3
III.
III.
III.
III.
III. Theory of Operation
Theory of Operation
Theory of Operation
Theory of Operation
Theory of Operation:::::
The HI 4002 or HI 4102 Bromide electrodes are potentio-
metric devices used for the rapid determination of free Bro-
mide ions in food products, beverages, plants, soils and as
an indicator in titrations. The electrode functions as a sen-
sor or ionic conductor. The HI 4002 requires a separate
reference electrode to complete its electrolytic circuit. The
HI 4102 incorporates a reference electrode. The silver Bro-
mide pellet is practically insoluble in the test solutions
being measured and produces a potential change due to
changes in the sample
’
s ion activity. When the ionic strength
of the sample is fixed by the addition of ISA, the voltage is
proportional to the concentration of bromide ions in solu-
tion and the electrode follows the Nernst equation.
E= E
a
+ 2.3 RT/nF log A
ion
E= observed potential
E
a
= Reference and fixed internal voltages
R= gas constant (8.314 J/K Mol)
n= Charge on ion (1-)
A
i
=ion activity in sample
T= absolute temperature in K
F= Faraday constant (9.648 x 10
4
C/equivalent)
