What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a quality assurance document issued by a supplier or third-party laboratory that certifies the test results for a specific batch of an ingredient or raw material. For food-grade, USP-grade, and cosmetic-grade ingredients, the COA is the primary document confirming that a product meets its stated specifications before it enters your supply chain or formulation process.
Whether you are purchasing vegetable glycerin, propylene glycol, MCT oil, triethanolamine, or any other bulk ingredient, you should always request and review the COA for each lot before accepting a shipment. This guide explains what to look for, how to interpret key sections, and what red flags to watch out for.
Key Sections of a COA
1. Product Identification
The top of any COA should clearly state:
- Product name and INCI/chemical name: Confirms you received what you ordered (e.g., "Glycerin, Vegetable" or "Propylene Glycol USP").
- CAS number: A unique chemical identifier. Cross-check this against your purchase order — glycerin is CAS 56-81-5; propylene glycol is CAS 57-55-6.
- Lot or batch number: Ties the COA to a specific production run. Always record this for traceability.
- Manufacturing date and expiration / retest date: Confirms the product is within its shelf life.
- Quantity and container information: Should match your shipment.
2. Supplier and Manufacturer Information
- Manufacturer name and address: Know where the ingredient was produced, not just who distributed it.
- Issuing laboratory: For third-party COAs, confirm the lab is accredited (e.g., ISO/IEC 17025).
- Authorized signature: A valid COA should be signed by a qualified QC representative.
3. Test Parameters and Results
This is the core of the COA. Each row lists a test parameter, the specification (what it should be), and the actual result for this batch. Common parameters by ingredient type include:
For Vegetable Glycerin (USP/Food Grade)
| Test Parameter | Typical Specification | Why It Matters |
|---|---|---|
| Assay (purity) | ≥99.5% | Confirms concentration of glycerin |
| Appearance | Clear, colorless, viscous liquid | Visual quality indicator |
| Specific gravity | 1.249–1.263 at 25°C | Density check for concentration |
| Water content | ≤0.5% | Excess water dilutes potency |
| Color (APHA) | ≤10 | High color may indicate contamination |
| Heavy metals | ≤5 ppm | Safety for food/cosmetic use |
| Chlorinated compounds | Passes | Common contaminant from processing |
| Fatty acids and esters | Passes | Residual from oil source |
| Microbial (TPC) | ≤100 CFU/g | Required for food/cosmetic safety |
For Propylene Glycol (USP/Food Grade)
| Test Parameter | Typical Specification | Why It Matters |
|---|---|---|
| Assay (purity) | ≥99.5% | Confirms PG concentration |
| Appearance | Clear, colorless liquid | Visual quality indicator |
| Specific gravity | 1.035–1.037 at 25°C | Density confirmation |
| Water content | ≤0.2% | Water lowers effectiveness as solvent |
| Acidity | Passes (pH ≈7) | Acidic PG may affect formulation pH |
| Heavy metals | ≤5 ppm | Safety for consumption/skin contact |
| Residue on evaporation | ≤0.007% | Detects non-volatile impurities |
For MCT Oil (Food/Supplement Grade)
| Test Parameter | Typical Specification | Why It Matters |
|---|---|---|
| Fatty acid profile (GC) | C8: 50–80%, C10: 20–50% | Confirms MCT composition matches label |
| Acid value | ≤0.5 mg KOH/g | Freshness indicator — higher = rancidity risk |
| Peroxide value | ≤5 meq/kg | Oxidation level — higher = degraded oil |
| Appearance | Clear, colorless liquid | Cloudiness may indicate contamination |
| Odor and taste | Bland/neutral | Off-odors indicate rancidity |
| Heavy metals | ≤5 ppm | Safety for food/supplement use |
| Microbial (TPC) | ≤100 CFU/g | Required for supplement grades |
4. Certifications and Compliance Statements
Depending on your application, the COA may also include or reference:
- Grade designation: USP, Food Grade, Cosmetic Grade, Pharmaceutical Grade — confirmed explicitly.
- Kosher / Halal certification: Certification body and certificate number.
- Non-GMO statement: Source verification for plant-derived ingredients.
- Allergen statement: Particularly relevant for food-grade ingredients processed in shared facilities.
- Country of origin: Required for import compliance and traceability.
- RSPO certification: Relevant for palm-derived ingredients such as palm MCT oil or palm-derived glycerin.
5. Conformance Statement
A properly issued COA should conclude with a conformance statement such as: “This product meets the specifications set forth above and conforms to [USP/NF monograph / food grade standard].” This is the supplier’s written declaration that the batch passed all tests.
Red Flags to Watch For
- Missing lot number: A COA without a lot/batch number cannot be tied to your shipment — reject it.
- No test results — only specifications: Some suppliers issue “spec sheets” disguised as COAs. If there are no actual test results (only the spec range with no measured value), it is not a valid COA.
- Results suspiciously close to the spec limit: A purity result of exactly 99.5% on the limit every time may warrant a request for third-party verification.
- No signature or issuing lab: Unsigned COAs from an unidentified lab have no accountability.
- Expired retest date: Using material past its retest date without retesting is a quality and compliance risk.
- Mismatched lot number: Always verify the COA lot number matches the label on your drums or containers upon receipt.
Best Practices for COA Management
- Request the COA before or at the time of shipment — not after you've accepted and used the material.
- Keep COAs on file for a minimum of 3–5 years (longer for pharmaceutical applications) for audit readiness.
- Cross-reference the COA lot number with your receiving records, inventory system, and production batch records.
- For critical ingredients, periodically send samples to an independent ISO 17025-accredited lab to verify supplier results.
- Set up a COA review checklist so anyone on your team can evaluate incoming documents consistently.
Related Ingredient Guides
Now that you know how to read a COA, explore our ingredient guides to understand what specifications to look for when sourcing specific raw materials:
- Vegetable Glycerin vs Propylene Glycol: What’s the Difference?
- How to Use Vegetable Glycerin in Skincare and Food
- What Is Triethanolamine (TEA) and What Is It Used For?
- MCT Oil: Coconut-Derived vs Palm-Derived
Source Bulk Ingredients with Full Documentation
Ingredient Supplier provides a COA, SDS, and certifications with every order. Our food-grade and USP-grade ingredients are batch-tested and fully documented so you can meet your quality, compliance, and traceability requirements.