Many industries rely on a nitrogen blowdown evaporator as a key step in processing their samples. These industries include environmental testing, agriculture, food and beverage, medicine, quality assurance, forensics, oil and grease, and many more. So, what exactly is it?
A nitrogen blowdown evaporator is a key piece of lab equipment that is used to prepare samples for chromatography, mass spectrometry or other analysis by removing excess solvent. The process works by lowering the vapor pressure above the sample, allowing excess solvent to evaporate more quickly. This method of concentration is especially effective for small volume samples in volatile or semi-volatile organic solvents. The precision of nitrogen blowdown makes it a great choice for those who are looking to evaporate to complete dryness or stop at a specific endpoint.
Compared to a heated sample, solvent molecules in a sample under ambient conditions are very low energy and therefore slow-moving. Due to this lack of speed, only some molecules can be vaporized and separated from the sample. Combined with the vapor pressure above the sample this causes many molecules to return, slowing down evaporation. This is where nitrogen blowdown evaporation is a useful tool. The evaporator works by applying a steady stream of nitrogen gas just above the surface of the sample, which gently pushes the vapor-saturated air out, preventing it from returning to the remaining liquid. Nitrogen Evaporation Graphic
The nitrogen gas cools the sample slightly, which decreases the energy of the molecules and slows them down, diminishing their ability to vaporize. To speed the molecules back up, heat can be applied in the form of a water bath or dry block in order to reenergize the sample. The combination of nitrogen blowdown and heat quickly vaporizes the molecules, leaving a perfectly evaporated sample behind.
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