Iminodiacetic acid functionalised monolithic silica chelating ion exchanger for rapid determination of alkaline earth metal ions in high ionic strength samples

Abstract

Iminodiacetic acid has been covalently bonded to a bare silica monolith to produce the first reported high-performance monolithic chelating ion exchange column. Using the new column, separation and determination of traces of alkaline earth metal ions (low ppm) in high ionic strength samples (up to 2 M NaCl and KCl brines), could be achieved in under 40 s. At an eluent flow rate of 4 mL min⁻¹ retention time precision was <1.2% (n = 9) for Mg(II) and Ca(II), with detector linearity (n = 5) over the range 2–10 mg L⁻¹ of between R² = 0.985 and R² = 0.995. In 1 M KCl and NaCl brine samples, detection limits of 0.2 mg L⁻¹ were possible.