A critical comparison of methods to quantify stratum corneum removed by tape stripping.

Skin surface stripping with adhesive tape has been used to study the barrier function of the stratum corneum. Usually, the amount of stratum corneum removed by stripping is not linearly proportional to the number of strips removed. The generally accepted quantitative method to determine the amount of stratum corneum material on a tape strip is weighing. This method however has certain drawbacks, it is time consuming and laborious because tape strips have to be weighed twice and sometimes it cannot be used to determine concentration profiles in the skin of active substances in topically applied vehicles. In this paper, the accuracy and reliability of an alternative method to determine the amount of stratum corneum removed by tape stripping of the skin was investigated and compared to weighing. It is based on the spectrophotometric examination of the tape. The light absorption by the proteins on the tape is correlated to the weight of the stratum corneum material. This method was found to be easier and faster than weighing, but it was less reliable because the light scattering of the stratum corneum on the tape largely overshadowed the absorption of the proteins. The light scattering showed a linear increase with an increasing amount of material on the tape, but with a large variability, resulting in calibration curves with correlations of 0.8400. However, direct spectroscopic analysis of stratum corneum tape strips has some distinct advantages even if it cannot be used for the exact quantification of stratum corneum proteins. With direct spectroscopic measurements, a tape strip can be laterally examined to inspect its homogeneity. Direct spectroscopic measurements on tape strips might also be employed to investigate the lateral and in-depth distribution of strongly light-absorbing substances in the stratum corneum.