本文基于维生素K_3(亚硫酸氢钠甲萘醌)或甲萘醌在碱性介质中与氨基硫脲生成紫色化合物的反应。在波长540nm处,测定该紫色化合物溶液的吸光度。浓度范围在4-40μg/ml,符合比耳定律。从回收率实验与样品测定数据看,方法可靠、简便,适用于维生素K_3注射液的含量测定。 This article is based on the reaction of vitamin K_3 (menaquinone bisulfite) or menaquinone with thiosemicarbazide in the formation of a purple compound in alkaline medium. At a wavelength of 540 nm, the absorbance of the purple compound solution was measured. The concentration range of 4-40μg / ml, in line with Beer’s law. From the recovery experiment and sample determination data, the method is reliable and simple and suitable for the determination of vitamin K_3 injection.