MATHEMATICAL-MODELING OF FIELD-AMPLIFIED SAMPLE INJECTION IN HIGH-PERFORMANCE CAPILLARY ELECTROPHORESIS

In field-amplified sample injection, the sample is prepared in a low-conductivity buffer and injected into the capillary column containing a high-conductivity buffer. A large amount of sample ions can be injected and concentrated in the column under the enhanced electric field. However, as the low-conductivity buffer migrates electoosmotically into the column, the field strength at the injection point changes continuously during sample injection. A mathematical model to calculate the total amount of injected ions using field-amplified sample injection is presented. Good agreements between theoretical calculations and experimental results are obtained.