OW MICROEMULSION IN SUNSCREENS 455 obtained from the 10/90 oil/surfactant mixture at all dilutions between 10% polar phase and 90% polar phase. Ninety percent of the 15/85 oil/surfactant mixture combined with 10% polar phase gave a transparent system. Figures 2 and 3 show the ternary diagrams of C•2_ • 5 alkylbenzoate/ cetearyl sulfate/decylpolyglucose diluted with 2-methyl-2,4-pentanediol/water and 1,2- hexanediol/water. Table I shows the percentages of different components of transparent systems using 1,2-hexanediol. This and subsequent tables clarify the exact proportions of components of the microemulsions. The amount of total water is that present in the 55% decyl- polyglucose aqueous solution within the cetearyl sulfate/decylpolyglucose mixture, plus that of the polar phase. To calculate the percentages of the microemulsion compo- nents, total water was considered. Figure 4 shows the ternary diagram of the C•2_•5 C•-C•s alkylbenzoate Water/ 2-m etl•j I-2,4-penthaned iol ?_5/1 8GF20 ,0 fid Sodium cety Isulfate 5% • Decylpolyglucose 95% Figure 2. Ternary diagram of systems with C•2-C •5 alkylbenzoate, sodium cetylsulfate, decylpolyglucose, water, and 2-methyl-2,4-penthanediol. C=- C• alkylbenzoate . ,,. ,uco. .% 2/1 Figure 3. Ternary diagram of systems with C•2_•5 alkylbenzoate, sodium cetylsulfate, decylpolyglucose, water, and 1,2-hexanediol.

456 JOURNAL OF COSMETIC SCIENCE Table I W/W Percentages of Components of O/W Microemulsions Obtained With Cx2_•5 Alkylbenzoate (CAB), Cetearyl Sulfate (CS)/Decylpolyglucose (DPG), Water, and 1,2-Hexanediol (HD) Surfactant/lipid Total blend Dilution HD water CAB DPG CS 85/15 10/90 3.33 39.37 13.5 37.97 3.83 90/10 10/90 3.33 41.30 9.0 42.32 4.05 90/10 50/50 3.33 52.57 5.0 23.51 2.25 90/10 90/10 30.00 63.85 1.0 4.70 0.45 C= -C•= a I ky I benzoate 1,2 hexanediol•l 211 e, • $oya Lecithin 33 % Decylpolyglucose 67% Figure 4. Ternary diagram of systems with C•2 •5 alkylbenzoate, soya lecithin, decylpolyglucose, water, and 1,2 hexanediol. Table II W/W Percentages of Components of Microemulsions With C•2_•5 Alkylbenzoate (CAB), Soya Lecithin (SL)/Decylpolyglucose (DPG)/water, and 1,2-hexanediol (HD) Surfactants/lipid Total phase Dilution HD water CAB DPG SL 70/30 30/70 10.00 34.77 21.00 18.06 16.17 70/30 60/40 20.00 48.44 12.00 10.32 9.24 70/30 70/30 23.33 53.00 9.00 7.74 6.93 80/20 40/60 13.33 41.14 12.00 17.69 15.84 80/20 70/30 23.33 53.91 6.00 8.84 7.92 80/20 90/10 30.00 62.41 2.00 2.95 2.64 alkylbenzoate/soya lecithin/decylpolyglucose/water, 1,2-hexanediol system. Table II shows the percentages of components of some microemulsions with C•2_•5 alkylbenzo- ate/soya lecithin/decylpolyglucose/water and 1,2-hexanediol. The 33/67 soya lecithin/decylpolyglucose mixture produced transparent formulations when the 70% of the 30/70 oil/surfactant mixture was diluted with 30% polar phase this mixture thus allowed microemulsions with the lowest surfactant/lipid percentage to