Chemical Science International Journal

Assessment of Heavy Metal Contamination in Red Seaweeds from the Coastal Areas of Zanzibar by Using EDXRF Technique

Suleiman A. Suleiman — 2021-11-25

The content of Mn, Zn, Ni, Cu, Fe, and Pb in 10 samples of Kappaphycus alvarezii (cottonii) and 10 samples of Eucheuma denticulatum (spinosum) from 15 different sites in the intertidal coastal area of Zanzibar were determined by using EDXRF. The heavy metals assessed in both species decreased in the order of Fe >Mn > Zn >Pb> Cu > Ni. In general, the cottonii samples in Unguja had significantly higher (p ≤ 0.05) concentrations of Fe, Zn, Ni, Cu and Pb than the spinosum samples, but the latter had significantly higher levels of Mn. Similarly, the cottonii samples in Pemba had significantly higher (p ≤ 0.05) concentrations of Ni, Cu and Pb than the spinosum samples, but the latter had significantly higher levels of Fe and Zn. The concentrations of heavy metals in cottonii and spinosum in the present study were noticed lower compared to publish results. The results from this study revealed that, the heavy metals contaminations in cottonii and spinosum along the coastal area in Zanzibar were mainly caused by effluents that directly flow into marine environments. Hence, serious measures should be taken to reduce the flow of waste effluents into the marine ecosystem.

Assessment of Occupational Risks in the Toxicology and Pharmacology Laboratory Using the FMECA Method

Khalid Laarej — 2021-12-02

The Toxicology and Pharmacology Laboratory is a high-risk work environment, especially the chemical risk that appears when people are exposed to reagents and chemicals. A corrective approach is required to identify and control these risks. The aim of this study is to determine how to manage the analytical risks at LTP designated for the dosage of drugs and poisons (narcotics, pesticides, mycotoxins, etc.). For this purpose, the risk analysis applying the FMECA method, a risk management tool that aims on the one hand, to qualitatively analyze the process, to analyze the failure modes, the causes and their effects, and to on the other hand, rate the criticality defined by the parameters of frequency of occurrence, severity and detection that will allow a quantitative analysis of each of the failure modes. Thus, the criticality calculation will help to determine the critical risks to be corrected, and to recommend corrective and preventive actions to be implemented within the service.

A Comparative Assessment on Antioxidant and Phytochemical of Trichilia monadelpha (Thonn) J.J. De Wilde (Meliaceae) Plant Extracts

P. D. Clark — 2021-12-08

This study was designed to evaluate the phytochemical screening and antioxidant activities of Trichilia monadelpha plant extracts. The leaves were extracted using two different solvents namely-(n-hexane and methanol). The dry or wet yield of n-hexane extract was 1.3%, while methanolic extract exhibited a percentage yield of 3.7 %. Phytochemical research revealed the presence of secondary plant metabolites such as; alkaloids, flavonoids, cardiac glycosides, terpenoids and saponins. In-vitro antioxidant activity was determined using three assays (DPPH free radical scavenging assay, reducing ability and hydroxy radical scavenging activity) with four concentrations (0.25, 5.0, 1.0 and 2.0 mg/L), vitamin C was also used as a standard antioxidant.

The percentage of inhibition was measured, and the results from all assay models showed a concentration-dependent percentage of inhibition by the methanol extract. However, the percentage values for the 2,2, -diphenyl-1-picrylhydrazyl (DPPH), reducing ability and hydroxy radical scavenging activity assays of T. monadelpha leaf was lower than that of standard vitamin C. The Pearson’s correlation coefficient was evaluated and the results showed that of the two extracts, the methanolic extract had the most antioxidant activity with the methanol extract exhibiting a better significant correlation that had a similar trend to that of the antioxidant compound (vitamin C). The results of this study have shown that the plant Trichilia monodelpha contains bioactive compounds which may have contributed to its antioxidant properties.

3D Series Metal Complexes Containing Schiff Base Ligand with 2,2'-Bipyridine: Synthesis, Characterization and Assessment of Antifungal Activity

B. Kpomah — 2021-12-08

The rapid increase in the number of multidrug-resistant of most pathogenic organisms is fast becoming a global concern, thus, the discovery of novel active pharmacological compounds against new targets is a matter of urgency. The incorporation of metal ions into organic ligands has introduced metal-organic drugs framework with synergistic effects for novel applications in the biological system. In this research work, metal(II) chloride complexes of copper, nickel and zinc containing methylphenylketone thiosemicarbazone (MPK-TSC) with 2,2’-bipyridine (bipy) were synthesized; they were further characterized by satisfactory microelemental analysis, Fourier Transform InfraRed (FTIR) spectra as well as electronic spectra study. The complexes are proposed to have the formulae [L₁ML₂(Cl₂)] where M=metal ion, L₁=methylphenylketone thiosemicarbazone L₂=2,2’-bipyridine. The complexes are of 1:2 (metal:ligand) stoichiometry and non-electrolytes in solution, the bidentate nature of the two ligands was evident from the FTIR spectra. The compounds were screened for their antifungal activity against four pathogenic fungi: Aspergillus niger, Penicillium Species, Rizopus and Candida albicans using disc diffusion method. The activities of the complexes have been found to be greater than those of the metal salts and the uncoordinated ligands.

Synthesis and Preservation of Organic Molecules with Homochiral Excess by Adsorption on Carbon in Carbonaceous Chondrites

V. M. Zhmakin — 2021-12-10

The nature of carbon, initial components, molecules of homochiral abiogenic synthesis and their preservation from decay and racemization for more than 4.5 billion years in carbonaceous chondrites has not been established. In the oxygen-free atmospheres of the nebula and early Earth, hydrogen and hydrogen-containing gases were oxidized with carbon monoxide and carbon dioxide to form carbon and water, as well as the intermediates of these reactions, formaldehyde and methane acid. Together with ammonia, they were the initial components of organic synthesis. According to the Rebinder rule, carbon adsorbs hydrogen well, including in organic molecules. In this connection, experiments with the assumed conditions of the early Earth were carried out by adsorption on carbon to obtain R-(rectus, Latin) ribose from formaldehyde, and S-(sinister) serine from formaldehyde, methane acid and ammonia. For other S-amino acids, a stereo chemical justification of their formation based on S-serine is given. For carbonaceous chondrites, the results of the above experiments were confirmed by the correlation of an increase in homochiral excess with an increase in the amount of hydrogen in aldonic acids and lactic acid with a coefficient of 0.94 and 0.85 in amino acids. The justification of the homochiral process will reduce the costs of searching for life on planets, for scientific research, for the production of medicines, perfumes, food, and so on. Doubts about the extraterrestrial origin of homochiral enantiomers in carbonaceous chondrites arise most often due to a lack of understanding of the reasons for their appearance. This work will significantly reduce such skepticism.

The Concentration Distance and the Average Kinetic Energy of a Diffusible Solute in its Medium

Mustapha Umar Abdullahi — 2021-12-13

Seven sets of diffusible samples were allowed to diffuse in their medium in order to observe how much meters of distance a given volume of sample will cover in its medium at particular condition. At the same time also to observe how much joules of average kinetic energy that given sample volume possess during the course of its traveling. After successful diffusion by using suitable apparatus, all data associated with this study was carefully observed repeatedly and recorded. In which, mean values were used. Series of findings were found including new equation X_c= which can be used in determining this new initiative (concentration distance of a diffusible solute in its medium (X_c)).

Efficacy of Herbal Medicine Administration using Neem (Azadirchta indica L) Leaves as Case Study

Duduyemi Oladejo — 2021-12-15

Plants used for treatment of diverse ailments primitively are concocted and used indiscriminately. The efficacy of "Herbal medicine" which is an ancient tradition, used in some parts of Nigeria was investigated to establish herbal applications of Neem (Azadirachta indica) leaves. Neem leaves (Azadirachta indica) was popularly recognised for the treatment of malaria fever. The leaves were plucked at appropriate peak period of the day when oil and moisture contents were recorded maximum. The peak period of contents was found to occurred between 8am-10am on a very sunny days, 10am to 12 on cool days, and 3:00pm to 5:00pm on cloudy days. Aqueous extract from macerated Neem leaves was subjected to qualitative and quantitative analysis. Available phytochemicals evaluated include; saponin (34.89mg/g), tannin (31.715mg/g), flavonoid (31.835mg/g), phenol (43.59mg/g), terpernoid (14.585mg/g), cardiac glycosides (39.335mg/g), steroid (16.185mg/g) and alkaloid (28.76mg/g). These values differ significantly to recommended oral dosage formulation for human consumption: Saponin (1.433ml), Tannin (1.418ml), Flavonoid (13.91ml), Phenol (2.29ml), Terpernoid (8.23ml), Cardiac Glycosides (0.003177ml), Steroid (0.62mg/g). Consequently, local consumption of herbal resources should be regulated to avoid abuse and long or short-term effects of drug contents as proven in the neem leaves as local herbs.

Computational Modelling and Antioxidant Activities of Substituted N-(Methoxysalicylidene) Anilines

Demehin, Abidemi Iyewumi — 2021-12-16

The computational modelling and total antioxidants activities of three N-(methoxysalicylidene) anilines namely N- (methoxysalicylidene)aniline [I], N-(methoxysalicylidene)-4-chloroaniline [II] and N-(methoxysalicylidene)-5-chloro-2-methylaniline [III] were reported. The compounds were synthesized and characterized by elemental analysis, infrared, ultraviolet, proton and carbon-13 nuclear magnetic resonance. Quantum chemical computations were also performed on the optimized structures of the compounds using Density Functional Theory. The infrared, nuclear magnetic resonance and ultraviolet spectra of the compounds were calculated and the results likened to the equivalent experimental spectra to enhance the structural identification. The calculated infrared, nuclear magnetic resonance and ultraviolet spectra were comparable to the experimental spectra. The total antioxidant capacities of the Schiff bases were evaluated by phosphomolybdenum assay and the results indicated that all the synthesized compounds displayed antioxidant activities.

Insight into the Sorption and Activation Energy Phenomenon of Kenaf Shive Sorbents in Crude Oil/Water Mixture

Z. M. Salisu — 2021-12-20

The secondary effect discovery of synthetic sorbents opened another research direction for many field of studies. However, the sorption parameters of lignocellulosic sorbents are rarely reported most importantly, kenaf shive. This paper centered at the sorption behavior of optimized kenaf shive sorbents using Response Surface Methodology (RSM) via surface deposit technique. Five-level Central Composite Design (CCD) experimental matrix was used to analyze the effect of particle sizes (125-1000 µm), stirring time (5-30min) and methyltrimethoxysilane (MTMS) concentration (5-20% v/v) as individual and combined variables process in the developed sorbents. The unmodified shive was compared with the modified, and it reveals a positive shift in the sorption capability. Instrumental analysis such as FTIR (Fourier Transform Infra-Red), DT-TGA (Differential Thermal-Thermogravimetric analysis) and BET (Brunaure-Emmett-Teller) were carried out on the optimized sorbent and the results were in conformity with the sorption results. The sorption behavior deployed fits the pseudo-first-order and Langmuir isotherm with regression coefficient R²=0.9496 and R²=0.9400. The sorption property was found to be spontaneous and exothermic, however, the activation energy studies shows physic-sorption phenomenon with 25.3 kJmol^-1 and R²=0.9360.