Electrodialytic membrane suppressors for ion chromatography make programmable buffer generators.

Area of Science:

• Analytical Chemistry
• Separation Science
• Biochemistry

Background:

• Buffer solutions are crucial in various scientific disciplines.
• Continuous pH gradients are essential for chromatographic separation of proteins and pK(a) determinations.
• Existing methods for pH gradient generation can be complex or limited.

Purpose of the Study:

• To demonstrate the use of electrodialytic membrane suppressors for buffer generation.
• To investigate the capability of these suppressors in creating continuous pH gradients.
• To evaluate the reproducibility, linearity, and control of the generated pH gradients.

Main Methods:

• Utilized cation-exchange membrane (CEM) and anion-exchange membrane (AEM) based electrodialytic membrane suppressors.
• Generated phosphate, citrate, Tris, and ethylenediamine buffers.
• Employed mixtures of phosphate, citrate, and borate ions for gradient generation.
• Investigated buffer generation with butylamine and NaCl for constant ionic strength.

Main Results:

• Generated pH values computed from first principles closely matched measured values.
• Demonstrated reproducible (avg RSD 0.20%) and temporally linear (pH 3.0-11.9) pH gradients using CEM suppressors.
• Achieved a similar linear pH gradient with near-constant ionic strength using butylamine and NaCl.
• Showcased the electrical control over pH gradient generation.

Conclusions:

• Electrodialytic membrane suppressors are effective for generating buffers and continuous pH gradients.
• This technique offers a valuable approach for creating eluents in biomolecule separation and online process titrations.
• The method provides precise control over pH and ionic strength, enhancing chromatographic applications.