Cuttica,1 Bulli and Fernandes,2 have reported the use of the triple nitrite compound, K2PbCo(NO2)6 as a sensitive test for the qualitative detection of potassium. They report a sensitivity of 1 part potassium in 10,000 parts water.
Proceedings of the Iowa Academy of Science
©1936 Iowa Academy of Science, Inc.
Kelm, Everett F. and Wilkinson, J. A.
"The Determination of Potassium as Triple Nitrites,"
Proceedings of the Iowa Academy of Science, 43(1), 169-170.
Available at: https://scholarworks.uni.edu/pias/vol43/iss1/29