Determination of sulfonamide residues in cultured sea cucumber by pre-column derivatization capillary electrophoresis with fluorescence detection

A simple and mild method for the separation of sulfonamide residues based on a condensation reaction with O -phthalaldehyde solution (OPA) as labeling reagent with capillary electrophoresis has been developed. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, pH, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 20 mmol L −1 borate buffer; pH 9.1; column temperature 20 °C; separation voltage 18 kV, pressure 50 mbar and injection time 8 s. Under the optimal conditions, 10 kinds of sulfonamide derivatives could be well-separated within 8 min, and the linear ranges were 0.35–100 μg kg −1 . The detection limit (at a signal-to-noise ratio of 3) was in the range of 0.12–0.25 μg kg −1 , and the quantification limit (at a signal-to-noise ratio of 10) was in the range of 0.35–0.70 μg kg −1 . The sulfonamide residues from cultured sea cucumber samples were determined under the optimal conditions with satisfactory results. • OPA was used for sulfonamide derivatization. • CE was used to determine the sulfonamides. • Sea cucumber contains sulfonamides residues.