CW-Department of Chemistry

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Comparative determination of heavy metals bioaccumulation in bamboo as a phytoremediative process to polluted riverine wetlands
(Kenyatta University, 2009) Orina, B.G.; Anyango, S.O.; Wanjau, R.; Murungi, J.
Nairobi's unplanned settlements have resulted into open drained domestic and industrial waste into tributaries that join the larger Nairobi River at different stages of its development. Polluted water, to is either directly taken up by planted riverine crops or used through irrigation by the residents. Crop production acts as an important commercial venture for the communities living around the basin. Bioaccumulation of heavy metals such as Zn, Cu, Cd and Pb is evident in these crops causing a health risk to urban consumers. Rehabilitating these wetlands with alternative plant species that reinstate purification, not consumed as food with significant commercial value is therefore urgently needed. Bamboo, due to its growth characteristics and heavy metal accumulation tendencies could serve to uptake heavy metals from polluted aquatic ecosystems and also provide an income generating alternative. four species of bamboo; water bamboo, giant bamboo (Dendrocalamus gingateus), yellow and green bamboo (Bambusa spp) and other plants were grown on potted polluted soils from Motoine riverine, and the accumulated levels of Zn, Cu, Pb and Cd were determined at regular intervals. The results showed that bamboo averagely absorbs 243 mg/kg of Zn, 1.3 mg of Cd, 222 mg/kg of Cu and 36 mg/kg of Pb annually in its initial years. Significant correlations were observed between heavy metal concentrations in the soils after the harvests and the bioaccumulations in the bamboo species (P>0.05, DF12, t-test). Very high correlations between reducing soil heavy metal contents and increasing bamboo heavy metal accumulation (r = -0.788).therefore due to the first growth rate and large biomass index, bamboo forms a good plant for bio filtration of these heavy metals. Bamboo production per year is estimated to be between 30-75 tons/ha per year. The total absorption therefore translates to 6.66-16.65 kg of Zn, 7.29- 18.23 kg of Cu, 1.08-2.7kg of Pb, 39-97.5g of Cd per ha/ year. The study recommends building up of bamboo systems along Motoine River in Kibera as a purifying model and substituting them for commercial edible vegetation in slums around wetlands a viable option.
Assessment of the impact of anthropogenic activities on the levels of nitrates and nitrites in Mathare-Gitathuru drainage basin
(Kenyatta University, 2009) Nguyo, J.M.; Wanjau, R.N.; Murungi, J.I.; Moko, F.N.
Animal feed suppliment from avocado residue and other locally available materials
(Kenyatta University, 2009) Ndungu, E.; Gitome, J.; Wanjau, R.; Murungi, J.; Makibia, J.
Kenya's population has been on the increase, and more than 15 million people are poor and live in rural Kenya. Of these, 70% are women, who are particularly vulnerable because they do not have equal access to social economic assets thus widening economic gap and rising poverty levels that erode self-esteem and growth in education, health, food security and employment. Most of the poor people are farmers who, apart from growing crops for subsistence, majority of them also keep livestock as a major source of farm income and manure. Proper feeding of the animals is a critical input in productivity as feeding alone accounts for about 40% of production cost or more depending on the sources of feeds and feed ingredients. The available feeds used by farmers including plant residual and napier grass do not meet all the needs of the cattle kept by most farmers which compromises the productivity of the animals leading to low income for the farmer. In order to improve and empower the small holder farmer, there is need to come up with technologies that. can improve their lives. This project aimed at reducing poverty in Evurore division in Mbeere District, by training the locals to prepare animal feed supplement, using locally available avocados. Avocado is one of the most commonly grown farm products in area and is available throughout the year. The fruit is mainly used as a salad fruit and a source of oil for cosmetic products as well as fuel. The seed and the peels of the avocado fruit have not been fully exploited and are normally thrown away with the garbage. This project was designed to come up with an economical way of producing commercial feed supplement using avocado peels and seed as well as other locally available materials in order to curb the problem of low animal feed resources for livestock. The avocado peels and seeds were analyzed for the levels of essential minerals using atomic absorption spectrometry (AAS) and were found to have substantial amounts of the minerals. The produced animal feed supplement will be used as a source of essential macro and micro nutrients which improve health and productivity of the livestock and consequently that of the farmers. The efficacy of the feed developed will be tested by feeding rats and comparing the results with those of commercially available feed concentrates .
Effectieveness of plant oils and essential oil of Ocimum plant species for protection of stored grains against damage by stored product beetles
(2015) Obeng-Ofou.D, D.; Jembere, B.; Hassanali, Ahmed; Reichmuth, Ch.
Conducting polyamic acid membranes for sensing and site-directed immobilization of proteins
(2013) Noah, Naumih M; Omowunmi, A. Sadik
Poly (amic) acid (PAA) is a functionalized conducting polymer substrate that provides electrochemical detection control of biospecific binding. In this work, we report a biosensor platform based on the PAA for oriented immobilization of biomolecules. The PAA was used to covalently attach biomolecules, resulting in a significant improvement in the detection sensitivity. The biosensor sensing elements comprise a layer of PAA antibody (or antigen) composite self assembled onto gold (Au) electrode via N-hydroxysuccinimide (NHS) and 1 ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) linking. The modified PAA was characterized by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), and electrochemical techniques. Cyclic voltammetry and impedance spectroscopy experiments conducted on electrodeposited PAA on Au electrode using ferricyanide produced a measurable decrease in the diffusion coefficient compared with the bare electrode, indicating some retardation of electron transfer within the bulk material of the PAA. Thereafter, the modified PAA surface was used to immobilize antibodies and then to detect inducible nitric oxide synthase (a pain biomarker) and mouse immunoglobulin G (IgG) using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and amperometric techniques. ELISA results indicated a significant amplified signal by the modified PAA, whereas the SPR and amperometric biosensors produced significant responses as the concentration of the antigen was increased
New Catalytic Reactions of Iron(III) Porphyrins
(2014) Mbuvi, Harun M.
Metalloporphyrins have long been known to be effective catalysts for a variety of organic reactions. These include cyclopropanation, epoxidation, and aziridination of olefins. Iron porphyrins are also efficient catalysts for the olefination of aldehydes and ketones in the presence of triphenylphosphine. This suggested to us that iron porphyrins might have the potential to mediate a variety of other processes. The work described in this dissertation broadly extends the reactions catalyzed by iron(III) tetraphenylporphyrin chloride by focusing on the use of metalloporphyrins, mainly iron(III), Fe(TPP)Cl, as catalysts for N-H, C-H and O-H insertion reactions and cyclopropanation of arenes using various diazo reagents as sources of carbenes. A tandem N-H insertion/cyclization reaction using ethylenediamine and ethanolamine to give 2-piperazinone and 2-morpholinone respectively has also been investigated. Fe(TPP)Cl is one of the most efficient catalysts for insertion of the carbene derived from EDA into amine N-H bonds. This insertion reaction can be performed at room temperature and atmospheric conditions in relatively short reaction times. Fe(TPP)Cl is also an effective catalyst for O-H insertion reactions to alcohols when substituted methyl 2-phenyldiazoacetates are used as sources of carbene. Aromatic and normal aliphatic alcohols give O-H insertion as the only product.
The Reaction of Molybdenum halocarbonyls , [Mo(CO)4X2]2 ( MoX=Cl,Br) with Cyclic Amine
(Kenyatta University, 2014-09-29) Mbuvi, Harun M
The reaction of tetrahalooctacarbonyldimolybenum (II) complexes with various alylamines has studied with the aim of finding out the nature of the organic oxidation products. In these reactions, piperidine, I-ethylpiperidine, I-methylpiperdine, 2-ethylpiperidine and benzylamine were used in the study. The results obtained show that as in the previous studies, molybdenum (II) is reduced to molybdenum (0). There is no evidence of molybdenum (III) species; hence the reaction must be proceeding via a redox mechanism. Our studies suggest that the amines are oxidized to imines and in a few cases; it was possible to isolate the imine salts.
Phytochemical and biological studies of the genus Croton for the development of agrochemical and pharmaceutical products
(2004) Chhabra, S. C.; Thoruwa, C. L.; Thiong'o, G. T.; Akeng'a, T. A.; Wambua, P.; Ndunda, B.; Onyango, I. O.
Over the past two centuries, research into the chemical and biological properties of natural products has yielded novel and more effective therapeutic agents for treatment of many human ailments. There is, therefore, need to focusing on these bioactive metabolites as possible biological controls of agricultural pests.The present study was intended to find some remedial measures to some common problems challenging to man. Seven Kenyan Croton plants, C. alienus Pax, C. dichogamus Pax, C. megalocarpoides Friis Gilbert, C. megalocarpus Hutch., C. menyharthii Pax, C. pseudopulchellus Pax, and C. sylvaticus Hochst. were selected for this study because of their reputation in folklore medicine.Crude extracts of the leaves, stembark and rootbark of these plants were bioassayed for antibacterial, antifungal and nematicidal activities. Based on the preliminary antimicrobial activity test results, four plants were selected for isolation and chemical characterization of compounds from their organic extracts to the chemical state of purity. The pure compounds were also investigated for antimicrobial and nematicidal activities.Liquid vacuum chromatography (LVC), column chromatography (CC) and thin layer chromatography (TLC) were used for isolation and purification of bioactive principles. Spectroscopic measurements like: Ultra violet and infrared radiations (UV IR), mass spectrometer (MS), proton and carbon-13 nuclear magnetic resonance (1HNMR and 13CNMR) were done to facilitate structure elucidation and identification of isolated compounds.Four compounds, lupeol, stigmast-5-en-3-β-ol, crotepoxide and harwickiic acid have been identified from these species which have been found to possess different biological activities.
Determination of insecticidal activity of Kenyan Bt isolates against the spotted stem borer, chilo partellus
(2010) Nyambaka, H. N.; Kimani, G.; Gichuki, S.; Amata, R.; Okomo, M.; Kasina, M.
The delta – endotoxin crystals containing insecticidal Cryproteins were isolated from 20 unidentified local Bacillus thuringiensis Berliner (Bt)isolates and a reference isolate Bt aizawai(Bta) using froth floatation and low speed centrifugation at KARI Biotechnology laboratories, NARL. The total protein was quantified using the Bradford assay method and protein yield from the nutrientbroths was estimated at 3.11 mg/ml ±0.938 mg/ml of nutrient broth culture with a purity level of 54.8% ±15.3% of the protein pellet. Leaf – dip bioassay was used to determine the efficacy of the isolates against Chilo Partellus (Swinhoe), a well-established and invasive stem borer in Kenya. Among the isolates, Bt44 and Bt48 had the most potent endotoxin crystals to 1stinstar C. partelluslarvae. In addition, the efficacy of these two isolates was not statistically different (P>0.05) from that of Btabased on LT50 values. The findings show that these two locally available unidentified Bt isolates could be used in management of C. partellusand their characterisation (Cryprotein) could aid in their utilization.

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