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    A preliminary study on the extraction of alginic acid from three species of brown algae: Sargassum polycystum, Sargassum cristaefolium and Turbinaria sp. in Taklong Is.,Guimaras
    Adelantar, Geoffrey V. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1996-04)
    Three species of brown algae were harvested in Taklong Is., Guimaras. These were Sargassum polycystum, Sargassum cristaefolium, and Turbinaria sp. These brown algae were subjected to physical and chemical treatment to extract and compare the amount of their alginic acid in the form of sodium alginate. Four seaweed collections for extraction were made between August to December, 1995. Values obtained during the first three extractions gave almost similar results. S. polycystum exhibited the highest percentage yield of sodium alginate with a mean of 22.84%. It was followed by S. cristaefolium at 22.21%. Turbinaria sp. gave the lowest yield with a mean of 14.12%. The last extraction somehow showed a decrease in the percentage yield of all three samples. S. polycystum yielded just 20.00%, S. cristaefolium at 19.00% and Turbinaria sp. at just. 10.10%. Several factors may have contributed to the differences in the amount of alginic acid of the three species of brown algae. Among these are the inherent capability of the different species of brown algae to produce alginates, the thickness and sturdiness of the samples, the viscosity of the extracts, and seasonal changes.
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    Geochemical association of Cr, Cu, Ni, and Pb in the sediments of Iloilo River estuary
    Arban, John Paul B. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2005-04)
    The geochemical association of Cr, Cu, Ni, and Pb in the sediments of Iloilo River Estuary has been studied using a modified Tessier’s sequential extraction procedure. The results obtained show that most of the metals studied are mostly associated in the residual and organic matter fractions of the sediment samples (Cr: 66.26% - 74.36% in the residual,15.43% - 24.08% in the Fe-Mn oxide fraction, 8.14% - 12.71% in organic matter fraction, and 0.000% - 2.996% in the exchangeable/carbonate fraction; Cu: 39.30% - 46.73% in the residual, 12.00% - 52.18% in the organic fraction, 3.227% - 11.41% in the Fe-Mn fraction, and 0.000% - 17.43% in the exchangeable/carbonate fractions; Ni: 42.75% - 57.02% in the organic matter fraction, 24.93% - 39.33% in the residual, 5.814% - 14.15% in the Fe-Mn fraction, and 5.504% - 13.12% exchangeable/carbonate fraction; and Pb in sample AAA-21: 48.02% in the residual, 38.55% in the organic matter fraction, and 7.33% in the Fe-Mn fraction, and 6.078% in the exchangeable/carbonate fraction). The analysis of the total metal concentrations of the sediment samples taken from Iloilo River are found to be above the reported concentration of uncontaminated sediment except for Pb in sediment sample AAA-21 (Chromium: 102.1 ug/g - 150.5 pg/g; Copper: 62.56 pg/g - 111.7 pg/g; Nickel: 53.40 pg/g - 75.44 pg/g; and Lead in sample AAA-21: 22.21 pg/g). The study shows that about 50% of the total metal concentration in the sediment samples are bioavailable to the aquatic organisms.
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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.