Analytical Method Development and Dermal Absorption of Pyrogallol, a Hair Dye Ingredient

Pyrogallol is an ingredient in hair dye. Its concentration in hair dye is managed at less than 2.0% in Korea. There have been no reports on the dermal absorption rate of pyrogallol. The two purposes of this study were to develop an analytical method and determine the dermal absorption rate of pyrogallol. An analytical method was developed and validated by high-performance liquid chromatography (HPLC) analysis of various matrices including swabs (SWAB), skin (SKIN, dermis + epidermis), stratum corneum (SC), and receptor fluid (RF). Linearity (r² = 0.9993-0.9998), accuracy (92.1-108.2%), and precision (0.5-9.5%) met the validation criteria in guidelines. A Franz diffusion cell was used to determine the dermal absorption of pyrogallol using the skin of mini pigs. Pyrogallol (2.0%) was applied to the skin (10 μL/cm²). For the actual hair dye conditions, the skin was wiped with a swab 30 min after application. Twenty-four hours later, it was wiped with a swab again and the SC was collected using tape stripping. All samples were extracted with water and analyzed. RF was recovered at 0, 1, 2, 4, 8, 12, and 24 h. The total dermal absorption rate of pyrogallol was determined to be 26.0 ± 3.9%.