SURFACTANTS AND BLOOD CLEANSING BY SLS SOLUTIONS 105 [ ß o o o 90 80 70 60 50 40 30 0.00 0.02 0.04 0.06 0.08 0.10 0.12 % SLS ß NaCI Solution/SLS 0 DI Water ß DI Water/SLS Figure 2. 2% NaC1/SLS solutions. I 0.14 0.16 cellular material deposited on the cloth. Overall, the cleansing decreases slightly because in lower concentrations of SLS, the micelles are able to lyse the cells efficiently, but they are not as efficient in cleansing the abundance of denatured cellular material deposited on the cloths. In the douche solution (pH = 3.32-3.38), the SLS is incapable of sufficient ionization (Figure 3). Micelie formation is not present therefore, the surfactant action of SLS is greatly restricted and cleansing is at a minimum. The blood cells are lysed in the solution, but the denatured cellular material deposited on the cloths cannot be cleansed by the sodium chloride. Therefore, the nonionized SLS interferes with the salt solution's ability to remove the blood from the cloth. In deionized water (darkened square, Figure 3) the SLS lysed the blood cells and removed

106 JOURNAL OF COSMETIC SCIENCE 100 80 -• •, _ o 70 o 60 - o 50- 40- 3O 0.000 0.005 0.010 0.015 0.020 % SLS 0.025 0.030 ß Douche/SLS O DI Water ß DI Water/SLS ß DI Water (ph=4)/SLS Figure 3. Sodium chloride-based douche/SLS solutions. 88% of the material, but in deionized water, with its pH adjusted to approximately 4 with HCI (darkened triangle, Figure 3), the cleansing dropped to 76%. The ability of SLS to cleanse by surfactant action relies on its ability to form micelies, but in acidic solution, SLS is not ionized to any great extent, and so no micelies are formed. If micelles are not formed, then the surfactant activity of SLS is reduced, resulting in drastically reduced blood cleansing. CETYL PYRIDINIUM CHLORIDE CPCI, as a cationic surfactant, is not recognized as a particularly powerful surfactant