Interpolation Formulas For Virtual-Internal-Standard Correction - Agilent Technologies 7500 ICP-MS Operator's Manual

Agilent 7500 ICP-MS ChemStation Operator's Manual
Appendix

Interpolation Formulas for Virtual-Internal-Standard Correction

These formulas are used to calculate the modification rates for all internal standards
used for the latest calibration curve and the current sample data. The concentration
level of the current data internal standards uses the value of level 1 of the calibration
curve, as with the existing internal-standard correction. In the case of "Linear" and
"Quadratic," one formula is created from all internal-standard modification rates. In
the case of "Point to Point," a formula is created for every two internal standards.
Cps _ ci
Conc
=
Ri
Cps _ si
Conc
where
Cps_ci, Conc_ci : CPS and concentration of the internal standard
Cps_si, Conc_si : CPS and concentration of the internal standard
Point to Point (Y = aX + b; Two adjacent internal standards are used; Default)
Linear (Y = aX + b; All internal standards are used.)
∑ ∑ ∑
−
n MiRi
=
i i
a
∑ ∑
−
2
n Mi (
i i
∑ ∑
Ri Mi
= −
i i
b a
n n
= +
Ra aMa b
_ ci
_ si
of the data last used to update the calibration
curve
of the current sample data (For the
concentration, use the value set for level 1 of
the calibration curve.)
Mi Ri
i
2
Mi )
A-23