Avoid missing pK_as: High-throughput workflow using solution pH-metric in tandem with UV-metric measurements

Area of Science:

• Analytical Chemistry
• Medicinal Chemistry

Background:

• Accurate pK_a determination is crucial for drug discovery and understanding Structure-Activity Relationships (SAR).
• Traditional methods can be time-consuming and may fail to identify all relevant pK_a values, especially for compounds with poor UV absorbance or solubility.

Purpose of the Study:

• To develop and validate a high-throughput automated workflow for pK_a determination.
• To integrate potentiometric (solution pH-metric) and UV-metric measurements for comprehensive pK_a profiling.
• To address limitations of existing methods in drug discovery settings, such as low solubility and overlapping pK_as.

Main Methods:

• Development of a high-throughput automated pK_a workflow using potentiometry with 10 mM DMSO stock solutions.
• Evaluation of two potentiometric approaches: neat DMSO stock and DMSO removal, with varying sample amounts and cosolvent systems.
• Validation of the automated workflow against traditional potentiometric measurements.
• Tandem execution of high-throughput solution pH-metric and UV-metric experiments.

Main Results:

• The automated workflow demonstrated efficiency and accuracy comparable to traditional methods.
• The combined pH-metric and UV-metric approach successfully identified pK_a values that might be missed by UV-metric analysis alone.
• The workflow effectively handles challenges including low solubility and overlapping pK_as.

Conclusions:

• The integrated high-throughput workflow offers significant sample and time savings for measuring numerous compounds in drug discovery.
• This combined approach enhances the ability to determine pK_as, aiding in preliminary SAR understanding and overcoming common analytical hurdles.