防曬化粧品常用 SPF 測定儀以體外方式 (In vitro) 測定產品的SPF 值。本研究主要目的是利用SPF 測定儀所提供的更大範圍及更多波長數目的I(λ)及EE(λ)。先進行I(λ)及EE(λ) 乘積對波長作圖後，以數學回歸法找出最貼近的數學函F(λ)，用於取代I(λ)及EE(λ) 的乘積，如此即可直接與任何測得的紫外吸收光譜結合，並積分測得未校正的SPF 值。 然後，利用 SPF 30 標準乳液，依上述的方法測出校正因子 CF 值為1590。 最後，以不同配方的防晒產品測定的已校正的SPF 值與SPF 測定儀所測得的SPF 作比較。 結果顯示含化學性防曬劑的防曬產品，利用這兩種方法所測得的SPF 值之間，具有線性迴歸係數r 值為0.9980 的線性變化關係。 Sunscreen products’ ability to protect against the sun has often been estimated by diffuse transmittance analyzer (diffuse spectroscopy) through measuring SPF value (Sun Protection Factor). In the present work, more data of I(λ) and EE(λ) from manual of Labsphere UV-1000S were included and a modifying model were achieved via a probability function. Furthermore, using an emulsion with SPF30 as a standard for determining corrective factor (CF), the corrected SPF value of sunscreen products measured by dilution spectroscopy can be calculated based on the 1590 of CF. Finally, the SPF measured by dilution spectroscopy was compared to that by diffuse spectroscopy. The results showed that there is a good linear relation with correlation coefficient of 0.9980 between the two methods.