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Instruction Manual

Ammonium Electrode

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

"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-

M = 18 ppm NH

+ =

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

Содержание AMMONIUM EPOXY

Страница 1: ...ck 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 NH4C...

Страница 2: ...he 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 20o and 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 ch...

Страница 3: ... 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 ...

Страница 4: ...ndard 2 Place the most dilute solution 10 4 M 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 3 M or 10 ppm on the magnetic stirrer and begin stirring After rinsing the electrode s with distilled wa...

Страница 5: ...mmonium 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 A...

Страница 6: ... 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 3 M or 100 ppm standard...

Страница 7: ...very 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...

Страница 8: ...e temperature since electrode potentials are influenced by changes in temperature A 1oC difference in temperature results in a 2 error at the 1 0X10 3 M 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...

Страница 9: ...d 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 1 M 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 f...

Страница 10: ...embrane 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...

Страница 11: ...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 c...

Страница 12: ...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 electro...

Страница 13: ... 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 3 M 18 ppm NH4 14 ppm as N sample carryover rinse electrodes thoroughly be...

Страница 14: ...monium 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 groun...

Страница 15: ...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 B...

Страница 16: ...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 ...

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