Principle

Chromium is a colorimeteric test. This test uses a 2, 5 diphenyl carbazide reagent.

The Indian Standard for drinking water holds that the acceptable limit is 0.05 mg/l and is not relaxable.

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
0.5 mg/l 10
1 mg/l 20
2 mg/l 30
3 mg/l 40

Minimal Calibration

Standard Drops
0 mg/l 0
20 mg/l 10
40 mg/l 20

Take 5 ml of the 0 mg/l Chromium standard, and add 2 drops of Chromium Reagent A and 5 Drops of Chromium Reagent B 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 Chromium.
  • 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 Chromium Reagent A and Chromium Reagent B.

  • Collect 5 ml of sample water, add 2 drops of Chromium Reagent A, and 5 drops of Chromium Reagent B, 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 > Chromium.
  • 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.