Selectivity enhancement on a poly(butadiene-maleic acid)-coated cation phase induced by ethylene oxide-based complexing agents

Abstract

Crown ethers as well as acyclic compounds bearing ethylene oxide units are well-known as complexing agents for different cations. They are mainly used as ionophores in ion selective electrodes. In ion chromatography some studies have been preformed using crown ether stationary phases. Using crown ethers as eluent components for the separation of alkali and alkaline earth metal cations on a poly(butadiene-maleic acid)-coated phase, it is possible to tune the selectivity to the special needs of the sample. An eluent with addition of 18-crown-6 elutes potassium after magnesium and calcium with an improved separation of sodium and ammonium compared to the same eluent without addition of 18-crown-6. In contrast, the addition of a polyethylene glycol improves the sodium ammonium separation without changing the elution order.