| This paper is consisted of five parts. It mainly studies the analytical techniques for determination of pesticides and veterinary drugs in foodstuffs including praziquantel, propargite, quinolones and N-methylcarbamates. In the first part of this thesis, the progress of the determination methods for pesticides and veterinary drugs were described. Variety of analytical methods, such as gas chromatography (GC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), have been used for the analysis of pesticides and veterinary drugs. These analytical techniques have been proven to be very reliable for the analysis of pesticides and veterinary drugs in foodstuffs. A relatively novel analytical technique that is a hybrid technique, which couples the selectivity of HPLC and the separation efficiency of CE, is capillary electrochromatography (CEC). The prospects for CEC in pesticides and veterinary drugs analysis are very promising because of its high efficiency, small quantity of samples, and short analysis time. In the second part, a HPLC method was developed and applied for determination of the praziquantel and propargite by using solid-phase extraction technique. Under optimized conditions, two analytes were separated baseline within 3 minutes. Using ethyl acetate as extract solvent, praziquantel and propargite can be enriched by solid phase extraction with Silica cartridge, good recoveries and RSD were obtained. The method was successfully applied to the analysis of praziquantel and propargite in fish tissues. In the third part, a high performance method has been developed for separation and determination of enrofloxacin (ENR) and its metabolite ciprofloxacin (CIP) by high performance capillary electrophoresis with end-column amperometric detection (CE-AD). At 18 kV applied voltage, the two analytes were completely separated in 20 mmol/L PBS buffer (pH 8.0) within 8 minutes. A simple sample pretreatment method was developed and the detection limits(S/N=3) for enrofloxacin and ciprofloxacin were 13.68 μg/kg and 14.35 μg/kg, respectively, which were lower than the maximum residue limits (MRLs≤100 μg/kg) established by the European Union. In the fourth part, a well know method that to separation and determination of five N-methylcarbamate (NMCs) pesticides was developed by pressurized capillary electrochromatography (pCEC). The effect factors on the migration behavior of five NMCs, such as the component of mobile phase, applied voltage and back-pressure regulator, have been investigated in detail. A solid-phase extraction method was developed on a florisil cartridge using a mixture of methanol-dichloromethane (50-50, v/v). The method is specific and the detection limits were between 0.07 mg/kg and 1.70 mg/kg for vegetable samples. Based on the pioneering work in the part Ⅴ, we developed a method to determine carbofuran and its metabolite 3-OH carbofuran et al. ten NMCs simultaneous with pressurized capillary electrochromatography by UV-Vis Detection. Several effect factors such as SDS were discussed. Under optimized conditions, all analtyes were separated baseline within 21 minutes. The potential method which used SPE has been exploited to detect the ten NMCs in vegetable samples. The average spiked recoveries ranged from 51.3±6.8% to 109.2±4.9%, RSD<11.4%. Comparing to the other present methods, the proposed pCEC method shows its advantages in simplicity, speed, selectivity and avoiding expensive reagent consumption for determination of NMCs. It may be very promising in foodstuffs analysis. |
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