SILVER(I) MEDIATED SEPARATIONS BY CAPILLARY ZONE ELECTROPHORESIS AND MICELLAR ELECTROKINETIC CHROMATOGRAPHY - ARGENTATION ELECTROPHORESIS

The addition of Ag(I) to the run buffer in capillary zone electrophore sis (CZE) and micellar electrokinetic chromatography (MEKC), containin g sodium dodecyl sulfate, applies the principles of argentation chroma tography to electrophoretic separations and is termed ''argentation el ectrophoresis''. This technique is shown to provide a complementary me thod to CZE and MEKC for the separation of specific types of solutes t hat selectively complex with Ag(I). Baseline resolution in the CZE sep aration of nine sulfonamides is achieved by the addition of 50 mM silv er nitrate to the run buffer, Retention mechanisms in MEKC separations can also be manipulated by the addition of Ag(I) to the micellar solu tion, Only slight resolution of a pair of sulfonamides was achieved un der normal MEKC conditions, Upon the addition of Ag(I) to the mobile p hase containing SDS micelles, baseline resolution of the compounds is shown, The retention order and resolution of five sulfonamides changed significantly when 25 mM Ag(I) was added to the SDS-containing buffer , The use of Ag(I) addition in MEKC is also applied to the separation of various other compounds that show selectivity toward Ag(I) complexa tion, including S-containing heterocycles and vitamin D compounds, The effect of the addition of Ag(I) on the elution range in MEKC is also investigated, A steady increase in the elution range is seen upon incr easing the concentration of Ag(I), With a constant percentage of organ ic modifier (15%), the addition of higher concentrations of silver nit rate (25-50 mM) results in elution ranges greater than 12, The results using Ag(I) as buffer additives in MEKC are also compared to studies utilizing a mixed counterion surfactant of sodium/silver dodecyl sulfa te.