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Physical Sciences and Engineering |  |
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The Gregar Extractor
Argonne's Gregar extractor, invented by Argonne's Master Glassblower Joe Gregar and scientist Ken Anderson, represents a major advance in solvent-based chemical extraction from solid samples. The design, available in two different configurations and several sizes, eliminates problems associated with conventional Soxhlet technology and can shorten extraction times. The Gregar extractor features a revolutionary new mode of continuous extraction, and it is uniquely adjustable to serve multiple extraction applications. The device performs one of the chemistry lab's most basic day-to-day activities: it extracts chemicals from a solid and places them in a liquid, the form needed for most chemical analysis. And it does so more efficiently, more reliably, and usually faster than the Soxhlet extractor, which has been the chemist's workhorse for this task since the middle of the 19th century. The extractor also eliminates many of the operational problems associated with the Soxhlet extractor and performs chemical extractions that a Soxhlet extractor simply can't do. "The Gregar extractor is elegantly simple," Anderson said, "essentially just allowing a liquid to find its own level. But it's a useful tool for chemists, something that makes extractions a lot easier." Anderson was using the Soxhlet extractor but experienced difficulties. The Soxhlet extractor carries out a series of cycles, with solvent vapor rising into the sample chamber, condensing, dripping over the sample and collecting at the bottom. When the liquid rises to a certain level, it automatically siphons out, and the process begins again. The cyclical process can create problems, particularly with samples, such as amber, that tend to swell and break up when soaked with solvent. To overcome these problems, Anderson and Gregar designed and hand-built a series of components and prototypes, each one coming a bit closer to solving Anderson's problems. The result was the "Gregar extractor" -- a major advance in chemical extraction technology. The Gregar extractor improves on the conventional extractor in a number of ways. It uses a porous glass "frit" instead of filter paper and replaces the cyclic siphoning action with a continuous solvent flow. In addition, redesigned glass arms and two new valves allow the Gregar extractor to perform extractions that are impossible with a Soxhlet extractor. It can also make extractions faster. "We can't say the Gregar extractor is always faster than the conventional extractor," Anderson said, "because extraction time depends on the specific sample. But we can say it's never slower." Two new valves make the Gregar extractor more versatile than any other extractor on the market. "By opening and closing the valves appropriately, you can extract liquids from liquids," Anderson said, "something you could never do with a Soxhlet extractor. One setting lets you perform extractions from liquids that are denser than the solvent, and another lets you work with liquids that are less dense. There's no other extractor out there that can do all this." The co-inventors have produced two different configurations of their basic extractor, both fully developed and demonstrated. Argonne has licensed the technology to ChemGlass Life Sciences of Vineland, NJ. The Gregar Extractor also won a 1999 R&D 100 Award. Development of the Gregar extractor was funded by DOE's Office of Energy Research, Basic Energy Sciences, Chemical Sciences Division. Gregar Extractor Advantages
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May 2010 |
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