Instructions for Using the Dissolved Oxygen Test Kit

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 kit in a safe, dry place on the ground. Look for a water sample collection site upstream of other classmates in the river.



2. Use the Dissolved Oxygen (DO) Bottle to collect flowing river water. Slowly submerge the tilted bottle with the opening pointing downstream.



3. Fill the DO bottle to 1/2 way up the neck of the bottle. Do not stopper the bottle yet. Stand the bottle back in the test kit.



4. Wear safety goggles and gloves. Open a Dissolved Oxygen #1 Foil Packet and a Dissolved Oxygen #2 Foil Packet. Carefully tap the contents of each packet into the DO bottle. Discard the empty packets into the garbage bag provided. This solution should be rinsed off if skin contact occurs.



5. Place the glass stopper into the DO bottle. Press on the stopper and quickly tip any overflow solution from the top of the DO bottle into the DO Waste Bottle. If an air bubble is trapped under the stopper, ask your guide for help.



6. Grip the bottle and stopper firmly. Invert to mix. A brownish flocculent (floc) precipitate will form. If any powdered reagent is left stuck to the bottom of the bottle it will not affect the test results.



7. Place the DO bottle back in the test kit. Allow the sample to stand until the floc settles to the white line on the bottle. Invert the bottle again and let the floc settle a second time (4 to 5 minutes).



8. Use the clippers to open one Dissolved Oxygen #3 Powder Pillow. Carefully add the acid contents of the pillow to the DO bottle. Restopper the bottle and tip any overflow into the DO Liquid Waste Bottle. At this point, trapped air bubbles are not important. Invert to mix. The floc will dissolve and a yellow colour will appear if oxygen is present.



9. Work over top of the open waste bottle while completely filling the plastic measuring tube with the prepared DO sample. Use the upside down square mixing bottle as a lid, then quickly flip both containers to transfer the contents from the tube into the square mixing bottle.



10. Add Sodium Thiosulfate drop-by-drop into the square mixing bottle until the solution changes from yellow to colourless. Hold the dropper straight up and make sure that drops fall directly into the sample liquid. Swirl to mix after each drop and compare against a white background. Count each drop and record the total number added. Each drop = 1 mg/L dissolved oxygen.



11. Clean-up by pouring the DO bottle solution into the plastic DO Waste Bottle. Next, use the clear solution in the square mixing bottle to rinse the DO bottle and test tube. Add the rinse to the waste bottle. If crystals remain in the DO bottle, rinse with a full square-mixing bottle of river water, swirl and empty into the waste bottle. If crystals still remain, repeat the rinse process.