Spectroquant Pharo 300 - Page 107

Spectroquant
®
Pharo 300 Operation
107
ba75703d07 04/2014
Example:
Determination of
chlorophyll a
according to Nusch
The chlorophyll determination is based on two measurements (before and
after adding an acid) of the optical density (= absorbance) of the extract of an
aqueous sample at 665 nm.
Converted equation For entry on the photometer, assign names that you can enter in the formula
editor on the photometer to the variables of the equation.
Chlorophyll a (µg/l) = 29.6 * (A
(before) 665 nm
- A
(after) 665 nm
)*(V
Extract
/V
Sam-
ple
)
with:
A
(before) 665 nm
1st absorbance measurement at 665 nm
(before adding the acid)
A
(after) 665 nm
2nd absorbance measurement at 665 nm
(after adding the acid)
V
Extract
Volume of the extract (in ml)
V
Sample
Volume of the aqueous sample (in ml)
R = 29.6 * (A
665nm
- A
665nm_2
)*(K
1
/K
2
)
with:
R (chlorophyll a (µg/l)) Result (concentration chlorophyll A
in µg/l)
A
x nm
(= A
(before) 665
nm
)
A
x nm_2
(= A
(after) 665 nm
)
Variables for absorbance.
These values are measured by the photometer.
Here: Two measurements at the same wave-
length, at different points of time.
K
1
(= V
Extract
)
K
2
(= V
Sample
)
Procedure variables
K1 = Volume of the extract (in ml)
K2 = Volume of the aqueous sample (in l)
Numerals Freely selectable numerical values