Assessment of pesticide residues, exogenous heavy metals and essential minerals in spinach after cleaning with traditional methodologies

Green leafy vegetables are a rich source of micronutrients but can usually contain contaminants such as pesticides and toxic heavy metals. In this work, we have evaluated the effectiveness of washing with tap water, vinegar-acidified water and basified water with sodium bicarbonate in eliminating three pesticides (methomyl, deltamethrin and lambda-cyhalothrin) and some exogenous heavy metals. The HPLC-UV method was validated for pesticides analysis in vegetable matrices using the QuEChERS method extraction. The results showed that a ca. of 57 to 71% and 73 to 97% of the 3 pesticides are removed after washing with acidified and basified water, respectively. On the other hand, the ICP-MS method was used for analysing heavy metals and essentials elements in spinach. Washing with both acidic and alkaline water removed a part of toxic heavy metals. The decrease in metals concentrations indicated that, probably, the metals contamination of vegetables was mainly through the foliar deposition. Acidified and basified water solubilise small particles containing these exogenous metals In conclusion, the performance of washing with the basic medium was better to remove pesticides and some of exogenous toxic heavy metals from the surfaces of spinach leaves and to preserve the essential elements of the plant.