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45 Calibration
3.9
Optimal mV for ISE calibration
Ammonium mV values
• NH
4
1 mg/L = 0 mV +/- 20 mV (new sensor only)
• NH
4
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
• NO
3
1 mg/L = 200 mV +/- 20 mV (new sensor only)
• NO
3
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
ISEs
Ammonium, Nitrate, & Chloride
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
ISE Calibration
1. Fill the calibration cup 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 calibration cup
with a small amount of the next calibration point standard. Discard
the rinse standard.
6. Fill the calibration cup 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 ( Figure 60 ). “Ready for cal point 3” will
be displayed in the message area.
9. Select Finish Calibration to complete a 2-point calibration.
Figure 60 Calibrate ISE