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| Methods of Removing Pesticide Residues in Tomato (Lycopersicon Esculentum) and Gotukola (Centella Asiatica) |
G.M.S.A. Sarada, C.P. Rupasinghe , C. Magamage
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Abstract:
Pesticides are widely used by the farmers in agriculture to increase the yield by controlling any undesirable plant or animal species. Pesticide residues can remain in fruits and vegetables as a result of neglecting recommended dosages of pesticides at the application and neglecting pre-harvest intervals. It is important to identify methods for removing pesticide residues in order to ensure food safety. This study was conducted to identify the methods for removal of pesticide residues in vegetables, to evaluate the effectiveness of those methods and to suggest the most appropriate method among them. Tomato (Lycopersicon esculentum) and Gotukola (Centella asiatica) were selected for the study as according to previous studies they contain higher amounts of pesticide residues and both are consumed mainly as fresh salads. Samples were collected from Central Market, Kandy. Analysis was carried out for the pesticides of Fipronil, Thiamethoxam, Imidacloprid and Pymetrozine, which are recommended for Tomato and Gotukola. Two samples from each vegetable were taken. In the first sample, tomato was spiked with 1000 ppm Fipronil and gotukola was spiked with 1000 ppm Pymetrozine. In the second sample, both vegetables were spiked separately with a mixture of all the four pesticides. Each spiked sample was divided into 4 portions; one part was kept as the control for direct residue analysis and the other three parts were subjected to removal methods; washing twice with tap water for 1 minute, dipping in 3% salt solution for 10 minutes and dipping in 4% vinegar solution for 10 minutes. The samples were extracted for pesticide residue analysis using QuEChERS, AOAC 2007.01 method. Residual analysis was carried out using Liquid Chromatography-tandem Mass Spectrometry (LC-MS-MS). According to the results, vinegar treatment has given the highest pesticide residual reduction. Salt treatment also has given considerable reduction percentages. Washing with tap water has given the lowest reduction percentages for all the four pesticides in both tomato and gotukola. So people are advised to consume these vegetables after dipping in 4% vinegar solution for 10 minutes. However, further studies should be carried out using more samples and for more pesticides by changing the concentrations of solutions and changing the time of applying treatments.
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