Flow injection of lithium ion using chromogenic 14-crown-4 derivatives as extraction-spectrophotometric reagents

Abstract

A system for flow injection of Li⁺ has been designed, with use of proton-dissociable chromogenic 14-crown-4 derivatives as the extraction-spectrophotometric reagents, and the analytical conditions have been optimised. This flow injection system showed high selectivity for Li⁺ reflecting the cation-complexing property of the chromogenic crown ethers. The determination of Li⁺ in the clinical range in blood under a high Na⁺ background of 130–160 mM was feasible, with a small sample size (50 µl) and high sampling rate (more than 100 injections per hour), with this method. The proposed extraction-spectrophotometric flow injection system was, therefore, found to be promising for the efficient determination of Li⁺ in biological samples, such as blood sera, with a high Na⁺ background.