Field enhanced bacterial sample stacking in isotachophoresis using wide-bore capillaries

Area of Science:

• Analytical Chemistry
• Microbiology
• Biotechnology

Background:

• Capillary isotachophoresis (CITP) is a powerful separation technique.
• Improving the limit of detection (LOD) for bacterial analysis is crucial.
• Existing CITP methods may lack sufficient sensitivity for certain applications.

Purpose of the Study:

• To optimize capillary isotachophoresis for enhanced bacterial detection.
• To investigate the impact of capillary internal diameter on analytical sensitivity.
• To establish a reliable method for quantifying specific bacterial strains.

Main Methods:

• Analysis of bacterial strains using CITP with varying capillary internal diameters (50–250 μm).
• Comparison of different injection modes to enhance the limit of detection.
• Development of a system suitability test based on separation voltage for result validation.

Main Results:

• Wider bore capillaries (up to 250 μm) significantly improved analytical sensitivity compared to 50 μm capillaries.
• Optimized CITP achieved a limit of detection as low as ~3000 cells/mL for Erwinia carotovora.
• The method demonstrated reliable quantification without the need for fluorescent or chromophoric additives.

Conclusions:

• Capillary isotachophoresis is a highly sensitive technique for bacterial quantification.
• Optimizing capillary dimensions and injection modes enhances analytical performance.
• This method offers a dye-free approach for detecting low bacterial concentrations, applicable to Gram-negative bacteria like Erwinia carotovora.