Chemical Purity Grades: Technical, Reagent, ACS, Food and Pharma Explained

The word grade on a chemical label is shorthand for a promise: this product meets a defined level of purity and a defined limit on specific impurities, tested by a defined method. Two products with the same name and CAS number can have very different grades and prices, and buying or selling the wrong one is a common source of disputes. This guide explains the main grades and how to describe your product accurately.

Technical and industrial grade

Technical (or industrial) grade is the commercial workhorse. It is made for large-scale industrial use where a few percent of impurities do no harm, such as sulfuric acid for fertiliser or caustic soda for pulp. The specification is often written around assay and a few impurities important for the process, and it is the lowest-cost grade. It is not suitable for food, medicine or sensitive analysis unless the supplier says it is.

Laboratory and reagent grade

Laboratory grade is cleaner than technical and used for teaching and general work, but without a strict standard behind it. Reagent grade is higher purity suitable for analytical use, often meeting an accepted standard. ACS reagent grade means the product meets the specifications published by the American Chemical Society, with limits for assay and named impurities. Analytical-reagent (AR), GR and similar names from manufacturers carry their own certificate limits. Where it matters, state the standard, not just the word.

Pharmacopoeial grades

USP (United States Pharmacopeia), BP (British Pharmacopoeia), EP or Ph. Eur. (European Pharmacopoeia) and JP (Japanese Pharmacopoeia) grades meet monograph requirements for medicines. These add tests for identification, specific impurities, microbial limits and sometimes endotoxins. A material labelled USP grade is not automatically suitable for injectable use, and pharmaceutical customers also expect manufacturing under good manufacturing practice with batch traceability. Do not claim a pharmacopoeial grade unless you can show the testing and supply chain to support it.

Food grade and feed grade

Food grade chemicals meet food additive specifications, such as the Food Chemicals Codex or limits set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and national regulations, with tight limits on heavy metals like arsenic and lead. Feed grade is set by animal-feed rules and may allow different impurity levels. Both require clean handling and often certification of the manufacturing site. Food grade phosphoric acid and technical phosphoric acid look the same but have different arsenic and fluoride limits, as discussed in our phosphoric acid guide.

Electronic and high-purity grades

Electronic or semiconductor grade (sometimes called SEMI grade) is a very pure product, with impurities measured in parts per billion, packaged to prevent contamination. These grades require clean-room packaging and specific certificates, and they command a large price premium.

How to state grade on your documents

A good specification names the product, the CAS number, the grade and the standard it meets, the assay with its test method, limits for key impurities, physical properties such as appearance and moisture, and packaging and shelf life. Your certificate of analysis then reports the actual measured value for each batch. See our guide to certificates of analysis, SDS and TDS for how these documents differ.

Why grade affects your SDS

Grade can change the composition listed in Section 3, particularly where impurities themselves are hazardous or where a hydrate or solution strength differs. A technical product with significant impurities may need those declared if they affect classification, and a high-purity pharma material might carry a simpler composition. If you sell several grades of the same chemical, do not assume one SDS fits all of them. Check CAS numbers for hydrates and forms, and confirm the classification of each grade.