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.

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6) Insertand positionthe innerglass/reference assem-
bly into the outer body so that the anti-rotation key
sitsinthecutoutontheouterprobebody.
7) Holdingthe electrodeupright,slidespringand elec-
trode cap down cable and screw cap on outer body
until fully engaged. Do not invert electrode. Do not
overtighten.
8) Install assembledelectrodeingassensortestvessel
orinelectrodeholderandconnectcableconnectorto
pH/mVmeter.
5.) Using dropper provided, add about 2 mL of ammo-
niainternalelectrolyte HI4001-40 intoouterprobe
body.
AMMONIA
HI 4101
AMMONIA
HI 4101

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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.Add2mLofISAHannaHI4001-00.
•Placesensorinto preparedsample.
•Add1mLof1000ppmor0.1MAmmoniastandard
tobeaker.RecordthemVvaluewhenstable.
•Addanadditional10mLofstandardtothesolution.
Record the mV when reading has stabilized. This
value should be less than the previous noted (more
negative).
•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
•Verifythattheuppercaphasbeenscrewedinallthe
way.
•Verifyelectrodeisconnectedproperlytometerandthe
meterisispowered.
•VerifyISAhas beenadded inthe correctratio tothe
standard.
•Examinethewhitemembrane andcheckforelectro-
lyte that might have leaked through the PTFE film.
Replace membrane if damaged.
•If sensor does not change mV verify the the glass
assemblyisoperational(SeesectionVIII).

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XII.XII.
XII.XII.
XII. Sample HandlingSample Handling
Sample HandlingSample Handling
Sample Handling
•Keepsamplesstoredintightlycoveredbottlestopre-
ventammonialossorammoniacontaminationfrom
othersources.
•Alkalinesamplesmustbemeasuredatonceoracidi-
fiedforstorage.(HClmaybeaddedtobringpHto6).
•Acidic samples such as wine or juice may require
additionISA. Samples shouldbe approximatelypH
11formeasurement.
•Measure sample and standards quickly after adding
ISAbecauseammoniagaswillescapefromthesolu-
tion.
•For solutions containing organically bound nitrogen
such as oil, sludge, waste, or samples which may
containsurfactants;digest samplefirstusingatotal
Kjeldahl nitrogen (TKN) procedure. This involves
oxidationwithhotsulfuricacidwhich convertsbound
nitrogentoammoniumions. ConsultMethod4500-
Norg from Standard Methods for the Examination of
WaterandWastewater.
•For samples found to penetrate or “wet”the mem-
brane,measurementsmaybemadeabovethesample
in a small headspace of a sealed system such as HI
4000-71 test vessel, provided the concentration of
NH3isgreaterthan10-3.M.Theheadspaceshouldbe
saturatedwithwatervaporandthemembraneendof
theelectrodesuspendedinthegassampleabovethe
sample with ISA added. Expect a longer response
timefromthesensorwhengasphasemeasurements
are made.

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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
The direct method can be used in the linear working re-
gionsofthesensor.(Seefigurefortypicalsensorresponse).
AdirectreadingISEmeter(HI4222orequivalent)deter-
mines concentration of the unknown by a direct reading
aftercalibratingthemeterwiththestandards.Themeteris
calibrated with two or more freshly made standards that
areinthemeasurementrangeoftheunknowns.HI4001-
00ISAisaddedjustbeforemeasurementofthe standard
or sample. Covering the vessel to prevent gas loss is ad-
vised.
A pH/mV meter in mV mode and semi-log graph paper
mayalsobeused.Two orfreshly preparedstandards that
areinthemeasurement rangeoftheunknowns (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.
Method4500-NH3D. from Standard Methods for the Ex-
amination of Water and Wastewater is a direct measure-
mentmethodforwatersamples.
For both direct reading and mV convertion, ISA is added
priortomeasurementandthevesselshouldbecoveredto
preventgasloss.
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.

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TypicalcalibrationcurveforHI4101AmmoniaISE
•Standardsshouldbracketthemeasurementrangeof
interestanddifferfromeachotherbyafactorof10in
thelinearregions.
•Standardsandsolutionsshouldbeatthesametem-
perature. 2 mL of ISA is added to each 100 mL of
sampleandstandard.Acolorchangeshouldoccurto
indicate the ISA has been added.
•Protect these solutions from loss of dissolved gas by
covering and using promptly.
3) FollowsectionVII;GeneralGuidelinestooptimizetest
set-up.
4) Duringcalibrationitisbesttostartwithlowerconcen-
trationsamplesfirst. Waitforastablereadingbefore
reading/recording values.
5) Topreventcarryoverandcontaminationofsamples,
rinse sensors with deionized water and blot dry be-
tweensamples.
6) Betweenmeasurementssuspendsensortipinasmall
sampleof NH3Conditioningsolution;
HI4001-45. Rinse bodywith deionizedwater and
blotdry beforeplacing innext sample.
Typical Linearity for HI 4101 Electrode
-300
-250
-200
-150
-100
-50
0
50
0123456
-Log of [M]
m
V

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XIVXIV
XIVXIV
XIV..
..
. Other Measurement TOther Measurement T
Other Measurement TOther Measurement T
Other Measurement Techniquesechniques
echniquesechniques
echniques
Known addition
Anunknownconcentrationofammoniacanbedetermined
byaddingaknownamount(volumeandconcentration)of
ammoniastandardtoaknownvolumeofthesample.This
technique is extremely useful for ammonia as the sensor
may drift from calibrated values over time, however the
slopes remain constant. With known addition, the stan-
dard and sample are measured within minutes of one
another.Thetechniquecanuseanidealsensorslope,but
actual slopes at the temperature of measurement should
bedeterminedand usedif possible.This willimprove ac-
curacy. Known addition is Method 4500-NH3 E. from
StandardMethodsfortheExaminationofWaterandWaste-
water.
1) Thevolumeoftheunknownsample(VSample)ismea-
sured accurately and placed into the closed sample
vessel.Thesensorissecuredinthevesselandthenthe
vesselisplacedonastirrer.
2) ISAisaddedat1partper50partssample.
3) When the measurement is stable the mV value is
noted.
4) A knownamount, volume(VStandard )andconcentration
(CStandard), ofNH3standardisthenaddedtothesample.
mVvaluesareagainnotedwhenthemeasurementis
stable.
5) ThemVchange isthen calculated(∆E).
6) Using the measured and calculated values, the
sampleconcentration(CSample)can bedetermined.
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:
Ammonia determination with known addition:
1. A50mLsampleofunknown(VSAMPLE)isplacedinan
cleanvesselwithanelectrode. 1mLofISAisadded
to the sample and the color change is noted. The
sample is covered and permitted to mix. The mV is
thenrecordedwhenthesensorhasstabilized.
2. 5mL (VSTANDARD)of 0.1M(CSTANDARD)standardisthen
addedtothevesselandispermittedtomix.ThemV
valuedecreasesastheconcentrationincreases.(Note:
forotherconcentrationsamples,addaknownvolume
and concentration of standard to produce a 30 mV
changeorgreater.
3. Theunknownammoniaconcentrationintheoriginal
sample(CSAMPLE)canthenbedeterminedbyusingthe
equation provided.

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XV.XV.
XV.XV.
XV. Storage and Care of the HI 4101 sensorStorage and Care of the HI 4101 sensor
Storage and Care of the HI 4101 sensorStorage and Care of the HI 4101 sensor
Storage and Care of the HI 4101 sensor
TheHI4101sensorcanbestoredassembledandreadyto
use in HI 4001-45 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
requiredafter doingthis.
For longer term storage (over a week), disassemble the
sensor completely and rinse off the internal pH/reference
assembly,theouterbodyandthemembranecap.Discard
the white PTFE membrane. (Note: keep black membrane
cap). Cover the glass tip with the protective shipping cap
andstorepartssecurelyintheoriginalshippingbox. When
reassemblingthesensorfollowsectionIX.
XVI.XVI.
XVI.XVI.
XVI. Conversion TConversion T
Conversion TConversion T
Conversion Tablesables
ablesables
ables
For NHFor NH
For NHFor NH
For NH33
33
3MultiplybyMultiplyby
MultiplybyMultiplyby
Multiplyby
Moles/L(M)NH3toppmNH3(mg/L) 1.70X104
ppmNH3(mg/L)toM(Moles/L) 5.882X10-5
For N-NH3 (ppm as nitrogen)For N-NH3 (ppm as nitrogen)
For N-NH3 (ppm as nitrogen)For N-NH3 (ppm as nitrogen)
For N-NH3 (ppm as nitrogen) MultiplybyMultiplyby
MultiplybyMultiplyby
Multiplyby
Moles/L(M)NH3toppmN-NH3(mg/L) 1.40X104

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XVII.XVII.
XVII.XVII.
XVII. HI 4101 AHI 4101 A
HI 4101 AHI 4101 A
HI 4101 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
HI4001-00 IonicStrengthAdjuster(500mL)
HI4001-01 Hanna0.1 Mstandard (500mL)
HI4001-02* Hanna 100 ppm N standard
(500mL)
HI4001-03* Hanna 1000 ppm N standard
(500mL)
HI4001-30 Nitratetestkit(Bulkpkg)
*Please Note: These calibration standards are ppm as
NH3-N.
For Maintenance:For Maintenance:
For Maintenance:For Maintenance:
For Maintenance:
HI4001-40 Hanna Ammonia Fill solution
(4X30mL)
HI4001-45 Hanna Ammonia conditioning
solution(500mL)
HI4000-47 Bulkpackageof10each
HI4000-47-4andHI4000-47-7
bufferpackets
HI4000-52 Replacement membrane cap
HI4001-51 Replacement membranes kit
(20pieces)
HI4000-51 ReplacementpH/referenceelectrode
assembly
HI4000-71 Gas sensortest vessel
HI740155P CapillaryPipettes(20piece)
HI740159 Plastictweezers(1piece)

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MAN4101 07/06R4
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.