CAPILLARY ELECTROPHORESIS OF PESTICIDES .5. ANALYSIS OF PYRETHROID INSECTICIDES VIA THEIR HYDROLYSIS PRODUCTS LABELED WITH A FLUORESCING AND UV ABSORBING TAG FOR LASER-INDUCED FLUORESCENCE AND UV DETECTION

Some representative standard pyrethroid insecticides, namely permethri n, phenotrin, cypermethrin, sanmarton and fenpropathrin, were subjecte d to base hydrolysis with the aim of facilitating the indirect determi nation of these neutral species of low water solubilities by aqueous c apillary electrophoresis. This first involved the base fragmentation o f the pyrethroids in alcohol buffer (pH 12.0), and then the selective tagging of the carboxylated hydrolytic products with 7-aminonaphthalen e-1,3-disulfonic acid (ANDSA) via a condensation reaction in the prese nce of organic soluble carbodiimide. The tagging of the hydrolytic pro ducts with ANDSA imparted each of the derivatives with two strong sulf onic acid groups whose permanent charges were necessary for achieving aqueous capillary electrophoresis. In addition, the labeling with ANDS A allowed the detection of the derivatives at low levels by capillary electrophoresis laser-induced fluorescence. The geometric and optical isomers of the ANDSA derivatives of the pyrethroid hydrolytic products were best separated when using electrolyte systems composed of sodium phosphate buffer, pH 6.5, containing n-octylglucoside chiral surfacta nt in the presence of small amounts of acetonitrile (e.g., 10% v/v).