Laboratory Basics 101: The Magnetic Hotplate Stirrer

Every functional laboratory needs certain items of basic equipment: Erlenmeyer and volumetric flasks, graduated cylinders, funnels, test tubes, utility clamps, balances, pipettes, droppers, the ubiquitous Bunsen burner…the list goes on. And its full complement of items and devices varies depending on the type of research and/or development you are pursuing.

A clinical laboratory may feature near-total automation these days, but research labs still look much as they did decades, or even centuries ago. That’s because they still require technologists and scientists to perform basic activities common to science. For instance, no lab would be complete without a magnetic stirrer or two. If they happen to serve as hotplate stirrers, so much the better. Better still? Digital magnetic hotplate stirrers.

From Simple Tool to Sophisticated Programmable Device

The basic magnetic stirrer employs a trick many of us experienced in childhood; the ability to move a magnetically reactive object (resting on a suitable surface) from below, using a moving magnet. A teflon-coated magnetically reactive bar of appropriate size is placed inside a flask with liquid and/or solids to be dissolved and stirred. A rotating magnet within the hotplate housing spins the stir bar, creating stirring action.

These simple devices have been around for a long time. They often featured the ability to spin at variable speeds, and occasionally incorporated the ability to heat the liquid being stirred. Only recently, however, have these workhorse devices benefited from the digital revolution.

Modern digital magnetic hotplate stirrers are simple, robust — yet sophisticated — pieces of basic laboratory equipment that give you the flexibility to program multiple parameters such as the target temperature of the liquid being stirred; the speed of the magnet that’s spinning to create the mixing action you desire; the length of time at a particular temperature, the length of time spent mixing, etc.

Safety and Convenience

Before the advent of digital programmable hotplate stirrers, controls were typically operated manually. Safe operation depended on the operator returning at the appropriate time to turn off the device’s heating element, and/or to turn off the stirring function. Old hotplate stirrers with purely manual controls posed certain safety risks. Because they were not programmable, there was a risk of evaporating all the liquid away, if the operator happened to become busy, or if he or she forget about turning off the device.

Modern digital hotplate stirrers take the risk — and guesswork — out of the equation. Now it’s a cinch to set customized parameters, including a default safety temperature. This is a preset temperature above which the device will shut down to prevent overheating or inappropriate evaporation of your solution.


CAT Scientific

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