JOURNAL OF COSMETIC SCIENCE 414 UV- VIS SPECTROPHOTOMETER MEASUREMENTS The O /W emulsions shown previously were used for UV-vis measurements (2,4,6,15). Turbid- ity was compared using a UV-vis spectrophotometer (OPTIZEN Alpha, KLAB, Daejeon, Korea). For measurements, 1 mL of each CUFO and CUPO were used and diluted with 15 mL of purifi ed water. Likewise, 1 mL of CJSO was diluted with 10 mL of purifi ed water, and 1 mL HF was diluted with 15 mL of purifi ed water. All measurements were carried out at 600 nm. Turbidity was measured using the following equation (1,4,15): 7XUELGLW\ 7 $ ORJ7 w here T is transmittance and A is absorbance. The measurements were performed in triplicate. TURB IDITY METER MEASUREMENT Turb idity was compared using a turbidity meter (TU-2016, Lutron, Taipei, Taiwan). Turbidities of the essential oils or the HF emulsions were measured with the turbidity meter (Lutron) after 1 week storage at room temperature (2–4). Turbidity by nephelometry as ntu (nephelometry turbidity unit) was measured by diluting with purifi ed water [CUFO emulsion 30% (v/v), CUPO and CJSO emulsions 50% (v/v), and HF emulsion 60% (v/v)]. Measurements were performed in triplicate. DROP LET SIZE ANALYSIS Oil droplet sizes of the O /W emulsions were determined by dynamic light scattering using a Nano Zeta sizer (Nano ZS, Malvern Panalytical, England). Tubes with the O /W emulsions were stored undisturbed at room temperature. On the seventh day, each emulsion was diluted using pure water (1:100). Measurements were performed in trip- licate, and the average droplet size was expressed by using the mean droplet diameter. RESU LTS AND DISCUSSION MACR OSCOPIC APPEARANCE OF THE EMULSIONS Appe arance of the O /W emulsion [surfactant X: sorbitan sesquioleate (HLB = 3.70) + poly- sorbate 60 (HLB = 14.90)] was observed after storing for 1 week at room temperature. Figures 1, 4, and 5 show that the lower the HLB value, the more the upper part is separated. Figures 2 and 3 show that the highest turbidity when HLB had the highest value, 14.90. The comparison of the degree of emulsifi cation by suspension or layer separation is diffi cult for the HF (Figure 4) and CJSO (Figure 5) emulsions in the HLB from 5.94 to 12.66. TURB IDITY MEASUREMENT UV-v is spectrophotometer. The O /W emulsions stored at room temperature for 1 week were used in this experiment. The turbidity values for liquid paraffi n, CUFO, CUPO, HF, and CJSO emulsions at different HLB values are illustrated in Figures 6 and 7.

DETERMINATION OF REQUIRED HLB VALUE 415 The highest turbidity of liquid paraffi n emulsions is 63.18% when the HLB value was 10.42. The highest turbidity was shown by the CUFO (79.62%) and CUPO (76.58%) emulsions when the HLB value was 14.90. The HF emulsion displayed the maximum turbidity at 7.06 (50.77%). The CJSO emulsion showed the maximum turbidity of 73.40% when HLB was 7.06 and turbidity of 72.6% when HLB = 5.94. The CUFO and CUPO emulsions had the highest turbidity when HLB had the highest value, 14.90. Therefore, CUFO and CUPO needed additional experiments with polysorbate 20 (HLB = 16.70) so that HLB has a value higher than 14.90. From the additional experiments, the CUFO emulsion showed the highest turbidity when HLB = 14.90 in Figure 8A and HLB = 14.75 in Figure 8B. The CUPO emul- sion had the maximum turbidity at HLB = 15.35 in Figure 8A and HLB = 15.40 in Figure 8B. To c onfi rm whether the additional experiments using polysorbate 20 showed the same tendency as the previous experiments, the experiments were conducted using HF and CJSO emulsions. The HF emulsion had the maximum turbidity of 53.22% at an HLB value of 6.30, and CJSO emulsion had the maximum turbidity of 55.88% at an HLB value of 6.30 (Figure 9). Figure 1. Appearance after 1 week storage of liquid paraffi n emulsions. Figure 2. Appearance after 1 week storage of CUFO emulsions.