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Evaporators

Evaporators

Selecting an evaporator for your lab, and how to avoid common errors in operation

Lab Manager
KNF RC 600 Rotary Evaporator, www.knf.com.
KNF

Evaporators remove water or organic solvents from samples, often for sample concentration, solvent recycling, or separating solvent mixtures. They are widely used in pharmaceutical and food and beverage industries, as well as many chemistry and life science laboratories. Rotary evaporators are often used to remove low boiling organic solvents, and the addition of vacuum can lower the boiling point. Nitrogen evaporators apply a steady stream of nitrogen to remove moisture. For a list of evaporator manufacturers, see our online directory: LabManager.com/evaporator-manufacturers

7 Questions to Ask When Buying an Evaporator:

  1. How much space is available? Is a compact benchtop model or a floor model a better fit for the space?
  2. Will it be used primarily for separation, cleaning, or concentrating? 
  3. Will you be working with heat-sensitive samples? Keep in mind a vacuum concentrator will add heat through friction.
  4. What type of samples will you be working with? A -50°C cold trap is ideal for aqueous samples, whereas most solvents require a -85°C cold trap, and -105°C is recommended for alcohols.
  5. What sample volumes will you be working with? Nitrogen blowdown is ideal for small sample volumes <50 ml.
  6. How many samples will you need to process simultaneously?
  7. What safety features are available?

Infographic

Rotary evaporators are common laboratory instruments, found in virtually every organic laboratory, and are used to remove or isolate components of reaction mixtures based on differences in their boiling points. Download this free infographic to stay informed about best practices for rotary evaporation: LabManager.com/PRG-2022-evaporator-infographic

Operating Tip

Foaming is a common problem that arises during evaporation and can lead to sample loss and contamination. To avoid foaming, use an anti-foam agent, a large flask, or dedicated glass condenser, which provides more space for foam to expand.