For Go Direct ISEs (order codes begin with GDX-), simply enable the sensor’s mV channel in the app.

For most LabQuest ISEs (order codes end in -BTA), there is an experiment file within Probes & Sensors–>ISE folder in Logger Pro (version 3.4 or newer) that converts the output to mV. (Note: There is not an experiment file for the Potassium ISE. See the equation option below.)

If you are using software other than Logger Pro, the mV output of the electrode can be calculated using the following equations:

For the Nitrate ISE, the equation that converts mg/L to mV is:
23.92*(13.8-ln(“Nitrate (mg/L)”))-168.23 = Nitrate (mV)

For the Chloride ISE, the equation that converts mg/L to mV is:
23.907*(18.415-ln(“Chloride (mg/L)”))-168.23 = Chloride (mV)

For the Calcium ISE, the equation that converts mg/L to mV is:
-11.96*(-14.942-ln(“Calcium (mg/L)”))-168.23 = Calcium (mV)

For the Ammonium ISE, the equation that converts mg/L to mV is:
-23.889*(-7.487-ln(“Ammonium (mg/L)”))-168.23 = Ammonium (mV)

For the Potassium ISE, the equation that converts mg/L to mV is:
-23.5*(-7.2-ln(“Potassium(mg/L)”))-168.23 = Potassium (mV)

These equations provide the mV output of the electrode, before amplification. If you want post-amplification Volts, the equation is:

V = 0.00727*mV + 1.223