Mass spectrometry is an analytical technique used to identify the mass of molecules by measuring the mass-to-charge ratio and abundance of gas phase ions. During analysis, molecules are converted to ions which are then detected by the instrument based on their mass-to-charge ratios. Mass spectrometers have been used in various applications such as proteomics, metabolomics, environmental analysis and more.

Quadrupole-Time of Flight Technology

One popular type of mass spectrometer is the quadrupole-time of flight or Q-TOF system. In a Q-TOF Mass Spectrometer, ions are separated based on their mass-to-charge ratios in both the quadrupole mass filter and orthogonal time-of-flight analyzer. The quadrupole is used to selectively transmit ions within a narrow mass window into the time-of-flight tube for high resolution mass measurement.

Quadrupole Mass Filter

The quadrupole mass filter utilizes four parallel metal rods that an RF voltage as well as a DC voltage are applied to. Ions entering the quadrupole travel down its central axis and are filtered based on their stability in the oscillating field produced between the rods. Only ions with a specific mass-to-charge ratio will successfully traverse the quadrupole whereas all other ions will collide with the rods and be neutralized. This allows the quadrupole to function as a high-pass, low-pass or band-pass filter for ion transmission.

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