Theory of Calibration
Evaluation with the Standard Addition Method

For the Standard Addition method, calibration and evaluation are slightly different from "normal" calibration. One reason is that the original sample has a spiked amount = 0. Therefore, multiplication with factors it not possible.

 Caution:

Only if the calibration curve is forced through the origin (i.e., in this case, through the calibration point of the original, unspiked sample), the amount of this sample corresponds to the negative intercept on the x-axis, i.e., to the average of all values based on this sample. For all other calibration types, the calculated amount of the original, unspiked sample may deviate from the negative intercept on the x-axis of the calibration curve.

'External' and 'Internal/External' Evaluation:

Calibration:

• Y(i,k) = RESPONSE(i,k) * (DILFAC(x)/WEIGHT(x)) * (INJECTVOL(k)/REFINJECT))

• X(i,k) = AMOUNT_NOMINAL(i,k)

Evaluation: Calculation of the Amount peak variable for peak i in the sample x

• AMOUNT(i,x) = RSP-FACTOR(i) * F[RESPONSE(i,x) * DILFAC(x)/WEIGHT(x)]

Description: see  Evaluation with Various Standard Methods.

'Internal' Evaluation:

Calibration:

• Y(i,k) = 100 * RESPONSE(i,k)/RESPONSE(ISTD,k) * DILFAC(x)/WEIGHT(x)

• X(i,k) = AMOUNT_NOMINAL(i,k)

Evaluation: Calculation of the Amount peak variable for peak i in the sample x

• AMOUNT(i,x) = RSP-FACTOR(i) * F[100 * RESPONSE(i,x)/RESPONSE(ISTD,x) * DILFAC(x)/WEIGHT(x)]

The ISTD peak itself will not be evaluated!

'Internal' Evaluation (with variable ISTD):

Calibration:

• Y(i,k) = AMOUNT_NOMINAL(ISTD) * (RESPONSE(i,k)/RESPONSE(ISTD,k)) * (DILFAC(x)/WEIGHT(x)) * (INJECTVOL(k)/REFINJECT)

• X(i,k) = AMOUNT_NOMINAL(i,k)

Evaluation: Calculation of the Amount peak variable for peak i in sample x

• AMOUNT(i,x) = RSP-FACTOR(i) * F[AMOUNT_SOLL(ISTD) * RESPONSE(i,x)/RESPONSE(ISTD,x) * DILFAC(x)/WEIGHT(x)]

The Internal Standard ("ISTD") peak itself is not evaluated!

'Internal/External' Evaluation (with variable ISTD):

Calibration:

Calibration is 'External', including the ISTD peak! However, the nominal amount for the ISTD peak from the sample list (ISTD Amount) is used. The sample weight of the ISTD peak is not considered.

• Y(i,k) = RESPONSE(i,k) * DILFAC(k)/WEIGHT(k) * REFINJECT/INJECTVOL(k)

• X(i,k) = AMOUNT_NOMINAL(i,k)

• Y(ISTD,k) = RESPONSE(i,k) * DILFAC(k) * REFINJECT/INJECTVOL(k)

• X(ISTD,k) = AMOUNT_NOMINAL(ISTD,k)

Evaluation: Calculation of the Amount peak variable for peak i in the sample x

• The ISTD peak itself is evaluated 'Externally', but without Weight correction.

• AMOUNT(ISTD,x) = RSP-FACTOR(ISTD) * F[RESPONSE(ISTD,x) * DILFAC(x)]

• FACTOR_IS(x) = AMOUNT_NOMINAL(ISTD,x)/AMOUNT(ISTD,x)

• AMOUNT(i,x) = RSP-FACTOR(i) * FACTOR_IS(x) * F[RESPONSE(i,x) * DILFAC(x)/WEIGHT(x)]