Study On National Method And Degradation Dynamics Of Carbendazim And Thiabendazole On Fruits

Carbendazim and Thiabendazole are benzimidazolic compounds and systemic fungicide.It is widely used in prevention of the disease caused by fungus in the fruits and other produces. According to the physical and chemical properties of Carbendazim and Thiabendazole and the results of previous research,a standard method was established to determine the carbendazim and thiabendazole by HPLC.The optimization of the extraction system, purification system and chromatographic conditions were the focus of the experiment.Meanwhile,degration dynamics,relations between degradation to temperature were studied.This thesis also focused on the detergent effect of 4 cleaning ways as ultrasound clerrning,detergent cleaning, rice washing water clearning and tap water cleaning.The main conclusions were as follows:(1) Optimizations of chromatographic conditionsAccording to full wavelength scan fluorescence of carbendazim and thiabendazole,the maximum excitation wavelength were obtained:carbendazim was 279.0nm; thiabendazole was 313.5nm. In the end, the emission wave lengths was 260nm and the excitation wave lengths was 312nm.According to the influence of different column temperature and column flow rate on the chromatographic parameter of carbendazim and thiabendazole,the column temperature was 50℃and column flow rate was 0.8mL/min.(2)The establishment of extraction systemThe influence of extractting method, extractting solvent, solvent volume and extractting time on the recovery of carbendazim and thiabendazole wer inspected. The results was showed that:In the first 10min we extracted the carbendazim and thiabendazole in mechanical oscillation then continue extractting 10min with ultrasonic extraction.The volume of acetonitrile was 30mL and the time of extraction was 3 min.(3)The establishment of purifying systemThe metord of purifying was the combination of GPC and SPE.First the effluent of 9～18min of GPC was collected.Then continue purifying the collected effluent with Waters Sep-pak DNPH-Silica (500mg,3mL). The results showed that the recovery of carbendazim was 86.67%～87.92% and the recorery of thiabendazole was 86.00%-87.17%at spiked levels of 0.05mg/kg～1mg/kg. (4)The study of degradation dynamicsThe degradation equation and half life of the carbendazim and thiabendazole in different temperature.The 50% WP 1000 times liquid of carbendazim:In apples with room temperature:C=C0*e-0.07376t (r=-0.9912), T1/2=8.92 dIn apples with low temperature:C=C0*e-0.3535t (r=-0.9772), T1/2=19.60dIn oranges with room temperature:C=C0*e-0.0777t (r=-0.9912), T1/2=8.92 dIn oranges with low temperature:C=C0*e-0.03454t (r=-0.9535), T1/2=20.06dThe 50%SC 1000 times liquid of hiabendazole:In apples with room temperature:C=C0*e-0.07451t (r=-0.9505), T1/2= 9.30 dIn apples with low temperature:C=C0*e-0.03262t (r=-0.9900), T1/2=21.24dIn oranges with room temperature:C=C0*e-0.07323t (r=-0.9938), T1/2=9.46dIn oranges with low temperature:C=C0*e-0.03462t (r=-0.9492), T1/2=20.02d(5) The study of remove methodThe influence of all kinds of washing methods to remove carbendazim and thiabendazole is that:ultrasound clerrning> detergent wash> rice washing water clearning> water cleaning.