A calculation model has been developed to numerically interpret the simultaneous mass transfer behaviour occurring in the absorption of CO2 and H2S into blended alkanolamines. The film theory and approximate film theory models are used to describe the mass transfer phenomena within the liquid phase, while gas phase resistance is neglected. Two distinctly different simulation modules have been developed : a classic representation of the reaction kinetics coupled with a simple Debye-Huckel representation of the thermodynamics, and the recent zwitterion mechanism coupled with the Deshmukh-Mather thermodynamic model. The objective of our work is to identify the key parameters of the system, via a parameter sensitivity analysis, to allow for process optimisation by parameter identification. Some parameters included in the study are : kinetics, equilibrium, thermodynamics, fluid hydrodynamics, temperature, etc..