Rapid and sensitive analysis of microcystins using ionic liquid-based in situ dispersive liquid-liquid...

Area of Science:

• Analytical Chemistry
• Environmental Chemistry
• Green Chemistry

Background:

• Microcystins (MCs) are potent cyanotoxins contaminating water sources.
• Accurate detection of MCs is crucial for public health and environmental monitoring.
• Traditional extraction methods can be time-consuming and environmentally burdensome.

Purpose of the Study:

• To develop and optimize an in situ dispersive liquid-liquid microextraction (in situ DLLME) method for MC preconcentration.
• To evaluate the efficiency of different ionic liquids (ILs) as extraction solvents for MCs.
• To determine the analytical performance of the optimized method using HPLC-UV and HPLC-MS.

Main Methods:

• In situ DLLME was employed using three distinct ionic liquids: [BMIM][Cl], [HeOHMIM][Cl], and [BeEOHIM][Br].
• Extraction parameters including pH, IL ratio, sample volume, IL quantity, and salt concentration were optimized.
• Analyte quantification was performed using High-Performance Liquid Chromatography with Ultraviolet (HPLC-UV) and Mass Spectrometry (HPLC-MS) detection.

Main Results:

• The ionic liquid 1-benzyl-3-(2-hydroxyethyl)imidazolium bromide ([BeEOHIM][Br]) demonstrated the highest extraction efficiency due to its unique chemical structure.
• HPLC-UV achieved limits of detection (LODs) of 0.7 μg L⁻¹ for both MC-RR and MC-LR.
• HPLC-MS significantly improved LODs to 0.005 μg L⁻¹ for MC-RR and 0.003 μg L⁻¹ for MC-LR.
• The method showed good accuracy with relative recoveries ranging from 45.0% to 109.7% in real water samples.

Conclusions:

• In situ DLLME using [BeEOHIM][Br] is a highly effective technique for the preconcentration of microcystins from aqueous samples.
• The developed method offers sensitive and accurate detection of MCs, particularly when coupled with HPLC-MS.
• This approach provides a promising tool for environmental monitoring of harmful algal blooms and water quality assessment.