MIXED CAPILLARY ELECTROPHORETIC AND REVERSED-PHASE ELECTROCHROMATOGRAPHIC SEPARATION OF 4-N-ALKYLBENZOIC ACID

The apparent electrophoretic mobilities of 4-alkylbenzoic acids with s ide chain lengths of greater than seven carbon atoms in bonded phase c apillaries were anomalously high compared to shorter homologues. This was identified as resulting from their slower migration rates caused b y interactions with the wall of the column. The effect could be reduce d by the addition of acetonitrile to the buffer solution suggesting a reversed-phase partitioning process. These compounds thus demonstrated a mixed electromigration and open-tubular reversed-phase electrochrom atographic separation. However, because a relatively wide bore column was used, the efficiencies were poorer than previously reported for op en-tubular electrochromatographic separations. (C) 1998 Elsevier Scien ce B.V.