How did we test the Potassium (K) in water?

Answer 1

you can test potassium in water by a standard procedure wich is called,atomic absorption spectrophotometry.

Answer 2

Potassium and its compounds emit a violet color in a flame. This fact is the basis of the flame test for the presence of potassium in a sample.

Answer 3

Although testing with atomic adsorption spectrometry can be done ... another easy and cheap way is simple volumetric titration techniques with suitable standard solution along with indicator.