Detection of ions by replacement-ion chromatography coupled to a microwave-induced nitrogen discharge at atmospheric pressure

The capabilities and limitations of replacement-ion chromatography (RIC) using a lithium-based replacement method and a microwave-induced nitrogen discharge at atmospheric pressure as the detector are critically evaluated for the determination of anions and cations. The system, including chromatographic columns, interface, and plasma-emission source, provides detection limits of 30–300 ng for anions and 100–500 ng for cations. Detectability and precision of the instrument are ultimately limited by multiplicative noise sources. The limitations imposed by multiplicative noise on RIC detection are assessed, and guidelines are presented that will allow judicious choice of alternative RIC detectors in the future.