The chemical potential of each metabolite is defined in terms of the metabolite concentrations and the standard chemical potentials which can be calculated using empirical methods such as the group\cite{Jankowski2008}\cite{Mavrovouniotis1988} and the component contribution method \cite{Noor2013}, or from nonempirical quantum chemistry methods such as density functional theory, post Hartree-Fock and molecular dynamics \cite{Jinich2014}.