Instruction Manual
Cyanide Electrode
5
1.
Prepare standard cyanide solutions whose concentrations vary by tenfold. Use either the
1.0X10
-2
M or the 1,000 ppm cyanide standard. Use the serial dilution method for this
preparation.
2.
To a 150 ml beaker, add 100 ml of the lower value standard and 1 ml of ISA. Place the
beaker on a magnetic stirrer and begin stirring at a constant rate. Lower the electrode tips
into the solution. Assure that the meter is in the concentration mode.
3.
Adjust the meter to the concentration of the standard and fix the value in the memory
according to the meter manufacturer's instructions.
4.
Rinse the electrodes with distilled water and blot dry.
5.
To a 150 ml beaker, add 100 ml of the higher value standard and 1 ml of ISA. Place the
beaker on a magnetic stirrer and begin stirring at a constant rate. Lower the electrode tips
into the solution.
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
TROUBLESHOOTING
section 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 the beaker.
Always rinse the electrodes with distilled water and blot dry between measurements. Use a clean,
dry tissue to prevent cross contamination.
When making low level measurements (below 1X10
-5
M), use only plastic lab-ware and cover the
beaker with Parafilm to avoid loss of cyanide. When making high cyanide measurements (above
1X10
-3
M), samples should be diluted before measurements.
Use fresh standards for calibration. Use 1 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