Why COA and SDS Matter
When sourcing water treatment chemicals, the Certificate of Analysis (COA) and Safety Data Sheet (SDS) are two of the most important documents you should review before placing an order. The COA verifies that the product meets your required specifications, while the SDS provides critical safety and handling information. Buying chemicals without reviewing these documents is like buying equipment without a spec sheet — you don’t really know what you’re getting.
Certificate of Analysis (COA) Explained
A COA is a quality document issued by the manufacturer or supplier that lists the actual test results of a specific production batch. It confirms that the product meets the agreed-upon specifications.
What Every COA Should Include
| Section | What to Look For |
|---|---|
| Product information | Product name, grade, CAS number, batch/lot number |
| Manufacturer info | Factory name, address, production date, shelf life |
| Specification reference | Standard followed (GB, ASTM, ISO, or customer-specific) |
| Test results | All key parameters with measured values and specification limits |
| Quality control stamp | QC signature, company seal, date of issuance |
| Packaging info | Net weight, packaging type, number of units |
COA Checklists by Product
PAC (Poly Aluminium Chloride) COA Checklist
| Parameter | Industrial Grade | Drinking Water Grade | Why It Matters |
|---|---|---|---|
| Al₂O₃ content | ≥ 28% (powder) / ≥ 10% (liquid) | ≥ 30% | Active ingredient concentration |
| Basicity | 40 – 90% | 40 – 60% | Coagulation performance |
| Water insoluble matter | ≤ 1.0% | ≤ 0.3% | Impurities; affects dosing system |
| pH (1% solution) | 3.5 – 5.0 | 3.5 – 5.0 | Corrosivity and compatibility |
| Arsenic (As) | — | ≤ 0.0002% | Drinking water safety |
| Lead (Pb) | — | ≤ 0.001% | Drinking water safety |
| Cadmium (Cd) | — | ≤ 0.0002% | Drinking water safety |
| Mercury (Hg) | — | ≤ 0.00002% | Drinking water safety |
| Chromium (Cr) | — | ≤ 0.005% | Drinking water safety |
PAM (Polyacrylamide) COA Checklist
| Parameter | Anionic | Cationic | Why It Matters |
|---|---|---|---|
| Solid content | ≥ 88-90% | ≥ 88-90% | Active polymer content |
| Molecular weight | 8-25 million | 4-15 million | Flocculation strength |
| Hydrolysis degree / charge density | 10-40% (hydrolysis) | 10-80% (charge) | Charge matching |
| Residual monomer | ≤ 0.05% (drinking water: ≤ 0.025%) | ≤ 0.05% | Toxicity; regulatory compliance |
| Dissolving time | ≤ 60 min | ≤ 90 min | Operational convenience |
| Water insoluble matter | ≤ 0.2% | ≤ 0.3% | Clogging potential |
| Bulk density | 0.6-0.8 g/cm³ | 0.6-0.8 g/cm³ | Storage volume |
| pH (0.1% solution) | 5-7 | 3-6 | Compatibility |
Activated Carbon COA Checklist
| Parameter | Typical Spec | Why It Matters |
|---|---|---|
| Iodine number | 800 – 1200 mg/g | Micropore volume / adsorption capacity |
| Methylene blue adsorption | 150 – 300 mg/g | Mesopore volume / color removal |
| Apparent density | 0.4 – 0.55 g/cm³ | Bed volume requirement |
| Hardness / abrasion number | ≥ 90% | Resistance to breakdown |
| Ash content | 5 – 15% | Purity / inorganic content |
| Moisture | ≤ 5 – 10% | Active carbon per kg |
| Particle size | 8×30, 12×40 mesh (GAC) | Pressure drop and kinetics |
| pH | 6 – 10 | Effluent pH impact |
PFS (Poly Ferric Sulfate) COA Checklist
| Parameter | Solid | Liquid | Why It Matters |
|---|---|---|---|
| Total Fe content | ≥ 21% | ≥ 11% | Active ingredient |
| Fe²⁺ content | ≤ 0.1% | ≤ 0.1% | Degree of polymerization |
| Basicity | 9 – 14% | 9 – 14% | Coagulation performance |
| Water insoluble matter | ≤ 0.5% | ≤ 0.3% | Sediment in storage |
| pH (1% solution) | 2 – 3 | 2 – 3 | Corrosivity |
| Arsenic (As) | ≤ 0.0002% (drinking water) | — | Drinking water safety |
Safety Data Sheet (SDS) Explained
The SDS (formerly MSDS) is a standardized document that provides comprehensive safety information about a chemical product. It follows the GHS (Globally Harmonized System) format with 16 sections.
16 Sections of a GHS SDS
- Identification: Product name, supplier, uses
- Hazard identification: GHS classification, signal word, hazard statements
- Composition: Ingredients, CAS numbers, concentrations
- First-aid measures: Inhalation, skin, eye, ingestion
- Fire-fighting measures: Suitable extinguishing media, hazards
- Accidental release: Personal protection, cleanup methods
- Handling and storage: Safe handling, storage conditions
- Exposure controls: PPE, exposure limits, engineering controls
- Physical and chemical properties: Appearance, pH, density, solubility
- Stability and reactivity: Stability, hazardous reactions, decomposition
- Toxicological info: Acute toxicity, irritation, sensitization
- Ecological info: Aquatic toxicity, biodegradability
- Disposal considerations: Waste treatment methods
- Transport info: UN number, transport hazard class, packing group
- Regulatory info: Applicable regulations
- Other information: Revision date, disclaimer
SDS Review Checklist
Critical Safety Items
- Hazard classification: Is it corrosive? Toxic? Flammable? Most coagulants (PAC, PFS, ferric chloride) are corrosive.
- Personal Protective Equipment (PPE): Verify required gloves, goggles, respirators, and protective clothing.
- First aid procedures: Ensure you have appropriate first-aid supplies and staff training.
- Storage requirements: Temperature, ventilation, incompatible materials, segregation requirements.
- Spill response: Neutralization agents, containment procedures, disposal methods.
- Environmental hazards: Aquatic toxicity — important for discharge permits and spill response.
- Transport classification: UN number, packing group — affects shipping costs and regulations.
Red Flags in SDS
- Missing or incomplete sections (all 16 GHS sections should be present)
- Generic SDS that doesn’t match the specific product grade
- Outdated SDS (should be revised within last 3-5 years)
- Inconsistent information between SDS and COA
- No supplier contact information or emergency phone number
- SDS written in wrong language (must be in language of the country of use)
Pre-Purchase Verification Steps
1. Before Quoting
- Request sample COA and SDS from the supplier
- Verify product specifications match your requirements
- Check that certifications (ISO, NSF, etc.) are current
- Compare specs against 2-3 suppliers to establish baseline
2. Before Ordering
- Request samples for testing (500g – 1kg minimum)
- Run jar tests or bench tests with your water
- Compare sample performance against current product
- Verify sample COA matches the sample you tested
- Confirm packaging and labeling meet your requirements
3. Before Accepting Delivery
- Inspect packaging for damage or tampering
- Verify batch/lot numbers match COA
- Check product appearance (color, form) against specification
- Request COA for the specific shipment batch
- Consider independent third-party testing for large orders
Third-Party Testing Options
For large or critical orders, consider independent verification:
| Test Type | When to Use | Cost |
|---|---|---|
| Supplier COA review | Every order | Free |
| In-house basic testing | Every delivery (pH, % active) | Low |
| Full specification testing | First order from new supplier | Medium |
| Third-party lab certification | Drinking water grade, critical applications | High |
| On-site factory audit | Large volume, long-term partnership | Highest |
Supplier Documentation Checklist
Before establishing a new supplier relationship, collect and verify:
- Business license and registration
- ISO 9001 quality management certification
- ISO 14001 environmental certification (optional but recommended)
- NSF/ANSI 61 certification (for drinking water products)
- Product COAs for representative batches
- Current SDS (GHS format, in your language)
- Export licenses and customs documentation
- Production capacity verification
- References from existing customers (preferably in your region/industry)
- Quality control procedures and testing capabilities
Common Quality Issues to Watch For
- Dilution / adulteration: Lower active content than specified. Verify with Al₂O₃ or Fe content testing.
- Wrong basicity / charge density: Different production parameters than advertised. Test performance with your water.
- High insoluble matter: Causes clogging and increased sludge. Check water insoluble content on COA.
- High heavy metals: Critical for drinking water applications. Always request heavy metal test results.
- Old stock: Some chemicals degrade over time. Check production date on COA.
- Counterfeit products: Repackaged lower-grade product under premium label. Buy directly from factory or authorized distributors.
Conclusion
Thoroughly reviewing COAs and SDS before purchasing water treatment chemicals is essential for ensuring product quality, protecting worker safety, and maintaining regulatory compliance. A systematic approach — starting with documentation review, progressing through sample testing, and ending with delivery verification — helps avoid costly mistakes and ensures you get what you pay for. Never accept a chemical shipment without a batch-specific COA, and always review the SDS before handling any new chemical product.
Have questions about COA/SDS review or need help verifying supplier quality? Contact our team for expert guidance on sourcing reliable water treatment chemicals.