LUMAT LB 9507 - Variable Zero Concentration Factor

Appendix LB 9507
4
A.1.2 Variable Zero Concentration Factor
Prior to the transformation of the concentration values, a fraction f
of the second standard is added to each value if the first
concentration value is zero, as follows:
X = In [conc + conc
2
/f] (i = 1, .... n)
X = ln ]conc + conc
2
/f]
This factor is determined according to the formula
yy
n
- y
x - x
!
- y
x - x
2
n2
1
21
2
the limits 1 < f < 100 are valid for ”f”.
As a consequence, the curve will be fairly linear at the zero point.
y =
B - NSB
B - NSB
max
conc
i
= conc +
conc
f
i
2
y
n
y
2
y
1
x
1
x
2
x
n