Optimization of the chromatographic separation using pure standards. A. Isocratic MeOH 100% as a mobile phase, T = 25°C. B. Isocratic MeOH 100% as a mobile phase, T = 60°C. C. Optimized gradient H2O/MeOH (10:90, v/v) - MeOH 100% in 1.5 min, followed by MeOH 100% for 2.5 min, T = 60°C. Other conditions are given in Materials and Methods. α-T, α-tocopherol; K, phylloquinone; PC-8, plastochromanol-8; PQ: plastoquinone-9 (oxidized form).