Instructions for Using Orthophosphate Test Kits

The Hach Orthophosphate Kit causes a chemical reaction to occur in a sample of river water. This chemical reaction is evidenced by a colour change and is measured using a colour comparator.

There is a source of error introduced with this test because of the difficulty in comparing and matching colours. Fainter colours at lower concentrations are hardest to match. Observers should get a second opinion when judging colour matches.

This test kit uses the contents of one chemical powder packet added to a river water sample.

Click here to for a listing of the powder packet contents.

WARNING: The chemicals in this kit may be hazardous to the health and safety of the user if inappropriately handled. Please read all warnings carefully before performing the test and use appropriate safety equipment.

1. Place the test kit on the ground in a safe, dry place.



2. Fill two square mixing bottles to the 20-ml mark with river water.



3. Wear safety goggles and gloves to open one powder packet containing PhosVer 3 reagent. Pour the contents into one of the square mixing bottles and swirl to mix. This is the prepared sample. Discard the empty packet into the garbage bag provided.



4. Let the solution stand 8 but no longer than 10 minutes. If phosphate is present in the sample, a blue-violet colour will develop.



5. Pour the prepared sample solution into one of the test tubes up to the 20 mL mark. Insert this test tube into the inside hole on top of the black colour comparator box.



6. Pour the untreated sample water from the second square-mixing bottle into the second test tube up to the 20-mL mark. Insert the test tube into the outside hole on top of the black colour comparator.



7. Hold the colour comparator up to the sky or sun and look through the two openings in the front. Rotate the colour wheel until a colour match is obtained. Read the number on the colour wheel scale.



8. Have another person try matching the colours and then read the number scale. Agree on the best value.



9. Find your colour wheel value on a Phosphate Conversion Chart. Choose the correct low range phosphate concentration. Record this result on your data sheet.



10. Clean-up by pouring all chemical solutions into the Phosphate Waste Bottle. Use the untreated sample water to rinse the containers and add the rinse solution to the waste bottle.