Effect on removal of pesticides by preparation for food

On vegetables in the market, we researched the change on concentration of pesticides residues by washing, boiling and dipping, and studied the methods for removal of pesticides residues. At preliminary experiment, we found that pesticides residues were scarcely contained in the frozen vegetables in the market. Therefore, the use of these vegetables is not suitable as samples. Because of these vegetables being not suitable, we added pesticides more to the vegetables artificially. After grinding, extracting and purifying these samples, contents of pesticides residues were measured by ‘gas chromatography-flame photometric detector’. In comparing among boiling, dipping, washing by water and washing by detergent, the rates of removal for pesticides were investigated. We inspected the collection rates of added pesticides respectively. Further, principal component analysis was made. Average removal rates of organophosphorus pesticides in spinach were, from point of higher grade, followed as boiling, dipping, washing by water and washing by detergent respectively. However, due to kinds of pesticides, removal rates were different. By principal component analysis, the methods of removal were divided into three groups: ‘boiling’, ‘dipping’ and ‘washing by water and by detergent’. Some percentages of removed pesticides were dissolved into water, or evaporated, or absorbed in equipments.