PerkinElmer aanalyst 200 User Manual page 177

Analyte Addition
Calibrate
Calculated
Intercept: Linear
Calculated
Intercept: Analyte
Addition
Bracketing
Calibration
sample is calibrated individually.
A calibration curve defined using this equation is forced to pass through
zero absorbance and zero concentration (i.e. the origin).
You can select the technique of addition calibration when the matrix
causes interference, but the matrix is consistent in all the unknown
samples. You establish the calibration curve for the first unknown sample
using the analyte addition technique and then use this calibration curve to
measure all subsequent samples.
This option allows the intercept of the calibration curve with the
absorbance axis to be calculated rather than forced through zero. In the
calculation algorithm the blank solution is treated as another point on the
curve.
You select the analyte addition technique when the composition of the
unknown sample is unknown and the matrix causes an interference that
varies in magnitude from sample to sample. With this technique, every
unknown sample is calibrated individually.
The intercept of the calibration curve with the absorbance axis is
calculated rather than forced through zero.
This option is applicable over a restricted concentration range at higher
concentration levels. The concentrations of the standards bracket the
concentrations of the unknown samples and only a limited section of the
calibration curve is used for the evaluation.
AAnalyst 200 User's Guide
7-19