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

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.