Quantitative evaluation of skin surface lipids.

More than 50 years of noninvasive studies of epidermal and sebaceous lipids has revealed a vast amount of information concerning secretion and regulation of SSLs. The first techniques developed (solvent extraction and cigarette paper) required very long experimental procedures to obtain valuable parameters; however, a great part of the knowledge on SSL production and regulation was obtained by these pioneers. Because of the difficulties encountered in these multistep procedures, applicability was restricted to a limited number of research centers. The sampling procedures in the newly developed techniques are significantly reduced and are followed by a fast and accurate evaluation. Moreover, the new sampling procedures permit us to study other aspects of sebum secretion, as demonstrated with the Sebutape method. When using photometric techniques an estimate of the SSL can be obtained within minutes (casual level measurements). After such a screening procedure, more standardized parameters can be accurately determined. Whatever the parameter under investigation, strictly controlled experimental procedures are required. Control of temperature and relative humidity of the experimental room, of the acclimatization periods, and of the volunteers during the collection periods is of capital importance. The studies discussed in this article clearly demonstrate the applicability of the new techniques not only for research and cosmetic purposes but also for clinical use.