When a potassium salt is added to a solution of phosphotungstic acid a characteristic dense, white, difficultly filterable precipitate is formed. The test is as sensitive as any of the tests commonly used; one cc. of a ten percent solution will give an easily distinguishable precipitate with 1 cc. of 0.02 M potassium chloride. Ammonium, which also forms a very insoluble compound, interferes, and must first be removed.
Proceedings of the Iowa Academy of Science
©1936 Iowa Academy of Science, Inc.
Miller, S. Porter
"Phosphotungstic Acid as a Test for Potassium in Qualitative Analysis,"
Proceedings of the Iowa Academy of Science, 43(1), 179-179.
Available at: https://scholarworks.uni.edu/pias/vol43/iss1/37