Best practices for the Vernier Go Direct® Chloride Ion-Selective Electrode

[madparker]

We’ve started working with the “Go Direct® Chloride Ion-Selective Electrode,” which senses the chloride concentration in a solution. After some initial issues with determining the levels of chloride, I determined a few best practices:

1. the sensor is light sensitive, so it’s important top place it in a situation where you can completely control the light (I’ve chosen a closet in my apartment where I keep the light on and the door shut while testing, see picture below).

2. It’s best to fill the small bottle provided with the solution to test, then put the cap on the sensor, then insert the sensor into the bottle and screw the top on.

3. Between tests, it’s best to rinse the sensor with distilled water and then soak it in distilled water until the reading hit the baseline (in my case ~5 mg/L).

4. Try to keep the sensor completely upright the whole time.

5. The documentation advises you to soak the sensor for “at least 30 min.” I’ve found that it can take more or less time. I think the best practice is to wait at least 30 min and then wait until the curve in the software is flat for at least 10 min if it hasn’t gotten there already (see picture below).

[madparker]

Update:

After working with the sensor more, I have a revised process:

1. Rinse the testing bootle and sensor after each use, dry both gently. Allow at least an hour for air drying followed by an hour in the storage “bottle” provided with the sensor. (add picture)

2. Fill the sample bottle with the solution you wish to test. Insert the probe, with the top on it, screw the top on to the sample bottle. Keep the sensor 1 cm from the bottom of the bottle.

3. Allow the sensor to stand upright, soaking in the solution for at least 4 hours.

4. Turn on the sensor, connect via blue tooth. Wait 5 minutes.

5. Take 2 180 seconds collections from the sensor. If the chloride levels change significantly in the 2nd test, try again in an hour. If the second test reveals level chloride levels, you have reliable results.