The effect of different washing methods assisted by ultrasound on the removal of cypermethrin and spirotetramat residues in apples

The simplest way to remove pesticide residues from fruits and vegetables is to wash them with tap water. However, this method is not effective enough. In this study, the effectiveness of different washing methods assisted by ultrasound on pesticide removal was investigated. For this purpose firstly, apples were soaked in a cypermethrin (CYP) and spirotetramat (SPI) solution, which are frequently used as insecticides. Subsequently, the apples were washed in solutions prepared with vinegar, lemon juice, and baking soda at different concentrations (0.5%, 1% and 2%) and assisted by ultrasound (2.5–5 min). The residues in the medicated and washed samples were analysed on an LC-MS/MS instrument after extraction using the QuEChERS extraction method. The results of the analysis showed that acidic vinegar and lemon juice were more effective than baking soda. Moreover, the application of ultrasound significantly increased this effect. When a 0.5% vinegar solution was assisted by ultrasound, 62% of the cypermethrin residue was removed and 82% of the spirotetramat residue was removed. These values were 51.5% and 49.6% higher than tap water, respectively. In conclusion, acidic solutions such as vinegar, which we can easily prepare at home, are highly effective in removing pesticide residues when assisted by ultrasound.