Efficient algorithm for simulation of isoelectric focusing.

IEF simulation is an effective tool to investigate the transport phenomena and separation performance as well as to design IEF microchip. However, multidimensional IEF simulations are computationally intensive as one has to solve a large number of mass conservation equations for ampholytes to simulate a realistic case. In this study, a parallel scheme for a 2D IEF simulation is developed to reduce the computational time. The calculation time for each equation is analyzed to identify which procedure is suitable for parallelization. As expected, simultaneous solution of mass conservation equations of ampholytes is identified as the computational hot spot, and the computational time can be significantly reduced by parallelizing the solution procedure for that. Moreover, to optimize the computing time, electric potential behavior during transient state is investigated. It is found that for a straight channel the transient variation of electric potential along the channel is negligible in a narrow pH range (5∼8) IEF. Thus the charge conservation equation is solved for the first time step only, and the electric potential obtain from that is used for subsequent calculations. IEF simulations are carried out using this algorithm for separation of cardiac troponin I from serum albumin in a pH range of 5-8 using 192 biprotic ampholytes. Significant reduction in simulation time is achieved using the parallel algorithm. We also study the effect of number of ampholytes to form the pH gradient and its effect in the focusing and separation behavior of cardiac troponin I and albumin. Our results show that, at the completion of separation phase, the pH profile is stepwise for lower number of ampholytes, but becomes smooth as the number of ampholytes increases. Numerical results also show that higher protein concentration can be obtained using higher number of ampholytes.