ABSTRACT
In the past few years ion pairing has become an important technique for the liquid chromatographic (LC) separation of acidic and basic organic compounds. The use of ion pairing as a means of improving detection is relatively new and just beginning to show its potential in LC. Pre-column ion pairing includes the systems where the counterion is added to the chromatographic system prior to chromatography, as in normal ion-pair chromatography. Prechromatographic counterion addition refers to the addition of the counterion to the chromatographic system, that is, to either the stationary or the mobile phase. The ion-pairing approach becomes particularly attractive for such compounds as tertiary amines, which are difficult to derivatize into suitable products for detection purposes. Because ion-pair formation is relatively fast, post-column mixing is always possible, making the technique suitable for automation, a feature that is more limited when actual chemical reactions are involved.
