[Determination of imidazolium ionic liquid cations by ion-pair chromatography using gradient elution]

Area of Science:

• Analytical Chemistry
• Separation Science

Context:

• Ionic liquids (ILs) are versatile compounds with applications in various fields.
• Accurate determination of IL cations is crucial for quality control and research.
• Existing analytical methods may lack the sensitivity or specificity required for certain IL analyses.

Purpose:

• To develop and validate an ion-pair chromatography method for the quantitative determination of five imidazolium ionic liquid cations.
• To optimize chromatographic conditions, including ion-pair reagent concentration, mobile phase composition, and column temperature.
• To assess the method's performance in terms of detection limits, precision, and accuracy.

Summary:

• A novel ion-pair chromatography method utilizing ultraviolet-visible spectrophotometry (UV/VIS) detection was established for five imidazolium ionic liquid cations.
• Separations were achieved on a ZORBAX Eclipse XDB-C18 column using 1-heptanesulfonic acid sodium and acetonitrile as the eluent system.
• The study investigated the impact of ion-pair reagent concentration, acetonitrile percentage, and column temperature on cation retention, achieving detection limits of 0.05–0.30 mg/L with <0.1% RSD.
• The method demonstrated successful application to the analysis of laboratory-synthesized ionic liquids, yielding high cation recovery rates (98.6%–102.1%).

Impact:

• Provides a sensitive and precise analytical method for imidazolium ionic liquid cation determination.
• Facilitates the quality control and characterization of synthesized ionic liquids.
• Contributes to the advancement of chromatographic techniques for ionic liquid analysis.