Abstract
It is known that there is a relation between the acidity of the skin surface and some skin protective functions.
Although water-soluble components in the sweat, horny layer and sebum are considered to contribute to the surface acidity, little is known about the quantitative relation among these factors.
Since lactic acid is thought to be one of the main acidic components, the relationship between skin pH and lactic acid value was investigated.
1. The amount of lactic acid was determined with our developing gas chromatography.
2. In vivo experiments were carried out on 20 healthy adults with respect to different seasons, regions and sexes. There were significant differences in skin pH and lactic acid values.
3. It was found that there was a significant correlation between skin pH (X) and lactic acid value (Y). The regression equation was X=5.289-log(Y-0.978).
