Quantitation; Internal Standard; Calculating Concentration - Agilent Technologies 7500 ICP-MS Operator's Manual

Agilent 7500 ICP-MS ChemStation Operator's Manual
Appendix

Quantitation

Internal Standard

When an internal standard is selected in the current calibration curve, the count of
the target ion of the sample data is divided by the ratio of the count per
concentration of the internal standard in the sample data. In this calculation, the
concentration of the internal standard in the first level of the calibration curve is
used as the concentration of the internal standard in the sample data. The count
value for each element reported on a quantitative report is therefore a count ratio.
( )
=
y
y / y / x ( y
σ
i i
where
x :
concentration of the internal standard of the first level in the calibration curve
i
y :
count of internal standard
i
y :
count of the target ion
σ
This value is used as the measured value of y in the following sections.

Calculating Concentration

Concentration of the target ion of the sample data is calculated as follows.
where
x :
concentration of the target ion
y :
measured count of the target ion
a :
coefficient " a" in the calibration curve
:
b
coefficient " b" in the calibration curve
c:
coefficient " c" in the calibration curve
= =
y
if x 0 )
σ
i
A-19