Determination of Zeaxanthin Dipalmitate and 2-O-(β-D-glucopyranosyl) Ascorbic Acid in Fruit of Lycium barbarum L.

Objective: To establish LC methods for zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid determination in the fruit of Lycium barbarum L. Methods: For the HPLC analysis of zeaxanthin dipalmitate, the test was performed on a Luna C₁₈ (2) column (4.6 mm×250 mm, 5 μm) with the column temperature at 25 ℃. The isocratic elution was adopted with the mobile phase of acetone/MeOH 55:45(V/V) at a flow rate of 1.0 mL·min⁻¹, and UV detection was performed at 450 nm. UPLC analysis of ascorbic acid was carried out on Torus TM Diol Column (3 mm×100 mm, 1.7 μm) at the temperature of 40 ℃. An isocratic system was also used at which the mobile phase (flow rate of 0.4 mL/min) consisting of acetonitrile (solventA) and 66.7 mmol/L ammonium acetate (solvent B) was set as 85% A and 15% B. UV detection wavelength was set at 260 nm. Results: The linear range of zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid were 0.01~0.1 mg/mL and 3.125~100 μg/mL, with the correlation coefficient being 0.9990 and 1.0000, the average recovery was 99.44% and 96.30%, while the RSD was 4.04% and 3.61% respectively. In 22 batches of L. barbarum samples, the contents of zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid were up to 0.51% and 1.33%, respectively. Conclusion: The two methods were accurate and reliable, which could be used to control the quality of L.barbarum fruit.