Quantitative determination of sulfonamide in meat by solid-phase extraction and capillary electrophoresis

This paper describes a newly developed capillary electrophoresis (CE) with solid-phase extraction (SPE) method for the quantitative determination of eight commonly used sulfonamides (sulfamethazine (SMZ), sulfamerazine (SMR), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfamonomethoxine (SMM), sulfaphenazole (SPA), sulfaquinoaline (SQF) and sulfisoxazole (SIA)) in meat. Complete separation of eight sulfonamides was achieved by using 35 mM Na3PO4-H3PO4 buffer (pH 6.5) at an applied voltage of 25 kV. 1-Naphthoxyacetic acid was used as an internal standard for quantitative analysis. Satisfactory linearity, 0.5-50 mug/ml, of each compound was obtained. Solvent extraction was used to extract sulfonamide from meat and SPE procedure was employed for sample cleanup and pre-concentration of sulfonamide prior to CE analysis. Meat samples were fortified at levels between 50 and 500 mug/kg. Sulfonamides were isolated from meat and then measured by CE. Good recoveries from 80 to 97% were determined. The detection limits of each sulfonamide approximately ranged from 5 to 10 mug/kg. The sensitivity of this newly developed method allows the determination of the sulfonamides at a residue level far below the maximum residue limit (MRL) established by European Community (EC). (C) 2003 Elsevier B.V. All rights reserved.