12. Semi-Quantitation based on Spectral Subtraction:
With the desired spectrum displayed on the screen in the ABSORBANCE mode, click on
"Add-Ons" and "Spectral ID".
Click on the "Tools" option at the top of the screen and “Choose Libraries…” select the desired
libraries from the listing. The click “OK”.
Click on "Search" then “Spectrum Search” to start the Search and when completed, the matches
will be shown, best to worst, based on the parameters set in the search options screen.
Use the first "hit", or the reference spectrum that looks closer to the sample, and under “Edit”
click “Subtract…” on the top. Three spectra are shown in the new box, the original, top hit and
the resultant subtraction will be displayed in this box.
At first, try to use the "Auto Subtract" button in the new box, and when it finishes, this will
show you a "factor" on the top of the screen. This represents an approximate percentage of the
reference material found in the unknown sample.
EXAMPLE: Factor = 0.67 means ~ 66 % or 2/3 of the sample contains THAT reference.
You may use the slider on the left side of the box to manually change the degree of subtraction
till it appears to be satisfactory.
Click on "Replace" button when finished and save the resultant scan or searched again and
subtracted to estimate the second most-prevalent component.
13. Default Settings: (set by computer for normal operations)
"View", then "Data Mode" or just F4 key should be “Overlaid” for QC work default is paged.
The buttons that show a red spectrum over a blue spectrum with an arrow pointing up and
down are to scroll through the spectrum.
"View", “Trace Limits…” should show 4000-600 cm
-1
and 100-0 % T for best %T printing.
"File", "Print Setup” should show the default printer in the Printers section in Window with
Landscape mode selected.
.
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