Application of Ionic Liquids as Mobile Phase Additives for Simultaneous Analysis of Nicotine and Its Metabolite Cotinine in Human Plasma by HPLC–DAD

Abstract

Nicotine and cotinine are very polar basic molecules, which makes it difficult to analyze them by reversed-phase liquid chromatography (RPLC), especially in biological samples. Additives with an ionic character have been traditionally used in RPLC as silanol suppressors. The aim of our study was to investigate the potential of selected ionic liquids in improving chromatographic performance in comparison with common additives. The experimental design was conducted using the following ionic liquids as the mobile phase modifiers: 1-butyl-3-methylimidazolium tetrafluoroborate, BMIM[BF4] and 1-butyl-3-methylimidazolium hexafluorophosphate BMIM[PF6], with a C18 chromatographic column. The separation of these alkaloids on silica-based RPLC stationary phases was successfully conducted by the addition of BMIM[BF4] in an acetonitrile:phosphate-buffer-based mobile phase in a pH range of 2.3–5.2. The presented chromatographic method can be used as alternative for monitoring studies or pharmacokinetic application necessary for the evaluation of tobacco smoke exposure.

Unveiling Novel Chaotropic Chromatography Method for Determination of Pralidoxime in Nerve Agent Antidote Autoinjectors

“…This reduces the chromatographic resolution, owing to complex matrix interference, and baseline disturbances at t0 can adversely affect the accurate quantification of the object to be analyzed [10,18]. For the HPLC separation of highly polar molecules, analytical methods such as the derivatization of the corresponding compounds, using a hydrophilic interaction chromatography (HILIC) column as a stationary phase, or adding ion-pairing reagents to the mobile phase are typically employed [19][20][21][22][23][24].…”

“…This reduces the chromatographic resolution, owing to complex matrix interference, and baseline disturbances at t0 can adversely affect the accurate quantification of the object to be analyzed [10,18]. For the HPLC separation of highly polar molecules, analytical methods such as the derivatization of the corresponding compounds, using a hydrophilic interaction chromatography (HILIC) column as a stationary phase, or adding ion-pairing reagents to the mobile phase are typically employed [19][20][21][22][23][24]. To solve these problems, cation-exchange chromatography, size exclusion chromatography, ion-pair chromatography (IPC), reverse-phase chromatography, normal-phase chromatography, capillary electrophoresis, and several other analytical methods have been reported [25][26][27][28][29].…”