Microwave corneosurfametry: a minute assessment of the skin compatibility of surfactant-containing products.

Objective: Surfactants may elicit several undesirable effects on the skin. The stratum corneum is one of the targets showing primary changes after a short contact with detergents. Corneosurfametry was introduced as an ex vivo bioassay to assess the interaction and compatibility of surfactants with human stratum corneum. The present work introduces a variant of the regular corneosurfametry test.

Methods: Microwaving set at 750 W for 30 s was used to shorten the duration of the technical procedure and to allow the rating of neat surfactant-containing products. The color of samples (L.* and Chroma C*) was measured to derive the colorimetric index of mildness (CIM), the values of which rise from 0 to 70 with increasing surfactant mildness toward human stratum corneum. Data were compared with standard corneosurfametry performed at 20 and 40°C.

Results: Data indicate that increasing the temperature of the test solutions and microwaving alter the CIM values of most surfactants. Only the most gentle products are little affected. An overall good correlation exists between the regular and microwave corneosurfametry data.

Conclusions: Microwave corneosurfametry is a new sensitive tool for predicting skin compatibility of surfactants.