Solvent extraction of calcium with 18-crown-6 and its separation from strontium and barium in picrate solution

Abstract

Calcium was extracted at pH 3.0–9.0 with 0.01 M 18-crown-6 in methylene chloride with 0.01 M picric acid as the counter ion. Calcium was then stripped with 1 M hydrochloric acid and determined by flame atomic emission spectrometry at 423 nm. Calcium was separated from other alkali and alkaline earth elements and common anions at large concentration ratios. The sequential separation of calcium, strontium and barium was shown to be possible. The method was extended to the determination of calcium in blood serum, milk and plant seeds.