How Does the Quadrupole Transmission Function in the TripleTOF® Systems Work?


日付: 01/31/2018
カテゴリー: QTOF Systems

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For research use only. Not for use in diagnostic procedures.


Answer

The quadrupole transmission of the QSTAR® system operates as follows:
For TOFMS, all ions pass through Q1 in RF mode. In general, Q1 and Q2 perform "hops" over the mass range, ensuring an appropriate envelope of masses is passed into the TOF analyzer. 

This envelope includes ions of m/z 80% below and 5x higher than the particular Q1 settings in the experiment editor. On older QSTAR systems for a mass range of 100-2000, ions are passed through Q1 and Q2 in two "hops". 

 This envelope is slightly different on the TripleTOF® systems. User-added image

For the TripleTOF® systems:
The Q1 transmission functions are pretty similar between QSTAR and the TripleTOF systems. Each time the quadrupole transmission characteristics are changed (e.g., drive frequency, mass limit, etc.), some minor changes need to be made to the coefficients/thresholds in the calculation. The quadrupole transmission characteristics do no change substantially between QSTAR, the TripleTOF, and the X500 systems.
 
In the TripleTOF systems, the same principle applies, whereby the Q1 is hopping between one or more RF values that are transmitting different mass ranges. In all cases, the low m/z cutoff is approximately 0.8x and is pretty sharp. At the upper end, transmission decreases asymptotically. On the TripleTOF 5600 system and newer instruments, the higher drive frequency (relative to QSTAR) allows for a broader range of masses to be transmitted at a given RF level, thereby permitting effective transmission on the newer instruments to more like 10x rather than 4-5x.