| 摘要: | 本研究利用紫外線-可見光吸收光譜儀和高效能液相層析儀-紫外光偵測器探討對羥苯甲酸甲酯、對羥苯甲酸乙酯、對羥苯甲酸丙酯、對羥苯甲酸丁酯、甲基異噻唑啉酮、苯氧乙醇、二羥甲基二甲基乙內醯脲、尿素醛以及市售複合型防腐劑等化粧品中常用之防腐劑對聚乙烯(PE)、線性低密度聚乙烯(LLDPE)和無延伸聚丙烯(CPP)薄膜型塑膠包材的滲透性。在紫外線-可見光吸收光譜分析中，首先測定防腐劑在紫外線波長範圍(200-400nm)的吸收特性，在測定防腐劑在在最大吸收波長處濃度與吸收度得關係，並藉此計算利用紫外線-可見光吸收光譜法測定防腐劑含量時的偵測極限與定量極限。而在高效能液相色層分析時，則首先探討不同組成與pH值的移動相對防腐劑層析結果的影響，並依此決定最佳的層析條件，接著也計算利用高效能液相層析法測定防腐劑含量時的偵測極限與定量極限。最後使用兩種方法與 Franz cell裝置測定防腐劑對薄膜型塑膠包材的滲透性。
從實驗結果發現，在雖然紫外線-可見吸收光譜法比高效能液相層析法的靈敏度高，但其無法分辨混合物中的不同成分，不適用於實際樣品的分析；但若要了解單一防腐劑對薄膜的作用關係，選擇紫外線-可見吸收光譜法則會優於高效能液相層析法。
在防腐劑的滲透性測試方面，單一個別防腐劑利用紫外線-可見光譜法分析其對PE膜的滲透效果，結果顯示，甲基異噻唑啉酮具有較高的滲透力，而以咪唑烷基脲的滲透力最低；至於將防腐劑混合後以高效能液相層析法分析的結果則顯示苯氧乙醇對PE膜的滲透力較高，而對羥基苯甲酸酯類的滲透力則隨著分子的增大而遞減。因此，防腐劑混合後個別防腐劑的滲透能力是否會改變值得進一步深入探討。
與單一個別防腐劑對其他塑膠薄膜的滲透性比較，甲基異噻唑啉酮對CPP膜的滲透率在受測的防腐劑中仍屬最高，而所有測試防腐劑中大部分對LLDPE之滲透率比對PE或CPP膜之滲透率來的低，可見LLDPE對防腐劑有較佳的阻隔效果。
此研究提供了防腐劑與對塑膠薄膜之滲透性的數據，對於為化粧品選擇適當的包裝材料應可提供重要的參考；但混合型防腐劑的滲透行為與單一防腐劑是否有所差異實在值得進一步深入探討。
In this study, ultraviolet - visible absorption spectroscopy and high-performance liquid chromatography with ultraviolet detection were used to investigate the permeability of methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, phenoxyethanol, methyl isothiazolinone, dimethylol-dimethylhydantoinc, imidazolidinyl urea and two commerical composite preservatives through thin film of plastic packaging materials, such as polyethylene (PE), linear low density polyethylene (LLDPE) or non-oriented casting polypropylene (CPP) In ultraviolet absorption spectroscopy, the absorption behavior of preservatives in the wavelength range of UV radiation(200-400nm) were first measured and the detection limit and quantification limit were calculated from the concentration and absorbance relationship at maximum absorption wavelength of respected preservatives. In high performance liquid chromatography, the influence of components and pH of the mobile phase on the chromatogram were studied to determine the optimum chromatographic condition. The detection limit and quantification limit of high performance liquid chromatographic method were also calculated. The above methods with the use of Franz cell were applied to study the permeability of preservatives through thin plastic film of packaging materials for cosmetics,
The results showed that, ultraviolet absorption spectrometry shows higher sensitivity than high performance liquid chromatographic method, but it is not possible to resolve the absorption of individual component in a mixture. However, ultraviolet absorption spectrometry is still a better method to study the interation of a single preservative and thin plastic film.
In the results of preservatives permeability through PE film from ultraviolet absorption spectrometry, methyl isothiazolinone shows much higher permeation rate than other preservatives and Imidazolidinyl Urea shows the least. However, phenoxyethanol shows the highest permeation rate in the study of the prentration behavior of mixed preservatives and analyzed by high performance liquid chromatography and the permeration rate of p-hydroxybenzoate esters were inverse proporational to the molecular size of the preservatives. Therefore, whether the permeability of preservative is changed after mixed is worth furth study.
Compared the permeability of a single preservative through other plastic films, methyl isobutyl thiazolinone shows highest permeability through the CPP film and most of all test preservatives shows lower permeability through LLDPE film. Therefore, it is suggested that LLDPE film has better barrier effect for preservatives.
It is concluded that this study provides informations on the permeability of preservative through plastic film, These informations could be an important reference when choosing the appropriate packaging material for cosmetics. But the penetration behavior of mixed preservatived is worth furth study. |
