Orbitrap mass spectrometry is a type of mass analyzer and the orbitrap itself looks something like this! It works based on 2 main principles. Similar to the moon orbiting around the Earth, it causes ions to orbit around this metal rod here in the middle. This is called a Kingdon trap and works by giving this rod an electrical charge which is opposite of the ion to be analyzed. The perpendicular motion cancels out the attraction between the electrically charged rod and the ion, causing the ion to exist in an “orbital” state. This is the reason why the ions stay in one place in orbitrap mass spectrometry.
However, in order to measure the mass-to-charge ratio we have to utilize something called the “Knight trap” which causes the ions within the trap to have harmonic motion in the x-direction. By measuring the frequency of this back and forward motion along the central axis we are able to determine the mass-to-charge ratio of the ions. Ultimately, just like in FTICR, we need to use a Fourier transform to turn this signal into a mass spectra.
The result is a mass spectrogram that is extremely high in its resolution as well as very accurate. In addition, the orbitrap mass analyzer is extremely robust due to its simple structure.
29 авг 2024
