeks before shipment — not months. If you receive a COA older than your order, ask which batch it covers.
Should the COA batch number match my shipment’s documents?
Yes. The batch number on the COA should match the batch number on the packing list and the drum labels. Any mismatch breaks traceability and is a documented red flag.
What does “≥” mean in the specification column?
“≥ 30%” means the value must be at or above 30%. The measured result column should show a number at or above that limit — a blank result cell does not satisfy the specification.
Do I need per-batch heavy metals, or is an annual test enough?
For regulated markets and food/supplement use, per-batch heavy metals are the working standard. Annual or periodic testing can support capability claims but does not release an individual lot.
What should I do if a COA section is blank?
Ask for a complete COA for the same batch before releasing payment or shipping. A blank section is an unanswered question, not a neutral one.
Browse certified extracts with batch-level COAs, or contact us with your target specification and destination market.