A new approach for automated liquid-liquid extraction in a sequential injection manifold

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Liquid-liquid extraction (LLE) is a crucial separation technique in analytical chemistry.
• Traditional LLE methods often face challenges like phase immiscibility, bubble formation, and difficulties with Teflon tubing.
• Sequential injection analysis (SIA) offers a platform for automating complex analytical procedures.

Purpose of the Study:

• To develop and validate a new SIA manifold for efficient liquid-liquid extraction.
• To address and overcome common issues encountered in LLE, such as phase affinity and bubble formation.
• To determine thiamine in pharmaceutical preparations and dietary supplements using the proposed method.

Main Methods:

• Implementation of a sequential injection manifold comprising two syringe pumps and a multi-position valve.
• Utilized a 30% MeOH/H2O (v/v) solution as the carrier and isobutanol as the extractant.
• Demonstrated the method's suitability through the determination of thiamine.

Main Results:

• Achieved detection and quantification limits of 9 μg L⁻¹ and 30 μg L⁻¹, respectively.
• Reported excellent repeatability (<3%) and intermediate precision (<7% over 3 days).
• Obtained a sample throughput of 14 samples per hour.

Conclusions:

• The proposed SIA manifold provides a robust and efficient platform for liquid-liquid extraction.
• The method is suitable for the accurate determination of thiamine in complex matrices.
• Results align well with established high-performance liquid chromatography-electrospray/mass spectrometry methods.