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Are formaldehyde and formalin the same substance?

Formaldehyde, in its basic form, is a gas. Most people think of formaldehyde as a liquid. The liquid is actually a mixture of formaldehyde gas and water. The most common concentration used is a 37% solution. That solution contains 37 grams of formaldehyde gas to 100 ml of solution. Formaldehyde solution will polymerize. To prevent polymerization of formaldehyde solution, about 10 - 15% of methyl alcohol is added. It is the addition of methyl alcohol that causes the substance to be called formalin as opposed to formaldehyde.

We have occasionally encountered some confusion about the difference between formaldehyde and formalin. This is an understandable problem, since the terms are sometimes used interchangeably. It is incorrect to use the two words this way. The concentrations of chemical fixative that the two names represent are quite different. A fixative labeled as 10% buffered formalin is actually only a 4% solution of formaldehyde. This is because 10% buffered formalin is an example of old-time histologist's jargon describing a 10% solution made from a stock bottle of 37-40% formaldehyde (or more precisely: a 3.7-4% solution of formaldehyde).

How do I dispose of formalin?

All formalin waste must be collected and arranged for disposal by the Office of Environmental Health and Safety, 328-6166 or

Is there an alternative to formalin?

Formalternate can be used in lieu of formaldehyde in the storage (NOT FIXATION) of biological specimens. Formalternate can be purchased in a concentrated form for about $16.10 for 500 mL, compared to $16.60 a liter for 10% Formalin. The concentrate is diluted one part of concentrate per nine parts of water to make 10 parts of solution. This solution is an alternative for formaldehyde only for biological specimen storage. It is not a chemical substitute.

Why should I consider using Formalternate instead of formalin?

Formalternate can be disposed of via the sanitary sewer system. Formalin must be disposed though the hazardous chemical waste disposal program. Five liters of formalin costs approximately $54, while five liters of Formalternate costs only $16.10. You department will save money and time by utilizing Formalternate in your specimen storage. Not only is Formalternate cheaper, you will not have to spend time preparing and storing waste formalin for disposal.

How do you dispose of specimens fixed in formaldehyde and stored in Formalternate??

Specimens fixed in formaldehyde and stored in Formalternate can be disposed of as you normally dispose of them, whether it is by incineration or by placing in the trash. You do not have to do anything different because of the new chemical. You can then pour the Formalternate down the sink or reuse it if possible. Be be sure to document any items poured down the sink in your drain log.

How Do I get More Information?

If you have any questions about Formalternate or any other hazardous material, contact Flinn Scientific at 1-800-452-1261.