The aim of our analysis is to estimate p j,t for all j, t to be able to infer the reactions' kinetics. We assume that our dataset consists of T spectra of the reaction mixture measured in consecutive moments t = 1, 2, . . . T. In principle, each of the time points t can be analysed separately and independently, and, for the sake of clarity, we will describe the working of our method on the single reaction mixture spectrum in the fixed moment t. However, later on, we will show that the results obtained for preceding moments can be used to speed up the computations.