Bridge Ion Separation Technology

Significance of BIST Technology

Bridge Ion Separation Technology (BIST) represents a novel liquid chromatography approach that enhances the separation of charged organic and inorganic molecules. By dynamically switching the surface polarity of the stationary phase in response to mobile phase ions, BIST addresses challenging analytes that are difficult to resolve using conventional HPLC columns and ion exchange methods.

Study Overview

This summary covers the development and practical evaluation of BIST™ columns for the retention and analysis of representative biomolecules:

• 3,3′-Diaminobenzidine (DAB) using a BIST B+ column with UV detection.
• Chondroitin 6-sulfate on a BIST A cation-exchange column with ELSD detection.
• Hyaluronic acid fractions assessed on the same BIST A column.

Methodology and Instrumentation

The core innovation lies in the stationary phase capable of reversible polarity inversion:

• Positive surface switches to negative when exposed to doubly charged anions (e.g., sulfate), enabling cation retention.
• Negative surface converts to positive in presence of multivalent cations (e.g., Mg2+, Ca2+, diamines), facilitating anion retention.

Key instrument details:

• Columns: BIST B+ and BIST A, dimensions 4.6×50–100 mm, particle size 5 µm.
• Mobile phases: mixtures of acetonitrile, water, and charged buffers (0.2% H₂SO₄ for DAB; N,N′-dimethylpiperazine formate pH 4.0 for glycosaminoglycans).
• Flow rate: 1.0 mL/min; detectors: UV at 280 nm for DAB, ELSD at 70 °C for sulfated polysaccharides.

Key Results and Discussion

• DAB showed efficient retention and peak resolution on the BIST B+ column using a gradient of acetonitrile and sulfuric acid buffer.
• Chondroitin 6-sulfate was successfully characterized on the BIST A column by forming a transient ionic bridge with multivalent buffer ions, delivering clear separation.
• Hyaluronic acid fractions across different molecular weight ranges were separated more selectively and rapidly compared to size-exclusion methods.

Advantages and Practical Applications

• Enhanced selectivity for both cationic and anionic species using a single stationary phase.
• Reduction of method development complexity via controlled polarity switching.
• Broad applicability to biomolecules, environmental ions, and small organic analytes.

Future Trends and Potential Applications

Anticipated developments include:

• Integration with mass spectrometry for high-sensitivity detection.
• Miniaturization into microfluidic formats for rapid screening.
• Expansion to environmental and clinical analytes leveraging dynamic polarity control.

Conclusion

Bridge Ion Separation Technology unveils a versatile and efficient approach for ion chromatography, overcoming limitations of traditional methods and enabling new analytical capabilities across diverse fields.