Instruction Manual
Iodide Electrode
5
6.
Adjust the meter to the concentration of the standard and fix the value in the memory.
7.
Read the electrode slope according to the meter manufacturer's instructions. Correct
electrode operation is indicated by a slope of 93-100%. See the
TROUBLESHOOTING
sections if the slope is not within this range.
MEASUREMENT
Measuring Hints
All samples and standards should be at the same temperature for precise measurement. A difference
of 1
o
C in temperature will result in about a 2% measurement error.
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, between the stirrer and beaker.
Always rinse the electrodes with distilled water and blot dry between measurements. Use a clean,
dry tissue to prevent cross contamination.
For samples with high ionic strength, prepare standards whose composition is similar to the sample.
Dilute concentrated samples (>0.1M) before measurement.
Use fresh standards for calibration.
Use 2 ml of ISA for each 100 ml of sample or standard.
Always check to see that the membrane is free from air bubbles after immersion into the standard or
sample.
Sample Requirements
All samples must be aqueous and not contain organics which can dissolve the epoxy electrode body
and/or the cement bonding the sensing crystal to the electrode body. Infrequent measurements in
solutions containing methanol, benzene, or acetonitrile are permitted. Highly polar solvents slowly
attack the electrode. Please check with Eutech Instruments Pte Ltd. before using these electrodes in
other organic solvents.
The temperature of the sample solutions and of the standard solutions should be the same and below
80
o
C.
The pH range for the iodide ion electrode is 0-14. Neutralize samples outside this range with acid or
base to bring them in range.
Interferences should be absent. If they are present, use the procedure found in the
Interference
and
Electrode Response
sections to remove them.
Units of Measurement