Integration table items
Several first lines of the integration table contain a default settings of basic integration parameters - Global Peak Width, Global Threshold, Global Bunching and Global Baseline Slope. These settings apply everywhere where no values for Local Peak Width, Local Threshold and Local Baseline Slope have been entered.
Global Peak Width / Local Peak Width [min]
This parameter defines the smallest peak width, which is to be detected. The value range is between 0,001 and 100 minutes.
The value is not critical, so even narrower peaks than the entered value will be detected, but if set incorrectly, the beginning and end of a peak may be inaccurately determined and the baseline could be incorrectly inset.
The Global Peak Width parameter is always displayed in the first row of the integration table and is applied to the whole chromatogram.
It is possible to set a different peak width for individual sections by adding the Local Peak Width parameters into further rows of the integration table which then override the Global Peak Width settings in the given area of chromatogram.
Global Threshold / Local Threshold [mV]
Determines the sensitivity the integration algorithm has to noise. The height of all peaks (measured from the baseline to the top) that should be detected has to be at least double this parameter. The value range must be 1 µV -10 V.
The Global Threshold parameter is always displayed in the second row of the integration table and is applied to the whole chromatogram.
It is possible to set a different noise threshold for individual sections by adding the Local Threshold parameters into further rows of the integration table which then override the Global Threshold parameter in the given area of the chromatogram.
Note:
In the Wave integration algorithm, peaks that are lower than twice the threshold may still appear in the chromatogram if they are on the same baseline with valid (higher) peaks not to influence the course of the baseline. Such peaks can be hidden using the Peak - Hide function or the baseline can be modified to remove them using the Integration - Minimal Height operation set to twice the threshold value (baseline changes in the latter case).
Sets the averaging of data points for the signal displayed (and calculated with) in the chromatogram. Global Bunching serves as a filter and reduces the high frequency noise. The value must be between 1 (no averaging performed) and 250 (for each 250 data points measured, only 1 is displayed). Applying higher Global Bunching values will significantly change the signal course.
The Global Bunching parameter is always displayed in the third row of the integration table and is applied to the whole chromatogram.
Global Baseline Slope / Local Baseline Slope
Determines the position of the peak starts and peak ends on peak sides. The value must be between 0 and infinity, the higher the value the higher on the peak slope the starts and ends will be. If the value is set to 0, default peak start and peak end position is used (the value is considered to be 8*Global Threshold. The slope on peak ends is considered as a negative value of the value entered, target slopes for negative peaks are using negative value for starts and positive one for peak ends.
Global Baseline Slope parameter is always displayed in the fourth row of the integration table and is applied to the whole chromatogram. It is only present for Wave algorithm.
It is possible to set a different slope for peak starts/ends for individual sections by adding the Local Baseline Slope parameters into further rows of the integration table which then override the Global baseline Slope parameter in the given area of the chromatogram.
Limits the time period over which the chromatogram will be integrated. This means that the chromatogram profile will be ignored beyond the set time interval. This is the main difference compared to Lock command, which cancels already integrated peaks only in defined sections and does not reintegrate the whole chromatogram. If the parameter is not defined, integration is done on the whole chromatogram.
Consists of several integration parameters which specify the conditions for including/excluding peaks in/from the integration. The peak parameters must be larger than the specified values, otherwise the peak will not be displayed.
This parameter sets the minimum peak area in mV.s. Peaks whose area is smaller than the specified value are not displayed.
This parameter gives the minimum peak height in mV. Peaks whose height is smaller than the specified value are not displayed.
This parameter gives the minimum peak half-width in minutes. Peaks whose W05 is smaller or equal to the specified value are not integrated.
Several parameters defining the integration of non-separated peaks.
Specifies the maximum slope of the baseline. If the baseline slope is smaller than the specified value, the separating perpendicular line is canceled and the baseline passes through the valley.
The default value of 0 prevents the baseline from passing through the valley.
Constitutes the first condition imposed on tangential separation. The condition is satisfied if the ratio of areas of the main and the separated peak exceeds the specified value.
The default value of 0 prevents tangential separation. If there is no Tangent Slope Ratio item defined in the Integration table, its value is considered to be 1.5.
This is the second condition imposed on tangential separation. The condition is satisfied if the ratio of slopes of the second and the first peak exceeds the specified value. The slope ratio is defined as the tangent to the first peak at its end point divided into the slope of the line connecting the beginning and end of the second peak.
The default value of 0 prevents tangential separation. If there is no Tangent Area Ratio item defined in the Integration table, its value is considered to be 0.1.
For the description of the other items in the table see the chapter "Chromatogram", namely topics Baseline, Peak, Separation and Noise & Drift.
The evaluation process does not proceed exactly in the same order as the parameters in the integration table are shown. The process is:
- Primarily initiated with the Global (Local) Peak Width, Global (Local) Threshold and Integration Interval parameters.
- Secondly the ValleyToValley Slope parameter will be applied. After all groups of non-resolved peaks have been tested by this parameter the remaining two parameters Tangent Area Ratio and Tangent Slope Ratio are applied to all remaining non-resolved groups. Tangential separation is used whenever the relevant criteria are met.
- Only then is the Integration Table used, followed by the Rejections parameters.
It thus follows that the separation parameters are not applied (e.g. to manually added peaks) and can be suppressed by the Together and Valley commands included in the Integration table.