| Sulfonamides are a group of synthetic antibiotics. They have been widely used as growth promoters to prevent and treat a series of diseases in animals'feeding. As a consequence of their extensive usage, undesirable residues can remain in food of animal origin. These residues are a great public health concern due to the risk of developing drug resistance, which leads to an inefficiency of this medicine for therapeutic use, and even some of the compounds are known to be carcinogenic. To safeguard human health, the European Union (EU) and other countries including China have established safe maximum residue limits (MRLs) at the total level of 100μg/kg. Therefore, monitoring these compounds has aroused many concerns in the scientific communities.Numerous methods have been employed to determine sulfonamide drugs such as TLC, GC, GC-MS, LC, LC-MS, and so on. Thin layer chromatography (TLC) is prone to interferences and is inadequate for quantitative analysis. GC and GC-MS methods require derivation because of the high polarity and low volatility of sulfonamides. HPLC and LC-MS are the most used methods. The difficulties involved in the analysis of complex biological matrices are the presence of interferences that are co-extracted. For this reason, the methods mentioned above need previous treatment of the sample. The thesis has established two easy to use and low time-consuming solid-phase extraction-chromatogram methods for quantitative determination of five sulfonamides in meat and water samples, with adopting different metierials as solid phase extraction sorbents.This paper included four parts:1. Introduce some information of sulfonamides, including the structures, pharmacological functions, the risk of drug residues, and the established MRLs.2. Review the recent developments of sulfonamides determinations in various samples including some unique sample treatment technologies and analytical methods.3. Establish the solid-phase extraction-capillary zone electrophoresis method for quantitative determination of sulfonamides in meat.The experiment has investigated influence of electrophoresis conditions on separation, including pH and concentration of buffer, separate voltage, temperature and injection volume etc. Using untreated fused silica capillary (75μm×57 cm, effective length was 50 cm ) as separation column, 0.02 mol/L phosphate (pH 8.0) as buffer, separation voltage was 20 kV, temperature was 25℃, samples were injected at 0.4 psi for 15 s, and detected at 254 nm. Meat samples were extracted by acetonitrile and solid phase extraction columns were used for cleaning up. Sulfadimethoxine (SDM), sulfathizole (STZ), sulfadiazine (SDZ), sulfamethazine (SMZ) and sulfamethoxazole (SMX) were baseline separated within 8.0 min. The calibration curves were linear in the range of 0.4 - 40.0μg/mL ( r2>0.9966 ). The detection limits were 0.05 - 0.10μg/mL. The recoveries of the added sulfonamides were 70.6% - 105.1%. This method is rapid, sensitive and avoided to use large volume organic solvent.4. Establish the solid-phase extraction-high performance liquid chromatography method to determine five sulfonamides in water. Carbon nano-tubes were used as the solid phase extraction sorbents.The adsorption efficiency of different carbon nanotubes to different water samples has compared. Hydroxylated carbon nanotubes were found to be the best one to concentrate the five sulfonamides in acid water (pH 5.0). The calibration curves were linear in the range of 0.005 - 50.0μg/mL ( r2>0.9993 ). The detection limits were lower than 2.0 ng/mL. The recoveries of the added sulfonamides were 72.96% - 110%. The method is sensitive and reliable. Nano tubes have good adsorption properties and potential application prospect in analytical chemistry. |
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