Enhanced field-amplified sample injection by mobility decrease in capillary electrophoresis for the analysis of trace...

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis
• Chiral Separations

Background:

• Chiral drugs like palonosetron hydrochloride (PALO) require strict enantiomeric impurity detection for safety and efficacy.
• Existing methods face challenges in separating and quantifying all potential enantiomeric impurities due to limitations in injection modes.
• Online preconcentration mechanisms in micellar electrokinetic chromatography (MEKC) are crucial for enhancing sensitivity in chiral drug analysis.

Purpose of the Study:

• To investigate the mechanism of online preconcentration in MEKC for PALO injection analysis using sodium taurocholate (STC) as a chiral selector.
• To develop a sensitive and robust method for the identification and quantification of trace enantiomeric impurities in PALO.
• To resolve the separation challenges associated with hydrodynamic injection by employing an electrokinetic injection mode.

Main Methods:

• Micellar electrokinetic chromatography (MEKC) utilizing sodium taurocholate (STC) as a chiral selector.
• Exploration of online preconcentration mechanisms, including field amplified sample stacking and solute interaction with STC micelles.
• Comparison and optimization of hydrodynamic injection versus electrokinetic injection modes for improved separation and sensitivity.
• Validation of the developed method for limit of detection (LOD), limit of quantification (LOQ), linearity, recovery, and precision.

Main Results:

• The study elucidated the online preconcentration mechanism involving conductivity differences, pH-induced dissociation, and solute distribution into STC micelles.
• Electrokinetic injection mode successfully resolved separation challenges, enabling the injection of sufficient sample in a shorter plug compared to hydrodynamic injection.
• Achieved a limit of detection of 0.014 μg mL⁻¹ and a limit of quantification of 0.05 μg mL⁻¹ for enantiomeric impurities, a nearly tenfold improvement in sensitivity.
• Demonstrated high linearity (R² = 0.993-0.998), spike recovery (96.1-100.6%), and precision (RSD ≤ 3.6%) for the analytical method.

Conclusions:

• The developed MEKC method with STC and electrokinetic injection provides a highly sensitive and effective approach for analyzing enantiomeric impurities in palonosetron hydrochloride.
• This method represents a significant advancement in chiral drug analysis, enabling the first successful identification and quantification of trace enantiomeric impurities in real PALO drug samples.
• The findings contribute to ensuring the safety and efficacy of chiral pharmaceuticals through improved analytical methodologies.