A limitation of most artificial sweat formulations used for in vitro assessment of chemical release from materials in contact with skin have little biological relevance to human sweat. The purposes of this paper are to provide guidance for preparation of a novel artificial sweat with chemical constituents at concentrations that match human sweat and to characterize chemical stability. The artificial sweat was characterized under conditions of use (with and without sebum at 36°C) and storage (without sebum at -4, 4, and 23°C) over 28 days by gas chromatography-mass spectroscopy, high-performance liquid chromatography, enzymatic assay kits, and ion-selective electrodes. Seven indicator constituents were tracked: sodium, chloride, glucose, lactic acid, urea, pantothenic acid, and alanine. With or without sebum at 36°C, the sweat solvent was chemically stable for 14 days. Storage by refrigeration at 4°C retained the chemical integrity of the solvent longest. Based on these results, the solvent should be used within 14 days of preparation. The artificial sweat model presented herein is most similar to human sweat and has applications as a dissolution solvent, donor solution in diffusion cells, or vehicle for patch testing. This sweat model may aid researchers in understanding potential release and percutaneous absorption of chemicals in contact with human skin surface liquids.
Aleksandr B. Stefaniak, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505