Abstract
Vitamin D2, also called ergocalciferol, has important effect on adjusting the in vivo metabolize of calcium and phosphorus. Vitamin D2 is manufactured by irradiation of ergosterol ( E). Many studies have been done on the reaction, showing that UV irradiation of ergosterol produces many isomers: vitamin D2, pre-vitamin D2(P), tachysterol, lumisterol and that the best irradiation wavelength is in the range of 270 ~310 nm for the conversion from ergosterol to pre-vitamin D2, which is not photochemieally but thermally isomerized into vitamin D2. The purpose of this paper is to find a new light source with a better result for the photoreaction with a low cost. The tube glass of the lamp could absorb most of the spectrum range below 254 nm which gives more by-products, so there was not any filter solution used. Firstly a certain amount of ergosterol was dissolved in ethanol to make a reactant solution (1.0 mg/mL). This solution was put in the photochemical reaction apparatus and irradiated by low pressure Hg lamp.