多效唑在番茄和土壤中的残留与降解动态研究

研究了多效唑（paclobutrazol）在番茄（Lycopersicon eseulentum）和土壤中的残留分析方法及残留动态。建立番茄和土壤样品中多效唑残留的固相萃取-高效液相色谱（SPE-HPLC）检测方法,样品用乙腈提取,再用φ（甲醇-二氯甲烷）=5∶95混合溶剂经LC-NH2固相萃取柱净化,以φ（乙腈-水）=55∶45作流动相,Shiseido C18色谱柱（4.6 mm×250 mm,5μm）于222 nm波长检测,外标法定量。在0.1~5.0 mg·L-1范围内,多效唑峰面积与其质量浓度之间呈良好线性关系,相关系数为0.9995。采用田间试验方法,在番茄幼苗期施用不同多效唑质量分数50、100、200、600 mg·kg-1,研究在不同处理时间1、6 h,1、2、3、7、14、21、30、45、60 d,多效唑在番茄以及土壤中的残留动态变化。添加质量分数水平为0.05、0.1、0.5 mg·kg-1时,多效唑在果实、植株和土壤中的添加回收率分别为92.45%~103.70%、94.52%~98.85%和94.30%~102.10%,变异系数分别为3.69%~5.00%、1.58%~4.53%和1.28%~3.35%。结果表明：多效唑在番茄植株和土壤中的降解规律均符合一级动力学方程C=Coe-kt。当施用质量分数为600 mg·kg-1时,其在番茄植株中的残留半衰期为1.66 d,在土壤中的半衰期为2.78 d;在植株中的降解速率大于在土壤中的降解速率。按照推荐使用的施用浓度,采收时多效唑在番茄和土壤中无残留,证明推荐施用浓度是合理的。

Dynamics of the residue and degradation of paclobutrazol in tomato and soil

The method for determination of the residue and degradation dynamics of paclobutrazol in tomato and soil was described. A method was established for the analysis of paclobutrazol residues in tomato and soil by using SPE-high performance liquid chromatography. The residues in the samples were extracted by acetonitrile, cleaned up by developed Supelclean LC-NH2 with the mixture of methanol-dichloromethane （5∶95,V/V） for the purification. Then, the sample were analyzed by the separation of C18 chromatographic column （4.6 mm×250 mm,5μm） with an acetonitrile and water （55∶45,V/V） mixed solution as the mobile phase and the determination with an ultraviolet detector at 222 nm. The analytes were by matrix matched standard solution, and the calibration curves shower good linearity within the concentrations of 0.1 to 5.0 mg·L-1 and the correlation coefficients were 0.9995. In field trial, The paclobutrazol of different concentrations 50, 100, 200, 600 mg·kg-1 was used on the tomato in its seeding stage,the residual dynamics were research on tomato and soil, under the different exposure of 0.04, 0.25, 1, 3, 7, 14, 21, 30, 45, 60 d. At different addition level of 0.05, 0.1, 0.5 mg·kg-1, the recovery were 92.45%~103.70%、94.52%~98.85% and 94.30%~102.10%, respectively. The CV were 3.69%~5.00%、1.58%~4.53% and 1.28%~3.35%, respectively. The results indicated that degradation of paclobutrazol in plant and soil samples were accordance with the first-order kinetic equationC=Coe-kt. When 600 mg·kg-1 of paclobutrazol was applied, the half life of tomato and soil was 1.66 d and 2.78 d. When applied according to the recommended dosage, There was no residues of paclobutrazol in the tomato can be checked in 30 d. The average growth period of tomato was 90 d. The terminal residues in tomato and siol were less than the detectable limits. So it testified that using this recommended dosage was reasonable.