Liquid chromatography with alkylammonium formate ionic liquid mobile phases and fluorescence detection

Area of Science:

• Analytical Chemistry
• Biochemistry
• Physical Chemistry

Background:

• Ionic liquids (ILs) are novel solvents with tunable properties.
• High viscosity of IL-water mixtures may enhance fluorescence detection.
• Understanding ILs' effects on biomolecules is crucial for analytical applications.

Purpose of the Study:

• To investigate the impact of alkyl ammonium formate ionic liquids on fluorescence detection of various compounds.
• To explore the potential of ILs and PEG 8000 in enhancing HPLC analysis of biomolecules.

Main Methods:

• Fluorescence spectroscopy was used to study low and high molar mass compounds in IL-water mixtures.
• High-Performance Liquid Chromatography (HPLC) with reversed-phase elution was employed for LDH analysis.
• The effect of varying concentrations of ethylammonium formate (EAF), isopropylammonium formate (IPAF), and Polyethylene glycol 8000 (PEG 8000) was examined.

Main Results:

• Warfarin fluorescence enhanced by factors of 4 (80% EAF) and 7 (70% IPAF).
• Tryptophan fluorescence was enhanced by both EAF and IPAF.
• Bromadiolone showed fluorescence enhancement with EAF.
• LDH peak intensity and activity were significantly enhanced with 6% PEG 8000 in the mobile phase.
• Higher PEG 8000 concentrations led to reduced stabilization and increased viscosity.

Conclusions:

• Alkyl ammonium formates can selectively enhance fluorescence of specific pharmaceuticals and tryptophan.
• PEG 8000 at 6% is effective in improving LDH detection in HPLC.
• Viscosity and concentration-dependent effects of ILs and PEG 8000 need careful consideration for optimal analytical performance.