EUTECH INSTRUMENTS AMMONIUM EPOXY User manual

Instruction Manual Ammonium Electrode
1
EUTECH INSTRUMENTS PTE LTD.
AMMONIUM ION ELECTRODE
INSTRUCTION MANUAL
GENERAL INSTRUCTIONS
Eutech Instruments Ammonium Ion Electrode is used to measure ammonium ions in aqueous
solutions in a more simple, quick, accurate, and economical manner.
Required Equipment
1. A pH/mV meter or an ion meter, either line operated or portable.
2. Semi-logarithmic 4-cycle graph paper for preparing calibration curves when using the
meter in the mV mode.
3. A magnetic stirrer.
4. Eutech Ammonium Ion Combination Epoxy-body Electrode, Code no. EC-NH4-03.
Required Solutions
1. Deionized or distilled water for solution and standard preparation.
2. Eutech Ionic Strength Adjuster (ISA), 5M NaCl, Code no. EC-ISA-AM1-BT to keep a
constant background ionic strength present in the solution. To prepare the 5M NaCl ISA
from your own laboratory stock, add 292 grams of reagent-grade sodium chloride (NaCl)
to a 1,000 ml volumetric flask about half full of distilled water. Swirl the flask to dissolve
the solid and fill to the mark with distilled water. Cap the flask and invert several times to
mix the solution. Add 2 ml of ISA to every 100 ml of sample or standard solution for a
background ionic strength of 0.10M.
3. Eutech Ammonium Standard, 0.1M NH4Cl, Code no. EC-SCS-AM1-BT. To prepare this
standard, add 5.34 grams of reagent-grade ammonium chloride to a 1 liter volumetric flask
about half full of distilled water. Swirl the flask to dissolve the solid and fill to the mark
with distilled water. Cap the flask and invert several times to mix the solution.
4. Eutech Ammonium Standard, 1,000 ppm NH4+1, Code no. EC-SCS-AM2-BT. To prepare
this standard, add 2.97 grams of reagent-grade ammonium chloride to a 1 liter volumetric
flask about half full of distilled water. Swirl the flask to dissolve the solid and fill to the
mark with distilled water. Cap the flask and invert several times to mix the solution.

Ammonium Electrode Instruction Manual
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GENERAL PREPARATION
Electrode Preparation
Remove any rubber cap(s) covering the electrode tip(s) and the rubber inserts covering the filling
holes of the reference electrode. Fill the combination electrode or the reference electrode with the
filling solution shipped with the electrode to a level just below the fill hole. No preparation is
required for a sealed reference electrode. Gently shake the electrode downward in the same manner
as a clinical thermometer to remove any air bubbles that might be trapped behind the ammonium
membrane. Prior to first usage, or after long term storage, immerse the ammonium electrode in
ammonium standard for thirty minutes. The electrode is now ready for use. Connect the electrode(s)
to the proper terminal(s) as recommended by the meter manufacturer.
Electrode Slope Check (with standard pH/mV meter)
(Check electrodes each day)
To a 150 ml beaker, add 100 ml of distilled water and 2 ml of ISA. Place the beaker on a magnetic
stirrer and begin stirring at a constant rate. After assuring that the meter is in the mV mode, lower
the electrode tip(s) into the solution.
Using a pipet, add 1 ml of 0.1M or 1,000 ppm ammonium standard to the beaker. When the reading
is stable, record the millivolt reading. Using a pipet, add 10 ml of the standard used above to the
beaker. When the reading has stabilized, record the millivolt reading.
Determine the difference between the two readings. A difference of 56±2 mV indicates correct
electrode operation, assuming the solution temperature is between 20oand 25oC. See the
TROUBLESHOOTING section if the potential change is not within this range.
Slope is defined as the change in potential observed when the concentration changes by a factor of
10.
Electrode Slope Check (with ion meter)
(Check electrodes each day)
Prepare standard ammonium solutions whose concentrations vary by tenfold. Use either the 0.1M
NH4+1 or the 1,000 ppm NH4+1 standard stock solutions. Use the serial dilution method for this
preparation.
To a 150 ml beaker, add 100 ml of the lower value standard and 2 ml of ISA. Place the beaker on
the magnetic stirrer and begin stirring at a constant rate. Lower the electrode tip(s) into the solution.
Assure that the meter is in the concentration mode. Adjust the meter to the concentration of the
standard and fix the value in the memory according to the meter manufacturer's instructions.
Rinse the electrode(s) with distilled water and blot dry. To a 150 ml beaker, add 100 ml of the
higher value standard and 2 ml of ISA. Place the beaker on the magnetic stirrer and begin stirring at
a constant rate. Lower the electrode tip(s) into the solution.
Adjust the meter to the concentration of the standard and fix the value in the memory. Read the
electrode slope according to the meter manufacturer's instructions. Correct electrode operation is

Instruction Manual Ammonium Electrode
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indicated by a slope of 90-100%. See the TROUBLESHOOTING section if the slope is not within this
range.
MEASUREMENT
Measuring Hints
The sensing membrane is normally subject to water uptake and might appear milky. This has no
effect on performance. All samples and standards should be at the same temperature for precise
measurement, preferably ambient temperature.
Constant, but not violent, stirring is necessary for accurate measurement. Magnetic stirrers can
generate sufficient heat to change the solution temperature. To counteract this effect, place a piece
of insulating material, such as styrofoam sheet or asbestos sheet, between the stirrer and beaker.
Always rinse the electrode tip(s) with distilled water and blot dry with a fresh tissue between
readings to prevent solution carryover.
Check the electrode for air bubbles adhering to the membrane surface after immersion in solution.
Agitate the electrode gently to remove the air bubbles.
A slow or sluggish electrode response may indicate surface contamination of the ammonium
electrode membrane. Soak the electrode tip in distilled water for about 5 minutes to clean the
membrane. Rinse the membrane and soak in diluted standard solution for about 5 minutes to restore
performance.
When measuring samples with high ionic strength, prepare standards with compositions similar to
that of the sample.
Dilute concentrated samples (over 0.1M) before measurement. Recalibrate every few hours for
routine measurement.
Sample Requirements
Make sure that the samples and standards are at the same temperature. About a 2% error will be
introduced for a 1oC difference in temperature. Temperature should normally be less than 40oC
with intermittent measurements allowed to 50oC.
All samples and standards must be aqueous. They must not contain organic solvents.
Interference found in Table 3 should be absent.
Units of Measurement
Ammonium concentrations are measured in units of parts per million as ammonium, parts per
million as N, moles per liter, or any other convenient concentration unit. Table 1 indicates some of
the concentration units.

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TABLE 1: Concentration Unit Conversion Factors
ppm NH4+ppm N moles/liter NH4+
1.80 1.40 1x10-4
18.00 14.00 1x10-3
180.00 140.00 1x10-2
Measurement Procedure
Direct Measurement
A simple procedure for measuring a large number of samples. A single meter reading is all that is
required for each sample. The ionic strength of samples and standards should be made the same by
adjustment with ISA for all ammonium samples. The temperature of both sample solution and of
standard solutions should be the same.
Direct Measurement of Ammonium (using a standard pH/mV meter)
1. Prepare 10-2, 10-3, and 10-4M or 100, 10, and 1 ppm standards by serial dilution of the
0.1M or 1,000 ppm standard. Add 2 ml of ISA per 100 ml of standard.
2. Place the most dilute solution (10-4M or 1 ppm) on the magnetic stirrer and begin stirring
at a constant rate. After assuring that the meter is in the mV mode, lower the electrode
tip(s) into the solution. When the reading has stabilized, record the mV reading.
3. Place the midrange solution (10-3M or 10 ppm) on the magnetic stirrer and begin stirring.
After rinsing the electrode(s) with distilled water and blotting dry, immerse the electrode
tip(s) in the solution. When the reading has stabilized, record the mV reading.
4. Place the most concentrated solution (10-2M or 100 ppm) on the magnetic stirrer and begin
stirring. After rinsing the electrode(s) with distilled water and blotting dry, immerse the
electrode tip(s) in the solution. When the reading has stabilized, record the mV reading.
5. Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against the
concentration (log axis). A typical calibration curve can be found in Figure 1.

Instruction Manual Ammonium Electrode
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A calibration curve is constructed on semi-logarithmic paper when using a
pH/mV meter in the direct measurement procedure. The measured electrode
potential in mV (linear axis) is plotted against the standard concentration (log
axis). In the linear region of the curve, only three standards are necessary to
determine a calibration curve. In the non-linear region, additional points must be
measured. The direct measurement procedures given are for the linear portion of
the curve. The non-linear portion of the curve requires the use of low level
procedures. Extrapolate the curve down to about 1x10-5M or 0.2 ppm.
6. To a clean, dry 150 ml beaker, add 100 ml of sample and 2 ml of ISA. Place the beaker on
the magnetic stirrer and begin stirring. Place the electrode tip(s) in the solution. When the
reading has stabilized, record the millivolt reading. Determine the concentration directly
from the calibration curve.
7. The electrode(s) should be re-calibrated every 1-2 hours. Simply repeat Steps 2-5 above.
Direct Measurement of Ammonium (using an ion meter)
1. By serial dilution of the 0.1M or 1,000 ppm ammonium standard, prepare two ammonium
standards whose concentration is near the expected sample concentration. Measure out
100 ml of each standard into individual 150 ml beakers and add 2 ml of ISA to each.
2. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate.
Assure that the meter is in the concentration mode.
3. Lower the electrode tip(s) into the solution.
4. Adjust the meter to the concentration of the ammonium standard and fix the value in the
memory according to the meter manufacturer's instructions after stabilization of the
reading.
5. Rinse the electrode tip(s) with distilled water and blot dry.
6. Place the more concentrated solution on the magnetic stirrer and begin stirring at a
constant rate.
7. Lower the electrode tip(s) into the solution.
8. Adjust the meter to the concentration of the ammonium standard and fix the value in the
memory according to the meter manufacturer's instructions after stabilization of the
reading.
9. For low level measurements, place the rinsed, dried electrode(s) into a solution containing
100 ml of distilled water and 2 ml of ISA. After stabilization, fix the blank value in the
meter according to the meter manufacturer's instructions.
10. Place 100 ml of the sample and 2 ml of ISA in a 150 ml beaker, place it on the magnetic
stirrer, and begin stirring.

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11. Immerse the electrode tip(s) in the solution and wait for the reading to stabilize. Read the
concentration directly from the meter display.
12. The electrodes should be re-calibrated every 1-2 hours. Simply repeat Steps 2-8 (2-9)
above.
Low Level Ammonium Determination (using a standard pH/mV meter)
This procedure is recommended for solutions with ionic strengths less than 1.0 x 10-2M. If the
solution is high in ionic strength, but low in ammonium, use the same procedure, but prepare a
calibration solution with a composition similar to the sample.
1. Using 20 ml of stock ISA, dilute to 100 ml with distilled water.
2. Dilute 1 ml of the 0.1M standard to 100 ml to prepare a 1.0x10-3M standard solution for
measurements in moles per liter. Dilute 10 ml of the 1,000 ppm standard to 100 ml to
prepare a 100 ppm standard solution for measurements in ppm.
3. To a 150 ml beaker, add 100 ml of distilled water and 1 ml of low level ISA. Place the
beaker on the magnetic stirrer and begin stirring at a constant rate.
4. Place the electrode tip(s) in the solution. Assure that the meter is in the mV mode.
5. Add increments of the 1.0x10-3M or 100 ppm standard as given in Table 2 below.
6. After the reading has stabilized, record the mV reading after each addition.
TABLE 2: Stepwise Calibration for Low Level Ammonium Measurements
Added Concentration
Step Pipet Volume (ml) M ppm
1 A 0.1 1.0X10-60.1
2 A 0.1 2.0X10-60.2
3 A 0.2 4.0X10-60.4
4 A 0.2 6.0X10-60.6
5 A 0.4 9.9X10-61.0
6 B 2 2.9X10-52.9
7 B 2 4.8X10-54.8
Pipet A = 1 ml graduated pipet
Pipet B = 2 ml pipet
7. On semi-logarithmic graph paper, plot the mV reading (linear axis) against the
concentration (log axis) as in Figure 1.
8. Rinse the electrode(s) in distilled water and blot dry.

Instruction Manual Ammonium Electrode
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9. Measure out 100 ml of the sample into a 150 ml beaker, add 1 ml of low level ISA, and
place the beaker on the magnetic stirrer. Begin stirring. Lower the electrode tip(s) into the
solution.
10. After the reading has stabilized, record the mV reading and determine the concentration
from the low level calibration curve.
11. Prepare a new low level calibration curve daily. Check the calibration curve every 1-2
hours by repeating Steps 3-7 above.
Low Level Ammonium Determination (using an ion meter)
Follow the procedure given for normal ammonium determinations using an ion meter and the blank
correction procedure.
ELECTRODE CHARACTERISTICS
Reproducibility
Direct electrode measurements reproducible to ±2% can be obtained if the electrode is calibrated
every hour. Factors such as temperature fluctuations, drift, and noise limit reproducibility.
Reproducibility is independent of concentration within the electrode's operating range.
Interference
Table 3 lists some common cations that, if present in high enough levels, will cause electrode
interference and measurement errors or electrode drift when using the ammonium ion electrodes.
Electrode drift and slow response could indicate the presence of high interference from the ions
listed. Soak the electrode(s) in distilled water for an hour, then for two hours in ammonium standard
solution to restore proper response.
TABLE 3: Concentration of Possible Interference Causing a 10% Error at Various
Levels of NH4Cl; Background Ionic Strength is 0.12M NaCl.
Interference
(moles/liter) 10-2M NH4+1 10-3M NH4+1 10-4M NH4+1
Cs+1 3.0X10-33.0X10-43.0X10-5
K+1 1.0X10-21.0X10-31.0X10-4
Tl+1 6.0X10-26.0X10-36.0X10-4
H+1 1.0X10-11.0X10-21.0X10-3
Ag+1 1.0X1011.0 1.0X10-1
+Tris+1 1.0X1011.0 1.0X10-1

Ammonium Electrode Instruction Manual
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Li+1 2.0X1012.0 2.0X10-1
Na+1 2.0X1012.0 2.0X10-1
+Tris+1 is the cation of tris(hydroxymethyl)aminomethane
Interference
(ppm) 100 ppm NH4+10 ppm NH4+1 ppm NH4+
Cs+1 1.0X1021.0X1011.0
K4+1 2.7X1022.7X1012.7
Tl+1 3.1X1033.1X1023.1X101
H+1 1.6 pH 2.6 pH 3.6 pH
Ag+1 2.7X1052.7X1042.7X103
+Tris+1 3.1X1053.1X1043.1X103
Li+1 3.5X1043.5X1033.5X102
Na+1 1.1X1051.1X1041.1X103
Temperature Influences
Samples and standards should be at the same temperature, since electrode potentials are influenced
by changes in temperature. A 1oC difference in temperature results in a 2% error at the 1.0X10-3M
level.
Provided that temperature equilibrium has occurred, the ammonium ion electrodes can be used at
temperatures from 0o-50oC continuously and 40o-50oC intermittently. Room temperature
measurements are recommended, since measurements at temperatures markedly different from
room temperature may require equilibrium times up to one hour. Table 4 indicates the variation of
theoretical slope with temperature.
TABLE 4: Temperature vs Value for the Electrode Slope
Temp (oC) S"(slope)
0 54.20
10 56.18
20 58.16
25 59.16
30 60.15
40 62.13
50 64.11

Instruction Manual Ammonium Electrode
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Electrode Response
Plotting the electrode mV potential against the ammonium concentration on semi-logarithmic paper
results in a straight line with a slope of about 56 mV per decade. Refer to Figure 1.
The time needed to reach 99% of the stable electrode potential reading, the electrode response time,
varies from one minute or less for ammonium concentration above 1.0X10-5M to several minutes
near the detection limit. Refer to Figure 2.
Electrode Storage
The ammonium ion electrode may be stored in 1.0X10-2M ammonium standard for short periods of
time. For storage over 3 weeks, rinse and dry the ammonium membrane electrode and cover the tip
with any protective cap shipped with the electrode(s). The reference portion of the combination
electrode (or the outer chamber of the reference electrode) should be drained of filling solution, if
refillable, and the rubber insert placed over the filling hole.
Detection Limit
The upper limit of detection is 1M in pure ammonium chloride solutions. The upper limit of
detection is above 1.0X10-1M when other ions are present, but the possibility of a liquid junction
potential developing at the reference electrode and the "salt extraction effect" are two limiting
factors. Some salts may be extracted into the electrode membrane at high salt concentrations
causing deviation from theoretical response. Calibrate the electrode at four or five intermediate
points, or dilute the sample, to measure samples between 1.0X10-1M and 1M.
The slight water solubility of the ion exchanger in the sensing module, which causes deviation from
theoretical response, determines the lower limit of detection. The theoretical response at low levels
of ammonium chloride compared to actual response is shown in Figure 1. A low level measurement
is recommended if ammonium measurements are made below 1.0X10-5M (0.18 ppm as
ammonium).

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pH Effects
Hydrogen ion interferes with measurements of low levels of ammonium ion although the electrode
can be used over a wide pH range. Table 3 should be used to determine the minimum pH at which
low level ammonium measurements can be made without more than a 10% error due to hydrogen
ion interference.
Electrode Life
An ammonium ion electrode will last six months in normal laboratory use. On-line measurement
might shorten operational lifetime to several months. In time, the response time will increase and
the calibration slope will decrease to the point calibration is difficult and electrode replacement is
required.
ELECTRODE THEORY
Electrode Operation
An ammonium ion electrode consists of an electrode body containing an ion exchanger in a sensing
module. This sensing module contains a liquid internal filling solution in contact with a gelled
organophilic membrane containing an ammonium selective ion exchanger.
An electrode potential develops across the membrane when the membrane is in contact with an
ammonium solution. Measurement of this potential against a constant reference potential with a
digital pH/mV meter or with a specific ion meter depends on the level of free ammonium ion in
solution. The level of ammonium ions, corresponding to the measured potential, is described by the
Nernst equation:
E = Eo+ S log X where:
E = measured electrode potential
Eo= reference potential (a constant)
S = electrode slope (~ 56 mV/decade)
X = level of ammonium ions in solution
The activity, X, represents the effective concentration of the ions in solution. Total ammonium
concentration, Ct, includes free ammonium ions, Cf, plus bound or complexed ammonium ions, Cb.
Since the ammonium electrodes only respond to free ion, the free ion concentration is:
C
f= Ct- Cb
The activity is related to the free ion concentration, Cf, by the activity coefficient, γ,by:
X = γCf
Activity coefficients vary, depending on total ionic strength, I, defined as:
I = ½ ΣCxZ2x
where:
Cx= concentration of ion X
Zx= charge of ion X

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Σ= sum of all of the types of ions in the solution.
In the case of high and constant ionic strength relative to the sensed ion concentration, the activity
coefficient, γ, is constant and the activity, X, is directly proportional to the concentration.
To adjust the background ionic strength to a high and constant value, ionic strength adjuster (ISA)
is added to samples and standards. The recommended ISA for ammonium is sodium chloride, NaCl.
Solutions other than this may be used as long as ions that they contain do not interfere with the
electrode's response to ammonium ions.
The reference electrode must also be considered. When two solutions of different composition are
brought into contact with one another, liquid junction potentials arise. Millivolt potentials occur
from the interdiffusion of ions into the two solutions. Electrode charge will be carried unequally
across the solution boundary resulting in a potential difference between the two solutions, since
ions diffuse at different rates. When making measurements, it is important to remember that this
potential be the same when the reference is in the standardizing solution as well as in the sample
solution or the change in liquid junction potential will appear as an error in the measured electrode
potential.
The composition of the liquid junction filling solution in the reference electrode is most important.
The speed with which the positive and negative ions in the filling solution diffuse into the sample
should be as nearly equal as possible, that is, the filling solution should be equitransferant. No
junction potential can result if the rate at which positive and negative charge carried into the sample
is equal.
Strongly acidic (pH = 0-2) and strongly basic (pH = 12-14) solutions are particularly troublesome to
measure. The high mobility of hydrogen and hydroxide ions in samples make it impossible to mask
their effect on the junction potential with any concentration of an equitransferant salt. One must
either calibrate the electrode(s) in the same pH range as the samples or use a known increment
method for ion measurement.
TROUBLESHOOTING
Troubleshooting Guide
The most important principal in troubleshooting is to isolate the components of the system and
check each in turn. The components of the system are: 1) Meter, 2) Electrodes, 3) Standard, 4)
Sample, and 5) Technique.
Meter
The meter is the easiest component to eliminate as a possible cause of error. Most meter are
provided with an instrument check-out procedure in the instruction manual and a shorting strap for
convenience in troubleshooting. Consult the manual for complete instructions and verify that the
instrument operates as indicated.
Electrodes
1. Rinse electrode(s) thoroughly with distilled water.

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2. Perform Electrode Slope Check.
3. If electrode(s) fail this procedure, see the section on Measuring Hints.
4. If the stability and the slope check out properly, but measurement problems persist, the
standards may be of poor quality, the sample may contain interference or complexing
agents, or the technique may be in error. See Standard, Sample,and Technique sections
below.
5. Before replacing a "faulty" electrode, review the instruction manual and be sure to:
clean and rinse the electrode thoroughly prepare the electrode properly use proper filling
solution, ISA, and standards measure correctly review TROUBLESHOOTING HINTS.
Standard
The quality or results depends greatly upon the quality of the standards. ALWAYS prepare fresh
standard when problems arise. It could save hours of frustrating troubleshooting! Error may result
from contamination of prepared standards, accuracy of dilution, quality of distilled water, or a
mathematical error in calculating the standard concentrations.
Sample
If the electrode works properly in standard but not in sample, look for possible interference,
complexing agents, or substances which could affect response or physically damage the sensing
electrode or the reference electrode. See Sample Requirements and Interference. Try to
determine the composition of the samples prior to testing to eliminate a problem before it starts.
Technique
Check the method of analysis for compatibility with your sample. Direct measurement may not
always be the method of choice. Also be sure that the expected concentration of the ion of interest
is within the electrode's limits of detection.
If problems persist, review operational procedures and the instruction manual to be sure that proper
technique has been followed. Call Eutech Instruments Pte Ltd. at (65) 6778-6876 and ask for the
Customer Services Department to answer any questions.

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TROUBLESHOOTING HINTS
Symptom Possible Causes Next Step
Out of Range defective meter check meter with Reading
shorting strap
(see meter instruction manual)
electrode(s) unplug electrode(s)
not plugged in and reset
properly
reference electrode be sure reference
not filled electrode is filled
air bubbles on remove bubble by
membrane redipping electrode
electrodes not put electrode(s)
in solution in solution
"Incorrect incorrect scaling plot millivolts on the linear
Answer" of semi-log paper axis. On the log axis, be sure
curve is good) concentration numbers within
(but calibration each decade are increasing
with increasing concentration
incorrect sign be sure to note
sign of millivolt number correctly
incorrect standards prepare fresh standards
wrong units used apply correct conversion factor:
10-3M = 18 ppm NH4+=
14 ppm as N
sample carryover rinse electrodes
thoroughly between samples
Drift (reading samples and standards allow solutions
slowly changing at different to come to room
in one direction) temperatures temperature
before measurement
electrode exposed soak electrode
to interference in ammonium standard
incorrect reference use recommended
filling solution filling solution

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Low Slope or standards contaminated prepare fresh
No Slope or incorrectly made standards
ISA not used use recommended ISA
standard used as ISA use ISA
defective electrode check electrode
operation
electrode exposed soak electrode
to interference in ammonium standard
air bubble on membrane remove bubble by
redipping probe
Noisy or Unstable defective meter check meter with
Readings (readings shorting strap
continuously or
randomly changing) air bubble on remove bubble by
membrane redipping electrode
defective electrode replace electrode
electrode exposed soak electrode
to interference in ammonium standard
meter or stirrer ground meter or
not grounded stirrer
outer filling solution fill electrode
level too low to level just below fill hole

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SPECIFICATIONS
Concentration Range: 1M to 5X10-6M (18,000 ppm to 0.01 ppm)
pH Range: 4 to 10
Temperature Range: 0o to 40oC (continuous)
40oto 50oC (intermittent)
Resistance: 100 megaohms
Reproducibility: ±2%
Samples: Aqueous solutions only; no organic solvents
Size: 110 mm length; 12 mm diameter; 1 m cable length
Storage: Electrode should be stored in dilute ammonium standard
ORDERING INFORMATION
CODE NO. DESCRIPTION
EC-NH4-03 Ammonium Ion Combination Electrode, epoxy body
EC-SCS-AM1-BT Ammonium Standard, 0.1 M NH4Cl
EC-SCS-AM2-BT Ammonium Standard, 1,000 ppm NH4+
EC-SCS-AM2-BT Ammonium Standard, 100 ppm NH4+
EC-ISA-AM1-BT Ammonium ISA (Ionic Strength Adjuster), 5 M NaCl

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TABLE OF CONTENTS
GENERAL INSTRUCTIONS ..........................................................................................................1
Required Equipment........................................................................................................................1
Required Solutions..........................................................................................................................1
GENERAL PREPARATION............................................................................................................2
Electrode Preparation......................................................................................................................2
Electrode Slope Check (with standard pH/mV meter)....................................................................2
Electrode Slope Check (with ion meter).........................................................................................2
MEASUREMENT..............................................................................................................................3
Measuring Hints..............................................................................................................................3
Sample Requirements......................................................................................................................3
Units of Measurement.....................................................................................................................3
MEASUREMENT PROCEDURE ...................................................................................................4
Direct Measurement........................................................................................................................4
Direct Measurement of Ammonium (using a standard pH/mV meter)...........................................4
Direct Measurement of Ammonium (using an ion meter)..............................................................5
Low Level Ammonium Determination (using a standard pH/mV meter) ......................................6
Low Level Ammonium Determination (using an ion meter)..........................................................7
ELECTRODE CHARACTERISTICS.............................................................................................7
Reproducibility................................................................................................................................7
Interference......................................................................................................................................7
Temperature Influences...................................................................................................................8
Electrode Response.........................................................................................................................9
Electrode Storage ............................................................................................................................9
Detection Limit ...............................................................................................................................9
pH Effects......................................................................................................................................10
Electrode Life................................................................................................................................10
ELECTRODE THEORY................................................................................................................10
Electrode Operation ......................................................................................................................10
TROUBLESHOOTING ..................................................................................................................11
Troubleshooting Guide..................................................................................................................11
Meter .............................................................................................................................................11
Electrodes......................................................................................................................................11
Standard.........................................................................................................................................12
Sample...........................................................................................................................................12
Technique......................................................................................................................................12
TROUBLESHOOTING HINTS.....................................................................................................13
SPECIFICATIONS..........................................................................................................................15
ORDERING INFORMATION.......................................................................................................15