| Sample preparation |
Weigh 2.0 g of the powdered sample and place it in a cellulose extraction thimble. Place the cellulose extraction thimble in soxhlet extractor. Add 300 mL of ethyl acetate to a 500-mL round bottomed flask. Perform the soxhlet extraction for about 12 h. Collect and air dry the residue. Transfer the residue to a 50-mL conical flask. Add 25 mL of absolute ethanol and 150 μL of 0.1 M hydrochloric acid. Sonicate (220 W) the mixture for 30 min. Filter and evaporate the solvent to dryness at reduced pressure in a rotary evaporator. Dissolve the residue in 0.5 mL of absolute ethanol |
| Mobile phase |
n-butanol, hydrochloric acid, ethyl acetate 8:2:0.5 (v/v/v) |
| Derivatization |
Spray with the reagent (Dissolve 0.85 g of bismuth subnitrate in 50 mL of acetic acid (20%, v/v) and then add 20 mL of potassium iodide solution (40%, w/v) to obtain potassium iodobismuthate solution. Transfer 1 mL of potassium iodobismuthate solution to a 10-mL volumetric flask. Add 2 mL of 0.6 M hydrochloric acid and make up to the mark with water) |