Reagent alcohol is a denatured ethyl alcohol blend made from about 95 parts SDA 3-A and 5 parts isopropyl alcohol by volume, which works out to roughly 90% ethanol, 4.5% methanol and 5% isopropyl alcohol, with the balance water. 200 proof ethanol is a different product: a single-component ethyl alcohol with under 0.5% water and no added denaturants. Labs and manufacturers choose between them based on purity, tax status and what the method allows.
What is in reagent alcohol?
Reagent alcohol is defined by its formula rather than by a single purity number. Under 27 CFR 20.117 it is built from SDA 3-A plus isopropyl alcohol. SDA 3-A itself is ethyl alcohol denatured with 5 gallons of cyclohexane or methyl alcohol per 100 gallons (27 CFR Part 21). Mixing 95 parts of that with 5 parts isopropyl alcohol gives the familiar ratio of about 90 / 4.5 / 5 ethanol, methanol and isopropyl alcohol.
Because it is denatured, reagent alcohol is not fit for beverage use, and that is what lets it ship without the beverage-spirits excise tax. Our reagent alcohol is produced from 100% Michigan corn ethyl alcohol in 100% stainless steel equipment at our Marysville, Michigan plant.
Why SDA 3-C cannot be substituted
SDA 3-C uses 5 gallons of isopropyl alcohol per 100 gallons of ethanol, so it looks close on paper. 27 CFR 21.37(c) expressly forbids using SDA 3-C to make reagent alcohol. The formula must start from SDA 3-A. For the differences between the two formulas see our guide to SDA 3-A vs SDA 3-C.
Reagent alcohol vs 200 proof ethanol
| Feature | Reagent alcohol | 200 proof ethanol |
|---|---|---|
| Composition | About 90% ethanol, 4.5% methanol, 5% IPA (SDA 3-A + IPA) | Ethyl alcohol, under 0.5% water |
| Denatured | Yes | No (undenatured) |
| Water content | Present, as part of the blend | Under 0.5% |
| Typical use | Lab cleaning, extractions, reagent preparation, general solvent work | Pharmaceutical, food-flavor, extraction and high-purity applications |
| Federal treatment | Denatured, not for beverage use | Beverage-grade excise rules apply unless a permitted use applies |
How to choose between them
- Choose reagent alcohol when your method calls for a denatured, general-purpose laboratory alcohol and can tolerate methanol and IPA.
- Choose 200 proof ethanol when water content matters or when the finished product cannot contain denaturants.
- Consider SDA 3-A when you want a denatured ethanol without the added isopropyl alcohol.
Terms like proof, percent and grade are easy to mix up; our explainer on ethanol purity, proof and grade covers them. Physical property data for ethanol is published by PubChem.
Where reagent alcohol is used
Reagent alcohol is a workhorse in laboratories and manufacturing plants. Typical uses include cleaning glassware and instruments, wiping down equipment surfaces, preparing stains and reagents, and serving as a general-purpose solvent where a denatured alcohol is acceptable. Because the blend is standardized, a lab can order it repeatedly and expect the same composition from one lot to the next, which is the main reason methods specify it by name.
It is a poor fit where methanol or isopropyl alcohol cannot be tolerated, such as an ingredient that ends up in a finished consumable, or a process where residual denaturants would interfere. In those cases buyers step up to 200 proof ethanol or a high-purity undenatured grade, and the documentation shifts toward the specifications covered in our guide to food-grade 200 proof ethanol.
What to specify when you order
Ordering reagent alcohol is simpler when your purchase request states the details up front. Give your intended use, the volume you expect to move, and whether you need a certificate of analysis with each lot. Then decide how it should arrive. Reagent alcohol ships in 55 gallon drums for smaller consumption, in 275 or 330 gallon IBC totes for steady use, and in tank truck loads of roughly 5,000 to 6,500 gallons for large operations. Matching the container to your usage rate reduces handling and keeps product from sitting open in storage.
Price is driven by several factors rather than a single number: the cost of the base ethyl alcohol, the two denaturants, the packaging you choose, order volume, and freight to your dock. Ask for a written quote that lists the container, quantity and delivery point so you can compare offers on equal terms.
Handling and storage
Reagent alcohol is flammable and should be stored in a cool, ventilated area away from ignition sources, in closed and grounded containers. Methanol makes the blend toxic if swallowed, so label secondary containers clearly and keep it out of any food or beverage workflow. For full detail on storage and disposal, read our guide to ethanol storage, handling and disposal and always follow the safety data sheet supplied with your lot.
Frequently asked questions
Is reagent alcohol the same as 200 proof ethanol?
No. 200 proof ethanol is a single-component product with under 0.5% water. Reagent alcohol is a denatured blend of roughly 90% ethyl alcohol, 4.5% methanol and 5% isopropyl alcohol by volume, so it contains water and two denaturants.
Can SDA 3-C be used to make reagent alcohol?
No. 27 CFR 21.37(c) expressly forbids using SDA 3-C to make reagent alcohol. The formula starts from SDA 3-A.
Why does reagent alcohol come with methanol and isopropyl alcohol?
Those are the denaturants that make the product unfit for beverage use, which is what allows it to move without the federal excise tax that applies to beverage-grade spirits.
Do I need a TTB permit to buy reagent alcohol?
Requirements depend on the product and your use. Contact us with your application and we will walk you through the paperwork before you order.
Ready to order? Request a quote or visit our contact page.