Florisil

The analytical portions of the leaves (16 disks, 1 cm in diameter each) and flowers (8 pieces), both with the addition of 100 mL of water, and fruits (16 pieces) were homogenized in a Waring Commercial 8010 EG blender (Waring, USA) with 150 mL of acetone (Chempur, Poland) and filtered through a Büchner funnel under vacuum. The blender jar was flushed with 50 mL of acetone, and the washings were used to wash the filter cake. One-fifth of the filtrate (the equivalent of approximately 15.4 g of fruit and approximately 0.1 g of leaves) was used for further analysis. It was placed in a separatory funnel together with 100 mL of 2.5% sodium sulfate (VI) (Chempur, Poland) solution. The pesticide residues were extracted three times with 20, 10, and 10 mL of dichloromethane (Chempur, Poland). The combined extracts were evaporated to dryness, dissolved in 10 mL of petroleum ether and purified using a Florisil (Chempur, Poland) mini-column (Sadło et al. 2014 (link), 2015 (link)). The pesticide residues were eluted with a 70-mL mixture of 3:7 (v/v) ethyl ether:petroleum ether (Chempur, Poland) as well as with a 70-mL mixture of 3:7 (v/v) acetone:petroleum ether. The solvents were evaporated to dryness, and the residue was transferred quantitatively using petroleum ether into a 10-mL volumetric measuring flask.

After extraction of surface residues with petroleum ether, four analytical portions of flowers collected on a given day were combined into single samples to increase the residue concentration in final extract. Likewise, leaf samples were processed. They were homogenised in the Waring Commercial 8010 EG blender (Waring, USA) with 100 mL of distilled water and 150 mL of acetone (Chempur, Poland) and filtered on the Büchner’s funnel under vacuum. The blender jar was flushed with 50 mL of acetone, and the washings were used to rinse the filter cake. One-fifth of the obtained filtrate volume was used for further analyses. The filtrate was transferred to a separatory funnel together with 100 mL of 2.5% sodium sulphate (VI) (Chempur, Poland) solution. Pesticide residues were extracted three times with 20, 10, and 10 mL of dichloromethane (Chempur, Poland). The combined extracts were evaporated to dryness, dissolved in approximately 10 mL of petroleum ether, and purified on a Florisil (Chempur, Poland) mini-column (Sadło et al. 2014 (link); Sadło et al. 2015 ). Pesticides were eluted with 70 mL of a 3:7 (v/v) ethyl ether-petroleum ether (Chempur, Poland) mixture, and then with 70 mL of a 3:7 (v/v) acetone-petroleum ether mixture. The solvents were evaporated to dryness, and the residues were transferred quantitatively with petroleum ether to a 10-mL measuring flask.