pH- and time-dependent hemoglobin transitions: a case study for process modelling.

The study of the pH- and time-dependent transitions of the hemoglobin is presented as a biochemical problem of interest and as a very complete example of the situations that can be encountered in the modelling of complex processes. Therefore, the aim is two-fold: providing a complete explanation of the biochemical phenomena studied and explaining the modelling strategies used to solve this problem that can be generally applied in processes of different origin. Multivariate curve resolution-alternating least squares (MCR-ALS) is the basic method used to recover the process contributions, expressed as the concentration profile and the pure spectrum of each of the compounds involved. What is the benefit of using multitechnique or multiexperiment data arrangements, how constraints should be selected and applied and how hybrid approaches combining hard- and soft-modelling can allow for the use of a partially known model when available are among the main issues presented.