High Range Test (3-12 mg/L DO)

Use scissors to carefully open chemical packets. Do not spill contents.

1. Record the temperature of the water you have collected.

2. Rinse the DO bottle and stopper & the square mixing bottle with distilled water.

3. Pour sample water into the DO bottle to the very top.

4. Place bottle on paper towel on table.

5. Drop glass stopper into liquid in bottle.

6. Leaving stopper firmly in, pour off extra water from top.

7. Remove stopper. Add 1 DO reagent #1 packet and 1 DO reagent #2 to the bottle.

8. Restopper. If an air bubble is in the bottle, place small amount of sample water in top, raise stopper, and then allow stopper to go down again with no air bubbles. (Air bubbles will add more oxygen to your sample!)

9. Hold stopper with thumb. Shake upside down about 15-20 shakes.

10. Set DO bottle on table to rest until brown solid particles are lower than the 1/2 way mark on the bottle.

11. Reshake again 15-20 times and let sit like step #9.

12. Remove stopper and add 1 DO reagent #3 packet..

13. It is now ok if air bubbles are in the bottle!

14. Replace stopper and shake well.

15. Fill the thin measuring tube with colored liquid from the DO bottle. Add to the square mixing bottle.

16. Add a 2nd measuring tube of colored liquid to the square mixing bottle.

17. Add 1 drop Sodium Thiosulfate to the square mixing bottle & mix well.

18. Add a 2nd drop of Sodium Thiosulfate to the square mixing bottle & shake.

19. Continue adding drops of Sodium Thiosulfate, making sure you count the total number of drops (probably somewhere between 3 and 24 drops).

20. You are done when the colored liquid in the bottle changes from yellow to clear. Hold the bottle against white paper to be sure!

21. If you used 6 drops or more of Thiosulfate, divide the # of drops by two.

22. This is the Dissolved Oxygen content of the water. Record this on your data sheet.

23. Dump contents of DO bottle and mixing bottle in Oxygen Waste bottle.

24. Rinse all equipment with distilled water.

25. Retest with new water sample. Follow steps 3-24.