[Studies on the separation method with multiple injection of proteins]

An abrupt change of the eluting curve of proteins in the RPC and HIC was reported in the previous paper. Here, we present a new multi-injection method of proteins in which the sample may be injected for many times in the same chromatographic run. When the composition of mobile phase is far away from the position of the abrupt change, the multi-injection of proteins before and/or after starting a gradient elution for one chromatographic separation in the RPC and HIC can be performed. Thus we may obtain the same chromatogram and retention of proteins as the ordinary one. This method can be used to overcome the difficulty that the loop is too small for injection big volume of sample solution. A larger sample size can be injected by many times in one chromatographic run to save time and to decrease the consumption of the experimental material. If there exist some impure proteins of weak retention, the impure proteins may go through the column with the solution A when the selected concentration of mobile phase is suitable. Therefore, a fixed column size can adsorb more related proteins, that is the effective column capacity is relatively raised. This injection method has an important value in the preparative chromatography of proteins.