In this paper, we have presented the interest that lies in studying buffer solutions in the root space of the derivative of the buffer index. It has allowed us to easily find optimal values of concentrations and pK a in the case of 2 and 3 weak acids mixtures, and, with greater difficulty, an optimal point in a symmetrical 4 weak acids case. As we restricted ourselves to simple optimization techniques, only the case with 2 weak acids could be dealt with while including the contribution of H 3 O + and OH -. Going beyond -for instance finding the optimal combination of parameters for mixtures of 3 weak acids at low or high pH target values -would involve numerical multiparameter optimization techniques, as is done in other approaches by combining stochastic and steepest descent methods , which goes beyond the scope of the present study. The question that will face such an enterprise will be that of the proper optimization technique as well as the proper target function(s). This will be the object of upcoming work. But it should be underlined that the flatness of buffer index curves obtained here appears encouraging for optimization methods based on the approach proposed here, as it finds mathematically well defined optima. Another route of investigation would be to optimize the dynamics buffer capacity , however in that case an additional parameter would have to be taken into account as the dilution effects depend on the concentration of the added solution.