Amplification of the potentiometric response to inorganic carbon by membrane mediated absorption into aqueous alkanolamine solutions: An equilibrium model

The results of equilibrium speciation modeling of the membrane mediated interaction between aqueous alkanolamine solutions and samples containing dissolved carbon dioxide and derivative inorganic carbon species are reported. The speciation of monoethanolamine and methyldiethanolamine were simulated over alkanolamine concentrations ranging from 0.1 mM to 1.0 M, and for sample inorganic carbon levels spanning eight orders of magnitude. Polynomials relating analyte concentration to potentiometric responses, including specific conductance and pH have been derived. This modeling exercise demonstrates alkanolamine mediated signal amplification as the basis for improved potentiometric quantitative analytical methods for carbon dioxide and related aqueous species.