Double-chain surfactants with two sulfonate groups as micelle-forming reagents in micellar electrokinetic chromatography of naphthalene derivatives

Abstract

Three surfactants having two sulfonate groups and two lipophilic chains, disodium 5,12-bis(dodecyloxymethyl)-4,7,10,13-tetraoxa-1-16-hexadecanedisulfonate (DBTHX), 5,13-bis(dodecyloxymethyl)-4,7,11,14-tetraoxa-1-17-heptadecanedisulfonate (DBTHP) and 5,13-bis(dodecyloxymethyl)-4,7,11,14-tetraoxa-9,9-dimethyl-1-17-heptadecanedisulfonate (DBTDMHP), were used in micellar electrokinetic chromatography (MEKC) to separate eight naphthalene derivatives as model analytes. Their capacity factors linearly increased as the concentration of each surfactant increased from 1 to 10 m M at pH 7.0. These double-chain surfactants exhibited different selectivity and wider migration time windows when compared with sodium dodecyl sulfate (SDS), which is used widely in MEKC. The eight naphthalene derivatives were baseline separated at 5 m M DBTHX and 2.5 m M DBTHP, respectively, and nearly baseline separated at 2.5 m M DBTDMHP. However, SDS at 60 m M could not completely resolve three of the analytes.