LaMotte AM-21 Water Pollution Detection Outfit - Manual (Page 30)

5. Fill a second test tube (0804) to the lower line marked “B” with
deionized or cyanide free tap water and add this amount to a second cell
on the demonstration stage. Mark this as the “Reference Sample.”
Compare the colors of the liquid in the two cells.
6. Add two drops of *Cyanide Reagent #2 (7389) to the Reference Sample
and mix by stirring with the Spatula (0691).
7. Add *Cyanide Reagent #3 (7390) one drop at a time to the Reference
Sample until the color matches the color of the Test Sample. Each drop
of *Cyanide Reagent #3 (7390) added is equal to 0.05 ppm Cyanide.
NOTE: If a strong oxidizing agent, such as chlorine, bromine, hydrogen
peroxide, or permanganate, is present in the sample to be tested,
the cyanide test may give a false positive indication that cyanide is
present. It is strongly recommended that positive cyanide test results
be verified by a distillation procedure as given in “Standard
Methods,” APHA,15th Edition.
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