Indirect detection in reversed-phase liquid chromatography : Response deviations in ion-pairing systems

Abstract Deviation effects in indirect detection have been studied in ion-pairing systems with several retained components in the eluent. The response extinction or reversal that appears in certain retention ranges have been given a theoretical explanation. Other response disturbances and peak deformations have been explained as due to pH instability and/or protolysis of the detectable eluent component (the probe) in the migrating compound zones. Principles are given for the design of indirect detection systems to optimize the sensitivity and avoid detection disturbances.