Determination of vitamin k1 in plasma by differential pulse polarography and its possible clinical application

Differential pulse polarography, following solvent extraction, is used to monitor the clearance of vitamin K₁ (2-methyl-3-phytyl-1,4-naphthoquinone) from human plasma after a 20-mg intravenous injection. The average recovery of vitamin K₁ added to plasma (200–3000 ng ml^-1) was 72.2%. The coefficient of variation was 3.0% at a concentration of 2.75 μg ml^-1 of plasma. Measurements of vitamin K₁ in plasma from patients given an intravenous injection of the vitamin, support the idea that a metabolic cycle involving vitamin K₁ underlies calcification of bone.