A Certificate of Analysis, or CoA, is a lab report for a specific batch of AdBlue®. It lists what was tested, the result for each test and the limit it had to meet. For fleets, mine sites and resellers it is the most direct evidence you'll get that the product in your tank meets ISO 22241. It's only useful, though, if you know what you're looking at.
The header: making sure it's the right batch
Before looking at any numbers, check that the certificate actually relates to your product. The top section should show:
- Product name – AdBlue, AUS 32 or aqueous urea solution 32.5%.
- Producer – the company that made it, with contact details.
- Batch or lot number – this must match the number on your drum, IBC label or delivery docket.
- Production and test dates – so you can see how old the batch is.
- Standard referenced – ISO 22241-1 for the limits, ISO 22241-2 for the test methods.
- Sign-off – who approved the results.
A CoA with no batch number is a general product sheet, not a certificate for your product. It may be accurate, but it doesn't prove anything about what you received.
The results table, line by line
Most AdBlue CoAs follow the ISO 22241-1 list of properties. A typical table has columns for the property, unit, specification limit, result and test method. The key lines are:
| Property | ISO 22241-1 limit | What it tells you |
|---|---|---|
| Urea content | 31.8–33.2% | Correct concentration. Target 32.5%. |
| Density at 20°C | 1087–1093 kg/m³ | A cross-check on concentration. |
| Refractive index at 20°C | 1.3814–1.3843 | Another concentration cross-check. |
| Biuret | ≤ 0.3% | A by-product of urea manufacture and heating. High levels can form deposits. |
| Aldehydes | ≤ 5 mg/kg | An organic impurity the standard keeps very low. |
| Insoluble matter | ≤ 20 mg/kg | Particles that can block filters and injectors. |
| Phosphate | ≤ 0.5 mg/kg | Can poison the SCR catalyst. |
| Calcium, iron, magnesium, sodium, potassium | ≤ 0.5 mg/kg each | Often from poor water or raw materials. |
| Copper, zinc, chromium, nickel | ≤ 0.2 mg/kg each | Often from incompatible metals in the process. |
| Aluminium | ≤ 0.5 mg/kg | From incompatible equipment or raw materials. |
Some certificates also report alkalinity (as ammonia) and appearance. Results for trace metals are often shown as "< 0.1" or similar, which means the level was below what the lab method could measure. That's what you want to see.
What to check before you file it
A quick review takes a couple of minutes:
- Batch match. The batch number on the CoA matches your container or docket.
- Every result within limit. Check each line, not just the urea content. A "pass" at the bottom is helpful, but look at the numbers.
- Metals reported individually. The metals should be listed separately. A single "total metals" figure doesn't let you compare against the standard.
- Methods referenced. Results should reference ISO 22241-2 or equivalent methods.
- Dates make sense. The test date should be close to production, and the batch shouldn't be so old that shelf life is a concern for your storage conditions.
- Producer identified. For product sold as AdBlue, the producer should hold a VDA licence. See our certification page for how that works.
One thing to do today: set up a folder, paper or digital, where every AdBlue delivery docket is kept with its matching CoA. If a vehicle ever has an SCR fault, being able to show the batch and its test results in two minutes makes the conversation with your workshop or supplier much simpler.
What a CoA doesn't cover
A CoA describes the batch when it was tested at the plant. It can't account for what happens afterwards. Storage in heat, incompatible fittings, reused containers or tap water on your site can all push good product out of spec. The CoA shows the product was right when it left; good handling keeps it right until it reaches the vehicle.
If you suspect a problem with product that had a clean CoA, keep a sealed sample, check your own storage and equipment, and talk to the supplier. They should be able to review the records and test results for that batch.
How Liquidia can help
Every batch of Liquidia AdBlue is lab-tested to ISO 22241 under VDA licence No. 0005569, and a Certificate of Analysis is available on request for any batch you receive. Find sample documents on our resources page or open a trade account for regular supply.