Residue Determination of Dimethoate in Leafy Vegetables (Spinach) using RPHPLC

Residues of Dimethoate present in locally available Spinach varities Palak : Beta maritima, Vendhai : Trigonella foenumgraecum, Thandan : Amarnathus mangostanus green and red were determined. The quantification was carried out using RP-HPLC for unprocessed (fresh) and processed (washed, washed and cooked) Spinach samples. The extraction was carried out with benzene. It was found that unprocessed Dimethoate Spinach contains dimethoate residue which is slightly more than the tolerance limit, while the processed sample contains dimethoate residue within the tolerance limit. The washed samples (3 times under ordinary tap water) showed 28-50 % reduction while the cooked samples (boiling for 15 min) shows 58-71 % reduction compared to the unprocessed samples. Hence it can be concluded that in case of greens, it should be washed three times with ordinary water and then cooked (cooked for fifteen minutes) so that the pesticide residue is very much reduced and it will be well within the tolerance limit as specified by EPA (Environmental Protection Agency). KEYWORDS; Dimethoate, Spinach, Palak, Vendhai, Thandan INTRODUCTION Leafy vegetables ‘Spinach’ is said to be the ‘Prince of vegetables’. The food value of spinach is very high as it is a source of high grade iron. The compositionof iron in leafy vegetables per 100 g edible portion of Spinach beet (Palak) is16.2 mg, Spinach10.9 mg.The other chemical constituents of spinach are essential amino acids, Vitamin A and ascorbic acid. It is also found to be the daily diet of common people and most of the patients being admitted in the hospital. Pesticidesare substances used for preventing, destroying, repelling or mitigating any pest. The agriculture sector dominates the economic scenario in India. The occupation of nearly 60% of the population is predominantly agriculture. Nearly 30% of the food production is lost in India due to insects, pests, plant pathogens, weeds, rodents, birds and in storage. The uses of pesticides have become absolutely essential for increasing food production. India is the third largest consumers of pesticides in the world. Pesticides have become essential to modern agriculture but they are a potential source of chemical degradation of soils. They are also hazardous to the health of domestic animals and human beings if not handled properly. All pesticides interfere with normal metabolic processes in the plant and are classified according to the type of organism they are intended to control, eg. Insecticides to control insects, acaricides to control mites; nematocides to control rats; herbicides to control weeds; molluscides to control snails, slugs etc; fungicides to control fungal or bacterial infections; antibiotics to control bacterial, fungal, viral and mycoplasmal infections. In recent years the role of pesticides in relation to human welfare has been discussed the world over emotionally. Insecticides being toxic in nature, they should be used with extreme caution. If the pesticide content crosses the tolerance limit specified by FDA it can lead to disastrous effects. From the survey conducted in the local regions of Coimbatore, it was found that ‘Rogor’ (dimethoate) was the most commonly used pesticides among vegetables and greens. . The EPA (Environmental Protection Agency) tolerance level for dimethoate in Spinach fresh and canned is 2 ppm. If this limitation is crossed it may cause adverse effects like numbness, tingling sensations, in coordination, headache, dizziness, tremor, nausea, abdominal cramps, sweating, blurred vision, difficulty in breathing or respiratory depression and slow heart beat. Very high doses may result in unconsciousness and convulsion or fatality. Hence our project aims at detecting and quantifying, dimethoate present in (unprocessed)