Citric acid, glycerine and caustic soda are each sold in more than one grade. The molecule is the same, so why does the price differ, and does it matter which one you buy?
What changes between grades
The difference is in what else is present and how carefully it is controlled. Higher grades set tighter limits on impurities such as heavy metals and require more testing and documentation for every batch.
| Grade | Typical standard | Use it for |
|---|---|---|
| Technical | Supplier specification | Cleaning, industrial processing, products that are not eaten or applied to skin |
| Food | Food Chemicals Codex or E-number purity criteria | Ingredients and processing aids in food and drink |
| Pharmaceutical | USP, BP or Ph. Eur. monographs | Medicines, and many cosmetics and personal care products |
It is not just purity
Food and pharmaceutical grades also come with traceability and handling requirements. The material must be stored and packed in a way that prevents contamination, and the supplier must be able to trace every batch back to its origin.
Buy the grade your product needs
Using technical grade in food is never acceptable, but using pharmaceutical grade for floor cleaner wastes money. Match the grade to the end use, and ask for the specification sheet if you are unsure. We will tell you plainly which grade fits your application.
Questions about this topic?
Our chemists can advise on your specific process.
