Browsing by Author "Mubiru, Edward"
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Item Development and Validation of a Gas Chromatography−Flame Ionization Detection Method for the Determination of Epoxy Fatty Acids in Food Matrices(Journal of Agricultural and food chemistry, 2014) Mubiru, Edward; Shrestha, Kshitij; Papastergiadis, Antonios; Meulenaer, Bruno DeA reliable and suitable method for the determination of epoxy fatty acids in various food matrices based on the Bligh and Dyer lipid extraction procedure was developed and validated. The method involves the use of a methylated epoxy fatty acid as internal standard (IS), extraction of the analytes from the matrices followed by room temperature methylation, a three- step solid phase extraction (SPE) separation of the fatty acid methyl esters (FAMEs), and detection with gas chromatography− flame ionization detection (GC-FID). The method was validated in four different food matrices chosen as model systems, namely, vegetable oils, unprocessed pork, fried potato crisps, and infant formula. The extraction technique allows the method to be applied for routine analysis of a large amount of samples. Intraday repeatability ranged from 1 to 19%, and interday reproducibility ranged from 2 to 9%. The limit of quantification (LOQ) ranged from 3.32 to 20.47 μg g−1 of sample with recoveries ranging from 94 to 115%. The results verify the accuracy and reproducibility of the analytical technique and its ability to provide reliable quantification of epoxy fatty acids. Finally, levels of epoxy fatty acids in several food products on the Belgian market were screened and are presented.Item Development of a Sensitive and Accurate Stable Isotope Dilution Assay for the Simultaneous Determination of Free 4-Hydroxy-2-(E)-Nonenal and 4-Hydroxy-2-(E)-Hexenal in Various Food Matrices by Gas Chromatography–Mass Spectrometry(Food analytical methods, 2014) Papastergiadis, Antonios; Mubiru, Edward; Van Langenhove, Herman; De Meulenaer, BrunoAn analytical method suitable for the determination of 4-hydroxy-2-(E)-nonenal (HNE) and 4-hydroxy-2-(E)- hexenal (HHE) in various food matrices was developed and validated. The method involves the use of deuterated HNE and HHE as internal standards, extraction of the analytes from the matrices followed by derivatization and detection with gas chromatography–mass spectrometry. Four different food ma- trices were chosen as model systems including vegetable oils, unprocessed meat, fried potato crisps, and infant formula and three different extraction techniques suitable for the different matrices were applied including the Quick Easy Cheap Effec- tive Rugged Safe method. The simplicity of the extraction techniques allows the method to be applied for routine anal- ysis of a large amount of samples. The results verify the accuracy and reproducibility of the analytical technique and its ability to provide reliable quantification of both analytes at concentrations as low as 12.8 ng g−1 in meat samples. Fur- thermore, a short overview of the levels of HNE and HHE in several products available in the Belgian market is presented.Item Exposure assessment of epoxy fatty acids through consumption of specific foods available in Belgium(Food Additives & Contaminants, 2017) Mubiru, Edward; Jacxsens, Liesbeth; Papastergiadis, Antonios; Lachat, Carl; Shrestha, Kshitij; Mozumder, N. H. M. Rubel; De Meulenaer, BrunoEpoxy fatty acids (EFAs) are secondary oxidation products formed from unsaturated fatty acid hydroperoxides. Seventeen food categories were analysed for C18 monoEFAs of food products available on the Belgian market. A quantitative exposure assessment was performed based on deterministic and probabilistic approaches combining these concentration data with consump- tion data obtained from the Belgian National Food Consumption Survey of 2004. A preliminary evaluation of any potential risk related to the intake of the studied EFAs through the studied foods was performed by applying the threshold of toxicological concern (TTC) concept. Three food categories out of 17 foods, mayonnaise, butter–margarine and ready-to-eat meals were found to contribute most to the intake of EFAs. According to probabilistic determination, these foods had P50 intakes of 0.4085, 0.3328 and 0.2997 mg kg–1 bw day–1 respectively. They had P99.5 intakes of 3.7183, 2.7921 and 38.6068 mg kg–1 bw day–1 respectively. The intake below the TTC was from the consumption of cooked meat, smoked salmon and raw cured ham, with P50 intakes of 0.0006, 0.0007 and 0.0011 mg kg–1 bw day–1 respectively, and the other foods were above the TTC. Based on the TTC concept, a risk to human health could be identified related to the consumption of cheese, snacks foods, plant oils, French fries, dry nuts, chips, cured minced raw meat, cookies, fresh and frozen salmon and bacon.Item Human and environmental exposure to PCDD/Fs and dioxin-like PCBs in Africa: A review(Chemosphere, 2019) Ssebugere, Patrick; Sillanpaa, Mika; Matovu, Henry; Mubiru, EdwardThis paper reviews literature for the last two decades with emphasis on levels, toxic equivalencies and sources of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in Africa. Further, we comprehensively analysed data, interpret differences and identify existing gaps with those from other continents.We observed that high levels of PCDD/ Fs and dl-PCBs were reported in environmental and biological samples near densely populated urban and industrialised areas compared to those in rural settings. In general, the concentrations of PCDD/Fs and dl-PCBs in the blood samples from Africa were in the same range as those from Asia but lower than those from Europe. The concentrations of dioxins and dioxin-like compounds in the atmosphere in Africa were comparable to and/or higher than those in developed countries. The reported sources of PCDD/Fs and dl-PCBs in Africa were industrial emissions, obsolete pesticide stockpiles, household heating, recycling of electronic waste, and incineration and combustion of domestic waste. Regional and intercontinental transport of dioxins could not be confirmed because of the lack of sufficient literature on them. Further data about the levels and sources of PCDD/Fs and dl-PCBs in Africa need to be generated to complete the chemical inventories for the continent and to facilitate the implementation of the Stockholm Convention on persistent organic pollutants. The reviewed literature shows that most analyses have been carried out in laboratories outside Africa because of the limited institutional capacity in Africa. More support needs to be given to laboratories in Africa to develop the capacity to accurately quantify dioxins on routine basis.Item Hydrothermal Liquefaction of Water Hyacinth: Effect of Process Conditions and Magnetite Nanoparticles on Biocrude Yield and Composition(2021) Egesa, Dan; Mulindwa, Patrick; Mubiru, Edward; Aturagaba, GodwinIn this work, an efficient way of converting the water hyacinth to biocrude oil using magnetite nanoparticles (MNPs) as potential catalysts was demonstrated for the first time. MNPs were synthesised by co-precipitation and used in the hydrothermal liquefaction (HTL) of water hyacinth at different reaction con- ditions (temperature, reaction time, MNPs to biomass ratio and biomass to water ratio). The best reaction conditions were as follows: temperature— 320˚C, reaction time—60 minutes, MNPs to biomass ratio – 0.2 g/g and bio- mass to water ratio – 0.06 g/g. HTL in presence of MNPs gave higher biocrude yields compared to HTL in absence of MNPs. The highest biocrude yield was 58.3 wt% compared to 52.3 wt% in absence of MNPs at similar reaction con- ditions. The composition of biocrude oil was analysed using GC-MS and ele- mental analysis. GC-MS results revealed that HTL in presence of MNPs led to an increase in the percentage area corresponding to hydrocarbons and a re- duction in the percentage area corresponding to oxygenated compounds, ni- trogenated compounds and sulphur compounds. Elemental analysis revealed an increase in the hydrogen and carbon content and a reduction in the nitro- gen, oxygen and sulphur content of the biocrude when HTL was done in presence of MNPs compared to HTL in absence of MNPs. The nanoparticles were recovered from the biochar by sonication and magnetic separation and recycled. The recycled MNPs were still efficient as HTL catalysts and were recycled five times. The application of MNPs in the HTL of water hyacinth increases the yield of biocrude oil, improves the quality of biocrude through removal of hetero atoms, oxygen and sulphur compounds and is a potentially economical alternative to the traditional petroleum catalysts since MNPs are cheaper, widely available and can be easily recovered magnetically and recy- cled. This will potentially lead to an economical, environmentally friendly and sustainable way of producing biofuels from biomass.Item Improved gas chromatography-flame ionization detector analytical method for the analysis of epoxy fatty acids(Clinical and Vaccine Immunolog, 2014) Mubiru, Edward; Shrestha, Kshitij; Papastergiadis, Antonios; De Meulenaer, BrunoIn this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co- elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88TM column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03–2 mg g−1 of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.Item Interventions to Reduce Pesticide Exposure from the Agricultural Sector in Africa: A Workshop Report(International Journal of Environmental Research and Public Health, 2022) Röösli, Martin; Fuhrimann, Samuel; Atuhaire, Aggrey; Rother, Hanna-Andrea; Dabrowski, James; Mubiru, Edward; Cueva-Vásquez, Henry; Viglietti, Paola; Aqiel Dalvie, MohamedDespite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.Item Malondialdehyde Measurement in Oxidized Foods: Evaluation of the Spectrophotometric Thiobarbituric Acid Reactive Substances (TBARS) Test in Various Foods(Journal of agricultural and food chemistry, 2012) Papastergiadis, Antonios; Mubiru, Edward; Van Langenhove, Herman; De Meulenaer, BrunoThe ability of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test to determine malondialdehyde (MDA) in various food matrices was evaluated. MDA was extracted from the foods; the extract reacted with thiobarbituric acid (TBA); and the formed TBA−MDA adduct was measured spectrophotometricaly at 532 nm. In parallel, the TBA−MDA adduct was analyzed with high-performance liquid chromatography (HPLC) coupled with fluorescence detection. Oils and unprocessed and uncooked meat and fish products did not exhibit any significant difference in the amount of MDA measured by the two methods, indicating that the major substance reacting with TBA and forming an adduct that absorbs at 532 nm was MDA. However, in products such as dry nuts, pork sausages, cooked fish, and gouda cheese, an overestimation of MDA was observed, indicating that TBARS test was unsuitable for accurate determination of MDA. Furthermore, the results in the present work suggest that the overestimation of MDA by the TBARS test as it was applied is related to the interference of other than secondary lipid oxidation products.Item Organochlorine pesticide residues in Uganda’s honey as a bioindicator of environmental contamination and reproductive health implications to consumers(Ecotoxicology and Environmental Safety, 2021) Mukiibi, Stuart Ben; Nyanzi, Steven Allan; Kwetegyeka, Justus; Olisah, Chijioke; Matthew Taiwo, Adewale; Mubiru, Edward; Tebandeke, Emmanuel; Matovu, Henry; Odongo, SilverHoney has multifaceted nutritional and medicinal values; however, its quality is hinged on the floral origin of the nectar. Taking advantage of the large areas that they cover; honeybees are often used as bioindicators of environmental contamination. The focus of the present paper was to examine the quality of honey from within the vicinity of an abandoned pesticide store in Masindi District in western Uganda. Surficial soils (< 20 cm depths) and honey samples were collected from within the vicinity of the abandoned pesticide store and analysed for organochlorine pesticide (OCP) residues using gas chromatograph coupled to an electron capture detector (GCECD). The mean level of ΣDDTs in all the soil samples was 503.6 μg/kg dry weight (d.w). ΣDDTs contributed 92.2% to the ΣOCPs contamination loads in the soil samples, and others (lindane, aldrin, dieldrin, and endosulfans) contributed only 7.8%. Ratio (p, p′-DDE + p, p′ -DDD)/p, p′ -DDT of 1.54 suggested historical DDT input in the area. In all the honey samples, the mean level of ΣDDTs was 20.9 μg/kg. ΣDDTs contributed 43.3% to ΣOCPs contamination loads in the honey samples, followed by lindane (29.8%), endosulfans (23.6%) and dieldrin (3.2%), with corresponding mean levels of 14.4, 11.4 and 1.55 μg/kg, respectively. Reproductive risk assessment was done based on the hazard quotient (HQ) and hazard index (HI) procedure. In our study, the calculated HIs for adults (102.38), and children (90.33) suggested high potential health risks to the honey consumers. Lindane, endosulfan and p, p′ -DDD detected in the honey samples at levels exceeding the acute reference dose (ARfD) are known risk factors for spontaneous abortion, reduced implantation, menstrual cycle shortening, impaired semen quality, and prostate cancer in exposed individuals and experimental animal models.Item Oxidative stability and proximate composition of silver cyprinid (Rastrineobola argentea) used for fishmeal in East Africa(Journal of Applied Aquaculture, 2021) Kawooya Kubiriza, Godfrey; Ssempijja, Drake; Mubiru, Edward; Semwanga, Nathan; Odoli, Cyprian O.; Zalwango, Julliet; Masette, MargaretFishmeal and oils used for feed formulation contain polyunsaturated fatty acids (PUFAs) that are easily oxidized, and affect farmed fish. In this study, the effects of season (dry orwet), drying methods (i.e., artisanal: bare ground, rock surface,meshes laid on the ground or raised racks or adopted), aswell as storage time on Rastrineobola argentea used for fishmeal in East Africa were examined. Lipid oxidation and proximate composition stability were determined at 30-day intervals over a period of 90 days. Lipid oxidation stability was monitored by determining free fatty acids (FFA), peroxide value (PV) and thiobarbituric acid-reactive substances (TBARs). Changes in proximate composition were based on moisture, ash, crude protein (CP), crude fat (EE), and gross energy (GE). The relationships among lipid oxidation and proximate composition parameters were also explored. Considerable oxidative rancidity reflected by significantly high levels of FFA, PV, and TBARs in dried R. argenteawas recorded in thewet than in the dry season.Drying of R. argentea on bare ground andmeshes laid on the ground led to higher lipid oxidation than drying on raised racks. Lipid oxidation was also significantly higher in salted and indirectly dried R. argentea than in the unsalted and directly dried samples. Dry matter tended to decrease with storage time, as ash was high in salted samples and those dried on bare ground. There was a general decrease in EE content with storage time that coincided with peroxidation. However, CP and GE were less affected by season, processing methods and storage time. Drying R. argentea on raised racks was the best among the processing method investigated.Item Polycyclic aromatic hydrocarbons in sediments and fish species from the White Nile, East Africa: Bioaccumulation potential, source apportionment, ecological and health risk assessment(Environmental Pollution, 2021) Abayi, Juma John Moses; Tombe Gore, Christopher; Nagawa, Christine; Bandowe, Benjamin A.Musa; Matovu, Henry; Mubiru, Edward; Chelangat Ngeno, Emily; Odongo, Silver; Sillanpaa, Mika; Ssebugere, PatrickThe impact of oil exploration and production activities on the environment of sub-saharan African countries is not well studied. This study aimed at determining concentrations, sources, and bioaccumulation of 13 polycyclic aromatic hydrocarbons (PAHs) in sediments and fish from the White Nile near Melut oil fields, South Sudan. The study also assessed the ecological and human health risk associated with PAHs in this aquatic system. Total ( P 13) PAH concentrations ranged from 566 to 674 ng g 1dry weight (dw) in sediments, while those in fish were 191e1143 ng g 1 wet weight (ww). P 13PAH concentrations were significantly higher in C. gariepinus than in other fish species. Low molecular weight PAHs (LPAHs) dominated the profile of PAHs in sediments (constituted 95% of P P 13PAHs) and fish (97% of 13PAHs). Compared to Sediment Quality Guidelines of the United States Oceanic and Atmospheric Administration, the levels of LPAHs in this study were all above the threshold effect limits, but below the probable effect level, while those of high molecular weight PAHs (HPAHs) were all below the lowest effect levels. The carcinogenic potency equivalent concentrations of PAHs in L. niloticus and C. gariepinus were above the US EPA screening level; suggesting consumption of these species could adversely affect human health. Biota-sediment accumulation factor values (range: 0.006e3.816 g OC g 1 lipid) for PAHs showed high bioaccumulation of LPAHs in fish muscle, and that bioaccumulation decreased with increase in hydrophobicity of the compounds. This is possibly because LPAHs have higher aqueous solubilities which increases their bioavailability through water-gill transfers compared to HPAHs. Profiles of PAHs in the White Nile environment indicate predominant contribution from petrogenic sources, which could be attributed to presence of crude oil reservoirs and oil production operations. More research into the levels of other environmental pollutants in the oil-rich area is recommended.