Abstract
In order to study the photostability of phylloquinone (K) and menaquinone-4 (MK-4) in injection and infusion solutions, high-speed liquid chromatographic determination was examined. Determination of K and MK-4 was made on a Permaphase ODS column with mobile phases of dioxane-H2O (68 : 32) and methanol-H2O (89 : 11), respectively for K and MK-4. Internal standards used were α-heptadecanyl naphthoate for K and α-pentadecanyl naphthoate for MK-4. K and MK-4 in the injection and infusion solution were stable when stored in the darkness, but decomposed by photo-irradiation according to the pseudofirst order reaction to yield phyllochromenol and menachromenol respectively as main decomposition products. These decompositions occurred by irradiation with the light of 350-500 nm region, with the maxima around 430 nm. Photodegradation of K and MK-4 was inhibited by excluding a light in the 350-500 nm region.
