Simultaneous determination of carotenoids, tocopherols and phylloquinone in 12 Brassicaceae vegetables

Abstract

At present, analysis of carotenoids, tocopherols and phylloquinone in vegetables are performed independently, suggesting a need for an effective analytical method to determine these lipophilic micronutrients simultaneously and accurately. A LC-APCI-MS/MS analytical method was developed and validated for the simultaneous determination of seven carotenoids, two tocopherols and phylloquinone in 12 Brassicaceae vegetables. The analytical run time was 35 min, with the full separation of lutein and zeaxanthin, using LCMS-friendly mobile phases comprising methanol and isopropanol mixtures. Limits of detection and quantification were 0.10–21.5 μg/g dry weight (DW) and 1.10–47.6 μg/g DW respectively. Intra-day and inter-day repeatability were less than 20% relative standard deviation (RSD), and recoveries were 89–128%. Data indicated that lutein and α-tocopherol were the predominant carotenoid and tocopherol in green leafy vegetables. Highest amounts of carotenoids, tocopherols and phylloquinone were found in rocket salad (1061 ± 11 μg/g DW), broccoli (286 ± 85 μg/g DW) and watercress (55 ± 4 μg/g DW), respectively. Our findings suggest that these vegetables are excellent sources of lipophilic micronutrients. Overall, this analytical method is ideal for the accurate and rapid determination of carotenoids, tocopherols and phylloquinone in vegetables.