Location:
Report Variable (Peak Results)
Default:
EP Formula
Related Variables:
Description:
The Theoretical Plates peak result variable is a measure of the separation capability of the column. With the standard formulas, theoretical plates are calculated from the peak width and the corresponding retention time.
TP does not have a unit. If it is placed in relation to the currently used column (L), the result is the theoretical plate height (H):
However, the reciprocal value reveals more about the quality of the currently used column. It indicates the number of theoretical plates per column meter.
A parameter allows you to define which standard is used.
Parameters:
EP/JP Formula
This is the default setting.
EP = European Pharmacopeia
JP = Japanese Pharmacopeia
Note:
The formula given in the Japanese Pharmacopeia for calculation of theoretical plates has been changed. The previously used factor was 5.55. You can still use this factor for calculation in Chromeleon. To do so, manually change the report variable formula to peak.theoretical_plates("JP").
USP Formula
USP = United States Pharmacopeia
where:
|
TP |
= Number of theoretical plates |
|
tR |
= Retention time |
|
W50% |
= Peak width at 50% height (half-width) |
|
BW |
= Peak width on the baseline. |
Formula using Statistical Moments
It is also possible to determine the number of theoretical plates via the second statistical moment, using the following formula:
where:
|
µ2 |
= Second statistical moment (variance). For details, refer to Statistical Moments. |
