Three dimensional characterisation of chromatography bead internal structure using X-ray computed tomography and...

Area of Science:

• Materials Science
• Analytical Chemistry
• Microscopy

Background:

• Chromatography beads are crucial in separation science.
• Understanding their 3D structure is key for optimizing performance.
• Existing imaging methods have limitations in characterizing bead microstructures.

Purpose of the Study:

• To compare X-ray computed tomography (CT) and focused ion beam (FIB) microscopy for 3D analysis of chromatography beads.
• To quantitatively assess physical characteristics such as tortuosity factor, porosity, and pore diameter.
• To validate tomographic approaches against existing literature values.

Main Methods:

• Critical-point dried agarose, cellulose, and ceramic beads were analyzed using X-ray CT and FIB microscopy.
• High-resolution 3D digital reconstructions were generated from the imaging data.
• Geometric analysis software was employed to evaluate bead properties.

Main Results:

• X-ray 'nano' CT achieved resolutions of 63 nm and 32 nm.
• FIB microscopy provided higher resolution (15 nm) for rigid ceramic beads but faced challenges with softer materials.
• Averaged simulated tortuosity factors were 1.36 (agarose), 1.37 (cellulose), and 1.51 (ceramic).

Conclusions:

• Both X-ray CT and FIB microscopy are capable of generating 3D representations for quantitative analysis of chromatography beads.
• The choice of technique depends on material properties and desired resolution.
• Tomographic approaches offer a powerful tool for characterizing bead morphology and informing chromatographic process design.