Microfluidic approach for studying CO2 solubility in water and brine using confocal Raman spectroscopy

This Letter reports a fast and accurate method to quantify dissolved carbon dioxide in water and salted water (NaCl) using microfluidic systems probed by confocal Raman spectroscopy. The relationship of CO2 solubility and Raman band intensity ratios (the νu of the CO2 Fermi dyad over the water stretching band) can be fit from third order polynomial forms, depending on NaCl concentration. This approach allows for a much faster determination of CO2 solubility measurements in pressurized aqueous media. More generally, by easily managing lithospheric fluids in microdevices, this strategy opens avenues towards true ‘Geological Lab on chip’.