| Separation of four sulfonamides i.e. sulfamethazine, sulfamerazine, sulfamethoxazole and sulfadimethoxine were carried out by capillary electrophoresis. Phosphate buffer was selected for separation. Parameters which influence separation, resolution and reproducibility, such as buffer pH, buffer concentration, applied voltage and temperature were studies and optimized. Calibration curves were established from 0.5μgml-1to 50μgml-1 with acceptable correlation coefficient (r2) of 0.99. Baseline separation of four sulfonamides was achieved within 9 min.Two different sample preparation methods were developed for the extraction of four commonly used sulfonamides from different kinds of meats. Solid-liquid extraction (SLE) and liquid-liquid extraction (LLE) techniques were combined for sample preparation. Sulfonamides were extracted from meat samples by acetonitrile. Protein denaturation was studied thoroughly and a unique approach was employed for the denaturation of proteins from sample matrix. n-Hexane was applied in first method while 1,2-dichloromethane was used in second method for the removal of fats. Recoveries obtained from both methods were ranged from 81% to 55% for first method and 83% to 60% for second method. As second method gave relatively better recoveries, so it was validated and precision was found to be good.A simple, rapid and reliable sample preparation method was validated for the trace determination of sulfonamides (sulfamethoxazole, sulfamethazine, sulfamerazine, and sulfadimethoxine) in edible meat. It combines clean-up by Cleanert PEP Solid Phase Extraction (SPE) polymer cartridge and quantification by Capillary Zone Electrophoresis (CZE) with photodiode array detector (PDA).1-propanol was used for the denaturing of the proteins present in the sample matrix. SPE procedure was employed for the clean-up and pre-concentration of sulfonamides prior to CZE analysis. After sample loading, sulfonamides were eluted with 4mL methanol. Complete separation was achieved by using 45 mmolL-1 phosphate buffer (pH= 6.3) at an applied voltage of 20kV. Overall obtained recoveries were from 94.5% to 83.3% for the sulfonamides. The detection limit of each sulfonamide approximately ranged from 4μgkg-1 to 6μgkg-1. The presented one step SPE clean-up method is highly applicable for the determination of the sulfonamides at a residue level below the maximum residue limit (MRL). Three different types of multiwalled carbon nanotubes (MWCNTs) as SPE adsorbent were compared for the extraction of four sulfonamides in edible meat. Four different sulfonamides were quantitatively adsorbed on MWCNTs packed cartridges and detected by capillary zone electrophoresis (CZE). Adsorption of sulfonamides on each type of MWCNTs was explained on the basis of their morphologies. MWCNTs (40-60 nm) were selected as the most suitable adsorbent. The effect of eluent, its volume, sample pH and its flow rate were investigated and optimized. Good recoveries from 95% to 84% were obtained. The detection limit for each sulfonamide was ranged from 8μgkg-1 to 19.5μgkg-1.The developed method has been applied to determine the sulfonamides residue in real sample. Satisfactory results were obtained under the optimized conditions.The applications of chemically modified-MWCNTs as SPE adsorbent material for the adsorption of four sulfonamides from meat samples were studied. Capillary electrophoresis was employed for the detection of analytes. Three different types of modified-MWCNTs were compared and suitable one was selected for further studies. Factors influence the pre-concentration efficiency, such as type and volume of eluent, sample flow rate and sample pH were studied and optimized. Recoveries of sulfonamides from the meat samples were ranged from 98% to 81%. The detection limit for each sulfonamide was ranged from 8μgkg-1 to 19.5μgkg-1. The proposed method has demonstrated that modified-MWCNTs based SPE-CE method is a precise and convenient method for the simultaneous extraction and detection of sulfonamides from meat samples. |
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