Undergraduate Theses

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Determination of instrument detection limit and method detection limit of Varian 55B flame atomic absorption spectrometer for cadmium, chromium, copper, iron, lead, manganese and zinc using sips-10 and manual sample introduction methods
Calawigan, Roland Joseph C. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2009-04)
Determination of detection limits is an essential measure of performance for a quantitative laboratory, method or analyst. In this study, the Instrument Detection Limit (IDL) and Method Detection Limit (MDL) of F-AAS Varian 55B for cadmium, chromium, copper, iron, lead, manganese and zinc were determined using the SIPS-10 and manual sample introduction methods. For IDL determinations, EPA’s SW-846 method (Test Methods for Evaluating Solid Waste and Physical/Chemical Methods) was employed for both sample introduction methods where deionized water was analyzed for twenty times for three non-consecutive days. MDL determinations were done based on the definition given by the United States Code of Federal Regulations (40 CFR part 136, Appendix B - Definition and Procedure for the Determination of the Method Detection Limit). In this procedure, MDLs were estimated by calculating the standard deviation from the analysis of a standard solution containing the analyte with a concentration determined from the estimated detection limit, which was also analyzed for twenty times. Results showed that for the determination of IDL, all of the elements have lower values (Cd 0.000887 mg/L, Cr 0.00435 mg/L, Cu 0.000128 mg/L, Fe 0.000816 mg/L, Pb 0.000742 mg/L, Mn 0.000985 mg/L, Zn 0.000585 mg/L) for the manual method than the SIPS-10 method (Cd 0.00399 mg/L, Cr 0.0150 mg/L, Cu 0.00222 mg/L, Fe 0.00913 mg/L, Pb 0.0217 mg/L, Mn 0.00132 mg/L, Zn 0.00445 mg/L). For MDL, the results showed variations for both the two sample introduction methods. The MDL values for cadmium, chromium, copper, iron, lead, manganese and zinc are 0.0374 mg/L, 0.0235 mg/L, 0.00203 mg/L, 0.0197 mg/L, 0.0805 mg/L, 0.00325 mg/L and 0.00686 mg/L in the manual method, respectively and 0.0101 mg/L, 0.0429 mg/L, 0.00280 mg/L, 0.0186 mg/L, 0.19 7 mg/L, 0.00312 mg/L and 0.0103 mg/L in the SIPS-10 method, respectively. Both methods have comparable precision for copper, iron, manganese and zinc determinations while SIPS-10 method is more precise for cadmium, chromium, and lead analysis.
Comparative study of trace metals and common impurities of table salt produced in Leganes, Iloilo and Tibiao, Antique
Calawag, Jerolet E. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2000-10)
Trace metals such as cadmium (Cd), chromium (Cr) and lead (Pb) as well as the common impurities in salt like magnesium (Mg), calcium (Ca), sulfate, moisture, matter insoluble in water (MIW) and matter insoluble in acid (MIA) were analyzed using spectrophotometric (Flame Atomic Absorption &UV-vis Spectrophotometers) and gravimetric methods. Results showed that percentage concentrations of magnesium and calcium were significantly higher in sample A (Tibiao table salt) than in sample B (Leganes table salt) at 1- percent level of confidence. The percentage concentrations of MIW, MIA, moisture and sulfate were significantly higher in sample B than in sample A. Results of Uv-vis absorption spectroscopy indicated that both chromium and cadmium were absent in both samples while the lead concentrations in samples A and B were 10.9190 and 11.4831 ppm respectively. At 5% level of probability, the lead concentrations of both samples did not differ from each other. Using another technique of analyzing trace metals, the flame atomic absorption spectroscopy based on flame atomization, different results were obtained. Lead concentration in samples A and B were 6.4874 and 9.4977-ppm salt respectively. At 5 % level of probability, sample B had higher lead concentration than in sample A. The lead concentrations in both samples were all higher than 0.015 ppm, the allowable maximum limit of lead in water, or any drinks. The over-all results showed that sample B had higher contaminants than in sample A.
A preliminary study on the average yield of crude capsaicin from common varieties of Capsicum frutescens L. at two stages (Young and mature) using three extracting solvent
Cadornigara, Ma. Sylvia C. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 1998)
Crude capsaicin content of the air dried and homogenized plant material of the three varieties of Capsicum frutescens L. namely cayenne, tobasco and ‘kitikot’ were determined using diethyl ether, 99.5 % ethanol and 1.0N NaOH as extracting reagents. Statistical analysis showed no significant difference on the average percent yield of crude capsaicin on the three varieties of Capsicum frutescens L. using similar extracting solvent, but a significantly higher yield of crude capsaicin was found with 99.5% ethanol and 1.0N NaOH. Through thin layer chromatography the major components of the extracts identified could probably be capsaicinoids (Rf 15-17), carotenoids (only in 99.5% ethanol, Rf 96-97), and capsanthin (Rf 27-29) using n-hexane-acetone.
Spontaneous formation of silver nanoparticles in humid acid-rich water of Santa Barbara, Iloilo
Cadelina, Mary Dored Ann D. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
Humic acid (HA) - rich water of Sta. Barbara, Iloilo is successful in acting as a reducing and capping agent in the synthesis of silver nanoparticles (AgNPs). UV-Visible spectroscopy was used to determine the effect of irradiation time, varying HA and AgNO3 concentration, and electrolyte addition. Furthermore, the bactericidal efficacy of AgNPs was evaluated using broth microdilution method. Measurement of AgNPs was done using transmission electron microscopy (TEM). Lower irradiation time (10- 40 min) shows an increasing absorbance trend. However, absorbance decreased and showed bathochromic shifts when irradiated at longer times (50-60 min). AgNP formulations of 40 ppm HA with 4 mM AgNO3 and 50 ppm HA with 4 mM AgNO3 showed the highest peak intensity for varying AgNO3 and HA concentration, respectively. These results were found in both irradiated and un-irradiated samples. Aggregation occurred upon the addition of 50 mM, 100 mM, and 500 mM NaCl but was more prominent at 500 mM NaCl. Dialyzed and un-dialyzed AgNPs have bactericidal activity. However, un-dialyzed AgNP was a more effective treatment because it showed a bactericidal activity up to 1:16 dilution for both Staphylococcus aureus and Escherichia coli as compared to the dialyzed AgNPs which showed a bactericidal activity up to 1:4 for S. aureus and 1:8 for E. coli. The dialyzed AgNPs are polydispersed but were mostly small with sizes less than 10 nm based on the TEM image.
Heavy metals (Cr, Cu, Pb, and Zn) concentrations of road-deposited sediments within six public plazas in Iloilo City
Caceres, Rizza Daphet E. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2011-04)
Contamination from overland transportation is an unavoidable result of urbanization. Cr, Cu, Pb, and Zn arc common heavy metals introduced to the environment by transportation. Road-deposited sediment (RDS) samples were collected from six public plazas (Villa Plaza, Molo Plaza, Mandurriao Plaza, Plaza Libertad, Lapaz Plaza and Jaro Plaza) in Iloilo City from March 2010 to May 2010. 0.5M HC1 was used as extractant and heavy metals (Cr, Cu, Pb, and Zn) concentrations were determined using Flame Atomic Absorption Spectrophotometer (FAAS). The mean concentrations of Cr, Cu, Pb, and Zn in road-deposited sediments from six plazas were 8.79 ± 1.93, 40.90 ± 24.21, 60.74 ± 22.32, and 164.25 ± 25.0 mg/kg, respectively. Metal enrichment of Cr, Cu, Pb and Zn were approximately xl, x8, x7 and x18 more than the background values respectively. There was no significant temporal variation in metals concentrations of RDS between sampling collections. Generally, RDS from Plaza Libertad has the highest metal concentrations. Cu and Pb metals were highly correlated (R2 = 0.891) indicating possible similar sources. A good correlation (R2 = 0.918) was observed between Pb concentration and the number of vehicles that pass along the plaza per hour. Heavy metal concentrations in sediments from plazas have low hazard quotients but bioaccumulation of metals in the body could cause health effects. Efficiency of digestion procedures varied depending on characteristics, texture and composition of road-deposited sediments. 0.5M HC1 digestion was used because it is simple, cost-effective, time-efficient and it leaches out meaningful amounts of bioavailable metals. Using HC1 as extractant simulates human digestion since human stomach contains HC1 that could leach out metals if road-deposited sediments were ingested.
Antidiarrheal activity of Pterocarpus indicus bark extracts using castor oil-induced diarrhea model on mice
Cabatea, Norberto C. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2010-04)
This study evaluated the antidiarrheal activity of the bark of Pterocarpus indicus (Narra). The crude methanolic extract of the bark was subjected to sequential extraction using hexane, DCM, and ethyl acetate. These extracts were tested for antidiarrheal activity in vitro using the castor oil induced diarrhea model in mice employing charcoal tracing method. Thin Layer Chromatography (TLC) was used in determining the chemical constituents present in every extracts using spraying reagents to aid in the visualization of spots. Crude methanolic extract dosage 200 mg/kg body weight is the comparable dosage to the reference drug loperamide (2 mg/kg body weight). The hexane extract was the most active fraction and 200 mg/kg dosage was more effective than with the positive control loperamide (2 mg/kg). No antidiarrheal activity found in the fraction of DCM and ethyl acetate extracts. Phytochemical screening revealed positive tests for tannins, phenolics, terpenes, cardiac glycosides, saponins and reducing sugars in all fractions. Tests for flavonoids and alkaloids, however, were negative.
In vitro antibacterial activity of Hibiscus rosa sinensis leaf extracts against some pathogens associated with urinary tract infections
Cabayao, Coney B. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2011-04)
The in vitro antibacterial activity of Hibiscus rosa sinensis leaf ( methanolic, dichloromethane, ethyl acetate, n-hexane, and aqueous ) extracts were studied against Gram-negative (Escherichia coli and Pseudomonas aeruginosa ) and Gram-positive ( Streptococcus faecalis) bacteria. The methanolic extract was subjected to sequential liquid-liquid extraction using solvents of varying polarity and concentrations. Out of the 5 extracts, methanolic and dichloromethane extracts exhibited the highest antibacterial activity as measured using the zone of inhibition. This was followed by ethyl acetate and n-hexane extracts. At 200 mg/ml concentration, all extracts were considered active when tested with E. coli and S. faecalis, and were partially active against P. aeruginosa. The aqueous extract was inactive towards the three bacteria. The 200 mg/ml concentration showed no significant difference when compared with the positive control, amoxicillin (12.51μg/ml). This shows that Hibiscus rosa sinensis exhibits a promising antibacterial activity. Phytochemical analysis of the active fraction- the methanolic extract- showed the presence of alkaloids, tannins, glycosides, saponins, steroids, flavonoids, terpenoids, and anthraquinones. These bioactive components could be responsible for the antibacterial activity of Hibiscus rosa sinensis leaf extracts.
Antifungal activities of alginate films incorporated with lemon grass (Cymbopogon citratus) essential oil on sliced bread
Bronzal, Lucile A. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
The accumulation of non-degradable and non-recyclable waste materials leads researches to venture on biopolymer films which have been regarded as the promising green substitutes of non-biodegradable plastic materials. However, food products can be subjected to contamination by bacteria and fungi. The addition of plant derived essential oil can control microbial contamination of foods by reducing the growth rate of target microorganisms or by inactivating microorganisms by direct or indirect contact. Incorporating antimicrobial compounds into films provides a different way to improve the safety of ready-to-eat foods. In this study, the efficiency of synthesized alginate films incorporated with lemon grass essential oil (LGEO) for antifungal activity on white bread was evaluated. Two sets of film were prepared the (1) LGEO - Ethanol incorporated films and (2) LGEO — β-cyclodextrin inclusion complex films via solution casting method. Furthermore, the FTIR analysis of the generated films was also assessed to identify the functional groups present in the film that facilitates its antifungal property. Experimental results showed that LGEO enhanced the antifungal properties in the films and significantly slowed down the propagation of fungi on white sliced bread. After two weeks of storage, all bread samples packed with various film samples showed fungal growth. It was found out that citral is the main component of essential oil which contributes to the inhibition of fungal growth. The incorporation of LGEO in the film decreased the O-H peak absorbance while the inclusion complex in the film increases the O-H peak absorbance and broad O-H peaks were also obtained.
Optimization of pretreatment process of lip gloss for the determination of lead by flame atomic absorption spectroscopy
Bolivar, Eduardo L., Jr. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2013-10)
The optimization of the pretreatment process for the analysis of lead in lip gloss using a flame atomic absorption spectrophotometer (FAAS) was proposed in this study. Two variables were tested for this study: volume of nitric acid, HNO3 and volume of hydrogen peroxide, H202. Results of the optimization and statistical analysis revealed that 47.3 mL HNO3 and 2 mL HNO3 were the optimum volumes suited for the digestion of lip gloss in obtaining high analytical results for the lead analysis. Five different samples were randomly purchased from local markets in Iloilo City that may contain high levels of lead due to a report from BFAD that warned people about the use of several lipsticks imported abroad. Lip gloss samples were analyzed using the optimized protocol. The heavy metal content in the lip gloss samples were found to be between 52.0 - 126.3 mg lead/kg of sample. Results show that these were slightly higher than the allowable limits for lead contents in lip gloss set by BFAD and WHO. One-way ANOVA statistics showed that there was a significant difference in the lead contents among the different lip gloss samples.
DPPH free radical scavenging activity and total phenolic content of Talisay (Terminalia catappa) seeds
Bohol, Lyan Jean B. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2013-04)
Free radicals, a class of highly reactive molecules derived from the metabolism of oxygen is believed to be involved in many health disorders. It is generated as by-products of biological reactions or from the environment. Antioxidant-based drugs and formulations for the prevention and treatment of complex diseases have attracted a great deal of research interest in natural antioxidants. It is deemed necessary to screen medicinal plants for their antioxidant potential. Terminalia catappa is a widely-distributed tree in the Philippines with promising potentials in pharmacology. Evaluation of the in vitro antioxidant activity of methanolic, dichloromethane, and hexane extracts of Terminalia catappa seeds were carried out using two assays: 1, l-diphenyl-2-pycrylhydrazyl (DPPH) free radical scavenging assay and total phenolic content assay. Results revealed that methanolic extracts showed a significantly higher free radical scavenging activity and a four-fold increase in its activity relative to the standard Butylated Hydroxytoluene (BHT). Furthermore, methanol, DCM and hexane extracts have high total phenolic content. Present results indicate that Terminalia catappa is a potential source of antioxidant and a good candidate for the development of new nutraceuticals for treatment of diseases. Phytochemical screening to determine the group of secondary metabolites present and toxicity evaluation for recommendation as nutritional substitutes and human consumption are recommended.

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