| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系所 === 105 === This thesis aims to fabricate a paper-based microfludic device with simplicity and fast speed. In conventional colormetric method, test strip would be compared with laves table after sequential color developments through chemical reactions. Color on test strip would change over time, which necessitate the comparison with laves table within predefined time frame, in order to quantify the contents by color development. Methyl p-hydroxybenzoate, commonly known as Methyl Paraben, has been widely used in foods, cosmetics, and pharmaceuticals, because its fine inhibitory effect on molds, yeasts, and bacterial. However, this compound could cause contact dermatitis and drug allergy, also reported as associated with breast cancer.
In order to detect methyl paraben contents, the principles of Fenton reaction were applied. Hydroxyl radical via Fenton mechanism would oxidize methyl paraben into phenol configuration, further complexed with Fe2+ to yield yellow-green coordination compound. Maximum absorbance was obtained after reaction of 5-10 minute in spectrophometric method, regression equation as y = 0.0007x – 0.1429, R2=0.9918, was acquired with standard solutions in 200-1000 ppm of methyl paraben. The limit of detection (LOD) by spectrophometric method was determined as 200 ppm. Paper-based device was designed utilizing WhatmanTM filter paper, and color developed via 4-5 minute of reaction on paper. Color laves were photographed and analyzed with Vision Assistant software. R (red), G (green), and B (blue) values were recorded, and R+G value was chosen to represent the color on paper-based device in accordance with principles of optics. Regression equation as y (R+G) = -0.031 x + 451.3, R2=0.996, was acquired with standard solutions in 1000-5000 ppm of methyl paraben. The limit of detection (LOD) by paper-based device was determined as 1000 ppm.
The device was applied to commercial cosmetics with approximately 85% of pertinence, in comparison with the results carried out by accredited laboratory via standard method (by TFDA), which indicates the application potential of this paper-based device for cosmetics. The maximum allowable addition of methyl paraben in cosmetics has been set at 1% (10000 ppm), and was commonly found between 1000 to 5000 ppm, which highlights the applicability of this simple detection device. Semi-quantitative results could be drawn without high cost nor sophisticated instruments.
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