An electric detector of direct current for inorganic ions on chromatographic paper during development: Electrometric determination in chromatographic development. I

Inorganic ions being separated by paper chromatography are estimated continuously by means of an electric method. Filter paper is clamped in due position with opposing two electrodes applied with D. C. voltage. When the developed inorganic ions come across the line of electrodes, an abrupt change in electric current is observed. A calibration curve is obtained from the height or area of the peak in the currenttime diagram. The value corresponding to Rf in paper chromatography (represented as Rφ for convenience) is given by the ratio of the distance from electrodes to original point and that from original point to the solvent front when the current reaches its maximum, and is constant for each ion. By selecting an organic solvent diffusing rapidly such as methanol for the developer the separation of peak is clear and the sensitivity of electric current is high. For example, there appears an intensive change of current 10500 μA for 550 μg of Na+ or K+. Micro estimation by chromatography of alkali metals such as Na+ and K+is possible by this simple and rapid method.