A new idea is proposed to utilize nonlinear dynamics in order to distinguish various chemical species. As an example of the application of this idea, an experimental result on an electrochemical cell connected to the Wien bridge oscillator is reported. It is shown that several kinds of modes of the entrainment of the electrical oscillator are generated in this system. The dynamics in coupled nonlinear oscillators are also discussed in relation to the informational processing in neural network. It is indicated that the concept of frustration is useful to predict the mode of entrainment.