EVALUATION OF SHAMPOO DETERGENCY 273 The rationale for using a synthetic sebum in the study was to obtain a reproducible soil composition and thus eliminate significant sources of variability (11). The sebum formulation was chosen to have a composition with a variety of functional groups similar to that in actual sebum (12). Functional group composition was: 1. Triglycerides-- 35 % 2. Fatty acids--30% 3. Waxes, hydrocarbons-- 15% 4. Esters--20% The actual formula for the Spangler sebum (10) used in our study was: Olive oil Coconut oil Palmitic acid Stearic Acid Oleic Acid Paraffin wax Squalene Spermaceti Cholesterol 20 0% 15 0% 10 0% 5 O% 15 0% 10 0% 5 O% 15 0% 5 O% 100.0% SOILING PROCESS Soiling of the hair tress was accomplished by dipping the tress in a sebum in hexane solution at the concentration under study. The soiled sample was manually agitated every 5 minutes while exposed to the soiling solution and then removed after 20 minutes. The solvent was then allowed to evaporate from the tress at room temperature (approx. 23 degrees C) for a period of 30 minutes. In this study two different soiling levels (2% and 10% sebum in hexane) were contrasted. The 2% solution represented a perceived soiled hair as determined in a panel perception study. The 10% soiling was performed to represent an overload situation. Comparisons of sebum removal at both total and component levels were made. CLEANING PROCESS One Of the greatest problems in a study of this type is the development of consistent methods which are representative of real-life conditions for sample soiling and treat- ment. In our efforts to be as "true to life" as possible, tap water was used for all rinsing. The tap water normally supplied in Hayward, California, is considered soft with an average hardness of 3 to 4 grains (about 60 ppm calcium carbonate). Formulations and single component actives were prepared using deionized water. Three different methods of sample cleaning were evaluated. 1. Bulk process. In this process the soiled hair tress is dipped into a surfactant solution and agitated for 5 minutes, rinsed, and the "clean" hair tress evaluated. In this study a 100-ml bath of 0.1% aqueous surfactant solution was used for each 1.5 grams of hair. Rinsing was accomplished by holding the hair swatch for 10 seconds per side in

274 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS running warm water (40 degrees C). The total rinse volume was approximately 500- 600 mi. The hair was then dried using a hand-held dryer. 2. Finger method. This technique most accurately mimics the "real world" shampoo procedure in that the solution being tested is applied and agitated in a manner con- sistent with actual consumer use. A 1.5-gram soiled tress was wetted under running water for 5 seconds per side (about 250 ml of water). Next 0.1 gram of undiluted shampoo (approximately 10% surfactant) was applied to the length of the tress. The tress was rubbed 15 times between the fingers as evenly as possible. Then the tress was reversed and rubbed 15 more times. Next the tress was rinsed under warm (40 degree C) water for 10 seconds per side and dried as before using a hand-held dryer. This yielded a total rinse volume of approximately 500-600 ml. 3. Sponge method. This technique is a modification of the "finger method" described above. The procedure is modified to provide a more consistent pressure upon the hair tress during the rubbing portion of the sample treatment. A 1.5-gram soiled tress was held under warm (40 degrees C) running water for 5 seconds per side, and then 0.1 gram of 10% surfactant solution was applied to the length of the tress. The tress was drawn 15 times between two prewetted sponges. A 100-gram weight was placed on the top sponge to simulate the approximate pressure applied by the fingers in that method. The tress was rinsed under 40 degree C running water for 10 seconds on each side and dried as previously stated. The sponges were cleaned before each use to prevent any buildup of sebum on them. We felt that this procedure combined the optimum combination of realism and simplicity. ANALYSIS The samples were placed in a forced air draft oven at 60 degrees C for 4 hours. This was to provide a uniform moisture content throughout the sample set. Karl Fischer moisture determinations indicated a residual moisture level of approximately 0.2% after the oven drying step. After samples were allowed to cool to room temperature, they were weighed (about 1 gram of hair) into 50-ml borosilicate serum vials. At this time exactly 20 ml of hexane was pipeted into the vial. The sample vessel was then sealed with a teflon-faced silicone septum and shaken on a mechanical shaker for 30 minutes. Hexane was chosen as the extraction solvent based upon the evaluation of available literature (10,12, 13,15) and on the basis of experimental data which indicates that it provides the best balance in extraction power, low toxicity, and relatively high boiling point compared with other nonpolar solvents. Other solvent systems which were investigated were methanol, isopropanol, methyl ethyl ketone, diethyl ether, carbon disulfide, chloroform, and isopropanol/hexane mixture (50:50). It was deter- mined early on in the course of our study that the hexane solvent system removed 95% of the available sebum from the sample using this procedure. Chromatographic profiles of the hexane extract of soiled hair tresses were comparable to profiles of standard sebum in hexane solutions used for the determination of component retention time. After the samples had been shaken for the set amount of time, the solvent was decanted from the sample. A portion of this was poured directly into an auto-sample vial, while the remaining extract was placed into a sample bottle and sealed for possible later examination. The auto-sampler vials were placed into the sampler and the analysis begun.