Residue kinetics analysis of 6-benzylaminopurine and pyraclostrobin in tomato plants and soils by QuEChERS-high performance liquid chromatography

In order to investigate the distribution behavior of 6-benzylaminopurine (6-BA) and pyraclostrobin (two active ingredients for root-treatment agent) in plants, tomato was used as a model plant. A QuEChERS-high performance liquid chromatography method was developed to determine their dynamic contents in tomato roots, leaves and the rhizosphere soils. Results showed that the recoveries of 6-BA and pyraclostrobin in tomato and the rhizosphere soil were in the range of 82%-107% and the quantitative limit (LOQ) range was 0.03-0.09 mg/kg. After the root treatment, there was no 6-BA detected in the soil, but it was detected in the tomato roots and leaves in the range from 0.043 to 2.0 mg/kg, indicating the bio-availability by plants was very high. 6-BA can be quickly absorbed by the roots and transferred to the side-leaf and the top-leaf. The order of distribution levels is side-leaf > root > top-leaf. 6-BA degraded at a high speed in both tomato roots and the leaves. Thus, it was not detected 7-10 days after the treatment. A proportion of pyraclostrobin was distributed into the soil and most of that proportion was absorbed by roots with a high level (1.2-3.0 mg/kg) for 28 days. A small amount of pyraclostrobin in roots was transferred to leaves and was kept with a level of 0.11-0.78 mg/kg for 4-6 days. This study has developed a method for the residue analysis of 6-BA and pyraclostrobin in the tomato root, leaf and soil, and it has also provided necessary data for evaluating the application of the root-treatment agent.