Location:

Peak Table tab page
Report Variable (Peak Table)

Default:

(for calculation:) linear interpolation

Related Variables:

Retention Time, Dead Time, Kovats Index

Description:

Retention indexes are used to facilitate positive assignment of substances in inter-laboratory data exchange. For programmed GC as well as for HPLC linear retention indexes are defined.

The Retention Index is defined for certain master peaks on the Peak Table tab page of the QNT Editor. For more information, refer to How to …:  Defining the Retention Index and the Kovats Index.

On the basis of the defined values, Chromeleon calculates the retention index for the remaining peaks. Use the Retention Index variable to display the results in the report. The following parameters are available:  

Parameters:

Interpolation function type

Determine the type of function used to calculate interpolation ((linear, quadratic, cubic, logarithmic). By default, Chromeleon calculates the following linear retention index:

Wherein:

RI: Retention index (usually RI = 100, 200, 300 is entered)

S: Substance

Z: number of the marker

The following is true:

If the peak occurs before the first marker peak, the following formula is used:

If the peak occurs behind the last marker peak, the following formula is used:

Retention Time Reference List

Specify which reference list (comprising retention time and retention index from the peak table) Chromeleon uses for calculating the retention index: the retention times of the current sample, or the retention times of the most recent sample that meets a certain condition.

If you clear the Include expected retention times for not detected peaks check box, the expected retention times of undetected peaks are excluded from calculation.

Extrapolation

If you clear the Extrapolate if the peak's retention time is outside the retention time reference range check box, Chromeleon excludes the retention times outside the specified retention time reference range from extrapolation.