Справочник Пользователя для Hanna Instruments c 214
6
PRINCIPLE OF OPERATION
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 substance according to the Lambert-Beer
Law:
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 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 C 99 & C 200 Series multiparameter
photometers is based on special subminiature tungsten lamps and
narrow-band interference filters to guarantee both high performance
and reliable results.
Four measuring channels (at four different wavelengths) allow a wide
range of tests.
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 C 99 & C 200 Series multiparameter
photometers is based on special subminiature tungsten lamps and
narrow-band interference filters to guarantee both high performance
and reliable results.
Four measuring channels (at four different wavelengths) allow a wide
range of tests.
C 200 Series block diagram (optical layout)
75
/PUP - Program Up
/PDN - Program Down
/PTM - Turn Test Mode On
/Brx - Set the baud rate
/PDN - Program Down
/PTM - Turn Test Mode On
/Brx - Set the baud rate
1 - 300
2 - 600
3 - 1200
4 - 2400
/KBL - Lock Keyboard
/KBU - Unlock Keyboard
?PR# - Send Current Program Number
?BRQ - Send current baud rate
/KBU - Unlock Keyboard
?PR# - Send Current Program Number
?BRQ - Send current baud rate
1 - 150
2 - 300
3 - 600
4 - 1200
5 - 2400
?CNQ - Send Concentration (three bytes)
conc
decimal point
unit
decimal point
unit
m - ppm
b - ppb
t - ppt
u - pcu
h - pH
?ERR - send error / status information
0 - No error
1 - CAP
2 - HI
3 - ZERO
4 - LO
5 - IDLE
6 - ZERO DONE
7 - TIMED READ
1 - CAP
2 - HI
3 - ZERO
4 - LO
5 - IDLE
6 - ZERO DONE
7 - TIMED READ