Hanna Instruments HI 95724 - Manual (Page 6)

6
Absorption of Light is a typical phenomenon of interaction between electromagnetic radiation and
matter. When a light beam crosses a substance, some of the radiation may be absorbed by
atoms, molecules or crystal lattices.
If pure absorption occurs, the fraction of light absorbed depends both on the optical path length
through the matter and on the
physical -chemical characteristics of the substance according to the
Lambert-Beer Law:
-log
I / I
o
ε
λ
c d
or
A ε
λ
c d
Where:
-log
I / I
o
= Absorbance (A)
I
o
= intensity of incident light beam
I
= intensity of light beam after absorption
ε
λ
= molar extinction coefficient at wavelength λ
c = molar concentration of the substance
d = optical path through the substance
Therefore, the concentration "c" can be calculated from the absorbance of the substance as the
other factors are known.
Photometric chemical analysis is based on the possibility to develop an absorbing compound
from a specific chemical reaction between sample and reagents. Given that the absorption of a
compound strictly depends on the wavelength of the incident light beam, a narrow spectral
bandwidth should be selected as well as a proper central wavelength to optimize measurements.
The optical system of Hanna's
HI 95 series colorimeters is based on special subminiature
tungsten lamps and narrow-band interference filters to guarantee both high performance and
reliable results.
PRINCIPLE OF OPERATION
Block diagram (optical layout)
19
REAGENT SETS
HI 93701-F
300 tests Free Chlorine
HI 93701-T 300 tests Free and 100 test Total Chlorine
HI 93711-D3 DPD3 reagent for 200 tests
OTHER ACCESSORIES
HI 95724-11 CAL CHECK™ Standard Cuvets (1 set)
HI 710009 Blue rubber boot
HI 710010 Orange rubber boot
HI 721310 9V battery (10 pcs)
HI 731318 Tissue for wiping cuvets (4 pcs)
HI 731331 Glass cuvets (4 pcs)
HI 731335 Caps for cuvets (4 pcs)
HI 93703-50 Cuvets cleaning solution (230 mL).
ACCESSORIES