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Spectradyne LLC, All rights reserved
34
Version 2.5.0 Revision 3, July 2020
Background Subtract Mode
Small particles generate small electrical signals, which are more easily masked by electrical noise
on an event-by-event basis using peak parameters and filters. To get more accurate
concentration measurements close to the noise floor of a given cartridge,
an estimate of
electrical noise false positives
can be visualized
and/or subtracted from the particle size
distribution.
➢
Under the Data Visualization tab, c
heck the “Subtract Backgrounds” box
➢
The estimated size distribution of electrical noise false positive events will be displayed in
CSD plots and parametric scatter plots when in Single or Combined viewing mode.
Procedure for Removing False Positives from the Set of Detected Peaks
➢
Load the desired Stats files into the Currently Loaded files list
➢
Navigate to the Peak Filtering tab of the Spectradyne Viewer
➢
Use the appropriate action buttons in the Filters frame of the Peak Filtering tab to apply
and remove existing filters as desired from files in the Currently Loaded file list.
➢
To create a new filter, use
the “+” button at the bottom of the available filters
list
➢
In the New Filter dialog box:
o
Choose one of two options for type of filter:
▪
Linear
–
Filter bounds have constant value of the non-diameter parameter
and include an infinite range of diameters
▪
Polygon
–
Filter has 2D, user-defined polygonal boundaries similar to a gate
commonly used in analysis of flow cytometry results.
o
Select the filter parameter of choice from the dropdown (e.g., Transit Time)
o
Specify a descriptive name for the filter
o
Specify the limits of the filter in one of two ways:
▪
Enter min and max values for the non-diameter parameter in the entries
provided (linear filters only)
▪
Specify the bounds of the filter directly on a scatter plot using the mouse
o
Click “Create” to add the filter to the list of available
filters.
o
The new filter does not get applied until it is selected in the filter list and applied
to the appropriate file(s)
using “Apply To:” either “Active” (the highlighted file) or
“All Loaded” (all files) in currently loaded window.
➢
The effects of peak filtering will be reflected in any of the viewing methods available (e.g.,
CSD plots, parametric scatter plots). In Single and Combined viewing mode, both the raw
and filtered datasets are displayed in the scatter plots.
The refined and filtered Stats files can now be saved individually or combined into a single
Combined file format as described in workflow step 3, below. To save one or more Stats files with
the applied filters and scaling, navigate to the Data Output tab of the Viewer and use the controls
in the Save frame.
➢
Saving a Stats file creates a new file with an incremented extension number, and does not
overwrite existing Stats files present in the current working folder.