7 multi wavelengths methods, Multi wavelengths methods 4.7.1 – Xylem photoLab 6600 UV-VIS User Manual
Page 73
photoLab
®
6600 UV-VIS
Operation
73
ba75848e01
08/2009
4.7
Multi wavelengths methods
4.7.1
Basic information on Multi wavelengths measurements
The multi wavelength function of the photoLab
®
6600 UV-VIS enables free
calculation of any parameters from the absorbance values of several
wavelengths. When doing so, two to ten wavelengths can be used.
Calculation takes place based on the following equation:
The wavelengths 1 to 10 can be freely selected within the measuring range.
Example: Protein
determination
according to
Warburg-Christian
Protein determination according to Warburg-Christian is based on
measurement of the optical density (=absorbance) at 260 and 280 nm in a
10 mm cell. From this the protein content is calculated as follows:
To convert the basic equation (1) into equation (2), the coefficients are set to
the following values:
All absorbances are measured in one step and the result is calculated
according to the equation.
with:
R
Result
a0 to a10; b0 to b10
Freely selectable coefficients
(entry range 0.000 to 1000,000)
A1 to A10
Measured absorbance at the individual
wavelengths 1 to 10
(equation 1)
10
10
...
2
2
1
1
0
10
10
...
2
2
1
1
0
A
b
A
b
A
b
b
A
a
A
a
A
a
a
R
⋅
+
+
⋅
+
⋅
+
⋅
+
+
⋅
+
⋅
+
=
a0 = 0
b0 = 1
a1 = 1,55
b1 = 0
a1 = A(280 nm)
A2 = -0,76
b2 = 0
A2 = A(260 nm)
A3 = 0
b3 = 0
A3 = Not used
A4 = 0
b4 = 0
A4 = Not used
a5 = 0
b5 = 0
a5 = Not used
a6 = 0
b6 = 0
a6 = Not used
a7 = 0
b7 = 0
a7 = Not used
a8 = 0
b8 = 0
a8 = Not used
a9 = 0
b9 = 0
a9 = Not used
a10 = 0
b10 = 0
a10 = Not used
(equation 2)
)
nm
260
(
A
76
,
0
)
nm
280
(
A
55
,
1
]
ml
/
mg
[
c
Protein
⋅
−
⋅
=