What’s in an Oil Drop?

Charge It!

Now for a look at one of these mass measurement marvels.

Below is pictured the MagLab's 14.5 tesla, 104 mm bore FT-ICR system – the highest-field superconducting ICR magnet in the world. Though you can't tell much by looking at it from the outside, wonderful things happen on the inside that reveal amazing details about the sample being studied.

The Magnet Lab's 14.5 tesla, 104 mm bore FT-ICR system is the highest-field superconducting ICR magnet in the world.

First off, though, the sample molecules need to be ionized – that is, turned into a charged particle. That charge – positive or negative – makes the molecule react to the magnetic field of the device. This is the core principle behind any mass spectrometer: Each type of ion will respond differently to that magnetic field, depending on its mass. There are various methods of ionization, each offering its own advantages. (Go to our Tools of the Trade page to learn more about electrospray ionization and other techniques.)

After the molecules are ionized, they are funneled by an ion guide into the analyzer cell (also called a Penning trap), which is located in the center, or bore, of a superconducting magnet. This whole set-up, by the way, is connected to a vacuum pump system that keeps unwanted outside molecules from straying into the sample. This allows ions to spin in circles more than 100,000 times without colliding into another particle.

Inside the analyzer cell, a great deal happens in an instant – as we’re about to see. When the cell’s work is done, we hit the home stretch of this operation: the signal reader and computer that will translate everything that happened in the cell into usable data.

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