High purity solvents are a part of every critical process. They are just as important to critical products as the quality of air. While there is a generally accepted standard for high purity laboratory chemicals, specifications vary among chemicals. Solvent manufacturers offer additional grades, as well. So how do you know whether the solvent is right for you?
Additions to the standards
The American Chemical Society (ACS)’s Reagant Grade meets the minimum impurity specification set by the ACS. This is the generally accepted standard. However, to address requirements of specific standards solvent manufacturers offer grades with additional constraints or specifications. A few examples include:
- “Electronic Grade” for electronic assemblies
- “HPLA Grade” for liquid chromatography
- “Semiconductor Grade” for wafer preparation uses
For these kinds of grades, suppliers may list limits for elements not included in the ACS Reagant Grade. Currently there are no industry-wide standards for specialized grades exceeding ACS specifications. In most cases, suppliers set these specifications. As a result, it can be difficult to compare two of the same grades from different suppliers. Each might list limits for trace elements that are different from the other.
The problem is that specifications list what was tested for, not necessarily what’s present. If there is a particular substance your application cannot tolerate, check with the manufacturer if that substance isn’t listed on the specifications.
Is pure better?
Purer does not always equal safer with solvent chemicals. Depending on the process, pure chemicals may or may not be suitable for consumption. Check with the manufacturer to see how purity was obtained and what traces may be left behind.
Other things to know
Solvents can also come by way of blends, and in some cases, with additives. Here are some things to keep in mind:
- Methanol and pyridine can be used to denature ethanol. Doing so makes it unsuitable to drink, and therefore circumvents excise taxes.
- Stabilizers can be added to prevent acidification and prolong the solvent’s life. If these additives are subject to regulatory constraints, they may be unsuitable for the product or environment.
- There are many potential issues with blends. For example, if a chemical used to suppress flammable components evaporates more quickly than the rest of the solvent, over time the solution may become flammable.
The smartest things to do are know your cleanliness requirements and communicate with the manufacturer about solvent safety. Look more closely at specifications and certifications than you do the name of the grade. You can never be too thorough when it comes to safety.
If you have questions about cleanrooms, validation, or certification, contact Gerbig Engineering Company at 888-628-0056 or info@gerbig.com. We are experts with your best interests in mind.