Nuclear Magnetic Resonance Technology Detects Specific Elements

The MobiLab130 is an instrument that measures the concentration of specific elements in levels as low as part per million. How does such an instrument work?

The science is easily understood, and in simple terms, it has to do with how specific elements behave when placed in a magnetic field. Every atom contains a specific number of protons and neutrons, which determines the element and its isotope. The combination of protons and neutrons give the property of nuclear spin. For example, there are 3 isotopes of hydrogen, hydrogen, deuterium, and tritium, all three respond differently in a magnetic field.

Hydrogen has a single proton, deuterium has one proton and one neutron and tritium has one proton and two neutrons. Placing these atoms in a magnetic field of 1 Tesla will cause them to resonate or precess, each at a different frequency. Hydrogen will precess at a frequency of 42.57 MHz, deuterium will precess at a frequency of 6.54 MHz, and tritium will precess at a frequency of 45.41 MHz. Each isotope has a different characteristic frequency called the Larmor frequency. It is the Larmor frequency which is the unique signature of each element and allows magnetic resonance to unambiguously identify and quantify a particular isotope. A few isotopes are not observable by NMR, but most are, with different degrees of sensitivity. For example, the most abundant isotopes of Carbon and Oxygen 12C and 16O, respectively, have a spin quantum number I = 0, which means that isotope is not observable by NMR technology.

The MobiLab 130 works by applying a radio-frequency pulses that are equal to the frequency of precession of the specific element. Since each nucleus has a unique frequency of precession, there is no interference with other elements and the signal is unique to a particular nucleus.

All of this allows the MobiLab130 to provide accurate results about how much of a certain element is present in a sample. This determination is extremely important when searching for elements like lithium or sodium or for scanning liquids at the airport to determine if they are safe to take on a plane.

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