Reversed-phase ion-pair chromatography with UV-absorbing ions in the mobile phase

Ion-pair reversed phase liquid chromatography-indirect conductivity detection and response deviations of underivatised amino acids

“…Two additional negative system peaks are induced which are additional perturbations from the injections of Pro and Ile. This phenomenon has already been observed previously [38] and theoretically explained by Crommen et al [32] for ion-pair indirect UV detection. According to these studies when the solute and the detectable mobile phase ion (the probe) have the same charge, the solute peaks are positive if they are eluted before the elution of the system peak and negative after, whereas when the solute and the probe have opposite charges the response pattern is reversed.…”

System peaks and their positive and negative aspects in chromatographic techniques

“…When the mobile phase contains unknown impurities, problems of indirect detection may occur [57]. Moreover, particularly large system peaks appear if the mobile phase gives a detector response itself and the injected sample is dissolved in a different solvent [22,56,58]. Indirect detection is a sensitive method for visualization of all kinds of compounds and can be combined with any sensitive and stable detector.…”

Basic Principles of Chromatography

“…Strong solvents (i.e., those that are retained in a pure weak solvent) compete with components of the sample for adsorption. For this reason, a pulse of a weak solvent generates as many peaks as there are components in the mobile phase [43], [44]. These peaks are called system peaks [44].…”