Go Direct® Potassium Ion-Selective Electrode (GDX-K)
Specifications and User Guide

-Primary Test: Check the readings in the standards. The high should be around 1000 mg/L. The low should be around 10 mg/L.
-Secondary Test: Refer to General tips for using Ion Selective Electrodes (ISE).

How do I calibrate my sensor?
Do any of your sensors require special storage?
Do you sell ISE Standards?
How do I sterilize an Ion-Selective Electrode?

-Range: 1 to 39,000 mg/L or ppm
-Interfering ions: Rb2+, Cs2+, NH4+, Ca2+, Mg2+, Li+
-Approximate calibration voltages: 166 mV (1000 ppm), 50 mV (10 ppm)
-Reproducibility (precision): ± 11% of full scale
-Accuracy: ±16 % of full scale
-Temperature range (can be placed in): 0 to 40°C (no temperature compensation)
-Electrode slope: +56 ± 3 mV/decade at 25 degC
-pH range: 2 to 12 (no pH compensation)
-Minimum immersion: 1.1 inch
-dimension ISEA: 8.5 cm height × 3 cm wide × 1.75 cm depth
-dimension electrode: 15.5 cm length, 12 mm OD
-shaft diameter: 12mm OD

-Calibrate? Yes. Conduct a two-point calibration, using the standard solutions that are shipped with the sensor. First point: The ISE should be soaking in the High Standard. Enter the concentration value of the High Standard. Second point: Remove the ISE from the High Standard, rinse well with distilled water from a wash bottle, and gently blot dry with a paper towel or lab wipe. Place the electrode into the Low Standard. Wait until the relative stability reading stabilizes; this may take several minutes. Enter the concentration value of the Low Standard.
-Important: Make sure the ISE is not resting on the bottom of the container and that the small white reference contacts are immersed. Make sure no air bubbles are trapped below the ISE. Hold the ISE still and wait for the voltage reading to stabilize.

If the sensor can be turned on when connected by USB but not when disconnected from USB, the battery either needs charging or has reached its end of life and can no longer hold a charge. First, try charging the sensor for several hours. If the sensor still won’t turn on when disconnected from USB, the battery has likely reached its end of life. If you intend to use this sensor wirelessly, the battery will need to be replaced. The rechargeable battery in this sensor is covered by a one year warranty but should last two to five years in typical use.
How do I replace the battery in a Go Direct Wand-Type Sensor?

-Potassium ISE Replacement Module, Potassium Replacement Module (K-MOD)
-Potassium ISE Low Standard, Standard Potassium Solution (K-LST)
-Potassium ISE High Standard, Standard Potassium Solution (K-HST)