456 JOURNAL OF COSMETIC SCIENCE Figure 6. Vitamin A: Typical chromatogram of the o/w formulations. container exposed to daylight for 72 or 96 hours, not controlled esposure). Twenty milligrams of vitamin A were dissolved in 25 ml of isopropyl alcohol. Two milliliters of this solution were dissolved in 10 ml of water, 10 ml of HCI iN, and 10 ml of H202, 100 vol., and refluxed for at least 30 minutes. Degradation was monitored as a function of

LIPOIC ACID STABILITY 457 Figure 7. Vitamin E: Typical chromatogram of the o/w formulations. time. Each solution was neutralized and suitably diluted with mobile phase in a 100-ml volumetric flask and examined by HPLC. Fifty milligrams of vitamin E were dissolved in 25 ml of isopropyl alcohol. Two milliliters of this solution were dissolved in 10 ml of water, 10 ml of HCI IN, and 10

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