The reverse phase - high performance liquid chromatography (RP-HPLC) method was developed to simultaneously determine three carotenoids, including lutein, lycopene, and β-carotene, in orange juice. Orange juice was extracted with n-hexane for 10 minutes, centrifuged for 5 minutes at 6000 rpm, and then evaporated under vacuum. A volume of 5 mL of the mobile phase was added, filtered through filter paper, and injected into the HPLC-PDA system under the following conditions: XBridge® C18 column (250 mm x 4.6 mm, 5 µm), mobile phase consisting of a mixture of acetonitrile: methanol: water: ethyl acetat = 70:9.6:0.4:20 (v/v/v/v) according to an isocratic program, detection wavelength 455 nm. The calibration curves for lutein, lycopene, and β-carotene determination had R² coefficients > 0.9997, and the validation parameters met AOAC standards. The method detection limits for lutein, lycopene, and β-carotene were 0.002 mg/L, 0.003 mg/L, and 0.006 mg/L, respectively. The validated method was applied to simultaneously determine lutein, lycopene, and β-carotene in 45 Vietnamese orange juice samples. Lycopene was not detected in the Vietnamese orange samples. The content of lutein and β-carotene varied depending on the orange variety and region. The β-carotene content in Citrus nobilis was much higher than in the other orange varieties in this study. The minimum and maximum contents of lutein in the collected samples were 0.018±0.008 mg/L and 0.221±0.039 mg/L, respectively, whereas these values for β-carotene content were 0.020±0.009 mg/L and 0.423±0.099 mg/L, respectively.

The reverse phase - high performance liquid chromatography (RP-HPLC) method was developed to simultaneously determine three carotenoids, including lutein, lycopene, and β-carotene, in orange juice. Orange juice was extracted with n-hexane for 10 minutes, centrifuged for 5 minutes at 6000 rpm, and then evaporated under vacuum. A volume of 5 mL of the mobile phase was added, filtered through filter paper, and injected into the HPLC-PDA system under the following conditions: XBridge® C18 column (250 mm x 4.6 mm, 5 µm), mobile phase consisting of a mixture of acetonitrile: methanol: water: ethyl acetat = 70:9.6:0.4:20 (v/v/v/v) according to an isocratic program, detection wavelength 455 nm. The calibration curves for lutein, lycopene, and β-carotene determination had R² coefficients > 0.9997, and the validation parameters met AOAC standards. The method detection limits for lutein, lycopene, and β-carotene were 0.002 mg/L, 0.003 mg/L, and 0.006 mg/L, respectively. The validated method was applied to simultaneously determine lutein, lycopene, and β-carotene in 45 Vietnamese orange juice samples. Lycopene was not detected in the Vietnamese orange samples. The content of lutein and β-carotene varied depending on the orange variety and region. The β-carotene content in Citrus nobilis was much higher than in the other orange varieties in this study. The minimum and maximum contents of lutein in the collected samples were 0.018±0.008 mg/L and 0.221±0.039 mg/L, respectively, whereas these values for β-carotene content were 0.020±0.009 mg/L and 0.423±0.099 mg/L, respectively.