Hanna Instruments HI 4012 User Manual
LEAD/SULFATE
HI 4012
HI 4112
LEAD/SULFATE
COMBINATION
Instruction Manual
HI 4012HI 4012
HI 4012
HI 4012HI 4012
HI 4112HI 4112
HI 4112
HI 4112HI 4112
Half-cell
Combination
Lead Ion
Selective Electrode
1
HI 4012 Lead Half-cellHI 4012 Lead Half-cell
HI 4012 Lead Half-cell
HI 4012 Lead Half-cellHI 4012 Lead Half-cell
HI 4112 Lead Combination ElectrodeHI 4112 Lead Combination Electrode
HI 4112 Lead Combination Electrode
HI 4112 Lead Combination ElectrodeHI 4112 Lead Combination Electrode
I. I.
Introduction:Introduction:
I.
Introduction:
I. I.
Introduction:Introduction:
The Hanna HI 4012 and HI 4112 are ion selective electrodes designed for the measurement of Lead ions in
aqueous solutions. The HI 4012 is a solid state half-cell
sensor that requires a separate reference. The HI 4112 is a
combination ion selective electrode.
IIII
SpecificationsSpecifications
II.
Specifications
IIII
SpecificationsSpecifications
Type: Solid State electrode with
a lead sulfide pellet.
+2 +2
+2
Ion(s) measured: Lead (Pb
+2 +2
)
Measurement range: 0.1 M to 1X 10
-6
M
20700 to 0.21 ppm
Interfering ions: Silver, Copper, Cadmium
Iron (2+ 3+) and Mercury must be absent. Any ion that
forms a more insoluble sulfide than lead sulfide will interfere
with the electrode response. Long term exposure in this ion
will poison the lead surface. Oxidation of the lead surface
will also poison the electrode.
Operating Temperature: 0-80°C
Operating pH: 4 to 7 pH
(recommended)
Dimensions: 12 mm (OD) X 120 mm
nominal insertion
(0.47” X 4.72”)
Connection: BNC
2
III. III.
Theory of OperationTheory of Operation
III.
Theory of Operation
III. III.
Theory of OperationTheory of Operation
::
:
::
The HI 4012 or HI 4112 lead electrodes are potentiometric
devices used for the rapid determination of free lead ions in
plating baths and as a detector for the titration of sulfate or
thorium with lead perchlorate
. Lead sensors are “elec-
trodes of the third kind” because they detect cations which
also form low-solubility salts with sulfide anions and forms
low-solubility salts with silver.
The electrode functions as a sensor or ionic conductor. The
HI 4012 requires a separate reference electrode to complete
its electrolytic circuit. The HI 4112 incorporates a reference
electrode. The mixed lead sulfide/ silver sulfide membrane
produces a potential change due to changes in the sample’s
lead ion activity. When the ionic strength of the sample is
fixed by the addition of ISA, the voltage is proportional to
the concentration of Lead ions in solution and the electrode
follows the Nernst equation.
E= Ea +2.3 RT/nF log A
ion
E= observed potential
Ea= Reference and fixed internal voltages
R= gas constant (8.314 volt coulomb/K Mole)
n= Charge on ion (2+)
A i=ion activity in sample
T= absolute temperature in K
F= Faraday constant (9.648 x 104 coulombs/mole)
3
IV. IV.
Design elements of the HI 4012 and HI 4112Design elements of the HI 4012 and HI 4112
IV.
Design elements of the HI 4012 and HI 4112
IV. IV.
Design elements of the HI 4012 and HI 4112Design elements of the HI 4012 and HI 4112
electrodeselectrodes
electrodes
electrodeselectrodes
Cap
Sensor Body
Sensing
Membrane
Upper Cap
Upper
Threads
HI 4012
LEAD/SULFATE
Spring
O-Ring
Ceramic Junction
on Inner Stem
Liquid junction
Fill Hole
O-Ring and
Plug
Outer Sleeve
Sensing
Membrane
4
V. V.
Equipment required:Equipment required:
V.
Equipment required:
V. V.
Equipment required:Equipment required:
• Hanna HI 5315 Double Junction Reference Electrode
with HI 7072 Fill Solution for HI 4012.
• Hanna HI 4222 pH/ISE/mV meter or other suitable
ion or pH/mV meter. (Note: log/linear graph paper is
useful if an ISE (ion) meter is not available).
• Hanna HI 180 Magnetic Stirrer or equivalent with TFE
coated stirring bars (HI 731320). Note: isolate beakers from stirrer motor heat by placing insulating
material such as foam or cork between them.
• Hanna HI 76404 Electrode Holder or equivalent.
• Plastic beakers (HI 740036P) or other suitable mea-
surement vessel.
VI. VI.
Solutions RequiredSolutions Required
VI.
Solutions Required
VI. VI.
Solutions RequiredSolutions Required
For Lead Measurements
0.1 M lead standard, (500 mL) HI 4012-01
ISA, (5 X 100 mL) HI 4012-00
For Sulfate Titrations
(used to standardize lead perchlorate solutions)
0.1 M sulfate standard, (500 mL) HI 4012-21
See Section XII ; Titrations
User supplied solutions:
A user supplied Methanol/Formalin solution is required to
decrease pellet solubility and oxidative effects. To prepare,
add 200 µL 37 wt. % formalin in H
O to 500 mL of
2
reagent grade methanol. Stir and store in tightly closed
glass bottle. This solution is used at a dose of 50 parts of
the Methanol/Formalin solution to 50 parts standard or
sample.
For Direct lead measurements- Using volumetric pipettes
and glassware, make dilutions of HI 4012-01 to bracket
the concentration of the samples. Note: 0.1M lead standard is equivalent to 20,720 ppm. Standards with concentrations < 10
-3
M (207ppm) should be prepared daily.
Store in tightly closed plastic bottle. To 50 parts standard or
sample add 50 parts Methanol/Formalin solution plus 2
mL of ISA.
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