What Happens During Q0 Dissociation when "Simple" or "Enhanced" Options Are Used in SCIEX OS Software?

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

Answer

With the SCIEX Triple Quad 7500 System, declustering is achieved using a voltage differential between the QJet® ion guide and the IQ0 lens or a voltage differential between IQ0 and Q0 (the quadrupole ion guide before Q1). Both of these voltage differences can be ramped, which is useful for de-tuning signals, removing interferences, and increasing signal-to-noise in some cases. Below, the two options available in SCIEX OS software for Q0 dissociation—simple and enhanced—are discussed.

1) Simple mode: This schematic explains the pressure drop that occurs when simple mode is selected.  


The blue circle shows the region of the pressure drop between the QJet ion guide and the IQ0 lens. Ramping these voltages difference is very useful for de-tuning signals as mentioned above.

2) Enhanced mode: The region of the pressure drop occurs between the IQ0 lens and the Q0 rods in the lower pressure region of the back end of the D Jet™ ion guide. (The tapered dodecapole geometry of the D Jet ion guide focuses the ions into the second stage QJet ion guide.)



The enhanced Q0D region adds significant energy to the precursor ion masses in a lower pressure region. This can lead to insufficient cooling in Q0 and often to dramatic shifts in optimal collision energy (CE). Therefore, it is recommended to only use simple Q0D for MRM scan types.