Determination of Phlorizin in Apple Trees by Capillary Electrophoresis

One of the characteristic and fundamental phenolic compounds in apple trees is phlorizin. This substance exhibits several therapeutic effects, which has prompted pharmaceutical research. Existing methods for extracting and determining phlorizin from apple trees have several drawbacks, including the use of toxic reagents, long analysis times, and the need to combine two separate analytical techniques. Therefore, an attempt was made to apply capillary electrophoresis. As a result, a method was developed for the quantitative determination of phlorizin by capillary electrophoresis using a background electrolyte containing 3 g/dm3 imidazole, 3 g/dm3 sodium tetraborate decahydrate, and 0.2 g/dm3 sodium sulfate, with a positive voltage polarity of 16 kV and a detection wavelength of 254 nm. Readily available, non-toxic components were used to formulate a time-stable electrolyte. The retention time of phlorizin was 3.5 ± 0.05 min, the detection limit was 0.5 mg/dm3, linearity was maintained up to 100 mg/dm3, and the calibration curve was obtained by the least-squares method. For experiments involving the preparation of biological material from apple trees, two extraction techniques were evaluated: infusion in 10% ethanol and ultrasonic extraction in 70% ethanol (comparison method). Unlike standard approaches, apple juice was analyzed without sample preparation. Verification of the results showed a high percentage recovery of added phlorizin—85.4 to 97% of the expected value—which confirms the reliability of the method. The phlorizin content in apple tree tissues was determined as follows: shoots of the Idared, Fuji, and Korea varieties contained 11.3–22.7 mg/kg; leaves contained 44.8–55.9 mg/kg; roots contained 77.3–84.2 mg/kg; and apple juices contained 2.9–3.7 mg/dm3.