Calculations for time reference compounds

If you use time reference compounds, the application corrects the absolute retention time windows based on possible shifts observed by selected time reference compounds. The application first identifies the reference peaks in a range based on the expected retention time, which is defined in the method. The following computations are then done for compounds that use this time reference.

Shift of the time reference compound

Shift_Ref = ActualRT_Ref - ExpRT_Ref

where
Shift_Ref	Time shift of the reference compound
ActualRT_Ref	Actual retention time of the reference compound
ExpRT_Ref	Expected retention time of the reference compound

RT of associated compound

For compounds that use a time reference, the expected retention time is calculated using an additional factor.

CorrectedExpRT = ExpRT + (Shift_Ref * Factor)

where
CorrectedExpRT	Corrected expected retention
ExpRT	Expected retention time
Shift_Ref	Time shift of time reference compound
Factor	Factor for compounds with associated time reference compound (Factor)

Start and stop time of associated timed group

For timed groups, the expected start and stop times are calculated accordingly:

Corrected Range Start = Range Start + (Shift_Ref * Factor)

Corrected Range End = Range End + (Shift_Ref * Factor)

where
Corrected Range Start	Corrected start time of timed group
Range Start	Start time of timed group
Corrected Range End	Corrected stop time of timed group
RangeEnd	Stop time of timed group
Shift_Ref	Time shift of time reference compound
Factor	Factor for timed groups with an associated time reference compound (Factor)