An automatic countercurrent liquid-liquid micro-extraction system coupled with atomic absorption spectrometry for...

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Accurate metal determination in environmental samples is crucial for monitoring.
• Existing microextraction techniques can be limited by solvent density and automation.

Purpose of the Study:

• To develop and validate a novel automatic sequential injection countercurrent liquid-liquid microextraction (SI-CC-LLME) system for metal determination.
• To couple the SI-CC-LLME system with flame atomic absorption spectrometry (FAAS) for enhanced sensitivity.
• To demonstrate the system's versatility with organic solvents heavier or lighter than water.

Main Methods:

• A newly designed microextraction chamber facilitating countercurrent flow of aqueous and organic phases.
• Online lead determination using 120 μL of chloroform as extractant and ammonium diethyldithiophosphate as chelating reagent.
• Optimization of experimental parameters including extractant volume and phase flow rates.

Main Results:

• Successful on-line lead determination in environmental water samples.
• An enhancement factor of 130 was achieved with 6 mL sample consumption.
• A low detection limit of 1.5 μg L⁻¹ and good precision (RSD 2.7% at 40.0 μg L⁻¹ Pb(II)).

Conclusions:

• The proposed SI-CC-LLME-FAAS system is a versatile and efficient method for trace metal analysis.
• The system demonstrates excellent performance for lead determination in environmental water.
• The method's robustness was confirmed by analyzing certified reference materials and spiked samples.