Thermo 335904, Operator'S Manual, Page: 86 / 94

Appendix C - Calculations
Thermo Electron Corporation C-6
Calculation Calculation(s) Graphs
Validity of
standard curves
Statistics
(Linear regression
general case)
Linear regression
through zero model
Absorbance Ratio
Absorbance Difference
A(c
1
) > A(c
2
)
for all c
1
> c
2
or
A(c
1
) < A(c
2
)
for all c
1
> c
2
where: A = absorbance
c
1
, c
2
= concentration
If this is not the case, then there will be more
than one solution within the specified domain,
and the message “Curve cannot be used to
determine unknown concentrations - it may
produce ambiguous results” will appear when
the curve is viewed.
where: n = degree of polynomial
Note: The calculation for the correlation
coefficient only applies to first-order
linear regression curves (first-degree
polynomials).
Abs
λ
1
or
Abs
λ
1
−
Abs
ref
Abs
λ
2
Abs
λ
2
−
Abs
ref
Result = Abs
λ
1
* factor 1 - Abs
λ
2
∗
factor 2
or
(Abs λ
1
- Abs λ
ref
)*factor 1 - (Abs λ
2
- Abs λ
ref
)*factor 2
Valid non-linear standard curve
Invalid non-linear standard curve
Appendix C - Calculations
Valid non-linear standard curve
Invalid non-linear standard curve