EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF POTASSIUM BY DIBENZO-18-CROWN-6 AND CALMAGITE AND ITS APPLICATION TO BIOLOGICAL-FLUIDS

A simple and sensitive extraction-spectrophotometric method for the determination of potassium is reported. The method is based on the extraction of a ternary crown-potassium-calmagite complex from aqueous solution into chloroform followed by spectrometric measurements. The Beer's law is obeyed over the range of 0.25-6.0 ppm at 495 nm with a molar absorptivity of 5.9 x 10(3) 1 mol-1 cm-1. The Sandell's sensitivity for 0.001 absorbance unit is 6.6 ng cm-2. Potassium ion can be separated from most alkali and alkaline earth cations as well as the biologically important anions. The method was used for analysis of potassium in blood serum, urine and nonalcoholic beer.