Principle

Zinc is a colorimeteric test. This test uses 4 separately packed reagents.

The Indian Standard for drinking water holds that the acceptable limit is 5 mg/L, but in the absence of any other toxic substances or an alternate source, this is relaxable upto 15 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
0.1 mg/l 2
0.25 mg/l 5
0.5 mg/l 10
1 mg/l 20
2.5 mg/l 50
5 mg/l 100

Minimal Calibration

Standard Drops
0 mg/l 0
0.05 mg/l 10
2.5 mg/l 50

Take 5 ml of the 0 mg/l Zinc standard, and add 10 drops of Zinc Reagent A, 5 drops of Zinc Reagent B, 5 drops of Zinc Reagent C, and 3 drops of Zinc Reagent D, and shake well.

  • 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 Zinc.
  • 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.
  • This test takes 10 minutes (600 seconds) to develop ideal colour. Click on Start Timer to start a timer, or you can Skip Delay if you have already waited 5 minutes.
  • You should have your first calibration point. Repeat similarly with the other calibration points.

Test

This test uses the four Zinc Reagents.

  • Collect 5 ml of sample water, add 10 drops of the Zinc Reagent A, 5 drops of Zinc Reagent B, 5 drops of Zinc Reagent C, and 3 drops of Zinc Reagent D, and place in the white cuvette.
  • Place the cuvette under the light box and turn it on.
  • Place the phone over the stand.
  • From the home screen choose Colorimetric Test > Water > Zinc.
  • 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.
  • This test takes 10 minutes (600 seconds) to develop ideal colour. Click on Start Timer to start a timer, or you can Skip Delay if you have already waited 5 minutes.
  • After some time, the app will display a result.