LANOLIN DERIVATIVES WITH DILUTE HYDROGEN PEROXIDE 367 stoppered flask, protected from dust, is then placed in a 100øC water bath for a period of 24 hours. The flask should be immersed so that the water level is not above the 50 ml mark on the flask, and the bottom of the flask is not resting on the bottom of the bath. After 24 hours, the flask is removed from the bath and its contents are cooled to room temperature. The volume is then readjusted to exactly 50 ml with deionized water and transferred to a beaker. If the upper sample portion is solidified in the test flask, reheat until the sample is completely fluid before attempting remove from the flask. After thorough mixing, the formulation is again analyzed for H202 concentration. Final H202 concentration Calculation ß % H202 Stability --• Initial H202 concentration X 100 The procedure for the 66 ø test is identical in all respects to the 100øC test except that the flasks are immersed in a 66øC constant temperature- water bath for 7 days. Room Temperature Samples Portions of the test formulations were also placed in 12 oz. bottles. which had been passivated in the same manner as the flasks used for elevated temperature tests, and were fitted with vented tops. These containers were maintained at 25øC (room temperature) for observation. Data on the compatibility of water-soluble lanolin derivatives with H 20 are presented in Table 1. Table 1 Data on Compatibility of Water-Soluble Lanolin Derivatives with H202 (See also Fig. Solution Appearance Initial H202 Stability H•O2 Additive Initially After 7 days Con- at at 5% Concentration at 25øC pH tent 100øC 66øC ethox. lan. alc. % % (16 tool EO) .. clear, yellow No change 4'75 6'01 99.3 99.7 ethox. lan. alc. (25 mol EO) .......... 4.80 6.05 99.5 99-9, • ethox. cholesterol (24 tool EO) .......... 4-30 6'04 96.0 99.• ethox. lanolin (75 tool EO) .. slight haze, yellow .... 5.05 6.02 99.2 99.7 compl. acer. ethox. lan. ester .. clear, colourless .... 4-35 6.04 99-3 99-6• part. acer. ethox. lan. ester .......... 6.10 6.04 96'5 97'4'. The data indicate that 6 per cent H•O,solutions, incorporating the water-soluble lanolin derivatives studied, are extremely resistant to decom-

368 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS position in the 66øC and 100øC accelerated tests described above. It could therefore be expected that these solutions would exhibit very satisfactory 'shelf stability when aged under normal room temperature storage conditions for extended periods of time. Water-Insoluble Derivatives (See also Fig. 1) Liquid multi-sterol extract, absorption base, solid multi-sterol extract, isopropyl lanolate, lanolin oil, acetylated lanolin alcohols, acetylated lanolin, cholesterol USP. Because these lanolin derivatives are water-insoluble, they could not be tested in as simple a manner as the water-soluble derivatives described pre- viously. Each derivative was incorporated in the following basic dispersed system in order to obtain a homogeneous product containing H 20 2. A water- soluble lanolin derivative previously tested was used as emulsifier and emulsion stabilizer. Cetyl alcohol, known to have good compatibility with H202, was used as the thickener. •GENERAL FORMULA FOR DISPERSING WATER-INSOLUBLE LANOLIN DERIVATIVES Water-insoluble lanolin derivative 5% Water-soluble lanolin derivative 5ø/0 Cetyl alcohol NF 10/0 Hydrogen peroxide 6ø/'0 Deionized water plus phenacetin 83% Procedure: The prescribed quantity of water was heated to 100øC and 400 rag/1 phenacetin was added with mechanical stirring. Precautions were taken to avoid water loss. After the phenacetin dissolved, the solution was cooled to approximately 70øC and added, with continuous stirring, to a mixture composed of the desired water-insoluble lanolin derivative+water- soluble lanolin derivative+cetyl alcohol, which had also been heated to approx. 70øC. The mixture was then cooled gradually, with agitation, to the 35øC-40øC range at which point the required amount of 35ø/ H202 was added. Mechanical mixing was continued until the solution reached 25øC (room •temperature).