MATERIALS and procedure
- Fill the Dissolved Oxygen bottle with water sample. Let the water overflow.
- Add the contents of one Dissolved Oxygen 1 Powder Pillow and one Dissolved Oxygen 2 Powder Pillow.
- Immediately put the stopper on the bottle. Make sure that no air bubbles are below the stopper. Shake the bottle vigorously.
- A brown-orange floc will develop. The floc slowly falls. Wait until the top half of the bottle is clear.
- Shake the bottle again. Wait until the top half of the bottle is clear.
- Remove the stopper. Add the contents of one Dissolved Oxygen 3 Powder Pillow.
- Immediately put the stopper on the bottle. Shake the bottle. The floc dissolves and a yellow color develops.
- Pour the prepared sample from the bottle until the volume in the bottle is 30 mL.
- Add the Sodium Thiosulfate solution by drops. Swirl to mix after each drop. Count the drops until the color changes to colorness.
- Multiply the number of drops of titrant solution by 0.2 to get the result in mg/L.