Principle

Fluoride is a colorimeteric test. This test uses a modified SPADNS reagent.

The Indian Standard for drinking water holds that the acceptable limit is 1 mg/l, but in the absence of any other toxic substances or alternate source, this is relaxable upto 1.5 mg/l.

Calibration

To prepare calibration standards, take 5 ml of distilled water. Depending on if you chose minimal or full calibration, prepare standards as below.

Full Calibration

Standard Drops
0 mg/l 0
0.5 mg/l 1
1 mg/l 2
1.5 mg/l 3
2 mg/l 4

Minimal Calibration

Standard Drops
0 mg/l 0
1 mg/l 2
2 mg/l 4

Take 5 ml of the 0 mg/l Fluoride standard, and add 5 drops of the Fluoride reagent.

  • Take the resulting coloured solution and fill it into the white cuvette provided.
  • Place the cuvette under the light box and turn it on.
  • Place the phone over the stand.
  • Go to Settings > Colorimetric Test > Calibrate and choose Fluoride.
  • Select the calibration point, 0 mg/l in this case.
  • Click on Start Camera.
  • Position the cuvette so that the middle, most uniformly lit portion is within the circle.
  • Select Analyze.
  • You should have your first calibration point. Repeat similarly with the other calibration points.

Test

This test uses the Fluoride reagent.

  • Collect 5 ml of sample water, add 5 drops of Fluoride reagent and place in the white cuvette.
  • Place the cuvette under the lightbox and turn it on.
  • Place the phone over the stand.
  • From the home screen choose Colorimetric Test > Water > Fluoride.
  • Choose No Dilution if this is the first test, you might have to dilute the sample and retry later if you get an error.
  • Click on Start Camera.
  • Position the cuvette so that the middle, most uniformly lit portion is within the circle.
  • Select Analyze.
  • After some time, the app will display a result.