Electrically driven microseparation methods for pesticides and metabolites: IV. Effects of the nature of fluorescent labels on the enantioseparation of pesticides and their degradation products by capillary zone electrophoresis with UV and laser-induced fluorescence detection

Three different fluorescent tags, namely 5-aminonaphthalene-1-sulfonic acid (ANSA), 7-aminonaphthalene-1,3-disulfonic acid (ANDSA), and 8-aminonaphtha lene-1,3,6-trisulfonic acid (ANTS) were evaluated in the precolumn derivati zation of some chiral phenoxy acid herbicides, some chiral transformation p roducts of pyrethroid insecticides, and in their subsequent enantiomeric se paration by capillary electrophoresis (CE). The electrolyte systems consist ed of sodium phosphate buffers containing chiral surfactants such as octylg lucoside (OG) or octylmaltoside (OM) at concentrations above the critical m icellar concentration (CMC). Among the three different tags investigated, t he ANDSA derivatives of the various solutes were more readily enantio-separ ated than the ANSA and ANTS derivatives. While the tagging with ANSA allowe d the enantioseparation of a limited number of the chiral solute-ANSA deriv atives investigated, the ANTS derivatization yielded derivatives that could not be enantioseparated. The polarity of the three different tags increase s by increasing the number of sulfonic; acid groups in the molecule in the following order: ANSA (one sulfonic acid) < ANDSA (two sulfonic acid groups ) < ANTS (three sulfonic acid groups). This seems to indicate that the inte rmediate polarity of the ANDSA tag allowed more equitable nonpolar/polar in teractions of the ANDSA-derivatized solutes with the OG. or OM micelles, an d consequently the enantioseparation of the solute-ANDSA derivatives. Thus, there is a solute polarity window for enantioresolution with alkylglycosid e micelle by CE. Solutes of intermediate polarity that undergo more equitab le nonpolar/polar interactions with the micelles exhibited chiral separatio ns.