Thermo Fisher Scientific Ion Selective Electrodes Ammonium User Manual

EUTECH INSTRUMENTS PTE LTD.

AMMONIUM ION ELECTRODE

INSTRUCTION MANUAL

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

Instruction Manual Ammonium Electrode

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 NH

Cl, 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 NH

, 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

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 20o and 25oC. See the

TROUBLESHOOTING section if the potential change is not within this range.

is defined as the change in potential observed when the concentration changes by a factor of

Slope

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

or the 1,000 ppm NH

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

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