Phosphate In Water Test

Testing Phosphate in water is notoriously difficult involving reagent kits and portable colorimeters. EDT directION have developed a rapid and accurate test method involving a unique Phosphate ISE and which is compatible with our QP459 Portable Ion Meter. The Phosphate concentration is directly read in ppm and a result is achieved within 3 minutes. The test is designed for a range of 0-100ppm Phosphate so higher value samples can be diluted to suit.

Image showing a portable ion meter.
Image showing a combination Ion Selective Electrode.
Image showing a bottle of standard solution.

Phosphate in Water:  The Method

Required Items:

Phosphate ISE-KIT (3292/KIT)

Phosphate Standards 10 and 100ppm

QP459 Portable Ion Meter

100ml Beaker, 50ml Measuring Cylinder.

The Method

The concentration of Phosphate in aqueous samples is determined indirectly by the use of a Phosphate ISE and the addition of two reagents to the sample being measured.

Please note:

  1. This method requires the use of a QP459 Ion Meter
  2. Calibration requires the use of EDT directION Phosphate Standards only.
  3. The test requires 50ml of sample and 5 ml additions of reagent A and Reagent B prior to measurement.
  4. The test is for Phosphate concentration of between 0 and 120ppm. For concentrations higher than this please dilute the sample with deionised water.



  1. Select the Phosphate Mode on the QP459 Meter
  2. Ensure the Phosphate ISE has been conditioned by standing in the low standard for 20 minutes.
  3. Insert the ISE into the 10ppm Standard and follow the CAL procedure on the QP459 meter.
  4. Measure out 50ml of each sample into a plastic beaker.. Add 5ml of Reagent A (Green Top) with the syringe provided. Stir and leave for at least 1 minute. Add 5ml of Reagent B (Red Top) with the syringe provided. Stir and leave for at least 1 minute.
  5. Follow the instructions on the QP459 to measure the samples.

After measuring the samples rinse electrode with DI water and store dry. Ensure the green and red syringes are used for their own reagents only. Seal all standards and reagent after use.

For any assistance with your measurements please email or call us on 01304 600960.