MST-Department of Chemistry

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Adoption of biogas technology as an alternative energy source in Gakawa Location, Nyeri County, Kenya
(Kenyatta University, 2018) Otondi, Ronald Nyakweba
Tsetse flies (Glossina spp.) are vectors of Animal African Trypanosomiasis and Human African Trypanosomiasis. Two approaches have been used to combat the diseases: parasite and vector control. Parasitic control by trypanocidal drugs has so far failed due to problems of availability, toxicity and resistance development. Vector control by use of insecticides is ineffective. Trapping using baits have been relatively successful, except among pastoralists. Integration of repellants and attractants to create push-pull strategy may provide an effective control tactic at individual farmer and pastoralist level. A previous study on waterbuck, led to the identification of a blend of 15 electrophysiologically active constituents: six C8-C13 methylketones, two phenolic compounds, six C5-C10 fatty acids and δ-octalactone that is repellant to savanna tsetse flies. δ-Octalactone has been shown to singly elicit allomonal responses, and a follow-up study has shown that its structural modification can bear both repellants and attractants. In the present study, the effects of some δ-octalactone analogues on two Glossina spp. were carried out to elucidate their activities. (RS)-3-propylcyclohexanone (15) and (RS)-δ-valerolactone (16) and were synthesized and their structures confirmed using spectroscopic techniques, while 2-propyloxane (14) and (RS)-3-propylcyclohex-2-enone (17) were acquired commercially. The responses of the two Glossina spp. to each of the four analogues were determined in a two-choice wind tunnel. Data collected were subjected to Analysis of Variance and means ranked using Student-Newman-Keuls test and the tsetse preferences were compared using t-Test. In the bioassays, it was noted that (RS)-δ-valerolactone (16) and (RS)-2-propyloxane (14) elicited avoidance; whereas (RS)-3-propylcyclohex-2-enone (17) and (RS)-3-propylcyclohexanone (15) elicited attraction. There was no significant difference between the repellency of (RS)-δ-valerolactone (16) and 2-propyloxane (14) (p > 0.05) to both Glossina spp. However, the repellency of both, (RS)-2-propyloxane and (RS)-δ-valerolactone, were significantly lower than that of δ-octalactone (5) (p < 0.05). When (RS)-δ-valerolactone (16) and (RS)-2-propyloxane (14) were blended it was noted that the repellency was comparable to that of δ-octalactone (5) (p > 0.05) when G. pallidipes were deployed, but there was no significant improvement in repellency against G. m. morsitans. The attractancy of (RS)-3-propylcyclohex-2-enone (17) and (RS)-3-propylcyclohexanone (15) to the two tsetse species were comparable (p > 0.05). Blending the two attractants did not lead to any change to both tsetse species (p > 0.05). The study identifies potent attractants and repellants on the two Glossina spp. and therefore lays a useful basis for the development of more effective behavioural control of the tsetse species
Adsorbent Materials from Rice Husks and Water Hyacinth Ashes Blended with Bone Char for Removal of Fluoride Ions from Contaminated Water
(Kenyatta University, 2020-11) Gitonga, Rose Kagwiria
Safe and readily available water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes. Consumption of contaminated water may lead to acute and chronic health effects. The most common water pollutants include heavy metals, pesticides, and anions such as fluorides, arsenic, arsenite, chromate and selenate, which cause various diseases such as brain, liver and bone ailments. Among the pollutants, fluoride is the most occurring contaminant in water. Fluoride ions are absorbed by the body mainly through drinking water containing a concentration of more than 1.5 mg/L for a long period of time. At high levels, they cause health problems which range from mild to severe teeth and bone fluorosis. Many methods have been used for removal of anionic contaminants such as fluoride from drinking water. These methods include reverse osmosis, precipitation, electro dialysis and adsorption. Most of these methods are too expensive. This study aimed at synthesizing an adsorbent material from low cost agricultural waste products materials namely water hyacinth ash (WHA) and rice husks ash (RHA) blended with bone char and determine its effectiveness in removal of fluoride ions from contaminated water. Five zeolitic materials were prepared and labelled as zeolitic A (ZA), zeolitic B (ZB), zeolitic C (ZC), black bone char (BBC) and white bone char (WBC) by varying the amounts of rice husks and the water hyacinth ashes and blending with white and black char. Analysis of various oxides contained in the adsorbents was done by X-ray Fluorescence Spectrometer (XRF). Adsorption tests for fluoride ions by the five adsorbents were carried out based on the batch adsorption studies. These include varying the shaking speed, temperature, contact time, initial anion concentration and adsorbent dose. The concentration of fluoride ions remaining in the solution after adsorption was analysed using Fluoride Ion Selective Electrode (FISE). Results for the adsorption capacities for the five adsorbents fitted best onto Freundlich isotherm model which gave adsorption capacity (Kf) values as follows; ZA 1.181, ZB 1.281, ZC 1.061, BBC 1.142, BWC 1.112. The zeolite B had the highest adsorption capacity. This indicates that blending a zeolitic material by black bone char improves its adsorption capacity for fluoride ions from contaminated water. At optimum concentration of fluoride ion and optimum temperature, ZB removes 75.50% and 80.00% of the ion respectively. It gives 75.50% at a shaking speed of 120 rpm and 77.00% at optimum contact time. Therefore it is necessary to optimize use of locally available materials for application in defluoridation of water.
Adsorption of Selected Heavy Metals Using Modified Pennisetum Purpureum Plant Stalks: A Case Study of River Ruiru, Kiambu County, Kenya
(Kenyatta University, 2022) Murage, Daniel; Eric Masika; Alphonse Wanyonyi
Water pollution is a global problem affecting the welfare of humanity. Availability of clean water is a fundamental prerequisite to public health safety and the survival of the human race as well as animals. However, pollution of river water by heavy metal ions deposition is a grave ecological problem especially in developing countries. Previous research work on analysis of fish, soil sediments and water samples obtained from Nairobi and Ruiru river confirmed the presence of heavy metals. These metal ions which include lead, chromium, and iron are mainly from industrial effluents discharged into the rivers. Presence of the heavy metals in the water, pose a serious health risk particularly to rural populations which rely majorly on the river water for domestic purposes. Several methods for elimination of the heavy metal pollutants from river waters have been previously employed. However, most of these methods have proved to be expensive and cumbersome, hence not sustainable. Simpler methods are, therefore, needed for better sustainability. This research explored the potential of modified Pennisetum purpureum plant adsorbent in eradication of lead (II), manganese (II) and chromium (VI) ions from Ruiru river water by adsorption process. Sampling was done at three different locations along the river, that is, Ruiru Town, Juja Farm and Fourteen Falls. The mean concentration of heavy metal ions was determined before and after the adsorption process in triplicates using Atomic Absorption Spectroscopy (AAS). Effect of changes in pH on adsorption was investigated by conducting adsorption at pH of 5, 7 and 9. Data was organized in excel worksheets before it was transferred into SPSS software for analysis. The results show high chromium and lead pollution of the Ruiru river. Average concentrations of chromium and lead were 1.495±0.09 ppm and 1.610±0.1 ppm respectively. Average Manganese levels were 0.05±0.01 ppm which was within the permissible level (0.5 ppm). Modification of the adsorbent surface improved its adsorption capacity. The modified adsorbent achieved greater % adsorption in all the three metals. Increase in the pH of adsorption from 5 to 9 had a reducing effect on the percent adsorption of metal ions from water samples with significant reductions in % adsorption being recorded for lead and manganese ions but not for chromium ions. These results show the potential of the Pennisetum purpureum plant in the purification and detoxification of river water by adsorption. This adsorbent presents a more readily alternative to many current adsorbents and adsorption methods in use. However further research is needed to ascertain the best set of conditions as well as the most suitable modification treatment for maximum adsorption.
An alternative route for manufacture of diammonium phosphate
(2011-08-23) Mutenyo, Maximilla Makhanu
The present study was undertaken with the aim of producing Diammonium Phosphate (DAP) using air as a source of nitrogen and bones as source of phosphoric acid. Oxygen was removed from air by passing air over heated copper granules in the temperature range of 300°C - 500°C. Copper granules were heated using charcoal packed in a ceramic charcoal stove e. The nitrogen was reacted with lithium to form lithium nitride which was hydrolysed to produce ammonia. The phosphoric acid extracted by boiling bones with concentrated hydrochloric acid or phosphoric acid was reacted with ammonia produced from hydrolysis of lithium nitride to form diammonium phosphate. The percentage concentration of phosphorus in the fertilizer was determined using U. V spectroscopy whereas that of nitrogen was determined by titration. The cost of energy for the production of one tone of DAP using this procedure was calculated and results show that the total energy required was 4.95 GJ. This is equivalent to 1375 kW. The cost of basic materials operational costs and production costs) of producing one tone of DAP using this procedure was found to be $1070.88 while the estimated cost of regenerating lithium from lithium chloride was 1.26 GJ, which is equivalent to 350 kW
Aluminophosphates derived from tea leaves and pumpkin seeds ashes for removal of sellected heavy metals from contaminated water
(Kenyatta University, 2015-11) Maingi, Mukora Francis
About 43% of people in Kenya have no access to clean water. Lack of clean water may worsen as industrial development and population increases as projected if drastic measures are not taken immediately Pollution of water by heavy metals arises from many sources but most commonly from purification of metals, smelting industries, paint industries and textile industries. Activated carbon and other commercial adsorbents are frequently used as adsorbents. Despite their extensive use in water and wastewater treatment, these methods remain expensive. To reduce the problem of clean water scarcity, it is important to develop cheap adsorbent materials to remove heavy metals and turbidity from wastewaters. In this study, tea leaves ash (TLA) and pumpkin seeds ash (PSA) were used to prepare aluminophosphates adsorbent materials for removal of selected heavy metals from contaminated waters. These plant materials were collected from Muranga and Molo. Tea leaves was ashed at 400 ⁰C and pumpkin seeds at 800 ⁰C and resulting ash analysed using energy dispersive x-ray spectroscopy. TLA was found to contain about 30.1% of aluminium oxide and PSA contained about 37.0% of phosphorous (V) oxide. Two adsorbents A and B were also prepared by varying ratios of TLA and PSA. Material A, (APA) was prepared by mixing TLA and PSA 1:1 while material B, (APB) prepared by mixing them in ratio of 1:2. X-ray diffraction was used for phase identification and characterization of synthesized materials. APA was found to contain , kaolinite, smectite and ilitite while adsorbent APB contained , , kaolinite, ilitite and smectite. Batch adsorption experiments were carried out to optimize the effect of initial metal ion concentration, initial pH, contact time, temperature, shaking speed and adsorbent dose on percentage removal of Pb2+, Cd2+, and Cr6+ using the aluminophosphate adsorbent. Column studies were carried out to determine effect of dosage on percentage removal of turbidity. The experimental data was fitted in Langmuir and Freundlich isotherms and was found to fit best in Langmuir isotherm, as it had the highest value of correlation coefficient. Adsorption capacities obtained from linearized graphs were 45.45 mg/g for cadmium, 91.91 mg/g for lead and 50.00 mg/g for chromium using APA. Adsorption capacities using APB were 40.00 mg/g for cadmium, 50.00 mg/g for lead and 41.67 mg/g for chromium. Based on adsorption capacities, APA was a better adsorbent than APB. The results from this study shows that agro based aluminophosphates are potential adsorbents for remediation of heavy metals from wastewaters.
Analysis and treatment of clays from Mwea to assess their value as a source of aluminium and ceramic products
(2011-10-24) Karoki, Bernard Kareru; Muriithi, Naftali T.; Gachanja, A.
Clays are alumino-silicate minerals which contain varying amounts of iron, magnesium, calcium and potassium as major contaminants and, trace amounts of many other inorganic elements This study was undertaken with two main objectives The first was to carry out elemental analysis of clays from Mwea, Kirinyaga District, in Kenya. The second objective was to find out whether it is possible to reduce the amount of iron in these clays after some chemical treatment with mineral acids without affecting the quality of the clay. Samples for analysis were collected from various sites at different depths. The results of the study have shown that the main materials, expressed as oxides, make up nearly100% of the total mass .These are:- silica, Si02(43-51%), alumina, A1203(17-22%,) Iron(III) oxide, Fe203(12l6%,) , Rutile, TiO2(3.5-5.2%,), lime CaO(1.6-2.8%,), magnesium (II) oxide, MgO(1.01.3%0,), Manganese (ii) oxide, MnO(0.20-0.40%,), Potash K20(0.15-0.4%,). Mwea clays are, therefore typical clays that could be used as a source of aluminium and aluminium compounds. Titanium was present as the mineral rutile, Ti02. If further studies could be carried out to confirm the extensiveness and depth of deposits, then this clay could be a reliable source of titanium since is recovered economically from deposits 5 % of titanium oxide. The second important finding of this study was that, the iron in the clay could not be extracted completely with mineral acids even when pre-heated to a temperature of 400°C. The iron was, however, readily extracted with concentrations of 8 M and above of the mineral acids if the clay was pre-heated to a temperature of 500°C. Unfortunately, this pretreatment also makes the aluminium in the clay readily removable and hence, the heat pretreatment actually destroys the clay. Elemental analysis was carried out using Atomic Absorption Spectroscopy, X-ray Fluorescence Spectrophotometry, and EDTA titrations. These techniques were used for comparison purposes and, within experimental error; the results were in very good agreement.
Analysis of amaranthus oil from selected agro-ecological zones in Kenya
(2012-03-28) Okoth, Kevin Otieno
Amaranthus is a pseudocereal that has its origin in Mexico, South America. It is commonly known as 'terere' in Kenya and is mostly used as leaf vegetable. It is fast gaining interest in Kenyan population as a grain due to its ability to adapt to different environments thus can be grown in semi-arid areas, its fast maturity time of 45-75 days, its high economic value and its vital nutrient composition. Amaranth is found to flourish in hot and dry climates where other cereals are difficult to grow. It also grows in diverse geographical areas. It is also recommended for those ailing from cancers, skin diseases, arthritis, allergies, diabetes, cardiovascular diseases and HIV and AIDS due to immune boosting properties of its composition. Very little is available on the quality of amaranth oil in Kenya. Therefore, the study set out to establish if the diversity affected the amaranth grain oil composition, quality and quantity. Four different regions namely: Bondo, Bureti, Kenyatta University and Nyeri were chosen and two species of amaranth: Amaranthus cruentus and Amaranthus hypochondriacus were grown. The oils from the grains were extracted using soxhlet and Dyer and Bligh methods. Cold pressed oil was obtained for Meru and Embu regions from All Grains Company in Nairobi. The fatty acids composition were determined using gas chromatography and were identified by comparison with the RF of fatty acid standards injected under the same conditions while polar and neutral lipid composition was determined using thin layer chromatography. The study showed that there was statistically no difference in the composition of oil extracted from Dyer and Bligh method and that of cold pressing. The fatty acid profile for Amaranthus cruentus included: linoleic acid (35-38 %), oleic acid (32-36 %), palmitic acid (22-24 %), stearic acid (2-4 %) and linolenic acid (1-2 %). There was no significant difference in the composition of fatty acids in the selected regions. The fatty acid profile for Amaranthus hypochondriacus was: linoleic (41-44 %), oleic (26-34 %), palmitic (19- 24 %), stearic (2-3 %) and linolenic acid (1-3 %) with no significant difference being observed between the study regions. This study reported capric, lauric, myristic, pentadecanoic, palmitoleic and heptadecanoic acids for the first time though in small amounts. The total lipid component ranged from (7-10 %) for Amaranthus hypochondriacus and (7-9 %) for Amaranthus cruentus. There was a significant difference in the iodine value of both Amaranthus hypochondriacus and Amaranthus cruentus when they were compared for the respective regions. Triacyglycerides were the major component of neutral lipids (73-83 %) while phosphatidylethanolamine (25-60 %) and phosphatidylcholine (15-35 %) were the major components of the polar lipids. The results of the study compared well with those done earlier in other countries. The results of the study will be used to sensitize the communities on the oil nutritional value of amaranth us. They will also be availed to relevant authorities for further action.
Analysis of chemical composition of cowpea floral volatiles and nectar
(2011-08-23) Ager, Consolata Atieno
Cowpea is one of the 14 species of grain legumes. It rewards insects by producing nectar and it advertises to the pollinators by producing floral volatiles. The volatiles act as cues that guide insect pollinators in terms of pollen and nectar. Floral volatile quality also influences the efficiency of pollination. Genetic manipulations involving selection of varieties with high quality floral volatiles and nectar can therefore increase pollination efficiency and hence cowpea yields. It is believed that efficiency of insect pollination in several food crops is dependent on the quality of floral volatiles. Several molecules, including allozyme, codominant and isozyme DNA molecular markers (AFLP, RAPD and SSR) among others are useful in the selection of disease resistant and high yielding food crop cultivars in breeding programmes. Floral volatiles and nectar profiles can therefore act as molecular markers in compea breeding programmes. This project involved the collection, analysis and characterization of cowpea floral nectar and volatile composition. The flowers bloomed for one day and nectar was secreted between 6.00 and 10.00 am East African time. The flower sizes in the six selected cultivars were measured, nectar withdrawn using microlitre syringe and its characteristics (volume and sugar composition) examined. The sugar composition of the nectar was analyzed using HPLC, LC-MS and co-injection with authentic standards. Hydro-distillation and static headspace trapping with adsorbents (activated charcoal, reversephase, CIa bonded silica and porapak Q) was done in the six selected cultivars and volatiles concentrated using gentle stream of NZ while cooling under ice. GC was used to analyze the composition of floral volatiles and GC-MS for identification of the components. Co-injection with authentic standards was used to confirm identity of the components. Nectar volume varied as a function of time. A correlation between nectar production and time was observed. There were significant quantitative differences in the volumes of nectar produced in the different cowpea cultivars. The highest volume collected (18 m) was from cultivar 219, with a mean of 7.99 ± 0.78 Eil and the lowest recorded value (0.2m) was from SP46 with a mean of 3.65 f 0.5911.1. The cultivars showed similar trends in the rate of reduction in the volumes of nectar produced with time. Sucrose (0.104 f 0.099 mg), glucose (0.0224 ± 0.006 mg), and fructose (0.0225 ± 0.012 mg) occured frequently in the nectars. Lactose (0.003 ± 0.001 mg), raffinose (0.004± 0.002 mg), and mannose (0.006 ± 0.004 mg) were present in trace amounts. The biggest flower size recorded (47 mm) was from cultivar 219 with a mean of 42.62 ± 0.65 mm while the smallest size (10 mm) was from SP46, with a mean of 17.13 ± 0.65 mm. The nectar volume is directly proportional to the flower size. The total number of trapped volatile compounds ranged from 43-109 for headspace trapping and hydrodistillation.Porapak Q trapped the largest number of compounds.Quantitative and qualitative differences in volatile composition of various cultivars were noted. Aliphatic compounds were the most abundant followed by benzenoids, monoterpenes, sesquiterpenes, norisoprenoids and other compounds. The most common cowpea floral volatiles were toluene, 1-hexanol, benzaldehyde, acetophenone, limonene, 1-octen-3-ol, artemisia alcohol and nerolidol. Palmitic acid was the most abundant component of steam distillates. Due to the high protein content, grain legumes should help in reducing protein deficiency cases in developing countries. Improved legume yields should be encouraged to address protein deficiency in children. There is need to intensify production of cowpea by developing more efficient and well adapted varieties with good pest and disease resistance through biotechnology
Analysis of Deltamethrin and Lambda-cyhalothrin Pestcide Residues in Selected Vegetables from Urban and Rural Areas in Kenya
(2011-12-14) Njagi, G. J.
Vegetables are considered a cheaper source of natural nutrients. They are therefore widely consumed and they play a vital role by providing vitamins and minerals in the diet, besides supplying protein and energy. These nutrients from vegetables help to overcome common disorder like anemia, deficiency disorders and other ailments in human beings. Vegetables are also very important in neutralizing the acids produced during digestion and also useful as roughage. However, pests, diseases, and weeds destroy vegetables. There are many chemicals with which they can be controlled, including pesticides. Among the insecticides used are the pyrethroids which include; deltamethrin, lambda-cyhalothrin and chismethrin. Most of these chemicals are poisonous to creatures besides those they are intended to kill. There is need, therefore for monitoring the pesticides residues because they can be injurious to the life of human beings, animals, fish, and birds. Although, vegetables are widely consumed by almost everybody in Kenya, there is little work done on the analysis of pesticides residues in the vegetables. In this study deltamethrin and lambda-cyhalothrin were analysed because they are the most commonly used pesticides on vegetables. Vegetable samples were bought from both urban and rural areas. Pesticide residues were extracted from the samples using organic solvents. The residues were then determined by high performance liquid chromatography. The study showed that, during the dry season there were higher levels of deltamethrin and lambda-cyhalothrin in vegetables than during the wet season in all the samples analysed from both urban and rural areas. This probably is due to wash off effect of the pesticides by the rainwater. Another reason could be probably some farmers rarely apply pesticides on vegetables during the wet seasons because there normally few pests than during the dry seasons. In this case the mean residue levels ranged between 0.0130 and 0.3400 mg/kg during the dry seasons and between non detectable level and 0.1100 mg/kg during the wet season. The differences in levels of the pyrethroids during the dry and wet seasons were significantly different at 95 confidence limits. It was also found that the vegetables consumed in the urban areas contained higher mean residue levels of deltamethrin and lambda-cyhalothrin than those consumed in the rural areas during the dry and wet seasons. Most of the vegetables consumed in the urban areas are obtained from large-scale farms in the rural areas. The farmers of these large-scale farms therefore, may not have waited for the elapse time before harvesting their vegetables. May be they did not follow the application instructions recommended for the pesticides. The mean residue levels in this case ranged between non-detectable level and 0.3400 mg/kg in the samples analysed from the urban areas and between 0.0012 and 0.1100 mg/kg in the samples analysed from the rural areas. The mean residue levels of kale samples from an experimental garden that were analysed in this study, decreased between day one and day five after the application of the pesticides as a result of degradation and wash off effect. However, most of the vegetable samples analysed in this study had the two pesticides' residue levels exceeding the ADI (acceptable daily intake) although most of them were less than the MRLs (maximum residue limits). This means that those who feed on large amount of vegetables daily may be exposed to high levels of pesticide residues even though the elapse time was waited upon harvesting. Therefore, alternative methods to pesticides use on vegetables may be used like; the biological control of pests or the use of botanical pesticides.
Analysis of essential elements in selected infant food formulations sold in Nairobi County, Kenya
(2014-07) Ropkoi, Joel K.
Apart from breast milk, infant food formulations have a special role to play in the diets of infants because they are the major sources of nutrients. The neonatal period is one of the most critical with respect to nutrition and specifically essential elements among others. Essential elements prevent diseases such as rickets and anemia. Both calcium and iron are needed to prevent these disorders. Copper and zinc are important as cofactors of major enzymes involved in the synthesis of collagen. Potassium is a very important mineral for the proper functioning of the cells, tissues and organs in the body. Chromium is essential for protection against cardiovascular diseases. There is need therefore to analyse infant food formulations for levels of essential elements. Selection of the infant food formulations was done through random sampling. The commercial milk and cereal based formulations selected in this study were analysed for levels of essential elements, K, Mg, Ca Fe, Zn, Cu, Mn and Cr. The analysis was done by Flame Atomic Absorption Spectroscopy (FAAS). Analysis of variance and students' t-test were used to compare the levels of essential elements in infant formulations for 0-6 months and 7-12 months age groups. Mean levels (mgll ~Og) of essential elements in 0-6 months' infant formulations varied with the highest being K (425.03±4.67) and Cr (0.03±0.01), the lowest. The mean levels (mgll OOg) contained in the cereal based infant formulations for 7-12 months age group ranged between K (394.53±2.29) and Cu (0.31±0.48). To allow an assessment of infant exposures from the essential elements in the formulations, daily intake was calculated on the basis of information specified by the manufacturers on the labels. The results show that the infant milk and cereal formula samples analysed contain adequate amounts of essential elements with respect to WHO/UNICEF recommendations. This data can be used by dietitians to advise the public on the elemental concentrations of some of the infant food formulations available in Nairobi market.
Analysis of Essential Minerals in Residues of Mangifera. Indica L. Grown in Selected Divisions of Mbeere South, Embu County, Kenya
(Kenyatta University, 2015-01-15) Njiru, Michael Kariuki
The mesocarp (edible part) of Mangifera. indica L. (mango) is known for its contribution towards addressing nutritional challenges that face most of the developing countries. Based on the Recommended Daily Allowance (RDA) recommended levels by National Research Council (NRC) USA, mangoes would provide sufficient amounts of essential minerals, sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), Zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). However, as a result of consuming mangoes, over 150,000 tonnes of the residues (non edible parts) namely the epicarp (peels), endocarp (shell) and the seed kernels that account for 40-50 % of the fruit are dumped thus posing a concern on environmental pollution. A knowledge gap on the potential nutritional contribution and benefits of these residues in the arm of reducing environmental pollution is therefore called for. The Mbeere south in Embu county Kenya, grows varieties of mangoes some of which are ngowe, apple and van dyke. Residues of these varieties of mangoes grown in Mbeere were investigated to assess their food value particularly with regard to mineral content (Na, K, Mg, Ca, Zn, Cu, Fe, Mn). Mangoes were sampled twice randomly during the harvest period and the minerals measured using Atomic Absorption and Emission Spectrometry. Data analysis by one-way ANOVA was done using SPSS 18 for windows. The range of concentration (mg/100g) of essential minerals from lowest to the highest levels were as follows: In seeds; 0.48±0.05 (Cu, in apple) - 1492.05±43.75 (Ca, in ngowe): In endocarp; 0.38±0.02 (Cu, in ngowe) - 1689.5±9.15 (Ca, in van dyke): In peels; 0.38±0.03 (Cu, in ngowe) - 1482±2.05 (Ca, in apple). In most cases, there were no significant differences (p<0.05) in the levels of essential minerals both, between the residues and mango varieties. The seeds and peels residues as well as the ngowe and van dyke mango varieties recorded significantly higher levels of most minerals. Similarly, the levels of essential minerals decreased in the order Ca>K>Mg>Na>Fe>Mn>Zn>Cu. With regard to the RDA recommended levels of minerals, these findings indicate that mango residues are a rich source of essential minerals. This potential can be explored for other benefits such as for use in animal feeds/supplements than to cause the present hazard of environmental pollution. It’s a way of waste management.
Analysis of Essential Trace Elements in Selected Medicinal Plants Used in Kenya
(Kenyatta University, 2017-07) Kariuki, Njenga Isaac
Kenya is endowed with nature where hundreds of medicinal plants are available. During photosynthesis and respiration process in plants, animals and other organisms, ions of metal elements play a major role with a few of the elements being essential to the body as nutrients. Trace elements Zn, Cr, V and Se with known immunological response and healing properties were analysed from selected medicinal plants available in Kenya. These plants were; Prunus africana, Urtica massaica, Maytenus obscura, Maytenus putterlickiodes, Azadiracta indica (Neem), Mondia whytei, Zanthoxylum usambarense, Maerua edulis, Trigonella foenum-graecum (fenugreek) and Glycyrrhiza glabra. The concentrations of elements were determined using Energy Dispersive X-ray Fluorescence Spectrometer (EDXRF). The levels of zinc varied from 25.94±1.89 to 70.58±4.70 mg/kg (mean 45.94± 12.42 mg/kg). Vanadium from 1.69±0.18 to 9.99±0.86 mg/kg with an average level of 5.89± 2.09 mg/kg. Chromium from 1.44±0.30 to 6.94±0.59 mg/kg with a mean of 3.49±1.32 mg/kg. For selenium the levels varied from 53.21±5.45 to 124.01±4.41 μg/kg with a mean of 90 ±19.17 μg/kg. The levels of the trace elements were compared with recommended dietary intake (RDI) and were found to provide these essential elements as part of therapeutic utility. The levels in different plant parts were found not to be statistically significantly different (P>0.05) except for vanadium levels in urtica massaica (P=0.05). The results of this study will be used to sensitize the public on the presence of essential trace elements in the studied medicinal plants and to contribute to the advancement of knowledge.
Analysis of essential trace elements in soils, amaranthus cruentus and amaranthus hypochondriacus grains, leaves and stems from selected parts of Kenya
(2012-11-07) Ngeno, Kipyegon; Wanjau, R. N.; Nicholas Gikonyo; Jane Murungi
Kenya has been experiencing rising cases of diseases such as diabetes, tuberculosis, liver complications, HIV / AIDS among others. Management of these conditions can be enhanced by use of plant-based trace elements. There is a need therefore to investigate crops that can provide a cheap source of these essential immune boosting trace elements. Grain amaranth is grown in different parts of Kenya including Bureti, Mt Elgon, Bondo, Meru and Embu. However, little research has been reported on the levels of trace elements in the amaranth plants in Kenya. Therefore this study analysed the levels of zinc, copper, manganese, chromium and selenium in Amaranthus cruentus (L-) and Amaranthus hypochondriacus (L-) leaves, stems and grains obtained from Kenyatta University, Bureti, Mt Elgon, Bondo, Meru and Embu. The study also analyzed the levels of the same elements in the soils in the areas in which the plants were grown. The analysis was done by Atomic Absorption Spectroscopy (AAS). The data was analyzed by use of statistical program for social scientists (SPSS) computer software version 11.5. Analysis of variance was used to compare the levels of trace elements at different maturity stages and from different areas. The mean levels of the trace elements in mg/lOO g in the soils from Kenyatta University were: Zn (5.908), Cu (1.056), Mn (37.303), Cr (0.665), and Se (0.285). The soils from Bureti had the mean amounts of Zn, Cu, Mn, Cr and Se of21.160, 2.093,95.741, 1.240 and 0.150 mg/IOO g. The mean levels (mg/IOO g) contained in the soils from Mt Elgon were: Zn (6.960), Cu (1.134), Mn (52.567), Cr (1.059) and Se (0.305). The trace elements mean content (mg/IOO g) of A. cruentus leaves were Zn (5.040), Cu (1.261), Mn (26.603), Cr (0.467) and Se (0.033). The mean amount of Zn, Cu, Mn, Cr and Se present in A. hypochondriacus leaves were 5.495, 1.264, 24.340, 0.309 and 0.054 mg/IOO g respectively. The levels of Zn and Cr in the leaves of both species increased with the plants' maturity from 25 to 50 days and then declined from 50 to 75 days while those of Cu, Mn and Se decreased with the plants' ages. Significant differences (P<0.05) in the mean levels of all the trace elements in the leaves of both species were noted except Cu in A. cruentus. The A. cruentus stems had mean values of 4.148,0.924,6.089,0.245 and 0.018 mg/IOO g of Zn, Cu, Mn, Cr and Se respectively. The mean amounts (mg/IOO g) contained in A. hypochondriacus stems were: Zn (2.943), Cu (0.946), Mn (7.000), Cr (0.230) and Se (0.009). The levels of Zn and Cr in the stems of both species generally increased with the plants' ages upto 50 days and then decreased while those of Cu, Mri and Se declined with the plants' ages. Between the study areas, significant differences (P<0.05) in the mean amounts of trace elements were recorded in the two species except Cu and Zn in A. cruentus and A. hypochondriacus respectively. The mean contents (mg/IOO g) of the trace elements in A. cruentus grain were: Zn (5.686), Cu (0.967), Mn (5.642), Cr (0.475) and Se (0.015) while those recorded in A. hypochondriacus were: Zn (6.303), Cu (1.058), Mn (6.720), Cr (0.304) and Se (0.016). Comparison of the levels of trace elements in grains of both species between the study areas depicted significant differences (P<0.05). There was a positive correlation between levels of trace elements in soils and levels in Amaranthus. From the results, it can be concluded that the two grain amaranth species at different maturity stage in different geographical locations have varied levels of trace elements. The results from the study will be used to sensitize farmers and public on the use of A. cruentus and A. hypochondriacus for their health as sources of essential trace elements.
Analysis Of L- Citrulline, L-Arginine And L-Glutamic Acid in Selected Fruits, Vegetables, Seeds and Nuts Sold in Nairobi City County, Kenya
(Kenyatta University, 2020-11) Mulwa, Peninnah Mueni
L-citrulline, L-arginine and L-glutamic acid are some of the amino acids which are vital in the human body. L-citrulline boosts immunity, combats sarcopenia, detoxifies the liver and enhances male fertility. L-arginine boosts internal production of nitric oxide thus enhancing dilation of blood vessels, inhibits aging process, prevents abnormal blood clotting and accelerates healing of wounds. L-glutamic acid cleanses the central nervous system and improves overall brain health, attitude and mental performance. However, only young and healthy people endogenously generate enough of these vital amino acids while premature babies and old people do not generate enough of the amino acids. Oral supplements are very expensive and have side effects such as; headache, vision impairment, flushing, heart attack and stroke. There is therefore the need for safe alternative and cheaper sources of these amino acids. Fruits, vegetables, seeds and nuts can be good sources of L-citrulline, L-arginine and L-glutamic acid. However, there is scarce data on the levels of these amino acids in the locally grown farm produce. The objective of this study was to determine the levels of L-citrulline, L-arginine and L-glutamic acid in selected fruits, vegetables, nuts and seeds sold in selected markets in Nairobi city County, Kenya. Thin Layer Chromatography (TLC) was used for identification and Liquid Chromatography-Mass Spectrometer (LC-MS) for quantification of the amino acids. The data was analyzed using one-way ANOVA. TLC profiles showed presence of both L-arginine and L-citrulline in most fruits, vegetables and nuts while L-glutamic acid was present in the seeds. The levels of the amino acids in the fruits and vegetables ranged as follows: L-citrulline ranged, 0.65-19.41 mg/100g in the button mushroom, cucumber, pumpkin, amaranthus, kales, 3.16-3.79 mg/100g in the watermelons and 1.57-10.21mg/100g in the macadamia nuts, pea nuts and cashew nuts. L-arginine was in the range; 1.73-16.48 mg/100g in the amaranthus, kales, button mushroom, butternut squash and cucumber, 5.44-6.56mg/100g in the fruits and 0.93-10.73mg/100g in the nuts and L-glutamic acid, 0.013-0.28 mg/100g in the seeds of ; pumpkin, butternut and watermelons. The results showed that locally available vegetables, fruits and nuts contain significant levels of L-citrulline and L-arginine, whereas seeds contain significant levels of L-glutamic acid. The information obtained from this study is vital to the ministry of health and nutritionists towards measures on improving the quality of life by encouraging dietary supplementation of the amino acids through consumption of locally available farm produce. The research findings will contribute to knowledge on presence of the amino acids in fruits, vegetables and nuts grown in Kenya.
Analysis of lead zinc and copper levels of roadside soil and plants across Thika-Nairobi highway, Kenya
(2011-08-23) Magothe, Jackson Mathenge; Wanjau, R. N.; Paul K. Tarus
The importance of studying highway pollution has increased dramatically in recent years due to the rapid growth in the transportation sector which has resulted in environmental degradation. Increase of registered motor vehicles has been on the rise with 70 % being petrol driven while 30 % having diesel propelled engines. In the year 2000, the number of registered vehicles increased by 20,262. But due to improvement in economic growth and reforms in transportation sector that facilitated the reinforcement of traffic rules and regulations by Kenya government on January 2004, a major influx of motor vehicles on Kenyan roads increased by 42,634 which rose further by 85,324 in the year 2007. This rapid increase in transportation services is now a major source of heavy metals pollution, particularly along the busy urban highways. The exposure of man to these heavy metals has caused great concern due to their effect on human health. Therefore, there is need to continue monitoring the heavy metal inputs and levels in the environment. This study was undertaken to determine the levels of Pb, Zn and Cu in the soil and plants across the Thika-Nairobi highway, which is one of the busiest road connecting Nairobi City and other provinces. The samples were collected from five different sites situated along the highway and their levels determined by X-Ray Fluorescence (XRF) technique. The soil and plants samples were investigated as a function of traffic density on the highway, distance from highway, and depth in soil profile. The results showed significant difference (P<0.05) for Pb, Zn and Cu to increase with increase in traffic volume. There was gradual decrease in soil metal levels with increase in distance (5-80 M) from the highway. The mean average levels of Pb distribution on the top soil (up to 10 cm below surface) in the five sampling sites along the Thika-Nairobi highway ranged from 83.2 to 208.1 µg/g during the dry season and 52.5 to 151.8 µg/g during the wet season. Similarly, Zn values ranged from 94.4 to 267.2 pg/g for the dry season and 57.5 to 212.6 µg/g during the wet season. In addition, Cu recorded between 10.4 to 25.3 µg/g during the dry season and 5.6 to 14.7 µg/g during the wet season. The study also showed higher accumulation of Pb, Zn and Cu in the soil depth, 0-10 cm than in the soil depths 10-20 and 20-30 cm. The mean Pb levels on 0-10 cm ranged from 14.5 to 343.5 pg/g and rapidly decreased with depth from ND to 167.6 µg/g at 20-30 cm while Zn registered 21.5 to 376.9 µg/g (0-10 cm) and ND to 194.3 µg/g (20-30 cm) in addition to Cu recording ND to 56.8 µg/g (0-10 cm) and ND to 19.2 µg/g (20-30 cm) across the highway during dry and wet seasons. The levels of Pb, Zn and Cu in pasture grass (Typha elephantina) were higher than in napier grass (Pennisetum purpureum). This indicated that pasture grass posed greater hazard potential than napier grass since it is widely spread along the highway and is oftenly harvested by farmers to make hay to feed animals. The study findings would enable planning and decision making by the concerned stakeholders in resource management geared towards attainment of vision 2030 and thus making Kenyan highways pollution free and therefore creating a habitable ecosystem for all
Analysis of Lycopene, Vitamin A and Beta Carotene in Red Cactus (Opuntia Ficus-Indica) Fruit in Nyeri County, Kenya
(Kenyatta University, 2020-08) Murage, Joyce Waruguru
Vitamin A deficiency (VAD) has been a serious public health problem in the developing countries especially in Africa, mostly in pre-school age children and in pregnant and lactating mothers. It contributes to 7 million pregnant women and approximately 127 million of preschool-aged children and about 1-2 million deaths every year. It has been reported that about half a million new cases of blindness emerge yearly. This has for a long time been solved in addition to modern medicines by using locally available dark green leafy vegetables (DGLVs), which are believed to also contain high levels of beta-carotene(BC). Unfortunately, they are seasonal. BC is an important source of vitamin A (retinol) and its deficiency causes morbidity and mortality in children and adults. A diet rich in lycopene is related to a decreased risk of cancer of digestive track, prostate and pancreas. Vitamin A, beta-carotene and lycopene have been found in tomatoes and carrots which require a lot of water for their growth. Red cactus (Opuntia ficus indica) fruit grows wildly along the road and in the forest in the dry areas and it is consumed by herders. This fruit has not yet entered the market, yet it could contain substantial amounts of phytochemicals (antioxidants) such as lycopene, vitamin A and beta-carotene. It grows throughout the year in arid and a semi-arid area (ASAL) hence it can supplement DGLVs, tomatoes and carrots. The objective of this study was to determine the levels of beta-carotene, lycopene and vitamin A in Red cactus at unripe, ripe and overripe stages using highperformance liquid chromatography (HPLC). The area of study was Chaka, Thegu area of Nyeri County. The unripe (the breaker stage), the ripe (completely red) and overripe (the ripe kept for 5 days to overripe) red cactus fruits were picked with the help of a taxonomist who helped in identifying the fruit and its botanical name. The phytochemicals were extracted from the fruits and analyzed using HPLC and the data was analyzed using ANOVA. The mean of beta-carotene levels in unripe red cactus was 0.04 ± 0.002 mg/100 g and increased to 0.07 ± 0.001mg/100g at the ripe stage and 0.09 ± 0.003 mg/100 g when overripe. The mean lycopene levels in red cactus was 3.26 ± 0.12 mg/100 g when unripe and increased to 7.06 ±0.11mg/100g when ripe and finally to 13.56 ± 0.50 mg/100 g when overripe. The mean vitamin A levels in (μg/100 g) in red cactus was 1.27 ± 0.05 μg/100 g when unripe and increased to 2.14 ± 0.03 μg/100 g when ripe and then decreased to 1.47 ± 0.06 μg/100 g when overripe. The results from this analysis showed that the amounts of beta-carotene, lycopene and vitamin A increased significantly (P<0.001) during ripening. From the results it’s important that people living in the dry regions and where this fruit grow should be encouraged to eat the red cactus fruits at the ripe and overripe stage of ripening to get the maximum benefit of VA and both lycopene and beta-carotene respectively. The fruits should not be consumed at the unripe stage since their levels are low and they cannot be of much benefit. This fruit can be a supplement to other sources. The information obtained on the levels should be availed to the industries set up to produce red cactus products to improve on the utilization.
Analysis of mycotoxins in foods in Nairobi and its surroundings
(2012-05-04) Gitu, Leonard Mwangi
Animal feeds samples were collected from feeding troughs and analyzed for levels of aflatoxin B1, atoxic and carcinogenic mycotoxin. When aflatoxin B1 is consumed by dairy cattle, some of it is hydroxylated to form aflatoxin M1 is also toxic and carcinogenic, it was also determined in liquid milk. The analytical techniques used to carry out the determinations were Thin-layer chromatography (TLC), which utilizes the fluorescent properties of these compounds, and Differential Pulse Stripping Voltammetry, a technique that utilizes the electrochemical behaviour of aflatoxin B1. Some of the feeds, particularly brewers grain, barley husks and used poultry feeds, were found to generally contain high concentrations of aflatoxin B1 that were above the maximum tolerated levels in foods and feeds in various countries.
Analysis of proximate, micronutrients and determination of phytochemicals in selected medicinal plants in Mbita-Homabay County
(Kenyatta University, 2016-11) Oyugi, John Owuor
About 80% of low income earners in developing countries rely on traditional medicine for their primary health care, hence medicinal plants play an important role in the society. Lannea schweinfurthii, Rhus natalensis and Euclea divinorum, has been extensively used in treating severe headache, dermatological, gastrointestinal, gynaecological, abdominal pains, female sterility among others in several parts of East Africa. In addition, many communities in Kenya including Mbita - Homabay County residents rely on these plants for their medicinal values. Many of the studies done on these plants have focused on isolation and characterization of phytochemicals. However, there is limited information on proximate and micronutrients analysis of these plants. Hence, this study focused on both qualitative and quantitative determination of the phytochemicals, micronutrients and proximate constituents. The analyses were done using conventional standard methods. The study revealed that the plants contained flavonoids, phenols, alkaloids and saponins. Mean levels of flavonoids were found to be 19.80±0.20% in L. schweinfurthii root barks and 9.46±0.12% in L. schweinfurthii leaves. Alkaloids were found to be 7.66±0.24% in E. divinorum leaves and 1.40±0.00% in E. divinorum root barks, saponins were found to be 47.60±0.05% in E. divinorum root barks and 7.65±0.05% in E. divinorum leaves and phenols were 8.54±0.12% in R. natalensis leaves. Proximate analysis revealed varied proportions of moisture, ash, crude protein, crude lipid, crude fibre and carbohydrates in all the plants investigated. The highest % by mass were; moisture content 14.50±0.50% in L. schweinfurthii root barks, crude protein 23.61±0.80% in R. natalensis leaves, crude fibre 1.80±0.20% in R. natalensis root barks, crude lipid 14.66±0.30% in R. natalensis leaves, ash 11.85±0.75% in E. divinorum root barks and carbohydrate 63.39±0.23% in E. divinorum. The dried plant parts were used for the study. Micronutrients analysis revealed presence of Cu, Fe, Zn and Mn which as 1.10±0.01 of R. natalensis leaves, 4.90±0.01 of L. schweinfurthii leaves, 4.50±0.01 of R. natalensis leaves and 2.30±0.01 of E. divinorum leaves in ppm respectively. Pb was 3.10±0.02 in E. divinorum root barks and Cd was not detected. T-test and ANOVA were used to analyze data. The findings provided evidence that crude aqueous and organic solvent extracts of plants studied contain compounds therefore used as traditional medicines. The findings suggested that the selected medicinal plants have a promising potential to cure ailments and maintain a healthy life and should be investigated further to determine the components responsible for activity.
Analysis of Selected Heavy Metals in Water from River Kuywa and Adjacent Wells in Bungoma Central Sub County- Kenya
(Kenyatta University, 2015-09) Wasike, Peter Wekesa
Industrial effluents, agricultural chemicals such as pesticides, herbicides and residential wastes are the major sources of heavy metals in drinking water. Presence of heavy metals in drinking water is the cause of many diseases in human beings. Worldwide over six million people lack access to clean drink water. In Kenya it has been reported that sources of drinking water such as rivers, boreholes and wells are having heavy metals. In Bungoma Central Sub County, residents depend on River Kuywa and well water for domestic consumption and agricultural activities. River Kuywa and adjacent wells are at risk of exposure to heavy metal by virtue of them passing through sections of factories and crossing several farms which intensively use agrochemicals and also through residential areas. The main objective was to determine levels heavy metals from both river water and well water and compared to the limits set by world Health Organization (WHO) and Kenya Bureau of Standards (KEBS). Sampling was done at various points along the river and from randomly selected wells adjacent to the river during the dry and rainy seasons. The levels of heavy metals were determined by use of FAAS and data analysis was achieved by use of ANOVA and t-test. Results for two seasons ranges as follows; levels in mg/l in river water are Pb (0.57±0.09 - 3.36±1.15), Mn (0.15±0.14 - 0.25±0.03), Cu (1.01±0.12-1.92±0.14) and Cd (0.32±0.02-0.99±0.67). In well waters the ranges (mg/l) were Pb (1.43±0.34-2.43±0.41), Mn (0.15±0.14- 0.25±0.03) Cu (1.39±0.24-1.92±0.14) and Cd (0.35±0.03-0.46±0.03). From the results the mean values of Pb, Cu and Cd were above those set by KEBS and WHO and levels Manganese were below the set value. This was attributed to the surrounding industrial and agricultural activities; as well as domestic wastes. These results signify high levels of heavy metal in drinking water of the Sub County and this pauses health risk to residents. Moreover, significant differences (p<0.05) were observed in the levels of heavy metals in water between the seasons (dry and wet). These findings call for urgent intervention by the government to set in place strategies that would
Analysis of the levels of arsenic, Nitrate, Nitrite and Phosphate in home made brews, spirits, tap water and in raw materials in Nairobi County
(2012-03-28) Masime, Jeremiah Odhek; Jane Murungi; Onindo, Charles O.
Alcohol and water may be an important source of exposure to arsenic, nitrate, nitrite and phosphate. Increased cases of deaths as a result of consuming home made brews/spirits have been a major concern in this country. Recently, many lives have been lost due to the ignoranceof the brewers and their patrons. Additives like methanol and use of untreated river waters that contain the effluents from chemical industries, domestic wastes from urban settlements and run-offs from agricultural activities can cause high levels of arsenic, nitrate and phosphorus in alcoholic drinks, which could be sources of health hazards to consumers since they are toxic. Arsenic, nitrate and nitrite are carcinogenic; phosphate does not have any notable health effects. Nitrite also causes metheglobinemia. Therefore, this study was carried out to determine the levels of these substances in home- made brews, home made spirits, raw materials and water. One hundred and thirty two (132) homemade alcoholic beverages, fourty eight (48) water and twelve (12) raw materials samples obtained from various parts of Nairobi slums and its environs were analyzed for arsenic, nitrate, and nitrite and phosphate. Methods of analysis included; colorimetry, hydride generation atomic absorption spectroscopy and UV -visible spectrophotometry. Some samples of brews and water had higher levels than those recommended by the Kenya Bureau of Standards (KEBS) and World Health Organization (WHO). Concentrations of arsenic ranged from non detectable to 0.88 ± 0.028 mg/l, nitrate from non detectable to 46.3 ± 1.404 mg/l, nitrite from non detectable to 11.919 ± 0.36 mg/l and phosphorous from 0.14 ± 0.008 to 4.16 ± 0.62 mg/I. The recommended maximum contamination levels set by KEBS/WHO for arsenic, nitrate, nitrite and phosphorus in water were as follows; arsenic, 0.01 mg/l for drinking water and beer and raw materials; nitrite, 0.03 mg/l; nitrate 50 mg/l and 2.2 mg/l for the phosphates in water. Most of the home made brews/spirits and water analyzed in this study had lower levels of nitrates than recommended by the Kenya Bureau of Standards, while a few had higher levels of nitrites. Arsenic recorded values lower than the maximum contamination limit of 0.01 mg/I. Nitrate levels were higher than the maximum contamination levels in some cases. Brews had low levels of nitrate, phosphorus and arsenic had low levels of the nutrients. Raw materials also had high levels of these nutrients while water had non detectable levels. The raw materials used may have contributed in elevating the levels of these pollutants in the brews. These findings are therefore useful since they provide a justified cause for the Kenyan Government to reconsider fighting the selling of local alcoholic beverages. Therefore the consumption of the brews with higher levels than those recommended could pose a problem for consumers and hence sensitization should be enhanced.