Hanna Instruments HI 4105 User manual

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HI 4105HI 4105
HI 4105HI 4105
HI 4105
CarbonDioxide
Ion
SelectiveElectrode
Instruction Manual
CARBON DIOXIDE
HI 4105

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HI 4105 Carbon Dioxide ElectrodeHI 4105 Carbon Dioxide Electrode
HI 4105 Carbon Dioxide ElectrodeHI 4105 Carbon Dioxide Electrode
HI 4105 Carbon Dioxide Electrode
I.I.
I.I.
I. Introduction:Introduction:
Introduction:Introduction:
Introduction:
TheHannaHI4105CarbonDioxide gassensingelectrode
isacombinationelectrodedesignedforthemeasurement
ofCarbonDioxideinaqueoussolutionssuchaswater,soft
drinksorwine,samples. CarbonateandBicarbonateions
are also measured by conversion to Carbon Dioxide gas
upon ISA addition.
II.II.
II.II.
II. SpecificationsSpecifications
SpecificationsSpecifications
Specifications
Type: CO2gas sensing
electrodewithglasspH
internal, Ag/ AgCl
referenceandgas
permeable membrane.
Speciesdetected: CO32-,HCO3-,CO2
CO2MeasurementRange: 0.02Mto4x10-4M
880to17.6ppm
Interferingions: SO2/SO32-, H2S/S2-
Operating Temperature: 0to40°C
Operating pH: 4-5 pH
Dimensions: 12mm(OD)X120
mm (insertion)
0.47”x4.72”
Wettedmaterials: Delrin®, body and cap
with PTFE membrane
Connection: BNC

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III.III.
III.III.
III. Theory of OperationTheory of Operation
Theory of OperationTheory of Operation
Theory of Operation:::::
TheCarbonDioxideelectrodeisacompletepotentiometric
cell that contains both a silver/silver chloride (Ag/AgCl)
referenceandapHmeasurementelement. Theseelements
arehousedwithina thermoplastic body in achlorideion-
containingelectrolyte,andareisolatedfromthesampleby
a PTFE membrane.
ISA addition changes the pH of the sample to approxi-
mately 4.7 pH and Bicarbonate (HCO3-) and carbonate
(CO32-)ionsinthesampleareconverted tocarbondioxide
(CO2). TheCO2inthesamplesolutiondiffusesthroughthe
PTFEmembranewhereitdissolvesintothethinfilmoffill
solutionfoundbetweenthemembraneandtheinternalpH
membrane. Here it converts back into bicarbonate and
hydrogen ions. The pH changes proportionally with the
concentrationofdissolvedgasinthesamplesolution.Dif-
fusionofCO2continuesuntilthepartialpressuresofthegas
in the sample and thin film are equal.
The Nernst expression for an Carbon Dioxide sensor is ex-
pressedintheequationbelow.Notethatthepotentialisa
functionoftheCarbonDioxidegas,whichinturnisrelated
tothehydrogenionconcentration. Theglassinternal,
Ag/AgCl reference, equilibrium constant and Henry’s law
constant are rolled into the E’and Eoterms. The Nernst
equationforthesensorbecomestheequationnotedbelow:
E = E’+2.3RT/nF log [CO2]= Eo+0.059 log [H+]
E = observed potential
E’= Reference and fixed internal voltages
R = gas constant (8.314 J/K Mol)
n= Charge on ion (equivalents/mol)
T = absolute temperature in K
F = Faraday constant (9.648 x 104 C/equivalent)
ThemV should increase in aNernstian manner as the
carbondioxidepartialpressure increases inthesample.

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Membrane/membrane cap
IV.IV.
IV.IV.
IV. Design ElementsDesign Elements
Design ElementsDesign Elements
Design Elements
The HannaHI4105CarbonDioxidegassensorhas3main
parts.These arethemembrane/membranecap,outer probe
bodywithantirotationkeyandthepH/referenceassembly
which includes the outer electrode cap, spring, inner cap
andpH/referenceelectrodeassembly.
Outerprobebody
antirotationkey innercap
pH/referenceelectrodeassembly
spring
outerelectrode
cap
pH
sensitive
membrane
Reference
electrode
cable
O-ring

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V.V.
V.V.
V. Equipment Required:Equipment Required:
Equipment Required:Equipment Required:
Equipment Required:
•Hanna HI 4222 pH/ISE/mV meter or other suitable
ionorpH/mVmeter.(Note:log/lineargraphpaperis
useful if an ISE meter is not available).
•Hanna HI 180 magnetic stirrer or equivalent with
stirringbars.(Note:Isolatebeakersfromstirrermotor
heat by placing insulating material such as foam or
corkbetweenthem).
•HannaHI4000-71gassensortestvessel or
HannaHI76404electrodeholderorequivalentwith
Beakers or other suitable measurement vessel with
plasticsealing film orwrap.
VI.VI.
VI.VI.
VI. Solutions Required for Calibration:Solutions Required for Calibration:
Solutions Required for Calibration:Solutions Required for Calibration:
Solutions Required for Calibration:
IonicStrengthAdjuster(ISA),500mL: HI4005-00
Hanna0.1M standard, 500mL: HI4005-01
Hanna 1000 ppm CO2standard, 500 mL: HI4005-03*
*PleaseNote: ThiscalibrationstandardsisppmasCaCO3
See Section XVII for additional solutions and accessories
used for maintenance.
Using volumetric pipettes and glassware prepare serial
dilutions of the standard. Select concentrations that will
approximatelybrackettheconcentrationofthesamplesto
bemeasured. Standardswith concentrations lessthan
10-3M shouldbepreparedfreshdaily. Storesolutionina
tightlysealed bottlewithoutISAadded.10mLofHI4005-
00ISA should be added toeach 100 mL sample ofstan-
dardandsamplesjustpriortomeasurement. ISAadjusts
the pH of the sample or standard to about pH 4.7 thus
convertingcarbonateand bicarbonate ion to carbondiox-
ide. It also provides samples and standards a constant
ionicstrengthbackgroundthatstabilizesthesolutionsac-
tivitycoefficientandpermitsconcentrationtobemeasured
directly.

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VIIVII
VIIVII
VII. General GuidelinesGeneral Guidelines
General GuidelinesGeneral Guidelines
General Guidelines
•Calibration standards and sample solutions should
havethesameionicstrength.ISAshouldbeaddedto
bothsamplesandstandardsimmediatelybeforetak-
ing measurements.
• Calibrationstandardsandsamplesolutionsshouldbe
stirredatthesamerateusingidenticalsizedstirbars.
Stir thoroughly and continuously.
• Calibrationstandardsandsamplesolutionsshouldbe
atthesametemperature.Thermallyinsulatesolution
vesselfrommagneticstirrerwithcorkorotherinsulat-
ing medium.
•Wait until sensor value has stabilized before taking
reading (at least 5 minutes when going from more
dilutetomoreconcentratedsamples,longerwhenthe
orderisreversed).
•SurfacecoatingonthePTFEmembranewilleffectthe
response. Inspectsensorbeforeusing.Washoffwitha
jet of deionized water or mild detergent to remove
film.
•Replace PTFE membrane if damage is evident or a
dropletofinternalelectrolyteisseen.
•Rinse electrode with distilled or deionized water be-
tweensamplesanddabdrywithlabwipeorothersoft
disposable absorbent toweling.
•Checkcalibrationevery1-2hours.Recalibrateifnec-
essary.
•Position sensorsatanangleofapproximately20°to
30°fromverticletoreducepossibilityoftrappinggas
bubbleson on the membranecap. Gas bubbles also
form from solution out-gassing due to temperature
change. Gentlytapbodyofsensortodislodgethem.
•ClosecontainerwithplasticwraporuseHI4000-71
gassensortestvesseltopreventgasfromleaving.
•Ifelectrodewasleftoutinairforaprolongedperiod,
gently pulling cable will permit an exchange of fill
solution at the membrane surface. Re-Calibration is
required.

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VIII.VIII.
VIII.VIII.
VIII. Inner Electrode CheckInner Electrode Check
Inner Electrode CheckInner Electrode Check
Inner Electrode Check
Prior to assembling the electrode for the first timefirst time
first timefirst time
first time or
subsquently reactivating it after extended periods of dry
storage, the inner electrode assembly should be hydrated
andthentestedasapHelectrode.
PreparepHtestsolutions HI4000-47-4andHI4000-47-
7bymixinganddissolvingeachbufferpacketinseparate
containerswith50mLdeionizedwater.ThesepHsolutions
containchlorideionsandpHbuffersthatareusedtoverify
the inner electrode (pH internal) is operational. See
SectionXVIIforreplacementaccessoriesandmaintenance
items.
Foranewsensor:
Remove the protective shipping cap from the glass inner
electrode.
Forexistingsensor:
Unscrew the upper cap on the top of the electrode and
carefullywithdrawtheinternalpH/referenceassembly.
Usetest
tubeor
graduated
cylinder
(weighed
Bottom)when
testingor
conditioning
pHinternal
Testbuffer
canbe
usedasa
conditioning
solution
forthe
pHinternal
Protectiveshippingcap
Forstablereadings,glassshouldbecoveredto the
bottomofthelongblack band.

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•Ifsensorhasbeenstoredorshippeddry,itshouldbe
“conditioned”by soaking the pH/reference assem-
bly1hourormoreinoneofthepHtestsolutions.
•Avoidtouching thepHglasswithyourfingers.
•Attention:ThepH/referenceassemblyisfragile!
Support the upper portion of the internal cell while
immersing the glass and reference assembly. A tall
narrowcontainerwithweighted bottom is best.The
pHtestsolutionshouldcoverthebottomofthelarge
black band.
Test:ConnecttheBNCconnectorontheelectrodecable toa
pH/mV(mVorORPmode)meter.Carefullyimmerse
thesensorassemblyintooneofthebuffers.Whenthe
measurmentstabilizesrecordthemVgenerated.Rinse
sensor tip in deionized water and dab dry between
bufferstopreventsolutioncarry-over.Donotrubthe
glass.Takeameasurementinthesecondbufferand
recordmV. Payattentiontominussignifpresent.
CalculatethedifferenceinmVbetweenthetwosolutions.
Example of typical values:
HI4000-47-7 -90.2mV
HI4000-47-4 80.66mV
Difference 170.8mV=80.6-(-90.2)
A calculated value equal or greater than 160 mV is ac-
ceptableforambienttemperaturesbetween20°and25°C.

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3.) Using dropper provided, add about 2 mL of carbon
dioxide internal fill solution HI 4005-40 into outer
probebody.
IX.IX.
IX.IX.
IX. Electrode PreparationElectrode Preparation
Electrode PreparationElectrode Preparation
Electrode Preparation
1) Removeglassinternalfromsensorbodyandperform
innerelectrodecheck.(SeesectionVIII).
2) TheHI4105sensorcomeswiththreeeasilyreplace-
ablemembranecaps(twowhicharespares).Remove
a cap from membrane box and screw on to lower
threadsofouterprobebody,compressingtheo-ring
seal. Avoidtouchingworkingareaofmembranewith
your fingers as skin oil will change the membrane
properties.

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4) Insertand positionthe inner glass/reference assem-
bly into the outer body so that the anti-rotation key
sitsinthecutoutontheouterprobebody.
5) Holdingtheelectrodeupright,slide spring andelec-
trode cap down cable and screw cap on outer body
until fully engaged. Do not invert electrode. Do not
overtighten.
6) Install assembledelectrodeingassensortestvessel
orinelectrodeholderandconnectcableconnectorto
pH/mVmeter.
CARBONDIOXIDE
HI 4105
CARBONDIOXIDE
HI 4105

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X.X.
X.X.
X. Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode Slope
•ConnectBNC(connector)topH/mV/ISEmeter.
•PlacemeterinmVmode.
• Place 100 mL of deionized water into a vessel with
stirbar.Add10mLofISAHannaHI4005-00.
•Placesensor intopreparedsample.
•Add 1 mL of 1000 ppm or 0.1 M Carbon dioxide
standard to beaker and stir sample. Wait approxi-
mately5minutes. RecordthemVvaluewhenstable.
•Addanadditional10mLofstandardtothesolution.
RecordthemVwhenreadinghasstabilized(approxi-
mately 5 minutes). This value should be greater
thanthepreviousnoted(morepositive).
•DeterminethedifferencebetweenthetwomVvalues.
An acceptable value for this slope is 54±4 mV at
ambienttemperaturesbetween20and25°C.
XI.XI.
XI.XI.
XI. Corrective actionCorrective action
Corrective actionCorrective action
Corrective action
•Verify standard has been properly added.
•VerifyISA has been addedin the correct ratio to the
standard(1partISAto10partssampleorstandard).
•Verifythattheuppercaphasbeenscrewedinallthe
way.
•Verifyelectrodeisconnectedproperlytometerandthe
meterisispowered.
•Verify membrane cap is tightened securely to probe
body.
•Examinethe membrane for discoloration or perfora-
tions or for internal fill solution that might have
leaked through the PTFE membrane. Replace mem-
brane cap if damaged.
Ifdriftisseen:
•Verifyelectrodeandstandardsareatsametempera-
ture.
•Verifyelectrodehasadaquatefillsolution.
•Verifyelectrode was not left in air for prolonged pe-
riod.

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XII.XII.
XII.XII.
XII. Sample HandlingSample Handling
Sample HandlingSample Handling
Sample Handling
•For optimum results, allow samples and standards
and the HI 4105 electrode to reach the same tem-
perature.
•AsCO2isvolatile,measuresamples immediately af-
tercollection.
•If sample must be stored: Completely fill collection
bottlewith dilutesamples and tightlycap container
topreventcarbondioxidelossorcontaminationfrom
othersources.
•If sample must be stored: For acetic samples. add
sodiumhydroxide(10N) toraisepHto8-9 forstor-
age.Tightlyclosecollectionbottle.
•If sample must be stored: keep sample at a lower
temperature than it was collected at until time of
measurement.
•Add Hanna HI 4005-00 ISA just prior to measure-
ment to adjust standards and samples to a pH
between 4.2-5.2 for measurement. ISA must mix
thoroughlywithsolutionsandtimeallowedtoconvert
carbonateandbicarbonatespeciestoCO2(dissolved).
•CoveringsampleandstandardsafteraddingISA will
minimizecarbondioxidelossfromthesolution.
•Calibrationstandardsandsamplesmustbethesame
ionicstrength.Theconcentrationforalldissolvedspe-
ciesinasampleshouldnotexceed1M.Samples that
exceed this should bedilutedwithCO2free deion-
izedwater.DonotreduceCO2below10-4M.Multiply
thefinal resultbythecorrespondingdilutionfactor.

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XIII.XIII.
XIII.XIII.
XIII. Direct Calibration and MeasurementDirect Calibration and Measurement
Direct Calibration and MeasurementDirect Calibration and Measurement
Direct Calibration and Measurement
Thedirectmeasurementmethodisbestusedinthe linear
workingregionsofthesensor.(Seefigurefortypicalsensor
response)andcanbeusedwhenmeasuringmanysamples.
AdirectreadingISEmeter(HI4222orequivalent)deter-
mines concentration of the unknown by a direct reading
aftercalibratingthemeterwiththestandards.Themeteris
calibrated with two or more freshly made standards that
areinthemeasurementrangeoftheunknowns.HI4005-
00ISAisaddedpriorto measurementandthesolution is
stirredthoroughlyandcontinuously.Coveringthevesselto
preventgaslossisadvised.
A pH/mV meter in mV mode and semi-log graph paper
mayalso be used. Twoor freshly preparedstandards that
areinthe measurementrangeoftheunknowns (withISA
added), are measured in mV mode on the meter. These
standards are plotted on semilog graph paper and their
points are connected to form a straight-line curve. When
samples are measured, their mV values are converted to
concentrationbyfollowingthemVtotheconcentrationaxis
onthesemi-logplot.
For both direct reading and mV convertion, ISA is added
priortomeasurement,the solution stirred thoroughly and
continuously and the vessel should be covered to prevent
gasloss.
Inthelowerconcentrationrangestheelectrodecalibration
becomes less linear, many more calibration points are
needed, and calibration will need to be repeated more
frequently. Known addition method may also be used in
these regions provided the actual slope of the sensor has
been determined.
DirectMeasurementProcedure
1. FollowsectionIXtopreparesensor.
2. FollowsectionVItopreparestandardsandsolutions.
•Standardsshouldbracketthemeasurementrangeof
interestanddifferfromeachotherbyafactorof10in
thelinearregions.

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TypicalcalibrationcurveforHI4105CarbonDioxideISE
•Standardsandsolutionsshouldbeatthesametem-
perature. 10 mL of ISA is added to each 100 mL of
sample and standard.
•Protect these solutions from loss of dissolved gas by
covering and using promptly.
3. FollowsectionVII;GeneralGuidelinestooptimizetest
set-up.
4. Duringcalibrationitisbesttostartwithlowerconcen-
trationsamplesfirst. Waitforastablereadingbefore
reading/recordingvalues(approximately5minutes).
5. Topreventcarryoverandcontaminationofsamples,
rinse sensors with deionized water and dab dry be-
tweensamples.
6. Betweenmeasurementssuspendsensortip inasmall
sample of CO2Conditioning solution; HI 4005-45.
Rinsebodywithdeionizedwateranddabdrybefore
placing in next sample.
7. CheckHI4105electrodecalibrationevery2hoursby
verificationofatleastonecalibrationpoint.
Typical response for HI 4105 Carbon Dioxide senso
r
-170
-150
-130
-110
-90
-70
-50
1.5 2 2.5 3 3.5 4 4.5
-log[M]
mV

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XIVXIV
XIVXIV
XIV..
..
. Other Measurement TOther Measurement T
Other Measurement TOther Measurement T
Other Measurement Techniquesechniques
echniquesechniques
echniques
Known Addition
Anunknownconcentrationofcarbondioxidecanbedeter-
mined by adding a known amount (volume and concen-
tration)of carbondioxidestandardtoaknownvolumeof
the sample. This technique is extremely useful for carbon
dioxidebecausechangesinthesensorcalibrationarecor-
rectedfor continuouslybecause,thestandard andsample
are measured within minutes of one another. The tech-
nique can use an ideal sensor slope, but actual slopes at
the temperature of measurement should be determined
andused if possible.This will improve accuracy.
1. Thevolumeoftheunknownsample(VSample )ismea-
sured accurately and placed into the closed sample
vessel.Thesensorissecuredinthevesselandthenthe
vesselisplacedonastirrer.
2. ISAisaddedat1partper10partssample.
3. When the measurement is stable the mV value is
noted.
4. A knownamount, volume(VStandard )andconcentration
(CStandard), ofCO2standardisthenaddedtothesample.
mVvaluesareagainnotedwhenthemeasurementis
stable.
5. ThemVchange is then calculated (∆E).
6. Usingthe measured and calculated values,the
sampleconcentration(CSample)canbedetermined.
Csample =(VT)10∆E/S - (VS’)
CstandardVstandard Vsample VS’
(Vsample+Vstandard+VISA)= VT
(Vsample+VISA)= VS’

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7. Theprocedurecanberepeatedwithasecondstandard
additiontoverifyslopeandoperationofthemethod.
Note:
This method is preprogrammed in the Hanna HI
4222pH/ISE/mVmeter,whichsimplifiesthemethod
greatly and permits repeated determinations easily.
Example:
Carbon Dioxide determination with known addition:
1. A50mLsampleofunknown(VSAMPLE)isplacedinan
cleanvesselwithanelectrode. 5mLofISAisadded
tothesample.Thesampleiscoveredandpermitted
to mix throughly and continueously. The mV is then
recordedwhenthesensorhasstabilized.
2. 5mL(VSTANDARD)of 0.1M(CSTANDARD)standardisthen
addedtothevesselandispermitted tomix.ThemV
valueincreasesastheconcentrationincreases.(Note:
forotherconcentrationsamples,addaknownvolume
and concentration of standard to produce a 30 mV
changeorgreater.
3. The unknown carbon dioxide concentration in the
original sample (CSAMPLE) can then be determined by
using the equation provided.
.

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XV.XV.
XV.XV.
XV. Storage and Care of the HI 4105 sensorStorage and Care of the HI 4105 sensor
Storage and Care of the HI 4105 sensorStorage and Care of the HI 4105 sensor
Storage and Care of the HI 4105 sensor
TheHI4105sensorcanbestoredassembledandreadyto
use in HI 4005-45 Conditioning solution overnight or
betweenmeasurements.Afterovernightstorage,gentlypull
on the cable to compress the spring mechanism thus
permittingelectrolytetoexchangefromthebulktothethin
film between the membrane and glass. Calibration is
requiredafterdoingthis.
For longer term storage (over a week), disassemble the
sensor completely and rinse off the internal pH/reference
assembly, the outer body and the membrane cap. It is
advised the membrane cap be discarded to prevent pos-
sible problems associated with reuse. Cover the glass tip
withtheprotectiveshippingcapandstorepartssecurelyin
theoriginalshipping box. When reassembling thesensor
followsectionIX.
XVI.XVI.
XVI.XVI.
XVI. Conversion TConversion T
Conversion TConversion T
Conversion Tablesables
ablesables
ables
For COFor CO
For COFor CO
For CO22
22
2MultiplybyMultiplyby
MultiplybyMultiplyby
Multiplyby
Moles/L(M)CO2toppmCO2(mg/L) 4.4X104
ppmCO2 (mg/L)toM(Moles/L) 2.273X10-3
For CaCOFor CaCO
For CaCOFor CaCO
For CaCO33
33
3 (ppm)(ppm)
(ppm)(ppm)
(ppm) MultiplybyMultiplyby
MultiplybyMultiplyby
Multiplyby
Moles/L(M)CO2toppmCaCO3(mg/L) 1.00X105

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XVII.XVII.
XVII.XVII.
XVII. HI 4105 AHI 4105 A
HI 4105 AHI 4105 A
HI 4105 Accessories and Replacement Pccessories and Replacement P
ccessories and Replacement Pccessories and Replacement P
ccessories and Replacement Partsarts
artsarts
arts
For CalibrationFor Calibration
For CalibrationFor Calibration
For Calibration :::::
CodeCode
CodeCode
Code
HI4005-00 IonicStrengthAdjuster(500mL)
HI4005-01 Hanna 0.1 M CO2 Standard
(500mL)
HI4005-03* Hanna 1000 ppm CO2Standard
(500mL)
*Please Note: This calibration standard is ppm as CaCO3
For Maintenance:For Maintenance:
For Maintenance:For Maintenance:
For Maintenance:
HI4005-40 Hanna Carbon Dioxide Fill Solution
(4X30mL)
HI4005-45 Hanna Carbon Dioxide Conditioning
Solution(500 mL)
HI4000-47 Bulkpackageof10each
HI4000-47-4andHI4000-47-7
BufferPackets
HI4005-53 Replacement Membranes Caps
(3MembraneCaps)
HI4000-54 ReplacementpH/referenceElectrode
AssemblyforCO2
HI4000-71 Gas Sensortestvessel
HI740155P Capillary Pipettes(20piece)

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MAN4105 07/06REV1
WARRANTYWARRANTY
WARRANTYWARRANTY
WARRANTY
HannaInstrumentsIonSelectiveElectrodesarewarrantedto
befreeofdefectsinmaterialandworkmanshipfor6months
from date of purchase when used for their intended purpose
andmaintainedaccordingtoinstructions.Iftheyfailtowork
whenfirstusedcontactyourdealerimmediately.Damagedue
to accidents, misuse, misapplication, tampering or lack of
prescribedmaintenanceisnotcovered.
Hanna Instruments reserves the right to modify the design,
construction or appearance of its products without advance
notice.