防曬劑的分析，長久以來不論是在防曬產品生產上之品管或政府管理的抽驗上，均為不可忽視的一環。防曬產品中防曬成分之多樣化，例如將水溶性和油溶性防曬劑同時添加於產品中，提高消費者使用時的清爽感，並降低防曬劑對皮膚產生的刺激性已成為目前防曬產品發展的主要趨勢。在眾多的防曬產品分析方法中，利用高效能液相層析法進行分析是最常見的一種方式，但是基於分析物的特性，傳統分析上通常將水溶性和油溶性防曬劑分離後再分別進行分析，不僅使用的溶劑多也耗費時間。因此本研究希望經由層析參數的探討，建立尋求防曬劑分析之最佳化條件的適當模式，以提供實際樣品分析上的重要參考。
實驗中選擇了四種防曬化粧品中常見的防曬劑，包括油溶性的Octyl methoxy cinnamate（OMC）、Butyl methoxy Dibenzyl methane（Parsol 1789）、Methylene bis-benzotriazolyl tetramethyl butyl phenol（Tinosorb M）與水溶性的Phenylbenzimidazole-5-sulfonic acid（Eusolex 232），進行探討。針對移動相組成和pH值對層析結果的影響經由理論板數與解析度的計算尋求最佳層析條件的方法進行研究。
結果發現，分析OMC、Parsol 1789、Tinosorb M時，其理論板數會隨著移動相中甲醇的比例升高而升高，但分析Eusolex 232時，其理論板數會隨著移動相中甲醇的比例升高而降低，而pH值的影響方面，OMC、Parsol 1789、Tinosorb M解析度會隨著pH值的上升而降低。由於其在單一組成移動相之沖提下，理論板數差異過高無法得到良好的層析結果，經由梯度沖提的方式發現可得到較佳的層析結果。實驗中針對市售樣品與自製樣品進行分析，可得到良好的層析結果。
綜上所述，防曬劑的分析可先經由單一成分理論板數的計算獲得分析成分在該層析條件下的沖提效果，對於較不易分離的成分可再經由解析度的計算了解其分離效果。當分析成分性質差異過大，單一組成移動相之沖提條件下無法有效沖提時就應考慮梯度沖提的方式。此方法應可作為尋求日新月異的防曬產品中其他防曬劑之分析條件的重要參考。 Sunscreen analysis has long being an important part of the quality control of product or the legislation management of government. The variety of sunscreen has been increased in lately development of sunscreen product to increase the fresh feeling and reduce the risk of irritation. Among the methods for sunscreen analysis, it is very common to use high performance liquid chromatography for the analysis. However, the separation of hydrophilic and hydrophobic sunscreen prior to analysis is usually needed. It costs not only more solvents but also a lot of pre-treatment time. Therefore, it is aimed to establish a model for the seeking of optimized condition for sunscreen analysis.
Oil-soluble Octyl methoxy cinnamate (OMC), Butyl methoxy Dibenzyl methane (Parsol 1789), Methylene bis-benzotriazolyl tetramethyl butyl phenol (Tinosorb M) and water-soluble Phenylbenzimidazole-5-sulfonic acid (Eusolex 232) were chosen for this study. The relationship between the composition and pH of mobile phase with chromatographic elution results was observed and determined optimized chromatographic conditions via the calculation of theoretical plate number and resolution in this study.
The results show that the theoretical plate number is increased for OMC, Parsol 1789 and Tinosorb M with the increasing of methanol content in the mobile phase. On the contrary, the theoretical plate number for Eusolex 232 is decreased as the methanol content in the mobile phase increased. For the effect of pH, OMC and Parsol 1789 can be well-separated only at acidic environment. According to the optimized conditions, self-made and commercial products were also analyzed.
In summary, the elution performance can be obtained by calculating the theoretical plate number for individual component first. The separation performance can be obtained via the calculation of resolution. If acceptable chromatographic results cannot be achieved with isocratic elution, gradient elution can then be considered especially when the analytes exhibit great physical properties difference. This optimization process should be appropriate for applying to the analysis of sunscreen even with other sunscreen than those in this study.
