Multi-residue analysis of sulfonamides in animal tissues by capillary zone electrophoresis with electrochemical detection

BACKGROUND: The objective of this study was to adapt and improve previously published analysis methods aimed at the simultaneous determination of sulfonamide residues in edible animal tissues by capillary zone electrophoresis with electrochemical detection. RESULTS: The effects of several factors such as the acidity and concentration of running buffer, the separation voltage, the applied potential and the injection time on CZE-ED were investigated. Complete separation of six sulfonamides was achieved within 17 min by using 40 mmol L-1 Na2B4O7/25 mmol L-1 KH2PO4 (pH 6.2) at an applied voltage of 18 kV. Excellent linearity was obtained over two orders of magnitude with the improved detection limits (S/N = 3) ranged from 1.7 x 10(-7) to 4.4 x 10(-9) g mL(-1) for all six sulfonamides in comparison with previous reports. A solvent extraction/centrifuge/evaporation procedure was used to extract sulfonamides from animal tissues, sample clean-up and pre-concentration of sulfonamides prior to CZE-ED analysis. Good recoveries from 81% to 92% were achieved. CONCLUSION: Results obtained in this work indicated that the proposed CZE-ED method was sensitive, rapid and simple for the simultaneous determination of sulfonamides in edible animal tissues. Therefore, the new faster and easy handling procedure provides an additional powerful tool that can be employed for the analysis of sulfonamide residues in foodstuff. (C) 2009 Society of Chemical industry