Hanna Instruments HI 4112 User manual

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HI 4012HI 4012
HI 4012HI 4012
HI 4012
HI 4112HI 4112
HI 4112HI 4112
HI 4112
Lead Ion
Selective Electrode
Instruction Manual
Half-cell
Combination
LEAD/SULFATE
HI 4012
HI 4112
LEAD/SULFATE
COMBINATION

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HI 4012 Lead Half-cellHI 4012 Lead Half-cell
HI 4012 Lead Half-cellHI 4012 Lead Half-cell
HI 4012 Lead Half-cell
HI 4112 Lead Combination ElectrodeHI 4112 Lead Combination Electrode
HI 4112 Lead Combination ElectrodeHI 4112 Lead Combination Electrode
HI 4112 Lead Combination Electrode
I.I.
I.I.
I. Introduction:Introduction:
Introduction:Introduction:
Introduction:
The Hanna HI 4012 and HI 4112 are ion selective elec-
trodes 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
IIII
II. SpecificationsSpecifications
SpecificationsSpecifications
Specifications
Type: Solid State electrode with
a lead sulfide pellet.
Ion(s) measured: Lead (Pb +2+2
+2+2
+2 )
Measurement range: 0.1M 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

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III.III.
III.III.
III. Theory of OperationTheory of Operation
Theory of OperationTheory of Operation
Theory 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)

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IV.IV.
IV.IV.
IV. Design elements of the HI 4012 and HI 4112Design elements of the HI 4012 and HI 4112
Design elements of the HI 4012 and HI 4112Design elements of the HI 4012 and HI 4112
Design elements of the HI 4012 and HI 4112
electrodeselectrodes
electrodeselectrodes
electrodes
Upper Cap
Spring
O-Ring
Ceramic Junction
on Inner Stem
Fill Hole
O-Ring and
Plug
Sensing
Membrane
Outer Sleeve
Upper
Threads
Liquid junction
Sensor Body
Cap
Sensing
Membrane
LEAD/SULFATE
HI 4012

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V.V.
V.V.
V. Equipment required:Equipment required:
Equipment required: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 bea-
kers 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.
VI.VI.
VI. Solutions RequiredSolutions Required
Solutions RequiredSolutions Required
Solutions Required
For Lead Measurements
0.1 M lead standard, (500 mL) HI 4012-01
ISA, (5 X 100 mL) HI4012-00
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 H2O to 500 mL of
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 stan-
dard is equivalent to 20,720 ppm. Standards with con-
centrations <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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VIIVII
VIIVII
VII. General GuidelinesGeneral Guidelines
General GuidelinesGeneral Guidelines
General Guidelines
• Use of a hood and protective clothings is advised
when handling lead solutions.
•Concentrated samples (>0.10 M) should be diluted
before measurement. Multiply the final result by the
corresponding dilution factor.
•Calibration standards and sample solutions should
have the same ionic strength. ISA and Methanol/
Formalin should be added to both samples and stan-
dards in the same ratio. 2 parts ISA to 50 parts stan-
dard (or sample)/50 parts Methanol/Formalin is the
normal dosing. Note: no correction for dilution factor is
required for this because standards and samples are
treated in the same way.
•For high ionic strength samples, use standard addi-
tion or titration methods.
•Calibration standards and sample solutions should
be at same temperature.
•The magnetic stirrer may generate heat. Thermally
insulate beaker containing standard or sample from
magnetic stirrer by placing cork or other insulative
sheet between beaker and stirrer plate.
•Calibration standards and sample solutions should
be stirred at the same rate using identical sized TFE
coated stir bars.
•Rinse electrode pair with distilled or deionized water
between samples and gently dab dry with soft dis-
posable absorbent toweling. Do not rub electrodes.
•Presoaking lead sensor in a dilute standard will opti-
mize response. Use concentrations approximately
10-3 M or less with Methanol/Formalim and ISA added.
•A scratched, pitted, or oxidized pellet surface can cause
drift, a loss of low level response, or poor repeatability.
Optimum response can be restored by removing the
damaged surface with the microabrasive strip HI 4000-
70. Use gloves to protect skin.
•Avoid large changes in temperature (thermal shock)
as it may damage the sensor.

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•Gas bubbles may form from solution out-gassing due
to temperature change. Gently tap body of sensor to
dislodge them from sensing membrane.
HI 4012
•Remove protective cover from sensor tip.
HI 4112
•Remove the protective plastic wrap that covers the
ceramic junction before assembling sensor for the first
time.
•HI 7072 reference fill solution should be added daily
to electrolyte reservoir before electrode use.
•During measurement always operate electrode with
the fill hole open.
•During normal use, fill solution will slowly drain out
of the tapered cone junction at the lower portion of the
electrode. Excessive loss (>4 cm drop within 24 hours)
is not normal. If this occurs verify cap is tightened and
the interface between the internal cone and outer
body is free of debris.
•Add fill solution daily to maintain a good head pres-
sure. For optimum response, this level should be main-
tained and not be allowed to drop more than 2-3 cm
(1-inch) below fill hole. Fill solution must cover the
ceramic found on the inner stem.
•If an erratic measurement occurs, check to see if for-
eign matter is seen trapped near the internal cone.
Drain, wipe off outer cone while depressing cap, re-
lease cap and refill with fresh fill solution.

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VIII.VIII.
VIII.VIII.
VIII. Electrode PreparationElectrode Preparation
Electrode PreparationElectrode Preparation
Electrode Preparation
HI 4012
1. Remove protective cover from sensor tip.
2. Prepare reference electrode by filling outer electrolyte
reservoir with HI 7072.
3. Place sensor and reference electrodes into electrode
holder and connect cable connectors to meter.
HI 4112
1. Unwrap plastic film seal found over ceramic junction
on inner stem and discard. This is only used for ship-
ping and long term storage.
2. Rinse inner stem with deionized water making certain
to wet the o-ring found on the inner stem.
3. Reassemble electrode by gently pushing the inner
assembly into the outer body, sliding spring down
cable, and screwing cap into place.
4. Remove fill hole cover and o-ring on fill hole spout.
5. Using the dropper pipette provided, add a few drops
HI 7072 fill solution to the electrode, wetting the o-
ring and rinsing out the fill solution chamber.
Deionized
Water
Remove
Parafilm

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6. Holding the body of the electrode gently press upper
cap with your thumb. This permits the fill solution to
drain out of the body. Release cap and verify elec-
trode returns to its original position. (You may need to
gently assist for this to occur).
7. Tighten the electrode cap onto the body and fill elec-
trode body until fill solution volume is just below fill
hole.
8. Position electrode in a Hanna HI 76404 electrode
holder (or equivalent) and connect plug to meter.
HI 4112
LEAD/SULFATE
COMBINATION

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IX.IX.
IX.IX.
IX. Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode Slope
Use of a hood and protective clothing is strongly advised.
•Connect sensors to pH/mV/ISE meter
•Place meter in mV mode.
•Place 50 mL of deionized water into a beaker with stir
bar and 2 mL of HI 4012-00 ISA. Add 50 mL of the
methanol/Formalin mixture. Add stir bar and place
on magnetic stirrer.
•Place electrodes into prepared sample.
•Add 1 mL of the stock standard HI 4012-01 (or .01 M
or .001 M standard by dilution) to the beaker.
Record the mV value when reading has stabilized.
•Add an additional 10 mL of standard HI 4012-01 (or
same dilute standard) to the solution. Record the mV
when reading has stabilized. This value should be
more positive than the previous noted.
•Determine the difference between the two mV values.
An acceptable value for this slope is +27 ± 4 mV.
X.X.
X.X.
X. Corrective actionCorrective action
Corrective actionCorrective action
Corrective action
•Verify protective cap has been removed (HI 4012).
•Verify plastic film has been removed from inner stem
(HI 4112).
•Verify electrodes are connected properly to meter and
meter is powered.
•Verify standard has been properly stored. Remake
standards if appropriate.
•If the sensor slope just misses the suggested slope
window, soaking the sensor in a dilute standard with
the methanol/formalin added may solve the prob-
lem. (<10-3 M standard).
•A scratched, pitted or oxidized sensing surface can be
polished with HI 4000-70 polishing strip. Cut off
approximately 1 inch of the micro-abrasive strip. Wear
protectice gloves. Wet the frosted side with deionized
water and place against damaged membrane of the
electrode. Place your gloved thumb against the shiny
backing and slowly rotate back and forth while