Gregar Extractor Makes Commonly Used Chemistry Laboratory Device Obsolete

Revolutionary tool offers increased efficiency and versatility

The Gregar extractor, invented by Argonne's Joe Gregar and Ken Anderson, represents a major advance in solvent-based chemical extraction from solid samples. The new design, available in two different configurations and several sizes, eliminates problems associated with conventional Soxhlet technology and can shorten extraction times. Argonne's Gregar extractor features a revolutionary new mode of continuous extraction, and it is uniquely adjustable to serve multiple extraction applications.The extractor is available for licensing.

The most useful inventions often spring from solutions to small problems encountered during the pursuit of larger ones. A case in point is a new device that promises to render obsolete a standard device used in virtually every high school, industrial and university chemistry laboratory in the world.

The new 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 new device, called the Gregar 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 was invented by scientific glass blower Joe Gregar and chemist Ken Anderson, both of Argonne's Chemistry Division.

"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's going to make extractions a lot easier."

Already, the Gregar extractor has advanced Anderson's research by making it possible to complete extractions he could not have done before. In fact, the driving force behind the Gregar extractor's invention was a problem Anderson encountered while using the Soxhlet extractor.

Anderson studies the natural processes that convert decayed plant life into coal. A key step in his research involves the analysis of amber, naturally formed fossil resins that provide a chemical snapshot of the plant decay process. Anderson used a Soxhlet extractor to remove compounds from amber for analysis. But amber swells when exposed to solvents, and the swelling creates problems for Soxhlet extractors.

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.

But 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 went to his colleague Joe Gregar, a fourth-generation, master scientific glassblower. Over the ensuing eight months, they designed and hand-built a series of components and prototypes, each one coming a bit closer to solving Anderson's problems. The result is 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."

Nor have Anderson and Gregar stopped with just one version. So far, the co-inventors have produced two different configurations of their basic extractor, both fully developed and demonstrated.

The potential market for the new apparatus is huge: Most chemistry labs around the world have several Soxhlet extractors on hand. Argonne has licensed the new technology to Kontes Glass Co. of Vineland, NJ. Development of the Gregar extractor was funded by DOE's Office of Energy Research, Basic Energy Sciences, Chemical Sciences Division.

Just how significant is this invention? Anderson and Gregar acknowledge that their creation is simply a tool -- but a highly useful one to chemists.

It has no disk drives or serial ports, no microchips or gauges or wires. It doesn't even have an "On" switch. Most of the materials and techniques required to build it were developed before Anderson and Gregar were born. Yet this simple, streamlined device seems destined to make every chemist's job easier and to put Gregar's name in every chemistry laboratory in the world.

Gregar Extractor Advantages

• Faster extraction than standard soxhelets (up to 50% depending upon the compound)
• Continuous extraction
  • No more"chugging" flow after siphoning occurs
  • No more solvent hangup in the siphon tube
• The Gregar Extractor is specifically designed for difficult extractors such as when the sample expands/swells or for"sticky" compounds, such as coal, plastics, resins, etc. It works just as well for non-problem compounds.
• 3-way valve permits ease of use and flexibility
• More efficient solvent extraction
  • No more solvent bypassing the sample due to packing or padding
• A variety of sizes and configurations are available
  • Horizontal, vertical, or mini-size
• Quick release valve for draining
• No"dead" spots for solvent or air bubbles
• "Easy fill" side leg attachment
• Can be fitted with a cold leg condenser

Argonne has licensed the Gregar extractor technology to industrial companies, including Kontes Glass Company (Vineland, New Jersey) and Chemglass (Vineland, New Jersey). Argonne is seeking additional licensees. For licensing information, contact Paul Betten, Office of Technology Transfer (630-252-4962, betten@anl.gov).

The Gregar Extractor is the winner of a 1999 R&D 100 Award. The development of the extractor was funded by the Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences Division.