Rapid pKa estimation using vacuum-assisted multiplexed capillary electrophoresis (VAMCE) with ultraviolet detection

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Biochemistry

Background:

• Accurate estimation of pK(a) values is crucial for understanding small organic molecule behavior in various chemical and biological processes.
• Traditional pK(a) determination methods can be time-consuming and require significant sample volumes, limiting high-throughput analysis.

Purpose of the Study:

• To develop and validate a rapid, high-throughput method for estimating the pK(a) values of small organic molecules.
• To establish vacuum-assisted multiplexed capillary electrophoresis (VAMCE) as a reliable technique for pK(a) determination.

Main Methods:

• Utilized a 96-capillary array VAMCE system with ultraviolet detection.
• Employed a series of running buffers covering a pH range of 2.2 to 10.7.
• Applied vacuum during separation to achieve rapid electrophoretic runs (under 5 minutes).

Main Results:

• Successfully estimated pK(a) values for eight compounds per run, with a throughput of 128-168 compounds in an 8-hour period.
• Demonstrated high reliability and reproducibility for within- and between-day pK(a) estimations.
• Achieved good agreement between VAMCE-derived pK(a) values and literature values, with an average absolute difference of 0.22 log units.

Conclusions:

• VAMCE offers a fast, efficient, and reliable approach for determining pK(a) values of small organic molecules.
• The method's high throughput and accuracy make it suitable for applications requiring rapid characterization of numerous compounds.