Sensitive and selective method for the determination of sodium monofluoroacetate by capillary zone electrophoresis

Sodium monofluoroacetate (SMFA) is a highly toxic substance and its determination is needed in several areas. Its chromatographic (GC or HPLC) determination is difficult because of its ionic and hydrophilic properties. A simple, sensitive and selective capillary zone electrophoretic method is described for the determination of SMFA. It is well separated from structurally related compounds (formate, acetate, chloroacetate, bromoacetate, etc.) in an acidic electrolyte buffer containing 5 mmol/l phthalate (pH 4.61) and 0.3 mmol/l cetyltrimethylammonium bromide (CTAB) or in a basic electrolyte solution containing 5 mmol/l 4-hydroxybenzoate, 0.3 mmol/l CTAB and 10 mmol/l ammonium (pH 9.49). Good resolution was achieved at relatively low electric field (200-250 kV/cm) and CTAB concentration (0.3 mmol/l). The separation selectivity was improved in acidic phthalate buffer. Using bromoacetate as internal standard, the calibration graph for SMFA was linear over the concentration range 1-10 mu g/ml. The detection limit was 0.4 mu ug/ml. The method was applied to the determination of SMFA in rodenticide baits.