2007 ANNUAL SCIENTIFIC SEMINAR 597 Conclusions SPF readings for melanin pellets dissolved in sodium hydroxide applied to TT may not give accurate results, because of the ability to rapidly lift the TT from the quartz plate during SPF readings. Furthermore, dissolving melanin in sodium hydroxide may result in alteration of physical properties. Pellets not dissolved in NaOH and mixed with gelatin could easily be spread on IT. In vitro SPF results for this method compare favorably with limited published data for in vivo SFP determinations (3,4,5). This method has potential for use as a screening tool for topical and systemic photoprotective agents that may provide biological photoprotection. Further evaluation of this in vitro method of melanin SPF determination is warranted. Acknowledgement The authors gratefully acknowledge Marion Margosiak for her contribution in setting up data tables and tabulations. References I. Federal Register 64(98), (May 21, 1999). 2. Optometries LLC, Application Note No. 1 available at www.optometrics.com 3. Cripps DJ. J. Invest Dermatol., 76(5): 154-157, (1981). 4. Kaidby KH, KligmanAM. Arch Dermatol., 114: 46-48, (1978). 5. Sheehan JM, Potten CS, Young AR. Photochem and Photobio, 68(4): 588-592, (1998). Table 1: 1 % Gelatin Control 220 uL of gelatin was applied to TI to obtain a baseline reading. SPF 0.93 UVA/B Ratio 0 Erythemal UV A PF 0.94 (Protection Factor) Average UV A PF 0.94 Table 2: Mouse Melanin (Intact Cells) A 0.3 gram pellet mixed with 110 uL of 0.2N NaOH to dissolve the pellet. 110 uL of a sunscreen-free moisturizing lotion was mixed with the melanin/NaOH. 210 uL was spread on TI. Lotion Control I SPF= 0.8 Mouse Melanin I SPF= 1.8 Note: TI detached from quartz plate during readings. Table 3: Synthetic Melanin (Stock= 1000 uelmL) A O .01 grams synthetic melanin powder dissolved in 10 mL 2N NaOH. 220uL lotion and 300 uL melanin stock. 220 uL oflotion/melanin in NaOH applied to TI. SPF I 2.38 Table 4: Synthetic Melanin (Stock= 100 uelmL) Diluted stock melanin. 200 uL stock melanin 1.8 mL of 0.2N NaOH 200 uL lotion and 300 uL diluted stock melanin, 220 uL of lotion/melanin in NaOh applied to TI. SPF I 1.5