SIM/Scan Combined Cycle Frequency

OpenLAB displays a Frequency (Hz) for the Scan Time Segments and a Cycle Time (Hz) for SIM Time Segments tables located in the Single Quadrupole MS Method Editor dialog.

 

 

 

When running the MSD in combination SIM/Scan mode, the frequencies displayed for the individual SIM and Scan modes do not apply to the SIM/Scan mode.

In SIM/Scan mode, to complete one cycle the MSD acquires a single group of SIM data followed by a single group of Scan data. When switching from the SIM data acquisition mode to the Scan mode, time is required to reset the MSD. This reset time consumes about 5% of the available run time.

SIM/Scan cycles/sec  = 1/ (( 1/A + 1/B) * 1.05)

Where:	A= scan cycles per second
	B= SIM cycles per second

1.05 represents the internal overhead required to switch from Scan mode to SIM mode within a SIM/Scan cycle.

The SIM groups can have start and stop times that are different from the Scan groups. The MSD cycles change each time the SIM or Scan groups change during the run. Calculate cycles based on the SIM and Scan groups that are active in the times of interest during the run.  

When using SIM/Scan, it may be necessary to increase the Scan speed or decrease the SIM dwell time to achieve the desired number of data points for effective chromatographic integration.