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Undergraduate Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/13

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2015 - 20173

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Committee Member: search.filters.committeemember.Martizano, Jay O.Start date: 2000

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    Determination of the anthocyanin content in Hibiscus sabdariffa L. (Roselle) calyses from fresh to spray-dried form
    Arganioza, Hannah Mae C. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    Hibiscus sabdariffa L. is an agricultural herb with calyces as the commercially important part this plant. The calyces is a good source of anthocyanin (pigments) with several potential applications in the food, pharmaceutical and cosmetic industries. These pigments are used worldwide in the production of drinks and as a source of natural food coloring. However, these pigments are very unstable due to processing and storage conditions. Thus, this present study investigated the amount of anthocyanin as it is processed into a commercial product in the form of spray-dried powder. The Roselle plant samples were obtained from Herbanext Laboratories farm. The fresh extract has 493.45 mg/L total monomeric anthocyanin. Compared to the fresh extract, concentrated aqueous spray-dried extract (261.06 mg/L) contains lower anthocyanin content, however, this is significantly higher than aqueous concentrate (124.41 mg/L). Both the aqueous extract and ethanolic extract contains the smallest amount of anthocyanin for each sets. Spray drying techniques increases the amount of anthocyanin which helps to prevent further degradation of the compound due to the influences of the storage environment and processing conditions.
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    Optimization of extraction Conditions of water-soluble phenolics from tawa-tawa (Euphorbia hirta L.) based on Densitometric TLC using gallic acid as marker compound
    Aborka, Ma. Ayanne B. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    The present study aimed to optimize the extraction conditions of water-soluble phenolics for tawa-tawa (Euphorbia hirta L.) with gallic acid as the compound of interest. Water was used as extraction solvent. The effect of the interactions of different extraction temperature (50°C, 60°C and 70°C) and extraction time (20 min, 40 min and 60 min) were investigated. To evaluate the importance of the parameters on the extraction efficiency of gallic acid, a factorial design was used. The normal probability plot and estimates of standard error showed that time and temperature were both significant parameters. It further showed that time was a more significant contributor than temperature to the extraction efficiency of gallic acid. The results revealed that interaction of time and temperature did not have significant effects. The ANOVA results showed that only extraction parameter with significant effect was time (p < 0.05). Temperature and its interaction with time did not have significant effects. Based on the desirability values generated by Design-Expert 9.0.4, the optimal conditions in extracting gallic acid were the following: extraction time of 60 minutes and extraction temperature of 70°C. Results of FTIR analysis confirmed the presence of the following functional groups: O-H, C=O, C-O, C-H (aromatic), C=C (benzene) and out-of-plane bending or oops. Gallic acid in tawa-tawa is present in esterified form and exists as part of hydrolysable tannins.
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    Optimization of lead (II) adsorption of EDTA-functionalized magnetic graphene oxide using response surface methodology
    Angeles, Christine Debbie Shanne V. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2017-06)
    Chronic intake of lead-contaminated water, even at low concentrations, can cause damage to the digestive, reproductive, and nervous systems. To effectively remove lead in water, solid phase extraction or adsorption is being used. In this study, EDTA-functionalized magnetic graphene oxide (EmGO) adsorbent was fabricated using a stepwise modification of graphene oxide (GO). It was characterized using SEM, FTIR, and XRD. EmGO was shown to have improved adsorption capacity towards Pb(II) in natural water. Also, the magnetic property of the adsorbent allowed an easier and more convenient mean of retrieval. The generated response surface model from Box- Behnken design (BBD) approximated the optimum condition for maximum removal efficiency of EmGO. Based on the results, the model had a 0.9113 (±0.0001) overall desirability, optimum values for pH, adsorbent dosage, and contact time were 5.99 (±0.01), 12.2135 (±0.0001), and 48.39 (±0.01), respectively. The highest percent removal efficiency of EmGO in the experiment was determined to be 73.41 (±0.01)%.