Study On Residues And Dissipation Of Chlormequat And Mepiquat In Tomato Cultivation Matrix And Tomato Plants

Xinjiang is a region suited for tomato plantation and growth, owing to its unique resources such as water, soil and temperature. Xinjiang has developed as one of the three largest tomato production area all over world; meanwhile, Xinjiang’s tomato ketchup export almost occupies1/4of the total world export, and has become the pillar industry in Xinjiang’s agri-products processing industry. Recent years, Xinjiang’s tomato ketchup industry has been suffering great loss because of the high residues of CQ and MQ, therefore it is indispensable to establish a method for determining CQ and MQ in tomato and its cultivation matrix, and further investigate their dissipation rate and safe usage interval.Importantly,the experimental results can be employed as benchmark for setting up maximum residue limit(MRL) and for effectively controlling and guiding proper application of CQ and MQ on tomato plantation.The method using UPLC-MS/MS for analyzing the CQ and MQ residues in tomato cultivation matrix(soil, seeding water and seeding cultivation), tomato roots, stems and leaves and tomato fruits was developed in this paper. The soil samples were extracted with ASE(Accelerated Solvent Extraction) and cleaned up with WCX solid phase extraction column. The seeding water samples were extracted with WCX solid phase extraction column. The Seeding cultivation samples were extracted with methanol-ammnnium acetate solution, no clean up involved. Samples of tomato roots, stems and leaves were also extracted with purified water on ASE, no clean-up involved. The results indicated that the established method was simple, rapid and sensitive, besides, the recovery and standard relative deviation meet the requirement of quantification and quantitiation.This paper firstly, using the established method, analyzed the CQ and MQ residues in the soil and irrigation water in tomato planting area located in Xinjiang, the seeding cultivation sold in Xinjiang’s market, and the tomato plants and fruits. Secondly, the dissipation rates of CQ and MQ in soil, seeding water, seeding cultivation and tomato root, stem and leaf were investigated. The results illustrated that the dissipation rate and half-life for CQ and MQ varied strikingly. The CQ and MQ in soil dissipated much faster with the half-life of5.89d and6.42d; but that in water dissipated much slower with the half-life of22.37d and33.65d; that in tomato fruits practically had not change after15days; the half-life of CQ and MQ in tomato roots, stems and leaves was3.76d and3.66d. Finally, a range of suggestions on safe usage were listed out based on the study results.