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    Microwave-assisted extraction of sulfated polysaccharide (Fucoidan) from Sargassum oligocystum Montagne
    Caceres, Kristhia Loren Maree R. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2016-06)
    Algae have been a source of food and medicine for humans. It contains sulfated polysaccharides that have been used as drugs. Fucoidan, a sulfated polysaccharide, found in brown algae have received more attention in recent years due to its potential biological properties that are important in cosmetics, pharmaceuticals and health industries. Fucoidan was recovered from brown seaweed Sargassum oligocystum Montagne by microwave - assisted extraction (MAE) technology. Different conditions of extraction time (10, 15 and 20 min) at 0.150kW were evaluated and the optimal fucoidan yield was 1.255 ± 0.0068 %, obtained at 20 minutes. Using this condition, a different set of samples was subjected to hot water extraction (HWE) and the average yield was 0.9767 ± 0.0002 %. The extracts from both methods were subjected to physico-chemical tests like gelling temperature, melting temperature, FTIR analysis, total carbohydrate content and total sulfate content. Having gelling and melting temperature values of 32 "C and 91"C for MA extracts and 30 "C and 89 °C for HW extracts showed qualities of a good agar gel. The total carbohydrate contents were 75.31 ± 0.015 % and 74.06 ± 0.0113 %, for MAE and HWE, respectively. It was also observed that the sulfate content of extracted fucoidan decreased with increasing extraction time. This study shows that MAE is an efficient technology to recover fucoidan from Sargassum oligocystum Montagne compared with the conventional heating method. This method provided enhanced extraction efficiency at reduced process time.
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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.