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Optimal
mV for ISE calibration
Ammonium mV values
• NH4 1 mg/L = 0 mV +/- 20 mV (new sensor only)
• NH4 100 mg/L = 90 to 130 mV greater than the mV reading in the 1 mg/L standard
• The mV span between 1 mg/L and 100 mg/L values should be approximately 90 to 130 mV.
The slope should be 45 to 65 mV per decade of ammonium concentration in mg/L
Nitrate mV values
• NO3 1 mg/L = 200 mV +/- 20 mV (new sensor only)
• NO3 100 mg/L = 90 to 130 mV less than the mV reading in the 1 mg/L mV standard
• The mV span between 1 mg/L and 100 mg/L values should be approximately 90 to 130 mV.
The slope should be -45 to -65 mV per decade of nitrate concentration in mg/L
Chloride mV values
• Cl 10 mg/L = 225 mV +/- 20 mV (new sensor only)
• Cl 1,000 mg/L = 80 to 130 mV < 10 mg/L mV value
• The mV span between 10 mg/L and 1000 mg/L values should be approximately 80 to 130 mV.
The slope should be -40 to -65 mV per decade of chloride concentration in mg/L
ISE Calibration
YSI recommends a 2-point calibration for ISEs. For best results, use standards that
differ by 2 orders of magnitude:
• 1 mg/L and 100 mg/L for Ammonium and Nitrate
• 10 mg/L and 1,000 mg/L for Chloride
1.
Fill the graduated cylinder to the appropriate level standard for calibration
point #1. Immerse the probe in the standard.
2.
Push the
Cal
key, then select the applicable ISE sensor.
3.
Select
Calibration value
and enter the value that corresponds to the first
calibration standard.
4.
Observe the actual measurement readings for stability (white line on
graph shows no significant change for 40 seconds), then select
Accept
Calibration
. “Ready for cal point 2” will be displayed in the message area.
5.
Discard the used standard and rinse the probe and graduated cylinder
with a small amount of the next calibration point standard. Discard the
rinse standard.
6.
Fill the graduated cylinder to the appropriate level with fresh standard for
the second calibration point. Immerse the probe in the standard.
7.
Select
Calibration value
and enter the value of the second calibration
standard.
8.
Observe the actual measurement readings for stability, and then select
Accept Calibration
. “Ready for cal point 3” will be displayed in the
message area.
9.
Select
Finish Calibration
to complete a 2-point calibration.
Sensors, Calibration, and Maintenance
