Thesis (M.Sc.)--Chulalongkorn University, 2011

In this work, lab-on-paper coupled with sensitive electrochemical and simple colorimetric detection was developed to simultaneously determine ferulic acid and total antioxidant capacity. Photolithography was used to create the hydrophilic channels on filter paper. An electrochemical sensor for the determination of ferulic acid was fabricated using screen-printing technology. The quantity of ferulic acid was measured by differential pulse voltammetry. Under optimal conditions, the oxidation peak current showed a good linearity dependent on the concentration of ferulic acid in the range of 3140 ppm with a correlation coefficient of 0.9994. The limit of detection (LOD) of the proposed method was found to be 1 ppm. This presented method was successfully applied for the determination of ferulic acid in corn cider samples. The recovery of ferulic acid ranged from 96.85 % to 103.20 %. Furthermore, the colorimetric detection was successfully employed by the Folin-Ciocalteau reagent to concurrently quantify the total antioxidant capacity. The results in their color change at the detection zone can be determined by monitoring with the digital camera method. This developed method produced results in good agreement with the standard detection methods: HPLC-UV for ferulic acid and UV-vis spectrophotometry for total antioxidant capacity. Therefore, this method can be used for simple, rapid, inexpensive and sensitive dual and simultaneous quantification of ferulic acid and total antioxidant capacity in a variety of samples.