Correction Of Working Curve Drift (Reslope Function) - Hitachi ZA3000 Series Instruction Manual

5.2 Correction of Working Curve Drift (Reslope Function)

Reslope function is used to measure a specific standard sample
at the determined intervals and correct sensitivity variations of
the working curve. It is also applicable when using a working
curve measured in the past (existing working curve).
Although this function is usable in the working curve method or
simple standard addition method, it is most effective when the
working curve is close to a straight line.
If the curvature of working curve is significant, the correction
error will expand. In this case, it is advisable to draw the entire
working curve again.
Correction of the working curve by the reslope function is carried
out as follows (when, for example, STD4 is specified for [STD for
Reslope] and correction is made once every 10 samples).
(1) Creation of Working Curve
Working curve
A: Absorbance
C: Concentration
a: Coefficient
n: Order of working curve
(2) Measurement of Unknown Samples 11 to 20 (using
working curve in (1))
(3) Measurement of STD4
Creation of Working Curve by resloping
n
A

 i
A 2 a C
i
A

i 0
1
A : Initial STD4 absorbance
1
A : STD4 absorbance in reslope measurement
2
(4) Measurement of Unknown Samples 21 to 30 (using
working curve in (3))
5 - 9
n


i
A a C
i

i 0
5.2