Two different approaches can be applied to calculate the mass transfer in a two-phase system using computational fluid dynamics and the volume-of-fluid method, single-field and two-field approaches. The used method affects the stability of the calculation as well as the accuracy of the result. Two volume-of-fluid-based approaches, namely, the generalized continuous species transfer model, a single-field approach, and a two-field approach are compared. The models are implemented in the OpenFOAM (R) framework and validated in a 1D test case. Although both approaches show great agreement with the analytical solution for large time steps, numerical instabilities of the two-field model are revealed with a reduced time step size, which leads to false results.