SpeedVacs, CentriVaps and other vacuum concentrators are common tools for sample evaporation. In summary, solvents are evaporated at lower temperatures due to the application of vacuum. As pressure drops in the system, so does the boiling point of the solvent. This allows high boiling point solvents to be evaporated off without damaging the samples with excessive heat.
As both centrifugal and nitrogen blowdown evaporators are capable of processing low volume samples, 15 mL or under, it's important to know when each is recommended. We've already established that vacuum concentrators such as SpeedVacs or CentriVaps are ideal when working with solvents with high boiling points. Below are examples of when blowdown evaporation is the better choice. The bottom line is that certain types of solvents are much better suited for nitrogen evaporation, especially when the right variation is selected, which will be discussed.
Volatile, potentially explosive solvents
Some of these solvents have fairly low boiling points and high vapor pressure which can lead to rapid evaporation and pose potential safety hazards in a vacuum environment. Gently concentrating samples with a stream of nitrogen air and adequate heat is the smart approach for removing excess amounts of the following solvents:
- Hexane
- Heptane
- Diethyl Ether
- Tetrahydrofuran (THF)
Our nitrogen evaporators also come with an optional Z-Purge device for added safety when evaporating volatile solvents. The Z-Purge is a device used to purge the bath case with a steady stream of nitrogen or other inert gas, keeping stray solvent vapor away from the heating unit and minimizing risk of explosion.
Chlorinated solvents
Solvents such as Chloroform and Dichloromethane (DCM) should generally be avoided in centrifugal evaporators due to their potential reactivity with the materials of construction and safety hazards associated with their use under vacuum conditions.
Corrosive solvents
Strong acids, such as Hydrochloric Acid (HCl), can seriously damage an equipment through corrosion. We recommend our blowdown models with acid resistant coatings for similar processes. We provide a Teflon coating on all parts of the instrument that may be susceptible to corrosion including the inner water bath pan, gas delivery needles, and other various manifold parts. With proper care, the Teflon coating can significantly increase the longevity of your evaporator.
Still unsure which evaporation method is best for you? Talk to our experts through our live chat, email, or try out our evaporation method quiz.
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