Hanna Instruments HI 4101 User manual

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HI 4101HI 4101
HI 4101HI 4101
HI 4101
Ammonia
Ion
Selective Electrode
Instruction Manual
AMMONIA
HI 4101

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HI 4101 Ammonia ElectrodeHI 4101 Ammonia Electrode
HI 4101 Ammonia ElectrodeHI 4101 Ammonia Electrode
HI 4101 Ammonia Electrode
I.I.
I.I.
I. Introduction:Introduction:
Introduction:Introduction:
Introduction:
TheHannaHI4101Ammonia gasselectiveelectrodeisa
combination electrode designed for the measurement of
ammoniainaqueoussolutionssuchaswastewatersamples,
wine,beer. Ammoniumionsarealsomeasuredbyconver-
sion to ammonia gas upon ISA addition.
II.II.
II.II.
II. SpecificationsSpecifications
SpecificationsSpecifications
Specifications
Type: NH3gas sensing
electrodewithglasspH
internal, Ag/ AgCl
referenceand gas
permeable PTFE
membrane.
SpeciesMeasured: NH4+, NH3
Measurement Range: 1.0Mto1x10-6M
17000to0.02ppm
Interferingions: Surfactants,wetting
agents, volatile amines.
Operating Temperature: 0to40°C
Operating pH: >11pH
Dimensions: 12mm(OD)X120
mm (insertion)
0.47”x4.72”
Wettedmaterials: Delrin®, body and cap
PTFE gas 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:::::
The ammonia electrode is a complete potentiometric cell
thatcontainsboth asilver/silver chloride(Ag/AgCl)refer-
enceandapHmeasurementelement. Theseelementsare
housedwithinathermoplasticbodyinachlorideion-con-
tainingelectrolyte,andareisolatedfromthesample bya
gaspermeablemembranemadeofpolytetrafluoroethylene
(PTFE).
Dissolvedgasinthesamplesolutiondiffusesintothemem-
braneandchangesthepHinthethinfilmofelectrolyteon
the surface of the pH glass. Diffusion continues until the
partialpressuresofthegasinthesampleandthinfilmare
equal.The changeinpHis proportionalto theconcentra-
tionofdissolved gasinthesample solution.
TheNernstexpressionforanammoniasensorisexpressed
intheequationbelow.Notethatthepotentialisafunction
oftheammoniagas,whichinturnisrelatedtothehydroxyl
ion concentration. The glass internal, Ag/AgCl reference,
and Henry’s law constant are rolled into the E’and Eo
constants.TheNernstequationforthesensorbecomesthe
equationnotedbelow:
E=E’–2.3RT/nFlog[A]=Eo–0.059log[OH-]
E=observedpotential
E’=Reference andfixedinternal voltages
R=gasconstant(8.314J/KMol)
n=Chargeon ion(equivalents/mol)
A ion=ion activityin sample
T=absolutetemperaturein K
F=Faradayconstant(9.648x104C/equivalent)
ThemV shoulddecrease ina Nernstianmanner asthe
ammonia partial pressure increases in the sample.

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IV.IV.
IV.IV.
IV. Design ElementsDesign Elements
Design ElementsDesign Elements
Design Elements
The Hanna HI 4101 ammonia gas sensor has 3 main
parts.Thesearethemembrane/membranecap,outerprobe
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
membrane/membrane cap

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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
plasticsealingfilm 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): HI4001-00
Hanna 0.1 M standard: HI4001-01
Hanna 100 ppm N standard: HI4001-02*
Hanna 1000 ppm N standard: HI4001-03*
*Please Note: These calibration standards are ppm as
NH3-N.
SeeSectionXVIIfor additionalsolutionsusedformainte-
nance.
Usingvolumetricpipettesandglasswaremakedilutionsof
the standard to bracket the concentration of the samples.
Standardswithconcentrationsless than10-3M should be
prepared fresh daily. Store solution in a tightly sealed
bottlewithoutISAadded.2mLofHI4001-00ISAshould
beaddedtoeach100mLsampleofstandardandsamples
justpriortomeasurement. ISAadjuststhepHofthesample
orstandardtoaboutpH11thusconvertingammoniumion
to ammonia. It also provides samples and standards a
constantionicstrengthbackgroundthatstabilizesthesolu-
tions activity coefficient and permits concentration to be
measureddirectly.TheISAprovidescolorindicationto verify
ithasbeenaddedtothesolutionandacomplexingagent
toremove metalions(i.ecopper,zinc)fromsolution.These

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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
atthesametemperature.Thermallyinsulatesolution
vesselfrommagneticstirrerwithcorkorotherinsulat-
ing medium.
•Calibration standards and sample solutions should
be stirred at the same rate using identical sized stir
bars.
•Surfacecoatingor“wetting“thePTFEmembranewill
effecttheresponse. Inspectsensorbeforeusing.Re-
place PTFE membrane if damage is evident.
•Rinse electrode with distilled or deionized water be-
tweensamplesanddabdrywithlabwipeorothersoft
disposable absorbent toweling.
•Checkcalibrationevery1-2hours.
•Position sensorsatanangleofapproximately20°to
lessen bubble adherence from solution out-gassing
dueto temperaturechange.
•Closecontainerwithplasticwraporuse
HI4000-71gassensortestvesseltopreventgas
fromleaving.
•Gently pulling cable will permit an exchange of fill
solution at membrane surface. Re-Calibration is re-
quired.
ionsarecapableofreducingthe ammoniaconcentration.
Ifothervolumesofsample/standardareused,addISAat2
partsper100 partsstandard/sample.

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VIII.VIII.
VIII.VIII.
VIII. Inner Electrode CheckInner Electrode Check
Inner Electrode CheckInner Electrode Check
Inner Electrode Check
Before assembling the electrode for the first timefirst time
first timefirst time
first time or if
reactivating it after storage, the inner electrode assembly
shouldbeconditioned andthentestedas apHelectrode.
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
Forstable readings,glassshould becovered tothe
bottomof thelongblack band.

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•Ifsensorhasbeenstoredorshippeddry,itshouldbe
“conditioned”by soaking the pH/reference assem-
bly1hourormoreinoneofthepHtestsolutions.
•AvoidtouchingthepHglasswithyourfingers.
•Attention:ThepH/referenceassemblyisfragile!
Support the upper portion of the internal cell while
immersing the glass and reference assembly. A tall
narrowcontainer withweightedbottom isbest.The
pHtestsolutionshouldcoverthebottomofthelarge
black ban.
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.
1) Removeglassinternalfromsensorbodyandperform
innerelectrodecheck.(SeesectionVIII).
2) Installmembraneontheouterprobebody.Usetwee-
zers provided and avoid touching working area of
membranewith yourfingers asskin oilwill change
thehydrophobicproperties.Discardthepaperback-
ing (blue) found between white PTFE membranes.
Hold membrane at corner with tweezers and drape
overloweropeningofouterprobebody.
IX.IX.
IX.IX.
IX. Electrode PreparationElectrode Preparation
Electrode PreparationElectrode Preparation
Electrode Preparation

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3) Holdonecorneragainstthethreadswiththumbwhile
gently stretching membrane over opening and cap-
turing opposite membrane corner against threads .
Smoothexcessmembranematerialaroundthethreads.
4) Screwoutermembranecapontobody
thus capturing the membrane between the cap and
outerbodythreads.