SAMPLE MATRIX EFFECTS IN CAPILLARY ELECTROPHORESIS .2. ACETONITRILE DEPROTEINIZATION

Acetonitrile deproteinization [acetonitrile-serum (3:2, v/v)] was found to be a suitable method for removal of serum proteins for the analysis of drugs and small molecules by capillary electrophoresis. Many compounds exhibited higher plate numbers and peak heights in the presence of 60% acetonitrile. This effect is due to a special stacking brought along by the low resistivity of the acetonitrile in the sample. In addition to removing serum proteins, acetonitrile improves the solubility of some compounds and increases the sample volume which can be introduced into the capillary. Serum theophylline analysis was used here as an example for the analysis of drugs by capillary electrophoresis using acetonitrile deproteinization.