Determination of vitamins K1 and K3 in green tea and in pharmaceutical supplements by capillary micellar electrokinetic chromatography

•A method to determine vitamins K1 and K3 by MEKC was developed.•High separation efficiency was achieved with low generation of waste.•Limit of detection was in the order of 10−5 g L−1 concentration level.•Recoveries of 96–105 % were obtained for green tea and supplement samples.•A detailed measurement uncertainty study was made.