A certificate of analysis (COA) is issued with every batch of sodium lignosulfonate. It reports the measured results for that batch against the agreed specification. Below is an example based on our Grade One COA template, with an explanation of each line.
Example COA: Sodium Lignosulfonate Grade One (GAC-NaLS-1)
| Parameter | Specification | Example result | Method |
|---|---|---|---|
| Appearance | Yellow-brown powder | Yellow-brown powder | Visual |
| pH (10% solution) | 7.0 – 9.5 | 8.2 | pH meter |
| Dry matter | 95% min | 96.4% | Gravimetric, oven-dry |
| Water-insoluble matter | 1.5% max | 0.9% | Filtration, gravimetric |
| Water reducing capacity | 8% min | 9.6% | Mortar flow test |
| Sulphate (SO₄²⁻) | 2 – 5% | 3.4% | Gravimetric as BaSO₄ |
| Calcium & magnesium | 0.5% max | 0.3% | Complexometric (EDTA) titration |
| Lignosulphonate content | 55% min (dry basis) | 58.7% | UV spectrophotometry |
| Reducing sugar | 7% max | 5.8% | Fehling titration |
| Moisture | 5% max | 3.6% | Loss on drying, 105 °C |
How to Read It
- Batch number and dates: must match the bags or tank and the packing list.
- Specification column: should match the TDS or your contract. If they differ, the contract applies.
- Result column: every result must fall inside the specification; the COA states PASS when it does.
- Method column: use the same method when you retest, or results will not be comparable.
- Signature and stamp: a COA is not valid unless signed or stamped by quality control.
COA, TDS and MSDS: What Each One Is For
| Document | What it tells you |
|---|---|
| TDS | Typical values and uses of the grade |
| COA | Measured results for one batch |
| MSDS | Hazards, handling, first aid and transport |
Documents for each grade are on the sodium lignosulfonate product page; Grade One safety data: MSDS. What is tested and how: manufacturing and quality control.
Frequently Asked Questions
What is on a sodium lignosulfonate COA?
Batch details, then each tested parameter with its specification, the measured result and the test method, usually appearance, pH, dry matter, insoluble matter, lignosulphonate content, reducing sugar, sulphate and calcium and magnesium.
Is the COA the same as the TDS?
No. The TDS gives typical values for the grade; the COA gives the measured results for one batch.
Can I get a COA before ordering?
Yes, a representative COA from a recent batch can be sent with the TDS and MSDS. The shipment COA comes with the goods.
What if my test result differs from the COA?
Check that you used the same method and a representative sample, then send both results to the supplier with the batch number.
