A Preliminary Study On Determination Method Of Suckercides And Pesticides And Degradation Of Butralin In Fresh Tobacco Leaves

Tobacco is an important cash crop in China, and it is important in national and local economy of China. Axillary buds is one of the important elements, and it affects quality and yield of tobacco during cultivation. a large number suckercides are used in order to reduce the affect; Therefore, suckercide residues will remain in tobacco leaves during harvest, that was potential harmful for the health of smokers. This is necessary to establish a method for the determination of suckercides in fresh tobacco leaves. This not only help to master the dynamic change of the content of suckercides in fresh tobacco leaves and prevent abuse but also constitute the best time to harvest tobacco, it has important practical significance for safe production.The main results includes fourparts:1. A method for determination of maleic hydrazide in fresh tobacco leaves using HPLC-MS/MS technique was developed, this method was quick, easy, effective,cheap and less solvent consumption. Samples were extracted with 2% acetic acid methanol and cleaned up with graphitized carbon blacks(GCB), The samples were quantified using external standard with the matrix matched standard calibration curve method. Good linearities were obtained for maleic hydrazide at the concentration of20-1000 μg/kg with the linear relative coefficients more than 0.995. The limits of detection(LOD) and the limits of quantification(LOQ) for maleic hydrazide were 50μg/kg and 15 μg/kg, respectively. The recoveries at three different concentration levels(15, 60 and 150 μg/kg) were in the range 85%-92%. The repeatabilities expressed as relative standard deviations(RSD) were ranged from 2.8% to 5.4%(n=6).2. An HPLC-MS/MS method was established for the simultaneous determination of two suckercides in fresh tobacco leaves. Using ethyl acetate as extraction solvent and including a cleanup step with primary secondary amine(PSA), graphitized carbon black(GCB) and C18 to reduce the high matrix effect found in these products. Thei Funnel technology was used to focus ions and multiple reaction monitoring(MRM)was used to monitor ions. The samples were quantified using external standard with the matrix matched standard calibration curve method. Under the optimized conditions, good linearities of two suckercides were observed in the range of 10-500μg/kg with correlation coefficients higher than 0.995. The limits of detection(LOD)and the limits of quantification(LOQ) for two suckercides were 1.5-2.4 μg/kg and5.0-7.9 μg/kg, respectively. The average recoveries at three spiked concentration levels ranged from 88.1% to 96.4%. The method was developed for the determination of pendimethalin and butralin residues in fresh tobacco leaves. This method could be a referece for advanced study of suckercide redidues in fresh tobacco leaves.3. A method was established for simultaneous determination of 24 pesticides in fresh tobacco leaves by GC-MS/MS. The method was developed for the determination of 24 pesticide residues in fresh tobacco leaves.4. The dynamic characteristics of residue and metabolism of butralin in fresh tobacco leaves was studied. The results showed that the residual amounts in fresh tobacco leaves increased, then decreased with the passage of time, The degradation dynamics rate of butralin was fast.