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Agilent 7500 ICP-MS ChemStation Operator’s Manual
Performing a Quantitative Analysis
Blank Subtraction
ChemStation enables you to subtract a blank data file from the sample data file, for
example, where the sample reagent blank is different from the standard reagent
blank. This blank subtraction is performed after both the blank data file and the
sample data file are quantitated (unlike the background subtraction where the
background counts are subtracted from the sample counts). Hence, the calculated
concentration of a given element in the blank data file is subtracted from the
calculated concentration of that same element in the unknown sample, resulting in a
blank-subtracted concentration for the unknown.
Background correction is not ordinarily used in quantitation. Its main purpose is to
subtract a background spectrum from a sample spectrum so the user can view the net
spectrum for qualitative purposes. Since background correction subtracts raw counts
before normalizing for internal standard response, it could give incorrect results
with internal standards.
To subtract the blank data file from your sample data files, complete the following
steps:
1 Select the Blank Conc Subtraction check box in the Edit Calibration dialog box.
2Click Browse.
The Select Data File dialog box will appear.
3 Select a blank data file.
4Click OK.
The Select Data File dialog box will close and the blank concentration subtraction
value will be set.
NOTE Blank data can be printed by selecting Calibration >> Print Blank Conc.
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