How to Order Laboratory Chemicals (Like a Pro Who's Made Every Mistake)

Who This Is For (And Why You Should Read It)

If you're the person in your lab or company who actually places the orders for chemicals—not the scientist who specifies them, but the one who navigates the Sigma-Aldrich website, checks the cart, and hits "submit”—this guide is for you.

I'm an office administrator for a 15-person R&D company. I manage all our chemical and supply ordering—roughly $40,000 annually across 8 vendors. When I took over purchasing in 2020, I made every mistake in the book. This checklist is what I wish I'd had.

Here are the 5 steps I follow to get the right chemical, at the right purity, with the right paperwork, without a headache.

Step 1: Start With the CAS Number, Not the Name

This is the biggest rookie mistake. Someone sends you an email: "We need sodium acetate for next week."

Don't search by name. Names have synonyms. "Sodium acetate" is also “acetic acid, sodium salt". It has a trihydrate form (CAS 6131-90-4), and an anhydrous form (CAS 127-09-3). They're not interchangeable.

Always ask for the CAS number. Type it into the Sigma-Aldrich search bar. That gets you exactly the right chemical, every time.

For example: sodium acetate CAS 127-09-3 on Sigma-Aldrich brings up product number 32315. That's the anhydrous form, ≥99% purity. Order the wrong CAS and your lab manager will let you know about it.

What most people don't realize is that even experienced researchers sometimes give you the wrong name for the wrong form. The CAS number is your safety net.

Step 2: Before You Order, Check the SDS (Safety Data Sheet)

Here's something vendors won't tell you: you can access the SDS for any chemical before you buy it. You don't need an account. You don't need to be a customer.

On any Sigma-Aldrich product page, scroll down to the "Documents" section. The SDS (Safety Data Sheet) is right there, in multiple languages.

Why check it before ordering? Because some chemicals are regulated for shipping, require hazmat fees, or need special storage. If your lab doesn't have a flammables cabinet, ordering a ton of acetone (which has a dipole moment of 2.91 D and is highly flammable) is a problem you'll discover after it arrives.

For example, methyllithium (for which you'd look up "sigma aldrich methyllithium sds hazard statements") is pyrophoric—it catches fire in air. The hazard statements include H250 (catches fire spontaneously if exposed to air) and H261 (contact with water liberates flammable gas). If your receiving team isn't trained for that, you have a serious safety issue.

Check the SDS for the following before you add to cart:

• Hazard statements (the H-codes)—do you have adequate ventilation, storage, and PPE?
• Shipping restrictions—some chemicals can't be shipped by air, or require overnight delivery with special packaging.
• Storage conditions—does it need to be refrigerated, or inert atmosphere?

The vendor who said "this isn't our strength—here's who does it better" earned my trust for everything else. But for Sigma-Aldrich, this is their strength: the documentation is exhaustive.

Step 3: Verify Pricing Against the Catalog Number, Not the Name

This was true 10 years ago when digital catalogs were less standardized. Today, the Sigma-Aldrich website is generally accurate, but here's the trick: always use the full catalog number (e.g., 32315-1KG) to verify price.

Why? Because the same chemical in different pack sizes or grades can have wildly different prices. Sodium acetate, anhydrous, ≥99%, in a 1KG bottle (cat. 32315-1KG) costs a fraction of the same chemical in a 5MG ampoule for a specific analytical method.

I once approved a PO for "sodium acetate" at $85. The researcher meant 500 grams of the standard lab grade. I accidentally ordered 5 vials of a high-purity reference standard. Price? $850. The researcher was not happy. The accounting team was less happy.

Always check the pack size and grade before you compare prices.

Step 4: Know When to Say "This Isn't for Me"

This brings me to a point that took me years to learn: know the limits of your supplier.

Sigma-Aldrich is fantastic for standard lab chemicals, reagents, and solvents. They have a catalog that's truly comprehensive. But for some specific applications, you might need a specialized supplier.

For example, if you're looking for surfactants for a specific clinical trial—say, a "eudract surfactant influenza ards trial" (which refers to the European Union Drug Regulating Authorities Clinical Trials Database—EudraCT—for a study on surfactants for ARDS caused by influenza), you don't order lab-grade surfactant from Sigma. You need pharmaceutical-grade material from a contract manufacturer who can provide batch documentation for a clinical trial. Sigma-Aldrich isn't that supplier.

Or if you're asking "will copper react with hydrochloric acid?"—yes, copper does react with concentrated hydrochloric acid in the presence of oxygen, forming copper(II) chloride and water. This is basic chemistry. But if you're asking this because you're designing a chemical process, you need a process chemist or a technical specialist. An ordering checklist can't substitute for that expertise.

The best suppliers tell you their boundaries. I'd rather work with a specialist who knows their limits than a generalist who overpromises.

Step 5: Don't Skip the Receiving Checklist

Approved the rush fee and immediately thought “did I make the right call?" Didn't relax until the delivery arrived on time and correct.

When the package arrives, do this before you sign for it:

• Check the label matches the PO. Is it the right CAS number? Right catalog number? Right pack size?
• Check the outer packaging. Is there any damage, leaking, or signs of tampering?
• Check the SDS is accessible. For regulated chemicals, the SDS should be part of the shipment documents or easily downloadable.

I once signed for a box that looked fine. Inside, a bottle of nitric acid had leaked. The cardboard was saturated. Luckily, I caught it before anyone opened it in the lab. That could have been a serious injury.

Common Mistakes (Learn From Mine)

1. Ordering from the wrong brand. Sigma-Aldrich carries many brands: SAFC, Supelco, Cerilliant, etc. They all have different quality grades and documentation levels. Make sure you're selecting the right brand for your application.

2. Not checking lead times. Some chemicals are in stock and ship next day. Others are made to order and take 4-6 weeks. Always check the product page's availability status.

3. Forgetting about storage. That bottle of methyllithium? It needs to be stored under inert gas and is shipped in a special container. Your standard chemical cabinet won't work. Plan ahead.

4. Assuming the first quote is final. For ongoing relationships, especially if you're ordering in bulk, there's often room for negotiation. It never hurts to ask your account manager.

In my opinion, most purchasing problems in this space come from rushing. Take the extra 10 minutes per order to verify the CAS number, check the SDS, and confirm the catalog number. It's a small investment that saves hours of rework and keeps your lab safe.