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FOrion 94-09, 96-09Orion ionplusFluoride Electrode

INSTRUCTION MANUAL

-

Analyze Detect Measure Control


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AQUAfast, Cahn, EZ Flash, Ionalyzer, ionplus, KNIpHE, No Cal, ORION, perpHect,PerpHecT, PerpHecTion, pHISA, pHix, pHuture, Pure Water, Sage, Sensing theFuture, SensorLink, ROSS Ultra, Sure-Flow, TEA Analyzer, Titrator PLUS, TURBO2and Wine Master are registered trademarks of Thermo Electron Corporation.

1-888-pHAX-ION, A+, All in One, Aplus, AQUAsnap, AssuredAccuracy,AUTO-BAR, AUTO-CAL, AUTO DISPENSER, Auto-ID, AUTO-LOG, AUTO-READ,AUTO-STIR, Auto-Test, BOD AutoEZ, Cable-Free, CERTI-CAL, CISA, DataCOLLECT,DataPLUS, digital LogR, DirectCal, DuraProbe, Environmental Product Authority,Extra Easy/Extra Value, FAST QC, Flash Titration, Flash Titrator, GAP, GLPcal,GLPcheck, GLPdoc, ISEasy, KAP, LabConnect, LogR, Low Maintenance Triode,Minimum Stir Requirement, MSR, NISS, One-Touch, One-Touch Calibration, One-

Touch Measurement, Optimum Results, Pentrode, pHuture MMS, pHuturePentrode, pHuture Quatrode, pHuture Triode, Quatrode, QuiKcheK, rf link,ROSS, ROSS Resolution, SAOB, Smart CheK, Stacked, Stat Face, The EnhancedLab, ThermaSense, Triode, TRIUMpH, Unbreakable pH, Universal Access aretrademarks of Thermo.

Guaranteed Success and The Technical Edge are service marks of Thermo.

PerpHecT meters are protected by U.S. patent 6,168,707.

PerpHecT ROSS are protected by U.S. patent 6,168,707.

ORION Series A meters and 900A printer are protected by U.S. patents5,108,578, 5,198,093 and German patents D334,208 and D346,753.

Sure-Flow electrodes are protected by European Patent 278,979and Canadian Patent 1,286,720.

ionplus electrodes and Optimum Results solutions are protected byUS Patent 5,830,338.

ROSS Ultra electrodes have patents pending.

ORION ORP Standard is protected by US Patent 6,350,367.

ORION Series A conductivity meters are protected by US Patent 5,872,454.

Copyright 2003, Thermo Electron Corporation. All rights reserved. Questioneverything, and Analyze.Detect.Measure.Control are trademarks of ThermoElectron Corporation.

The specifications, descriptions, drawings, ordering information and partnumbers within this document are subject to change without notice.

This publication supersedes all previous publications on this subject.


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TABLE OF CONTENTS

General Information 1Introduction 1Required Equipment 2Required Solutions 3

Using The Electrode 5Electrode Preparation 5Filling Instructions 5Checking Electrode Operation (Slope) 6

Before Analysis 7Units of Measurement 7Sample Requirements 7

Measuring Hints 8Analytical Procedures 9Analytical Techniques 9

Direct Calibration 11Low-Level Measurement 14Known Addition 16Titrations 22

Fluoride in Acid Solutions 24Fluoride in Alkaline Solutions 25Electrode Storage 26

Troubleshooting 28Troubleshooting Checklist 28Troubleshooting Guide 30

Assistance 32Electrode Characteristics 33

Electrode Response 33Reproducibility 33Limits of Detection 34Temperature Effects 34Interferences 35pH Effects 35Complexation 37Electrode Life 37Theory of Operation 38

Warranty 41

Ordering Information 45Specifications 46


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1

GENERAL INFORMATION

Introduction

The Orion 94-09 Half-Cell Fluoride and Orion 96-09 CombinationFluoride Electrodes measure free fluoride ions in aqueoussolutions quickly, simply, accurately, and economically. General

analytical procedures, required solutions, electrodecharacteristics, and electrode theory are discussed in thismanual. Operator instructions for Orion meters are outlined inthe individual meter instruction manuals.

The measurement of fluoride in drinking water is an approved

ASTM method: Approval number ASTM D 1179.

Thermo Electron Corporation Technical Service Chemists can beconsulted for assistance and troubleshooting advice. Pleaserefer to TROUBLESHOOTINGfor information before contactingThermo.


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Required Equipment

MeterThe easiest instruments to use are direct concentration readoutspecific ion meters, such as Orions EA 940, 920A, 920Aplus,720A, 720Aplus, 710A, 710Aplus, 290A or 290Aplus. Ifunavailable, use a pH/mV meter with readability to 0.1 mV, suchas Orions 420A, 420Aplus, 520A, 520Aplus, 525A or 525Aplus.

Reference ElectrodeFor Orion 94-09: Use with Orion 90-01Single Junction Reference Electrode.

For Orion 96-09: None required.

Stirring AccessoriesMagnetic stirrer or stir bars are highly recommendedfor laboratory measurements.

Graph Paper4-cycle semilogarithmic paper for preparing calibrationcurves (for use with digital pH/mV laboratory meters).

Plastic Labware

Plastic beakers are highly recommended forfluoride measurements.

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Required Solutions

Distilled or Deionized WaterTo prepare all solutions and standards.

Standard SolutionsSelect the appropriate Thermo Electron Corporation standard(s)from the list below.

Standard Solutions Orion No.

0.1 M Sodium Fluoride Standard 940906100 ppm Fluoride Standard 940907

1 ppm Fluoride Standard with TISAB 040906



Electrode Filling SolutionsInner Chamber Filling Solution 900001(Orion 90-01 Single Junction Reference)

Optimum Results TM A 900061(Orion 96-09 Combination Electrode)

Total Ionic Strength Adjustor (TISAB)To provide constant background ionic strength, decomplexfluoride and adjust solution pH

TISAB II:(50 mL TISAB II to 940909each 50 mL sample or standard)

TISAB III:(5 mL TISAB III to 940911

each 50 mL sample or standard)

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USING THE ELECTRODE

Electrode Preparation

Orion 94-09 1. Remove the rubber cap covering the electrode tip.

Orion 90-01 1. Remove the rubber cap covering the electrode tip.

2. Fill reference electrode with Orion No. 900001.

Orion 96-09

1. Remove the rubber cap covering the electrode tip.2. Fill outer chamber with Orion No. 900061.

NOTE:The Optimum Result TM A filling solution(Orion No. 900061) supplied with Orion 96-09 electrodeis designed to minimize junction potentials and fluoride ion contamination of the sample, and can be used for all

fluoride measurements. Use of any other filling solutions will void the warranty on the electrode.

Filling InstructionsThe electrode is shipped without filling solution in the referencechamber. To fill from the flip-spout bottle:

1. Lift the spout to a vertical position.2. Insert the spout into the filling hole in the outer sleeve and

add a small amount of filling solution to the chamber. Tipthe electrode to moisten the 0-ring at the top and returnelectrode to a vertical position.

3. Holding the electrode by the barrel with one hand, use the

thumb to push down on the electrode cap, allowing a fewdrops of filling solution to drain to wet the inner cone.

4. Release sleeve. If sleeve does not return to its originalposition immediately, check to see if the 0-ring is moistenough and repeat steps 2-4 until the sleeve has returned tooriginal position. Add filling solution up to the filling hole.

NOTE: Add filling solution each day before using electrode. The filling solution level should be at least one inch above the level of sample in the beaker to ensure a proper flow rate. If the filling solution is less than one inch above the sample solution level, electrode potentials may be erratic. Do not seal the filling hole whenmaking measurements.

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Before Analysis

Units of MeasurementFluoride concentration can be measured in units of moles perliter, parts per million, or any convenient concentration unit(see Table 1 ).

Table 1Concentration Unit Conversion Factors

Moles/Liter ppm F-

10-1 1900

10-2 190

10-3 19

10-4 1.9

Sample RequirementsThe epoxy electrode body Orion 94-09 and Orion 96-09 areresistant to attack by inorganic solutions. The electrode may beused intermittently in solutions containing methanol benzene oracetone. Consult Thermos Technical Service Chemists forinformation on using the electrode in specific applications.

Samples and standards should be at the same temperature.Temperature must be less than 100 C.

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Measuring Hints Pipet 50 mL of TISAB II per 50 mL standard or sample,

or 10 mL of TISAB III per 90 mL standard or sample.

Stir all standards and samples at a uniform rate duringmeasurement. Magnetic stirrers may generate sufficient heatto change solution temperature. Place a piece of insulatingmaterial such as cork, cardboard, or styrofoam between thestirrer and beaker.

Verify calibration every two hours by placing electrodes in afresh aliquot of the first standard solution used forcalibration. If the value has changed, recalibrate.

Always use fresh standards for calibration.

Always rinse electrodes with deionized water betweenmeasurements (see Electrode Preparation ). Shake afterrinsing to prevent solution carry-over. Do not wipe or rub

the sensing element. Allow all standards and samples to come to the same

temperature for precise measurement.

After immersion in solution, check electrode for any airbubbles on element surface and remove by redippingelectrode into solution.

For high ionic strength samples, prepare standards withcomposition similar to that of sample.

Highly acidic or highly basic solutions should be adjusted topH 5-6 before addition of TISAB.

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Analytical Procedures

A variety of analytical techniques are available to the analyst.The following is a description of these techniques.

Direct CalibrationThis simple procedure is for measuring a large number ofsamples. Only one meter reading is required for each sample.Calibration is performed in a series of standards. Theconcentration of the samples is determined by comparison tothe standards. ISA is added to all solutions to ensure thatsamples and standards have similar ionic strength.

Incremental TechniquesThis is a useful method for measuring samples with nocalibration requirements. As in direct calibration, anyconvenient concentration unit can be used. The differentincremental techniques are described below. They can be used

to measure the total concentration of a specific ion in thepresence of a large (50-100 times) excess of complexing agent.

Known Addition is an alternate method useful for measuringdilute samples, checking the results of direct calibration(when no complexing agents are present), or measuring thetotal concentration of an ion in the presence of an excesscomplexing agent. The electrodes are immersed in thesample solution and an aliquot of a standard solutioncontaining the measured species is added to the samplesolution. The original sample concentration is determinedfrom the change in potential before and after the addition.

Known Subtraction is useful as a quick version of a titration,or for measuring species for which stable standards do notexist. It is necessary to know the stoichiometric ratiobetween standard and sample. For known subtraction, anelectrode sensing the sample species is used. Stablestandards of a species reacting completely with the sample ina reaction of known stoichiometry are necessary.

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Analate Addition is often used to measure soluble solidsamples, viscous samples, small or very concentratedsamples, or to diminish the effects of varying sampletemperatures. This method is not suitable for dilute or lowconcentration samples. Total concentration is measuredeven in the presence of complexing agents. The electrodesare immersed in a standard solution containing the ion to bemeasured, and an aliquot of the sample is added to thestandard. The original sample concentration is determinedfrom the change in potential before and after the addition.

Analate Subtraction is used in the measurement of ions forwhich no ion-selective electrode exists. The electrodes areimmersed in a reagent solution, which contains a speciesthat the electrode senses, and that reacts with the sample.It is useful when sample size is small, or samples for which astable standard is difficult to prepare, and for viscous or veryconcentrated samples. The method is not suited for verydilute samples. It is also necessary to know thestoichiometric ratio between standard and sample.

Specific instructions for known addition, known subtraction,analate addition, and analate subtraction can be found inThermo Meter Instruction Manual Orion 960.

TitrationsTitrations are quantitative analytical techniques for measuringthe concentration of a species by incremental additions of areagent (titrant) that reacts with the sample species. Sensingelectrodes can be used for determination of the titrationendpoint. Ion-selective electrodes are useful as endpointdetectors, because they are unaffected by sample color

or turbidity. Titrations are approximately 10 times moreprecise than direct calibration, but are more time-consuming.Orion 960 is an excellent source of automated titrationinstrument.

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Direct Calibration

Setup1. Remove the rubber cap covering the electrode(s) tip.

2. If using Orion 94-09 electrode with Orion 90-01 ReferenceElectrode, fill the reference electrode chamber withOrion No. 900001. If using Orion 96-09, fill the chamberof the electrode with Orion No. 900061.

3. Connect electrode(s) to meter.

4. Prepare two standards that bracket the expected samplerange and differ in concentration by a factor of ten.Standards can be prepared in any concentration unit to suitthe particular analysis requirement. All standards should beat the same temperature as the samples (for details ontemperature effects on electrode performance, refer toTemperature Effects ).

Using a meter with direct concentration readout capabilitySee individual meter instruction manuals for morespecific information.

1. Measure 50 mL of the more dilute standard and 50 mL ofTISAB II or 5 mL of TISAB III into a 150 mL beaker.Stir thoroughly.

2. Rinse electrode(s) with deionized water, blot dry and placeinto the beaker. Wait for a stable reading. Then calibrate themeter to display the value of the standard as described in theMeter Instruction Manual.

3. Measure 50 mL of the more concentrated standard and50 mL of TISAB II or 5 mL TISAB III into a 150 mL beaker.Stir thoroughly.

4. Rinse electrode(s) with distilled water, blot dry, and placeinto the beaker with the more concentrated standard. Waitfor a stable reading then adjust the meter to display the valueof the second standard as described in the MeterInstruction Manual.

5. Measure 50 mL of the sample and 50 mL of TISAB II or5 mL of TISAB III into a 150 mL beaker. Stir thoroughly.

6. Rinse electrode(s) with deionized water, blot dry andplace into sample. The concentration will be displayedon the meter.

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Figure 1Typical Calibration Curve

In the direct measurement procedure using a pH/mV meter, a calibration curve is constructed on semilogarithmic paper.Electrode potentials of standard solutions are measured and plotted on the linear axis against their concentrations on the log axis. In the linear regions of the curve, at least three standards are needed to determine a calibration curve. In the non-linear regions, more points must be taken. The direct measurement

procedures in this manual are given for concentrations in the region of linear electrode response. Low-level measurement procedures are given for measurements in the non-linear region.

12

10 - 5

0.1

180

160

140

120

100

8060

40

20

0

-20

-40

-60

1 10 100 1000

10 - 4

10 - 3

10 - 2

10 - 1

molarity

ppm fluoride as F -

10-fold change

electrodepotential(mV)

~ 56 mV


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Using a meter with millivolt readout only1. Adjust the meter to measure mV.

2. Measure 50 mL of the more dilute standard with 50 mL ofTISAB II or with 5 mL of TISAB III into a 150 mL beaker.Stir thoroughly.

3. Rinse electrode(s) with deionized water, blot dry and placeinto the beaker. When a stable reading is displayed, recordthe mV value and corresponding standard concentration,

4. Measure 50 mL of the more concentrated standard with50 mL of TISAB II or with 5 mL of TISAB III into a 150 mLbeaker. Stir thoroughly.

5. Rinse electrode(s) with deionized water, blot dry andplace into the second beaker. When a stable reading isdisplayed, record the mV value and correspondingstandard concentration.

6. Using a semilogarithmic graph paper, prepare a calibrationcurve by plotting the mV values on the linear axis, and thestandard concentration values on the logarithmic axis.See Figure 1.

7. Measure 50 mL of sample with 50 mL of TISAB II or with5 mL of TISAB III into a 150 mL beaker. Stir thoroughly.

8. Rinse electrodes with deionized water, blot dry, and placeinto the beaker. When a stable reading is displayed, recordthe mV value.

9. Using the calibration curve prepared from step 6, determinethe unknown concentration.

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Low-Level Measurement

These procedures are for low ionic strength solutions with afluoride concentration of less than 2x10-5M (or 0.38 ppm) andcontaining no fluoride complexing agents. For solutions low influoride but high in total ionic strength, perform the sameprocedure by preparing a calibrating solution with a compositionsimilar to the sample. Accurate measurement requires that thefollowing conditions be met:

Adequate time must be allowed for electrodestabilization. Longer response time will be needed atlow-level measurements.

Stir all standards and samples at a uniform rate.

Always use low level TISAB for standards and samples.

For meters with only a millivolt scale, without special low levelprocedures, or without blank correction, prepare a calibrationcurve as follows:

Setup1. Remove the plastic cap covering the electrode(s) tip.

2. If using Orion 94-09 Fluoride Half Cell, fill the Orion 90-01Single Junction Reference Electrode with Orion No. 900001.If using Orion 96-09 Fluoride Combination Electrode, fill theelectrode chamber with Orion No. 900061.

3. Connect the electrodes to the meter. Set the meterto read mV.

4. Prepare 100 mL of standard solution. Either dilute the100 ppm NaF (Orion No. 940907) to 10 ppm or dilute the0.1 M NaF (Orion No. 940906) to 10-3 M. Add 100mL oflow-level TISAB to 100 mL standard.

5. Prepare low-level TISAB. Use low-level TISAB for low-levelmeasurements only.

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Making Measurements1. Measure 50 mL deionized water and 50 mL low-level TISAB

into a 150 mL beaker.

2. Rinse the electrode(s) with deionized water and place intobeaker. Stir thoroughly.

3. Add increments of 19 ppm or 10-3 M, which has been dilutedwith low-level TISAB standard, to the beaker using stepsoutlined in Table 2 . Record stable millivolt reading after eachincrement. On semi logarithmic paper, plot the concentration(log axis) against the millivolt potential (linear axis). Preparea new calibration curve with fresh standards each day.

4. Measure 50 mL of sample diluted with 50 mL of low-levelTISAB from a beaker. Rinse the electrode(s) with distilledwater, blot dry, and place into sample.

5. Stir thoroughly. When a stable reading is displayed, record

the mV value.6. Determine the sample concentration corresponding to the

measured potential from the low-level calibration curve.

Table 2Calibration Curve For Low-Level MeasurementsAdditions of standard (with added TISAB) to 50 mL distilledwater and 50 mL low-level TISAB.

Pipet Added ConcentrationStep Size Volume ppm Molarity

1 1 mL 0.1 mL 0.01 1 x 1 0-6

2 1 mL 0 1 mL 0.02 2 x 1 0-6

3 1 mL 0.2 mL 0.04 4 x 10-1

4 1 mL 0.2 mL 0.06 6 x 10-6

5 1 mL 0.4 mL 0.10 1 x 10-5

6 2 mL 2.0 mL 0.29 2.9 x 10-5

7 2 mL 2.0 mL 0.48 4.8 x 10-5

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Known Addition

Known addition is a convenient technique for measuringsamples because no calibration curve is required. It can beused to verify the results of a direct calibration or to measurethe total concentration of an ion in the presence of a largeexcess of a complexing agent. The sample potential ismeasured before and after addition of a standard solution.Accurate measurement requires that the following conditionsbe met:

Concentration should approximately double as a result ofthe addition.

Sample concentration should be known to within a factorof three.

In general, either no complexing agent or a large excess ofthe complexing agent may be present.

The ratio of the uncomplexed ion to complexed ion must notbe changed by addition of the standard.

All samples and standards should be at thesame temperature.

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Setup1. Remove the plastic cap covering the electrode(s) tip.

2. If using Orion 94-09 Fluoride Half Cell, fill the Orion 90-01Single Junction Reference Electrode with Orion No. 900001.If using Orion 96-09 Fluoride Combination Electrode, fill theelectrode chamber with Orion No. 900061.

3. Connect the electrode(s) to the meter.

4. Prepare a standard solution, which upon addition to thesample will cause the concentration of the fluoride ion todouble. Refer to Table 3 as a guideline.

5. Determine the slope of the electrode(s) by performing theprocedure under Checking Electrode Operation (Slope).

6. Rinse electrode(s) between solutions with deionized water.

Table 3Guideline For Known Addition

Volume of Addition Concentration of Standard1 mL 100 x sample concentration

5 mL 20 x sample concentration

10 mL* 10 x sample concentration

*Most convenient volume to use

Using a meter with direct known addition readout capabilitySee individual meter instruction manuals for morespecific information.

1. Set up the meter to measure in the known addition mode.2. Measure 50 mL of the sample and 50 mL of TISAB II or

5 mL of TISAB III in a beaker. Rinse electrode(s) withdistilled water and place in sample solution. Stir thoroughly.

3. When a stable reading is displayed, calibrate the meter asdescribed in the meter instruction manual.

4. Pipet the appropriate amount of the standard solution intothe beaker. Stir thoroughly.

5. When a stable reading is displayed, record thesample concentration.

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Using a meter with millivolt readout onlyUse this procedure when known addition is not available.

1. Set the meter to relative millivolt mode; if unavailable, usemillivolt mode.

2. Measure 50 mL of sample and 50 mL of TISAB, or 5 ml ofTISAB III into a 150 mL beaker. Stir thoroughly.

3. Rinse electrodes with distilled water, blot dry, and place intobeaker. When a stable reading is displayed, set the readingto 000.0 by turning the calibration control. If the readingcannot be set to 000.0, record the mV value.

4. Pipet the appropriate amount of standard solution into thebeaker. Stir thoroughly.

5. When a stable reading is displayed, record the mV value.If the meter could not be zeroed in step 3, subtract the firstreading from the second to find E.

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6. From Table 4 , find the value, Q, which corresponds to thechange in potential, E. To determine the original sampleconcentration, multiply Q by the concentration of theadded standard:Csam = QCstd

where:

Cstd = standard concentration

Csam = sample concentration

Q = reading from known addition table

The table of Q values is calculated for a 10% volume Change.The equation for the calculation of Q for different slopes andvolume changes is given below.

Q =p

[(1+p ) 10E/S]-1

where:

Q = reading from known addition table

E = E2 - E1

S = slope of the electrode

p =volume of standard

volume of sample

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Table 4Known Addition Values for Q vs.E at 25 C for 10% VolumeAddition. Slopes are in units of mV/decade.

E Q1 Concentration Ratio

Monovalent (57.2) (58.2) (59.2) (60.1)5.0 0.2894 0.2933 0.2972 0.30115.2 0.2806 0.2844 0.2883 0.29215.4 0.2722 0.2760 0.2798 0.28355.6 0.2642 0.2680 0.2717 0.2754

5.8 0.2567 0.2604 0.2640 0.26776.0 0.2495 0.2531 0.2567 0.26036.2 0.2426 0.2462 0.2498 0.25336.4 0.2361 0.2396 0.2431 0.24666.6 0.2298 0.2333 0.2368 0.24026.8 0.2239 0.2273 0.2307 0.2341

7.0 0.2181 0.2215 0.2249 0.22827.2 0.2127 0.2160 0.2193 0.22267.4 0.2074 0.2107 0.2140 0.21727.6 0.2024 0.2056 0.2088 0.21207.8 0.1975 0.2007 0.2039 0.2071

8.0 0.1929 0.1961 0.1992 0.20238.2 0.1884 0.1915 0.1946 0.19778.4 0.1841 0.1872 0.1902 0.19338.6 0.1800 0.1830 0.1860 0.18908.8 0.1760 0.1790 0.1820 0.1849

9.0 0.1722 0.1751 0.1780 0.18099.2 0.1685 0.1714 0.1742 0.17719.4 0.1649 0.1677 0.1706 0.17349.6 0.1614 0.1642 0.1671 0.16989.8 0.1581 0.1609 0.1636 0.1664

10.0 0.1548 0.1576 0.1603 0.163110.2 0.1517 0.1544 0.1571 0.159810.4 0.1487 0.1514 0.1540 0.156710.6 0.1458 0.1484 0.1510 0.153710.8 0.1429 0.1455 0.1481 0.1507

11.0 0.1402 0.1427 0.1453 0.147911.2 0.1375 0.1400 0.1426 0.145111.4 0.1349 0.1374 0.1399 0.142411.6 0.1324 0.1349 0.1373 0.139811.8 0.1299 0.1324 0.1348 0.1373

12.0 0.1276 0.1300 0.1324 0.134812.2 0.1375 0.1277 0.1301 0.132412.4 0.1230 0.1254 0.1278 0.130112.6 0.1208 0.1232 0.1255 0.127812.8 0.1187 0.1210 0.1233 0.1256

13.0 0.1167 0.1189 0.1212 0.123513.2 0.1146 0.1169 0.1192 0.121413.4 0.1127 0.1149 0.1172 0.119413.6 0.1108 0.1130 0.1152 0.117413.8 0.1089 0.1111 0.1133 0.1155

14.0 0.1071 0.1093 0.1114 0.113614.2 0.1053 0.1075 0.1096 0.111814.4 0.1036 0.1057 0.1079 0.110014.6 0.1019 0.1040 0.1061 0.108214.8 0.1003 0.1024 0.1045 0.1065

15.0 0.0987 0.1008 0.1028 0.104815.5 0.0949 0.0969 0.0989 0.100916.0 0.0913 0.0932 0.0951 0.097116.5 0.0878 0.0897 0.0916 0.093517.0 0.0846 0.0865 0.0883 0.0901

17.5 0.0815 0.0833 0.0852 0.0870

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E Q1 Concentration Ratio

Monovalent (57.2) (58.2) (59.2) (60.1)18.0 0.0786 0.0804 0.0822 0.083918.5 0.0759 0.0776 0.0793 0.081019.0 0.0733 0.0749 0.0766 0.078319.5 0.0708 0.0724 0.0740 0.0757

20.0 0.0684 0.0700 0.0716 0.073220.5 0.0661 0.0677 0.0693 0.070821.0 0.0640 0.0655 0.0670 0.068621.5 0.0619 0.0634 0.0649 0.066422.0 0.0599 0.0614 0.0629 0.064322.5 0.0580 0.0595 0.0609 0.0624

23.0 0.0562 0.0576 0.0590 0.060523.5 0.0545 0.0559 0.0573 0.058724.0 0.0528 0.0542 0.0555 0.056924.5 0.0512 0.0526 0.0539 0.055225.0 0.0497 0.0510 0.0523 0.0536

25.5 0.0482 0.0495 0.0508 0.052126.0 0.0468 0.0481 0.0493 0.050626.5 0.0455 0.0467 0.0479 0.049127.0 0.0442 0.0454 0.0466 0.047827.5 0.0429 0.0441 0.0453 0.0464

28.0 0.0417 0.0428 0.0440 0.045228.5 0.0405 0.0417 0.0428 0.043929.0 0.0394 0.0405 0.0416 0.042729.5 0.0383 0.0394 0.0405 0.041630.0 0.0373 0.0383 0.0394 0.0405

31.0 0.0353 0.0363 0.0373 0.038432.0 0.0334 0.0344 0.0354 0.036433.0 0.0317 0.0326 0.0336 0.034634.0 0.0300 0.0310 0.0319 0.032835.0 0.0285 0.0294 0.0303 0.0312

36.0 0.0271 0.0280 0.0288 0.029737.0 0.0257 0.0266 0.0274 0.028338.0 0.0245 0.0253 0.0261 0.026939.0 0.0233 0.0241 0.0249 0.025740.0 0.0222 0.0229 0.0237 0.0245

41.0 0.0211 0.0218 0.0226 0.023342.0 0.0201 0.0208 0.0215 0.022343.0 0.0192 0.0199 0.0205 0.021244.0 0.0183 0.0189 0.0196 0.020345.0 0.0174 0.0181 0.0187 0.0194

46.0 0.0166 0.0172 0.0179 0.018547.0 0.0159 0.0165 0.0171 0.017748.0 0.0151 0.0157 0.0163 0.016949.0 0.0145 0.0150 0.0156 0.016250.0 0.0138 0.0144 0.0149 0.0155

51.0 0.0132 0.0137 0.0143 0.014852.0 0.0126 0.0131 0.0136 0.014253.0 0.0120 0.0125 0.0131 0.013654.0 0.0115 0.0120 0.0125 0.013055.0 0.0110 0.0115 0.0120 0.0124

56.0 0.0105 0.0110 0.0115 0.011957.0 0.0101 0.0105 0.0110 0.011458.0 0.0096 0.0101 0.0105 0.010959.0 0.0092 0.0096 0.0101 0.010560.0 0.0088 0.0092 0.0096 0.0101

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Titrations

The electrode makes a highly sensitive endpoint detector fortitrations of a fluoride-containing sample using lanthanumnitrate as the titrant. Titrations are more time-consuming thandirect electrode measurements, but results are more accurateand reproducible. With careful technique, titrations are accurateto 0.2% of the total fluoride concentration of the sample canbe performed. The sample should be at least 10 -3 M totalfluoride in concentration for a good endpoint break.Titrations for fluoride give low results in the presence of1% or more (based on total fluoride) of aluminum, iron, ortrivalent chromium.The fluoride electrode can also be used to detect titrationendpoints of samples containing species that react withfluoride - such as aluminum, lithium, lanthanum, and thorium.Details are available from the Thermo Technical ServicesDepartment.

The following procedure is for the titration of a fluoridecontaining sample with lanthanum nitrate.

1. Prepare a 0.1 M lanthanum nitrate solution by dissolving43.3 g. reagent-grade La(NO3)3-6H20 in a 1-liter volumetricflask containing approximately 700 mL of distilled water.Once dissolved, fill to mark with distilled water.

2. Standardize the lanthanum nitrate solution by titrating againsta 0.1 M fluoride standard. Pipet exactly 25 mL of fluoridestandard into a 250 mL plastic beaker and add about 50 mLdistilled water. Place electrode(s) in sample. Use magneticstirring throughout measurement.

3. Using a 10.0 mL burette, add increments of lanthanumnitrate and plot the electrode potential against mL of

lanthanum nitrate added. The endpoint is the point ofgreatest slope. See Figure 2. Record the endpoint, Vto.Rinse electrode(s) and blot dry.

4. Titrate unknowns. Pipet exactly 25 mL sample into a 250 mLbeaker and add about 50 mL distilled water. Placeelectrode(s) in sample. Use magnetic stirring throughoutthe measurement.

5. Using a 10 mL burette, add increments of lanthanum nitrateand plot the electrode potential against mL of lanthanumnitrate added. Determine the endpoint, Vtx, as above.

22


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6. Calculate sample concentration, Csx:

Vtx VfoCsx = (Cso)

Vfx Vto

Where:

Csx = sample concentration

CSo = fluoride standard concentration (0.1M)

Vtx = volume of titrant added in unknown sample titrationat endpoint

Vto = volume of titrant added in standardization titrationat endpoint

Vfx = volume of sample used in sample titration (25 mL)

Vfo = volume of standard used in standardization titration(25 mL)

Figure 2Titration of 0.114 M F - with 0.1 M La(NO3)3

23

-100

-50

0

50

100

5 10 15 20 25

titrant volume (mL)



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Fluoride in Acid Solutions

In solutions with a pH below 5, hydrogen ion complexes aportion of the fluoride ion, forming HF or HF2

- which cannot bedetected by the electrode. To free the complexed fluoride, the pHof the solution must be adjusted into the weakly acidic to weaklybasic region before making the determination. A strong base,such as sodium hydroxide should not be used for pHadjustment, since the total ionic strength of the adjustedsamples and standards will vary according to the originalsolution pH and the amount added from sample to sample willvary. (Variations in total ionic strength affect the accuracy ofconcentration measurements.) Dilution of samples andstandards with a large excess of sodium acetate, on the otherhand, buffers the pH to above 5 and help adjust the total ionicstrength of samples and standards to the same level.

Procedure1. Prepare 15% sodium acetate. Dissolve reagent grade

sodium acetate (CH3COONa) in distilled water. Preparein sufficiently large quantities to dilute all samplesand standards.

2. Prepare a background solution containing all componentsexcept fluoride. Use this solution to prepare standards.

3. Prepare standards in the concentration range of theunknowns by adding fluoride to the background solutionsDilute each standard 10:1 with sodium acetate solution(9 parts sodium acetate and 1 part standard). Prepare freshstandards every two weeks if standard contains less than10 ppm fluoride. If a direct concentration readout specificion meter is used, at least two standards are needed. It apH/mV meter is used, a calibration curve should be drawn

and at least three standards should be prepared.4. Calibrate the electrode(s) following the instructions in

Checking Electrode Operation (Slope).

5. Measure unknowns: Dilute each unknown 10:1 with sodiumacetate before performing the determination (9 parts sodiumacetate and 1 part unknown).

NOTE:In many cases, standards need not to be prepared from background solutions. If a standard prepared from the background solution gives the same reading (after dilution with sodium acetate) as a standard prepared from pure sodium fluoride, then the use of the background solution is unnecessary.

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Fluoride in Alkaline Solutions

In basic solutions containing low fluoride content (less than10-4 M at a pH of 9.5 or above), the electrode responds tohydroxide ion as well as to fluoride ion. The potential reading,caused by the concentration of both hydroxide and fluoride ion,is lower than it would be if fluoride alone were present.See Interferences.

Adjusting the pH to between 5-6 with a 4.0 M buffered potassiumacetate solution eliminates any hydroxide error and raises the

total ionic strength of both samples and standards to the samevalue. After both samples and standards are diluted 10:1 with thebuffer solution, the fluoride ion concentration can be determinedin the usual manner.

Procedure1. Prepare a 4.0 M buffered potassium acetate solution by

diluting 2 parts 6.0 M acetic acid (CH3COOH) with one partdistilled water, surrounding the reaction with a water bath.Add 50% KOH solution to the acetic acid slowly, stirringconstantly, until a pH of 5 is reached. Prepare in a sufficientlylarge quantity to dilute all samples and standards 10:1(9 parts buffer and 1 part sample or standard).

2. Prepare standards, calibrate electrodes, and measureunknowns as described under Fluoride in AcidSolutions section.

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Electrode Storage

Orion 90-01

The Orion 90-01 Reference Electrode may be stored in its fillingsolution between sample measurements (up to two hours).For short periods of time (up to one week), the Orion 90-01should be stored in filling solution. Fluoride standard (0.01 M)or 100 ppm are acceptable storage solutions. The solutionsinside the electrode should not be allowed to evaporatecausing crystallization.

For storage longer than one week, drain the reference electrode,

flush the inside with distilled water, and store dry.

Orion 94-09 The Orion 94-09 Fluoride Electrode should be rinsed thoroughlyand stored dry in the air at all times. When storing for longperiods of time, replace the cap to protect the sensing element.

Orion 96-09 The solution in the Orion 96-09 Fluoride Combination Electrodeshould not be allowed to evaporate, causing crystallization.For short periods of time between sample measurements,and up to one week, store the electrode in least fluorideconcentration standard.

For storage longer than one week or for an indefinite period oftime, drain the electrode, flush the inside with distilled water,and store dry with the cap to protect the sensing element.

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Disassembly and CleaningFor Orion 90-01 and Orion 96-09:

Disassembly is not normally required and is not oftenrecommended. When the area between free electrode sleeveand inner cone becomes clogged with sample or precipitatefrom filling solution, the chamber can be cleaned by flushingout with filling solution or distilled water.

1. Holding the electrode upright, wrap around the electrodebody with your palm and place your thumb on the cap.

2. Push with your thumb on the cap will drain solution fromthe chamber.

3. If the chamber is not completely cleaned, repeatthe procedure.

4. Refill with Thermo Filling Solution Orion 900001 forOrion 90-01 or with Orion 900061 for Orion 96-09.

If a more thorough cleaning is required, the electrode can bedisassembled using the following instructions:

1. Tip the electrode so that the filling solution moistens theo-ring on the electrode body. Hold the electrode body by thecap with one hand and push the outer sleeve of the electrodeup into the cap to drain the chamber.

2. Unscrew the cap counter clock-wise and then slide the capand the epoxy-coated spring up along the cable.

3. Hold the outer sleeve with one hand and firmly push downon the threaded portion with the thumb and forefinger toseparate the inner body from the sleeve.

4. Grasp the cone with a clean tissue and withdraw the body

from the sleeve with a gentle twisting motion, Do not touch the AgCl pellet above the cone, it may cause damage to the pellet. Rinse the outside of the electrode body and theentire sleeve with distilled water. Allow to air dry.

Reassembly1. Moisten the o-ring on the electrode body with a drop of

filling solution. Insert screw-thread end of the electrode bodyinto the tapered, ground end of sleeve.

2. Push body into sleeve with a gentle twisting motion untilbottom surface of inner cone is flush with the tapered end ofthe sleeve.

3. Place the spring onto the electrode body and screw on the

cap. Refill with filling solution. The electrode is now readyfor use.

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TROUBLESHOOTING

Troubleshooting Checklist

28

Possible Causes

Defective meter

Electrodes not plugged in properlyReference electrode junction is dry

No reference electrodeReference electrode not filled

Air bubble on elementElectrodes not in solutionStatic electricity

Defective meterMeter or stirrer improperly groundedAir bubble on elementWrong reference electrodeTISAB not used

Samples and standards atdifferent temperatures

Sensing element dirtyIncorrect reference filling solution

Standards contaminated orincorrectly madeTISAB not usedStandard used as TISABDefective electrodeGlassware used

Incorrect scaling of semilog paper

Incorrect signIncorrect standardsWrong units usedComplexing agents in sample

Incorrect TISAB dilution

Symptom

Off-scale or

Over-rangereading

Noisy orunstable

readings(readingsrapidlychanging)

Drift (Readingslowly changing

in one direction)

Low slope orNo slope

WrongAnswer (Butcalibrationcurve is OK)


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Solution

Perform meter checkout procedure (see Meter

Instruction Manual )Unplug electrodes and resetHold reference electrode and push cap to expel a few drops offilling solutionUse Orion 90-01 Reference Electrode with Orion 94-09Be sure reference electrode is filled with Orion No. 900001 and

Orion 96-09 filled with Orion No. 900061Remove bubble by redipping electrode in solutionPut electrodes in solutionWipe plastic parts of meter with detergent solution

Check meter with shorting cap (see Meter Instruction Manual )Check meter and stirrer for groundingRemove bubble by redipping in solutionDo not use calomel reference electrodeUse recommended TISAB

Allow solutions to come to the same temperaturebefore measurement

Remove organic deposits (see Measuring Hints )Use recommended filling solution

Prepare fresh standards

Use recommended TISABUse TISAB IRefer to Troubleshooting GuideUse plastic labware

Plot millivolts on the linear axis. On the log axis, be sureconcentration numbers within each decade are increasing withincreasing concentrationBe sure to note sign of millivolt value correctlyPrepare fresh standardsApply correct conversion factor: 10-3 M = 19 ppm as F-

Use known addition or titration techniques,or a decomplexing procedureAdd 50 mL TISAB II or IV, or 5 mL TISAB III to each 50 mLstandard or sample

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Troubleshooting Guide

The most important principle in troubleshooting is to isolate thecomponents of the system and check each in turn. Thecomponents of the system are: 1) Meter, 2) Electrodes,3) Standard, 4) Sample, and 5) Technique.

MeterThe meter is the easiest component to eliminate as a possiblecause of error. Orion meters are provided with an instrumentcheckout procedure in the instruction manual and a shortingstrap for convenience in troubleshooting. Consult the manualfor complete instructions and verify that the instrument operatesas indicated and is stable in all steps.

Electrodes1. Rinse electrodes thoroughly with distilled water.

2. Check electrode operation (slope).

3. If electrode fails this procedure, see Measuring Hints.

4. Repeat step 2, Checking Electrode Operation, (Slope).

5. It the electrodes still do not perform as described, determinewhether the fluoride or reference electrode is at fault. To dothis, substitute a known working electrode for the electrodein question and repeat slope check.

6. If the stability and slope check out properly, butmeasurement problems persist, the sample may containinterferences or complexing agents, or the technique may bein error. See Standard, Sample, and Technique sections.

7. Before replacing a faulty electrode, or if another electrodeis not available for test purposes, review the instruction

manual and be sure to: Clean the electrodes thoroughly

Prepare the electrodes properly

Use proper filling solutions, TISAB, and standards

Measure correctly

ReviewTroubleshooting Checklist

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StandardThe quality of results depends greatly upon the quality of thestandards- ALWAYS prepare fresh standards when problems arise - it could save hours of frustrating troubleshooting! Errormay result from contamination of prepared standards, accuracyof dilution, quality of distilled water, or a mathematical error incalculating the concentrations.

The best method for preparation of standards is by serialdilution. This means that an initial standard is diluted, using

volumetric glassware, to prepare a second standard solution.The second standard solution is similarly diluted to prepare athird standard, and so on, until the desired range of standardshas been prepared.

SampleIf the electrodes work properly in standards but not in sample,

look for possible interferences, complexing agents, orsubstances, which could affect response or physically damagethe sensing electrode or the reference electrode. If possible,determine the composition of the samples and check forproblems. See Sample Requirements, Interferences,and pH Requirements.

TechniqueCheck the method of analysis for compatibility with yoursample. Direct measurement may not always be the method ofchoice. If a large amount of complexing agents are present,known addition may be best. If the sample is viscous, analateaddition may solve the problem. If working at low-level, be sureto follow the Low-Level Measurement Technique.

Also, be sure that the expected concentration of the ion ofinterest is within the electrodes limits of detection.

It problems persist, review operational procedures andinstruction manuals to make sure that proper technique hasbeen to followed. Reread Measuring Hints andAnalytical Procedures.

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Assistance

After troubleshooting all components of your measurementsystem, contact The Technical EdgeSM for Orion products. Withinthe United States call 1.800.225.1480, outside the United Statescall 978.232.6000 or fax 978.232.6031. In Europe, the MiddleEast and Africa, contact your local authorized dealer. For themost current contact information, visit www.thermo.com.

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ELECTRODE CHARACTERISTICS

Electrode Response

The electrode potential plotted against concentration onsemilogarithmic paper results in a straight line with a slope ofabout 54-60 mV per decade. See Figure 1

The time response of the electrode, that is, the time required toreach 99% of the stable potential reading, varies from severalseconds in concentrated solutions to several minutes near thelimit of detection. See Figure 3.

Figure 3Typical Electrode ResponseTo Step Changes in NaF Concentration

Reproducibility

Reproducibility is limited by factors such as temperaturefluctuations, drift, and noise. Within the electrodes operating

range, reproducibility is independent of concentration. Withcalibration every hour, direct electrode measurementsreproducible to 2% can be obtained.

33

time (minutes)

10 - 3 M to 10 -

6 M

10 - 3 M to 10 -

5 M

10 - 3

M to 10 - 4

M

10 - 3 M to 10 -

2 M


1

160

120

80

40

0

-40

-80

2 3 4


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Limits of Detection

In neutral solutions, fluoride concentration can be measureddown to 10-6 M (0.02 ppm) fluoride. However, care must betaken in making determinations below 10-5 M to avoid samplecontamination. The upper limit of detection is a saturatedfluoride solution.

Temperature Effects

Since electrode potentials are affected by changes in

temperature, samples, and standard solutions should be within 1 C ( 2 F) of each other. At the 10-3 M level, a 1 Cdifference in temperature results in a 2% error. The absolutepotential of the reference electrode changes slowly withtemperature because of the solubility equilibria on which theelectrode depends. The slope of the fluoride electrode alsovaries with temperature, as indicated by the factor S in the

Nernst equation Values of the Nernst factor for fluoride ion aregiven in Table 5. If temperature changes, meter and electrodesshould be recalibrated.

The electrode can be used at temperatures from 0 to 100 C,provided that temperature equilibrium has occurred. For use attemperatures substantially different from room temperature,equilibrium times of up to one hour are recommended. Theelectrode must be used only intermittently at solutiontemperatures above 80 C.

Table 5Values of Theoretical Slope vs. Temperature

Temperature (C) Slope (mV)0 - 54.2

10 - 56.2

20 - 58.2

25 - 59.2

30 - 60.1

40 - 62.150 - 64.1

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Interferences

Most cations and anions do not interfere with the response ofthe fluoride electrode to fluoride. Anions commonly associatedwith fluoride, such as Cl-, Br-, I-, S04

2-, HC03-, P04

3-, and acetate,do not interfere with electrode operation. The OH- ion is anelectrode interference. See pH Effects. Some anions, such asC03

= or P04-3, make the sample more basic, increasing the

OH- interference, but are not direct electrode interferences.

pH Effects

In acid solutions with a pH below 5, hydrogen complexes aportion of fluoride in solution, forming the undissociated acid HFand the ion HF2

-. Figure 4 shows the proportion of free fluorideion in acid solutions. Hydroxide ion interferes with the electroderesponse to fluoride when the level of hydroxide is greater thanone-tenth the level of fluoride ion present. For example, at pH 7,

when the hydroxide concentration is 10-7

M or less, there is nohydroxide interference with fluoride measurements. At pH 10,where the hydroxide concentration is 10- 4 M, there is no error at10-2 M fluoride, about a 10% error at 10-4 M fluoride andconsiderable error at 10 -5 M fluoride. SeeFigure 5. Addition ofTISAB II or III to fluoride standards and samples will buffer thepH between 5.0 and 5.5 to avoid hydroxide interferences or the

formation of hydrogen complexes of fluoride. TISAB IVadjusts the pH to about 8.5, and should not be used for verylow-level measurements.

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Figure 4Fraction of Free Fluoride

As a function of solution pH, hydrogen is the onlycomplexing species.

Figure 5Electrode Response in Alkaline Solutions

36

1

0.2

0.4

C fC t

pH

0.6

0.8

1.0

2 3 4 5 6

solution pH

7

100

75

50

25

0

-25

8 9 10 11


10 - 3 M F -

10 - 4 M F -

10 - 5 M F -


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Complexation

Fluoride forms complexes with aluminum, silicon, iron (+3), andother polyvalent cations as well as hydrogen. The extent ofcomplexation depends on the concentration of complexingagent, the total fluoride concentration, and pH of the solution,and the total ionic strength of the solution.

TISAB II and III contain a reagent, CDTA, that preferentiallycomplexes aluminum or iron in the sample. In a 1ppm fluoridesample, TISAB II or III complexes about 5 ppm aluminum oriron. Higher levels of aluminum or iron can be complexed byusing TISAB IV.

Electrode Life

Electrode should last at least through the warranty period. Intime, the electrode slope will decrease and readings will start todrift, indicating that electrode should be replaced. Beforereplacement, refer to Troubleshooting Checklist to verify thatthe electrode causes the symptoms.

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Theory of Operation

The fluoride electrode consists of a sensing element bondedinto an epoxy body. When the sensing element is in contactwith a solution containing fluoride ions, an electrode potentialdevelops across the sensing element. This potential, whichdepends on the level of free fluoride ion in solution, is measuredagainst a constant reference potential with a digital pH/mVmeter or specific ion meter. The measured potentialcorresponding to the level of fluoride ion in solution isdescribed by the Nernst equation.

E = Eo + S log (A)

where:

E = measured electrode potential

Eo = reference potential (a constant)

A = fluoride ion activity level in solution

S = electrode slope (about 57 mV per decade)

The level of fluoride ion, A, is the activity or effectiveconcentration of free fluoride ion in solution. The fluoride ionactivity is related to free fluoride ion concentration, Cf, by theactivity coefficient, yi

A = yCfIonic activity coefficients are variable and largely depend on totalionic strength. Ionic strength is defined as:

Ionic strength = 1 /2CiZi2

where:

Ci = concentration of ion i

Zi = charge of ion i

and symbolizes the sum of all the types of ionsin solutions.

If background ionic strength is high and constant relative to thesensed ion concentration, the activity coefficient is constant andactivity is directly proportional to concentration.

Total ionic strength adjustor buffer (TISAB) is added to all

fluoride standards and samples so that the background ionicstrength is high, fluoride is decomplexed, and the pH of thesolution is adjusted.

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Reference electrode conditions must also be considered. Liquidjunction potentials arise any time when two solutions of differentcomposition are brought into contact. The potential results

from the interdiffusion of ions in the two solutions. Since ionsdiffuse at different rates, the electrode charge will be carriedunequally across the solution boundary resulting in a potentialdifference between the two solutions. In making electrodemeasurements, it is important that this potential is the samewhen the reference is in the standardizing solution as well as inthe same solution; otherwise, the change in liquid junction

potential will appear as an error in the measured specific ionelectrode potential.

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Orion 96-09Combination Fluoride Electrode

The most important variable, which analysts have under theircontrol, is the composition of the liquid junction filling solution.The filling solution should be equitransferent. That is, the speedwith which the positive and negative ions in the filling solutiondiffuse into the sample should be nearly as equal as possible. Ifthe rate at which positive and negative charge is carried into thesample solution is equal, then no junction potential can result.

However, there are a few samples where no filling solutionadequately fulfills the condition stated above. Particularlytroublesome are samples containing high levels of strong acids(pH 0-2) or strong bases (pH 12-14). The high mobility ofhydrogen and hydroxide ions in samples makes it impossible toswamp out their effect on the junction potential with anyconcentration of an equitransferent salt. For these solutions, itis recommended to calibrate in the same pH range as thesample or use a known increment method for ion measurement.For more information, call Thermo Technical Service Chemists.See Assistance.

40

cap

epoxy-coatedspring

cable

O-ring

filling hole

inner cone

referenceelement

filling solutionchamber

outer inner

electrodebody


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41

Warranty

For the most current warranty information, visitwww.thermo.com.

The Thermo Electron Corporation, Orion products warrantycovers failures due to manufacturers workmanship or materialdefects from the date of purchase by the user. User shouldreturn the warranty card and retain proof of purchase. Warrantyis void if product has been abused, misused, or repairsattempted by unauthorized persons.

Warranties herein are for product sold/installed by Thermo or itsauthorized dealers.

Any product sold by a U.S. or Canadian distributor must bereturned to Thermo for any warranty work. Please contact ourTechnical Service department for further information. A ReturnAuthorization Number must be obtained from The TechnicalEDGESM For Orion Products before returning any product for in-warranty repair or replacement.

In the event of failure within the warranty period, Thermo will atthe companys option, repair or replace product not conformingto this warranty. There may be additional charges, includingfreight, for warranty service performed in some countries. Forservice, call Thermo or its authorized dealer outside the United

States and Canada. Thermo reserves the right to ask for proof ofpurchase, such as the original invoice or packing slip.

Field Service is available on Orion BOD AutoEZ, EZ Flash GCAccessory and TEA Analyzer. Contact our Field Servicedepartment for details on quotations, service, other field service-related activities.

The following products are warranted to be free from defects inmaterial and workmanship in the period listed below from thedate of purchase from the user or from the date of shipmentfrom Thermo, whichever is earlier, provided use is in accordancewith the operating limitations and maintenance procedures in theinstruction manual and when not having been subjected toaccident, alteration, misuse, abuse or breakage of electrodes:

Thirty-six months from date of purchase by the user (or forty-two months from date of shipment from Thermo)

Waterproof Meters (Orion 630, 635, 830A, 835A, 260A,261S, 265A, 266S, 130A, 131S, 135A, 136S, 1230, 142 and842), Conductivity Meters (Orion 105Aplus, 115Aplus,125Aplus, 145Aplus, 150Aplus and 162A), PerpHect


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42

pH/ISE Meters (Orion 310, 320, 330, 350, 370) pH/ISEMeters (Orion 210Aplus, 230Aplus, 250Aplus, 290Aplus,410Aplus, 420Aplus, 520Aplus, 525Aplus, 710Aplus,720Aplus and 920Aplus), pHuture MMS Meters (Orion535A and 555A), pH/Conductivity Meter (Orion 550A),Dissolved Oxygen Meters (Orion 805Aplus, 810Aplus,850Aplus and 862A).

Twenty-four months from date of purchase by the user (orthirty-six months from date of shipment from Thermo)

Orion ROSS Ultra Electrodes, AQUAfast IV Colorimeters,AQUAfast IV Turbidimeter, Orion 925 Flash Titrator, Series100 DuraProbe Conductivity Cells and Series 800 DissolvedOxygen Probes.

Twelve months from date of purchase by the user (or eighteenmonths from date of shipment from Thermo)

Laboratory pH Meters, (Orion 301, 611 and 940),

SensorLink

, pHuture

pH Meters (Orion 610 and 620),Smart Chek meters, Sage Pumps, Cahn Balances, 930Ionalyzer, 950 ROSS FAST QC Titrator, 960 TitratorPLUS, Karl Fischer Titrators, Autosamplers, LiquidHandling Devices, Liquid Handling Automation Workstations(Orion AS2000, AS2500 and AS4000), Pumps (OrionSP201, SP201-HR, SP201-S, Peristaltic and Rinse),

pHuture

Conversion Box, Wine Master

, 607 Switchbox, rflink, AQUAfast II Colorimeters, Vacuum Degasser andFlowmeter.

Orion EZ Flash GC Accessory, Orion TEA Analyzer 610 and510 excluding consumable items carry twelve monthswarranty only.

Orion Ion Selective Electrodes, ionplus Electrodes, ROSS

Electrodes, Sure-Flow Electrodes, PerpHecT Electrodes,AquaPro Professional Electrodes, No Cal pH electrodes,Standard Line pH Electrodes, Tris pH Electrodes, KNIpHE

electrode, ORP Triode (Orion 9180BN), pHuture pH Probes(Orion 616500) and pHuture MMS Quatrode and Triode

(Orion 616600 and 617900), Orion 97-08 DO Probe, Series100 Conventional Conductivity Cells, temperature probesand compensators (except those products noted).

Orion 93 and 97 ionplus Series sensing modules arewarranted to give six months of operation if placed inservice before the date indicated on the package, except 93-07 and 97-07 Nitrate modules are warranted to give ninetydays of operation if placed in service before the date


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43

indicated on the package.

Six months from date of purchase by the user (or twelvemonths from date of shipment from Thermo)

Orion Flash Titration Probe (Orion 092518), pHuture

Electrode (Orion 615700), pHuture MMS Pentrode (Orion617500), Quatrode (Orion 617800) and Triode (Orion615800), Low Maintenance Triode (Orion 9107BN), ORPLow Maintenance Triode (Orion 9179BN), and PerpHecT

Low Maintenance Triode (Orion 9207BN), WaterproofTriode (Orion 9107WP, 9107WL, 9109WL and 9109WP),QuiKcheK Meters and Micro Electrodes.

Three months from date of purchase by the user (or sixmonths from date of shipment from Thermo)

Economy Line Electrodes, Orion 91-05, 91-06, 91-15, 91-16, 91-25, 91-26, 91-35, 91-36, 92-06. Warranty alsoincludes failure for any reason (excluding breakage), except

abuse, provided the electrode is not used in solutionscontaining silver, sulfide, perchlorate, or hydrofluoric acid;or in solutions more than one (1) Molar in strong acid orbase at temperatures above 50 C.

Out-of-Box Warranty - Should any of the following productsfail to work when first used, contact Thermo immediately forreplacement.

Orion Solutions, Standards, Reagents, Cables, Ferrules,Tubing, Line adapters, Printers, Software, Cases, Stands,Probe Membranes, AQUAfast Test Strips, EZ Flash

columns, Liquid Handling Probes, Adapter Plates and Racksand general accessories.

For products in the catalog not listed in this warranty statement,please visit our website at: www.thermo.com

THE WARRANTIES DESCRIBED ABOVE ARE EXCLUSIVE AND INLIEU OF ALL OTHER WARRANTIES WHETHER STATUTORY,EXPRESS OR IMPLIED INCLUDING, BUT NOT LIMITED TO, ANYIMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR

A PARTICULAR PURPOSE AND ALL WARRANTIES ARISINGFROM THE COURSE OF DEALING OR USAGE OF TRADE. THEBUYERS SOLE AND EXCLUSIVE REMEDY IS FOR REPAIR ORREPLACEMENT OF THE NON-CONFORMING PRODUCT ORPART THEREOF, OR REFUND OF THE PURCHASE PRICE, BUT INNO EVENT SHALL THERMO (ITS CONTRACTORS ANDSUPPLIERS OF ANY TIER) BE LIABLE TO THE BUYER OR ANY

PERSON FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR


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44

CONSEQUENTIAL DAMAGES WHETHER THE CLAIMS AREBASED IN CONTRACT, IN TORT (INCLUDING NEGLIGENCE), OROTHERWISE WITH RESPECT TO OR ARISING OUT OF THEPRODUCT FURNISHED HEREUNDER.

REPRESENTATION AND WARRANTIES MADE BY ANY PERSON,INCLUDING ITS AUTHORIZED DEALERS, REPRESENTATIVESAND EMPLOYEES OF THERMO WHICH ALTER OR ARE INADDITION TO THE TERMS OF THIS WARRANTY SHALL NOT BEBINDING UPON THERMO UNLESS IN WRITING AND SIGNEDBY ONE OF ITS OFFICERS.


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ORDERING INFORMATION

Orion No. Description

900100 Orion 90-01 Single Junction Reference Electrode900001 Filling Solution for Orion 90-01

900061 Optimum Fluoride Filling Solution for Orion 96-09

Combination Fluoride Electrode940906 0.1 M Sodium Fluoride Standard Solution, 475 mL

940907 100 ppm Fluoride Standard Solution, 475 mL

940909 TISAB II, 1-gallon bottle

940999 TISAB II; case of four 1-gallon bottles

940911 TISAB III, 475 mL940916 Fluoride Activity Standard Bulk Pack, includes

four 1 ppm Fluoride/TISAB Standard 040906,four 10 ppm Fluoride/TISAB Standard 040908

040906 1 ppm Fluoride Standard with TISAB II, 475 mL



45


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46

SPECIFICATIONS

Concentration RangeSaturated solutions to 10 -6 M (0.02 ppm)

pH RangepH 5-7 at 10-6 M (0.02 ppm F-) to

pH 11 at 10-1 M (1900 ppm F-)

Temperature Range0 to 80 C continuous use, 80 to 100 C intermittent use

Electrode Resistance

150 - 200 kilohms

Reproducibility 2%

Minimum Sample Size

3 mL in a 50 mL beaker

Size

Orion 96-09 94-09Body Diameter 13 mm 12 mm

Cap Diameter 16 mm 16 mm

Cable Length 1 m 1 m

*Specifications subject to change without notice


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Environmental InstrumentsWater Analysis

North America166 Cummings CenterBeverly, MA 01915 USATel: 978-232-6000Dom. Fax: 978-232-6015Intl. Fax: 978-232-6031

Europe12-16 Sedgeway Business ParkWitchford, CambridgeshireEngland, CB6 2HYTel: 44-1353-666111Fax: 44-1353-666001

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Customer SupportToll Free: 800-225-1480

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