The carbonate/bicarbonate system as a pH indicator for infrared spectroscopy

Area of Science:

• Biophysical Chemistry
• Spectroscopy
• Chemical Kinetics

Background:

• Caged compounds enable pH-jump studies in time-resolved infrared spectroscopy.
• Current methods lack control over initial pH and accurate final pH measurement in micro-liter volumes.

Purpose of the Study:

• To develop an experimental approach for accurate initial and final pH determination in pH-jump experiments.
• To overcome limitations of existing techniques for micro-volume pH measurements.

Main Methods:

• Utilized a combination of inorganic ions (carbonate/bicarbonate) as internal pH reporters.
• Employed infrared spectroscopy to analyze spectral differences.
• Compared experimental difference spectra to a synthetic library of reporter ion spectra.

Main Results:

• Successfully measured initial and final pH values in UV-photolysis experiments.
• Demonstrated accurate pH determination using carbonate and bicarbonate ion absorption bands.
• Validated the approach in micro-liter volumes.

Conclusions:

• The developed method accurately quantifies pH changes in pH-jump experiments.
• This technique enhances the utility of time-resolved infrared spectroscopy for acidification-triggered phenomena.
• Offers precise pH control and measurement capabilities for micro-scale biological and chemical studies.