Bulletin of the Chemical Society of Ethiopia

Determination of pesticide residues in raw cow milk using a newly developed and validated high performance liquid chromatography method

Büşra Aydın, İbrahim Bulduk , Safiye Elif Korcan — Tue, 27 May 2025 00:00:00 +0000

This study investigates the presence of pesticide residues in 87 cow milk samples collected from Uşak and surrounding regions, focusing on four commonly used agricultural chemicals: imazalil, acetamiprid, 2,4-dimethylamine salt (2,4-DMA), and tebuconazole. High-performance liquid chromatography (HPLC) was employed to simultaneously detect and quantify these pesticides. The results indicated that while tebuconazole, 2,4-DMA, and acetamiprid were detected in a limited number of milk samples, imazalil was found in the majority, with the highest concentration recorded at 6.32 mg/L. Although this level does not present an immediate risk to human health, prolonged exposure and accumulation of imazalil in the body may lead to adverse effects, such as carcinogenicity and endocrine disruption. Consequently, regular monitoring of pesticide residues in animal-derived food products is imperative to ensure food safety and safeguard public health. The findings of this study underscore the necessity for continuous surveillance of pesticide levels in the food chain to mitigate potential health risks. Ensuring the responsible use of pesticides through appropriate regulatory measures is crucial for both environmental and public health protection. This research highlights the importance of maintaining rigorous standards in agricultural practices to prevent harmful effects from pesticide exposure.

KEY WORDS: Liquid chromatographic method, Raw milk, Imazalil, Acetamiprid, 2,4-Dimethylamine salt (2,4-DMA), Tebuconazole

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1451-1464.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.1

Selective solvent extraction followed by solid-phase clean-up for quantitative enrichment of trace level multiclass pesticide residues in the honey samples for GC-ECD determination

Tura Gemechu, Teshome Tolcha, Selamawit Zeregze, Negussie Megersa — Tue, 27 May 2025 00:00:00 +0000

In this study, a new selective solvent extraction analytical method combined with solid phase cleanup procedure was developed for the analysis of residues of organochlorine, organophosphate and pyrethroid pesticides in the honey samples, using GC-ECD instrumentation. Parameters affecting the extraction and clean-up processes such as the type and volume of extraction solvent, type and volume of clean-up solvent, time of extraction and shaking speed were studied. The optimum experimental conditions required silica gel cartridge for matrix cleanup; with 15 mL of 80:20 v/v volume ratio of n-hexane/ethyl acetate as elution solvents, 70 mL of acetonitrile as extraction solvent, 30 min extraction time and a shaking speed of 280 rpm. Under the optimal experimental conditions, the developed analytical method offered good linearity with the correlation coefficients greater than or equal to 0.997, low detection limit (0.07-0.78 μg kg-1) and quantification limit (0.25-2.49 μg kg-1). The reproducibility and repeatability of the method were ranged from 0.45 to 10.7% and 0.61 to 4.34%, respectively. Recovery of the method was determined and found to vary from 71.5 and 93% that lies within the acceptable range. Only chlorothalonil was detected at trace level in the honey sample.

KEY WORDS: GC-ECD, Honey, Multiclass pesticide residues, Selective solvent extraction, Silica gel clean-up

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1465-1478.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.2

Assessment of the eco-friendliness profiles of spectrophotometric methods for the quantification of vonoprazan fumarate in pharmaceutical formulations utilizing N-bromosuccinimide

Tue, 27 May 2025 00:00:00 +0000

Vonoprazan fumarate (VON) has been examined utilizing precise, accurate, environmentally friendly, and validated spectrophotometric methods in both its pure form and pharmaceutical formulations. These approaches employ N-bromosuccinimide (NBS) as an oxidizing agent in conjunction with three dyes: indigocarmine (IC), rhodamine B (RB), and orange G (OG). In acidic conditions, excess NBS is employed to oxidize VON, and the remaining unreacted NBS is then measured by its reaction with known quantities of the dyes. Absorption measurements were obtained at 610 nm for IC, 550 nm for RB, and 478 nm for OG. The analytical technique was executed and validated through meticulous examination and optimization of various factors that could influence the reaction. These methods demonstrated efficacy within concentration ranges of 1.0–14, 1.0–12 and 1.0–16 µg/mL, respectively with correlation coefficients between 0.9990 and 0.9994. The limit of detection was 0.29 µg/mL for IC, whereas for RB and OG was 0.30 µg/mL. The accuracy and precision of these methods were evaluated using intra-day and inter-day measurements. No substantial interference was observed from typical tablet excipients. The environmental impact of the proposed methods was assessed using three evaluation tools designed to measure eco-friendliness.

KEY WORDS: Vonoprazan fumarate, N-Bromosuccinimide, Spectrophotometry, Method validation, Tablets, Greenness assessment tools

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1479-1492.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.3

Split application of biochar for humic acids structural characteristics enhancement during chicken manure composting

Mahmoud G.M. Abd El-Rahim, Sen Dou, Randa A. Althobiti , Gomaa A.M. Ali — Tue, 27 May 2025 00:00:00 +0000

Applying biochar to composting substrates promotes more complexity and stability of the formed humic acids (HA). This study investigated how different biochar addition methods affect HA formation during chicken manure composting. Two methods of adding biochar were compared: split addition (2.5% for four times during the bio-oxidative phase) with mixing (A) and total addition (10% in one time) at the beginning of composting (B). The treatment without biochar addition was considered as a control. Compared to the control, A treatment had a HA with the highest oxygen/carbon (O/C) molar ratio (0.52), and it was the nearest to the O/C molar ratio of the soil HA (0.55). The FTIR, DTA, and TGA analyses indicated that HA isolated from the A compost exhibited the highest aromaticity, and it was similar to soil HA. These findings demonstrated that the split addition method of biochar could enhance the structural characteristics and stability of the formed HA during composting.

KEY WORDS: Composting, Biochar, Humic acid, Chicken manure, Split addition, Organic fertilizer

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1493-1508.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.4

Preparation, kinetics, and thermodynamic investigation of Janus green dye removal from aqueous solutions using MnO2 nanoparticles as an adsorbent

Nagham Hameed Abood , Sundus Hadi Merza — Tue, 27 May 2025 00:00:00 +0000

In this study, manganese dioxide (MnO₂) nanoparticles (NPs) were synthesized via the hydrothermal method and utilized for the adsorption of Janus green dye (JG) from aqueous solutions. The effects of MnO₂ NPs on kinetics and diffusion were also analyzed. The synthesized NPs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), and Fourier-transform infrared spectroscopy (FT-IR), with XRD confirming the nanoparticle size of 6.23 nm. The adsorption kinetics were investigated using three models: pseudo-first-order (PFO), pseudo-second-order (PSO), and the intraparticle diffusion model. The PSO model provided the best fit (R² = 0.999), indicating that the adsorption process is chemical in nature. Kinetic analysis revealed that the MnO₂ surface exhibited faster adsorption kinetics during the film diffusion step (rate constant 0.2776) compared to intraparticle diffusion (0.0042) at 298.15 K. Thermodynamic parameters, including enthalpy change (∆H*), entropy change (∆S*), and Gibbs free energy change (∆G*) of activation, were calculated from the Eyring equation to be 37.48 kJ/mol and -144.69 J/mol, respectively. The positive ∆G* value (80.62 kJ/mol) suggests that the adsorption process is energy-intensive, requiring higher energy to form chemical bonds between JG and MnO₂ nanoparticles.

KEY WORDS: Hydrothermal method, Janus green dye, Manganese dioxide nanoparticles, Kinetic behavior, Intraparticle diffusion model

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1509-1523.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.5

Detection and removal of eosin dye from water samples using zein bio-nanoparticles and a dispersive solid-phase microextraction

Wasan A. Al-Uzri, Hind Hadi , Tabarak Mohammed — Tue, 27 May 2025 00:00:00 +0000

Eosin dye is widely used in textiles, cosmetics, and pharmaceuticals due to its vibrant color and staining properties. A simple and environmentally sustainable method using zein nanoparticles (ZNPs) as an adsorbent in dispersive solid-phase microextraction (DSPµE), integrated with a UV-Vis spectrophotometry, has been developed for the preconcentration and removal of eosin (EO) dye in environmental water samples. Different factors influencing the extraction process were studied, such as pH, buffer concentration, sorbent amount, extraction duration, ionic strength, and the type and volume of eluent. Under optimal conditions, the method demonstrated a linearity range of 5-500 ng mL⁻¹, with a correlation coefficient (r²) of 0.9987. It exhibited strong reproducibility, showing relative standard deviations below 4% (n=5). The proposed method was used to analyze two environmental water samples (canal and river water), achieving dye recoveries within the range of 97.0% to 102.0%. Furthermore, the environmental impact of the method was assessed using Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI) metrics. The results showed excellent greenness, with an AGREE score of 0.73 and eight green GAPI segments, indicating the method's reliability and sensitivity for detecting eosin in water samples.

KEY WORDS: Eosin, Dispersive solid phase extraction, Zein nanoparticles, Analytical GREEnness, Green analytical procedure index metrics

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1525-1538.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.6

Synthesis and characterization of manganese ferrite nanoparticles (MnFe2O4) to remove crystal violet dye

Tue, 27 May 2025 00:00:00 +0000

This study presents crystal violet dye (CVD) removal from water-based solutions by using nanoparticles of manganese ferrite (MnFe₂O₄). Nanoparticles of manganese ferrite were synthesized using the sol-gel technique. The aqueous solution containing (CVD) was subjected to batch adsorption. The effect of contact durations, concentrations, and temperatures were studied. A contact time of 30 min was found to be effective for removal of more than 97% of cases. With a concentration of 5 mg/L, the dye clearance percentage reached its peak, surpassing 78%. When the adsorption capacity increases as the temperature rises, it means that the dye adsorption process is endothermic. According to the Freundlich model, the R² values for (CVD) on MnFe₂O₄ at 25, 27.5, and 30 ℃ were 0.9843, 0.917, and 0.9722, respectively. The ΔG^o values were all negative under different temperatures, indicating the thermodynamically spontaneous and favorable adsorption of (CVD) on MnFe₂O₄. While the positive values of enthalpy ΔH^o indicate that the adsorption is endothermic. On the other hand, the positive ΔS^o values conﬁrmed the increased randomness at the solution solid interface during adsorption process.

KEY WORDS: Manganese ferrite nanoparticles, Crystal violet dye, Adsorption, Isotherm, Thermodynamic

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1539-1548.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.7

Mixed ligands of (E)-1-(3-(((1H-1,2,4-triazol-3-yl)imino)methyl)-4-hydroxy-5- methoxyphenyl)ethan-1-one and chloroanilic acid: Synthesis, characterization and thermal stability study

Bayader Fadhil Abbas, Mahmoud Najim Abid Al-Jibouri , Fatima Haitham Zuhair — Tue, 27 May 2025 00:00:00 +0000

The present work involved the synthesis, characterization and thermal study of metal complexes of Co(II), Cu(II), Ni(II) and Zn(II) derived from mixed ligands;HL¹: (E)-1-(3-(((1H-1,2,4-triazol-3-yl)imino)methyl)-4-hydroxy-5-methoxyphenyl)ethan-1-one and H₂L²: 2,3-dichloro-5,6-dihydroxycyclohexa-2,5-diene-1,4-dione. The new ligands and their metal complexes were fully identified on the basis of FT-IR, EI-MS, NMR, UV-Visible spectroscopy, molar conductivity and magnetic susceptibility measurements. The new metal complexes were prepared in their solutions in ethanol and in solid state with respect 1:1:1 mole ratio of M:L¹: HL². As well as the elemental microanalysis was carried out to confirm the skeletal structure of the metal complexes. The physicochemical properties such as melting point, magnetic susceptibility and molar conductivity at room temperature were determined. The spectral data of IR, UV-Visible spectra and magnetic moments revealed the formation of octahedral environment around Co(II), Ni(II), Cu(II) and Zn(II) ions. As well as the TG-DTA measurements confirmed the thermal stability due to the cleavage of weak points in the skeletal structures of metal complexes.

KEY WORDS: (E)-1-(3-(((1H-1,2,4-triazol-3-yl)imino)methyl)-4-hydroxy-5-methoxyphenyl)ethan-1-one, Thermal stability of apocynin, Thermal stability of mixed ligands

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1549-1558.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.8

Synthesis and characterization of new azo dye complexes and studies of antioxidant, bioactivity and thermal analysis

Asseel A. A. Al-naemi , Abbas Ali Salih Al-Hamdani — Tue, 27 May 2025 00:00:00 +0000

A new azo dye, 5,5-[1,2-phenylenebis(2,1-biazenediyl)]bis[8-quinolino], was synthesized by reacting the diazonium salt of o-phenylenediamine with 8-hydroxyquinoline. The ligand was subsequently used to prepare a series of metal complexes with V(IV), Fe(III), Cr(III), Mn(II), Mo(VI), and Ru(III). The ligand was characterized using ¹H and ³C-NMR spectroscopy, while the metal complexes were analyzed using UV-Vis, FT-IR, and mass spectrometry, along with thermal analysis (TGA, DSC), (C.H.N.), conductivity measurements, magnetic susceptibility, and metal and chlorine content analysis, the results indicated that the ligand exhibits tetra-coordination. The complexes predominantly formed octahedral geometries, except for the vanadium complex, which exhibited a square pyramidal structure. Furthermore, all complexes were found to be non-electrolytes. The antioxidant activity of all the compounds were evaluated using DPPH as a free radical and gallic acid as a reference standard. The inhibition efficiency of the complexes varied according to their IC₅₀ values. Additionally, the compounds were tested for antibacterial activity against Escherichia coli and Bacillus spp. and for antifungal activity against Penicillium, Aspergillus niger, Fusarium, and Trichoderma at two different concentrations. The results revealed varying degrees of bacterial and fungal growth inhibition compared to the control.

KEY WORDS: Antioxidant, Azo dye complexes, 8-Hydroxyquinoline, Thermal analysis, Bioactivity

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1559-1578.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.9

Capturing Mn(II), Zn(II), and Cd(II) ions using gallic acid: Synthesis, spectroscopic analysis, thermal stability, and microscopic imaging

Tue, 27 May 2025 00:00:00 +0000

This study aimed to investigate and analyze the complexes formed between the naturally occurring plant-derived phenolic compound gallic acid (GA) and three transition metal ions: Mn(II), Zn(II), and Cd(II). A combination of stoichiometric, structural, thermal, and microscopic evaluation techniques was employed for this purpose. The GA-Mn, GA-Zn, and GA-Cd complexes were prepared through a multi-step process involving five key stages: dissolving the reagents, combining the reagents, collecting the precipitates of the complexes, and filtering and refining the complexes. A variety of physicochemical analysis techniques were used to thoroughly examine and characterize the structural, compositional, morphological, and thermal properties of the created complexes. The results show that the GA complexes with Mn(II), Zn(II), and Cd(II) ions can be represented by formulas containing (NH₄)₂[Mn(NH₄HL)₂].4H₂O, (NH₄)₂[Zn(NH₄HL)₂(H₂O)₂].8H₂O, and (NH₄)₂[Cd(NH₄HL)₂].4H₂O, respectively. TEM imaging revealed that the complexation of the GA ligand with metal ions substantially modified the microstructural features of the pristine ligand, suggesting the complexation significantly impacted the microstructure of the synthesized materials. This investigation concludes that the synthesized GA-Mn, GA-Zn, and GA-Cd complexes possess interesting structural and microstructural properties that could be exploited for various applications such as catalysis, materials science, and biomedical engineering.

KEY WORDS: Gallic acid, Metal ions, Spectroscopic analyses, Thermal degradation, Electron microscopy

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1579-1592.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.10

Combinatorial library of some aryl thioamides derivatives: Synthesis, chemical design, biological study and insecticidal evaluation against Spodoptera frugiperda

Tue, 27 May 2025 00:00:00 +0000

Significant agricultural losses are caused by Spodoptera frugiperda, one of the most polyphagous migratory lepidopteran pest species. The exponential increase in resistance to existing chemical pesticides is another important factor driving the development of novel insecticidal active agents. To overcome this obstacle, it is essential to investigate new insecticidal substances with different modes of action. New aryl thioamide derivatives have been created by reacting aroyl chlorided, ammonium thiocyanate, and aromatic amines in dry acetone in a single pot with three components. Several spectroscopic techniques, such as elemental analysis, ¹H-NMR, ¹³C-NMR, and infrared spectroscopy, were used to validate the structures. Eight substituted aryl thioamides derivatives were used in the study of the antifeedant, toxicity, and nutritional effects on Spodoptera frugiperda larvae in order to achieve crop sustainability. LC₅₀ of 2,4-dichloro-N-[(3-chlorophenyl)carbamothioyl]-benzenecarbothioamide 5 is more hazardous than modest to strong toxicological actions screened compounds.

KEY WORDS: Aryl thioamides, Lufenuron, Toxicity, Spodoptera frugiperda, Insecticidal activity

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1593-1605.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.11

Analysis on the performance and emission traits of a CI DI engine employing papaya biodiesel and its blends

V. Dinesh Kumar, Vinayak B Hemadri , M. S. Vijay Manikandan — Tue, 27 May 2025 00:00:00 +0000

Diesel engine plays a primary role in the sectors of energy and transportation. In the present research investigation, the methyl ester derived from the seeds of papaya is used to access the performance, emission and combustion traits of a single cylinder diesel engine, the employed feedstock seed falls under second generation feedstock and it has an oil content of 38%. The process of transesterification which is employed to enhance the properties of neat oil resulted in 82% of methyl ester. The results outcomes revealed that the blend B25 performed better in contrast to other employed blends and it is suggested as optimum. The specific fuel consumption, brake thermal efficiency, the emission of carbon monoxide, hydrocarbon and nitrous oxide of the optimum blend at maximum load is 0.280 kg/kW h, 31.44%, 0.093% (by volume), 55 ppm and 988 ppm, respectively. While the exhaust gas temperature and smoke density is 318 ^oC and 49.02 HSU. The cylinder pressure and heat release rate of the optimum blend at maximum load is 75.84 bar and 41.06 kJ/m³ deg.

KEY WORDS: Second generation feedstock, Papaya oil, Methanolysis, Combustion, Performance, Emission, Diesel engine

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1607-1619.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.12

Optimisation of bioethanol production using cardboard waste as a promising feedstock via the yeast fermentation process

Noorulhuda G. Al-Abdallha, Ahmed G. S. Al-Azzawi — Tue, 27 May 2025 00:00:00 +0000

The present study employed cardboard waste as feedstock for bioethanol production. Physicochemical and biological treatments were utilized to enhance the free sugar level from cardboard waste converted to bioethanol through metabolic pathways using yeast. The minimum production of sugar was 16.2 mg/mL when the cardboard waste was pre-treated with dilute sulfuric acid (1%) at an acid/waste ratio of 10 mL: 1 g, which produced the highest bioethanol yield after fermentation. To concentrate the bioethanol obtained, distillation and dry agent were used respectively to afford high-purity bioethanol with yield of 29.0%. The bioethanol produced was characterized through NMR and FTIR spectroscopy techniques. Furthermore, bioethanol and traditional gasoline were blended at different ratios to produce blends E0, E6, E8, E10, and E12. The binary mixtures were evaluated experimentally using American Standard for Testing and Materials (ASTM) methods, including Reid vapor pressure (RVP), density, water content, and, research octane number (RON). The fuel blend densities increased linearly with an increasing ratio of ethanol content in the binary mixture, while RVP values decreased. RON and water content of bioethanol-gasoline blended fuel steadily increased with the addition of bioethanol.

KEY WORDS: Acid pre-treatment, Bioethanol-gasoline blends, Lignocellulosic wastes, S. cerevisiae

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1621-1637.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.13

Polyaniline-coated activated carbon from Prosopis juliflora for hexavalent chromium removal in aqueous solutions

Melaku Belay, Asmamaw Taye, Negash Getachew, Solomon Mehretie, Shimelis Admassie — Tue, 27 May 2025 00:00:00 +0000

This study explores the development and application of polyaniline-coated activated carbon (AC-PANI) derived from Prosopis juliflora for the efficient removal of hexavalent chromium (Cr(VI)) from aqueous solutions. Prosopis juliflora, an abundantly available invasive plant species was utilized as a sustainable precursor for activated carbon production. The activated carbon was subsequently modified with polyaniline to enhance its adsorption capacity and surface functionality. Characterization of the synthesized material was performed using FTIR and XRD. Batch adsorption experiments were conducted to investigate the effects of pH, contact time, adsorbent dosage, and initial Cr(VI) concentration on removal efficiency. The results demonstrated that AC-PANI exhibits remarkable adsorption capacity under optimal conditions, following Langmuir isotherm and pseudo-second-order kinetic models. At a pH of 1.0, AC-PANI achieved a maximum adsorption capacity of 1156.7 mg/g, reaching equilibrium within 420 minutes. The material also demonstrated a reuse efficiency of over 42% across five consecutive cycles. Furthermore, thermodynamic analysis revealed that the adsorption process was both endothermic and spontaneous. This study highlights the potential of AC-PANI as an eco-friendly and cost-effective adsorbent for treating chromium-contaminated water, offering a sustainable solution to environmental pollution.

KEY WORDS: Hexavalent chromium, Prosopis juliflora, Activated carbon, Adsorption

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1639-1652.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.14

Chemical composition of essential oil of Acacia crassicarpa Benth. (Fabaceae) from Vietnam

Tue, 27 May 2025 00:00:00 +0000

This research aimed to identify the volatile compounds found in the fresh leaves of Acacia crassicarpa Benth. This is the first phytochemical investigation of this species. Essential oils from the leaves of A. crassicarpa were obtained by hydro-distillation and analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Sixty-one compounds accounting for 95.8% of the leaf oil were identified. The classes of compounds identified in the oil sample were aldehydes (30.7%), sesquiterpene hydrocarbons (25.2%), alkanes (19.1%), oxygenated monoterpenes (3.6%) oxygenated sesquiterpenes (2.3%), monoterpene hydrocarbons (0.8%) and others (14.2%). The major constituents in the leaf oil were tridecanal (24.5%), (E)-caryophyllene (11.7%), n-heneicosane (7.2%), squalene (6.5%), and 7-tetradecenal (5.9%).

KEY WORDS: Acacia crassicarpa, Essential oil, Tridecanal, (E)-Caryophyllene

Bull. Chem. Soc. Ethiop. 2025, 39(8), 1653-1660.

DOI: https://dx.doi.org/10.4314/bcse.v39i8.15