Zum qualitativen Nachweis von Kalium, Rubidium und Caesium auf nassem Wege: eine kritische Betrachtung

Qualitative test for potassium using sodium tetraphenylboron

“…Probably because of supersaturation, neutral solutions containing less than 10~4 M K+ were found to give no observable precipitate with 0.1 M reagent. This is in qualitative agreement with the sensitivity determinations reported by Amin (9), Crane (10), and Geilmann and Gebauhr (15). Concentrations of K+ of the order of 10-1 M are often found in student unknowns as the result of traces of K+ in reagents, or possibly from storage in soft glass reagent bottles.…”

Absorptiometric Method for Determination of Cesium

“…A number of methods have been reported in recent years for determining small quantities of cesium (less than 1 mg.) but only a few were absorptiometric methods (6,7). As cesium is commonly encountered only in small amounts, the absorptiometric approach is especially appropriate as a means of determination.…”

“…or dipicrylaminate. dissolving the colored precipitate, and measuring the color intensity of the resultant solution, are also applicable to the determination of rubidium and potassium (6,7).…”