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Saurabh Levin edited this page Aug 29, 2018 · 9 revisions


Calibration is the process of setting up your device (in this case - your phone) to return accurate values. A phone needs to be calibrated individually for every parameter that it is testing for. The process of calibration is roughly the same for all parameters, so for this tutorial, we will focus on calibrating for fluoride testing. The only difference between the parameters is the range of standards required. For that information, refer to the table below:

Parameter Test type Units Values
Fluoride Water ppm 0, 0.5, 1.0, 1.5, 2.0
pH Water - 4, 5, 6, 7, 8, 9, 10
Nitrate Water ppm 0, 10, 25, 50, 75, 100
Phosphate Water ppm 0, 0.3, 0.6 ,0.9, 1.2, 1.5, 2.0
Iron water ppm 0, 0.5, 1.0, 1.5, 2.0
Iron water ppm 0, 0.5, 1.0, 1.5, 2.0

Things You Will Need

  1. A range of calibration standards. Refer to the table above for specific values for each test.

  1. A smartphone with the ffem Collect and ffem Water apps installed, and an alignment sticker around the camera

  2. A Cuvette and pipe

  3. A 10 ml measuring tube

  4. Tissue Paper

  5. Reagent necessary to test for the analyte you are calibrating for


  1. Open the ffem Water app, and select "Calibration".
  1. Select the test that you want to calibrate for. In the next screen, you will see a page with empty calibration points and an edit button
  1. Tap the edit button. You will be prompted to enter a calibration expiry date. Refer to the table above for details on when the calibration will expire, and input the date accordingly.

  1. This part of the process is similar to testing for a parameter. Begin with the first calibration point, measure out the required volume of the corresponding standard, and conduct a test with it, as you would if you were testing. However, instad of running a test from FFEM Collect, tap the corresponding calibration point (i.e, if you are calibrating the 0.0 mg/l point, run a test with the 0.0 mg/l standard and tap that corresponding calibration point.

  1. After hearing the "Test Completion" sound, you will have calibrated your first point. Repeat the process with all the other standards and calibration points.
  1. Your phone is now calibrated. You may begin testing samples. If there are any errors in the calibration, recalibrate any point that looks off

Dilution Ranges

Validation Testing

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