Mindray BS-120 - Page 252

10 Calculation Methods 10-9
Multi-point linear calibration
Calibration formula: baCR
+
=
.
This calibration method adopts two calibration parameters:
a
and b .
This calibration method requires n (n ≥ 3) calibrators.
i
C is the concentration of calibrator
i
.
i
R is the response of calibrator
i
.
a
and b can be obtained through the method of
least squares.
nCC
nRCRC
a
n
i
i
n
i
i
n
i
i
n
i
i
n
i
ii
/)(
/))((
2
11
2
111
∑∑
∑∑∑
==
===
−
−
=
−=
∑
=
nRb
n
i
i
/)(
1
nC
nCC
nRCRC
n
i
i
n
i
i
n
i
i
n
i
i
n
i
i
n
i
ii
/)](
/)(
/))((
[
1
2
11
2
111
∑
∑∑
∑∑∑
=
==
===
−
−
10.2.3.2 Calculating Nonlinear Calibration Parameters
Logistic-Log 4P
Calibration formula:
)]ln(exp[1
1
0
Cba
KRR
+−+
+=
This calibration method adopts four parameters:
0
R ,
K
,
a
and b .
This calibration method requires at least four calibrators. The concentration (or activity) of
calibrator 1 is 0, and the corresponding
R
is equal to
R
0
.This calibration method is
applied to the calibration curve that the response becomes smaller and smaller with the
concentration increase. SeeFigure 10-8
Figure 10-8 Logit-Log 4P calibration curve
R
C
C1 C2 C3 C4
Logistic-Log 5P
Calibration formula:
)]ln(exp[1
1
0
cCCba
KRR
++−+
+=
This calibration method adopts five parameters:
0
R ,
K
,
a
, b and
c
.
This calibration method requires at least five calibrators. The concentration (or activity) of
calibrator 1 is 0, and the corresponding
R
is equal to
R
0.
The applications of the