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- ItemEffect of Copper-Based Fungicide on Chemical Composition of Cocoa Seeds(2025) Lawal, A. R.; Olayinka, B. U.; Olahan, G. S.; Omorinoye, O. A.; Abdulsalam, H. A.; Abdulra’uf, L. B.Production of cocoa seeds, one of Nigeria’s major non-oil foreign exchange earners as well as a major raw material for the beverage industry, is greatly hindered by diseases caused by various species of the genus Phytophthora. To avert this, copper-based fungicides are sprayed on the leaves of cocoa trees to control or prevent the survival of this organism by the farmers without paying attention to the effects of this chemical on the proximate composition of cocoa seeds. This study therefore investigated the effects of a copper-based fungicide (Ridomil Gold Copper) on the quality of the cocoa seeds by spraying cocoa trees, including the pods, with 50.00 g/L of copper-based fungicide. The results obtained showed that cocoa seeds from the control trees showed significantly higher contents of fiber (4.51%), protein (15.1%), and fat (36.1%) when compared to the respective values of 3.45, 3.95, and 7.59% obtained for the cocoa seeds harvested from the fungicide-treated cocoa trees. All other proximate compositions did not show any statistical difference, except for carbohydrate and calorific values, which were significantly higher in cocoa seeds from fungicide treated cocoa trees. Seeds from fungicide-treated trees showed significantly higher potassium, phosphorus, and magnesium contents but lower zinc and copper contents. However, phytochemicals such as phenols, alkaloids, flavonoids, and tannins were significantly lower in content in the seeds of fungicide-treated cocoa trees. The contents of glycosides and antioxidants in the cocoa seeds were statistically similar for both the control and treatment, except for ascorbic acid, which showed a significantly lower value (4.8 mg/100 ml) in cocoa seeds from fungicide-treated cocoa trees, compared with the value recorded for the control in this study (13.33%). The foregoing results showed that the use of copper-based fungicides for the control of black pod disease in cocoa adversely affected the quality of cocoa seeds from the treated trees.
- ItemSPME fibers for the analysis of pesticide residues in fruits and vegetables: A review(Critical Reviews in Analytical Chemistry, Taylor and Francis., 2012-11-22) Abdulra’uf, L. B., Adebayo, W. H and Tan, G. H.Food samples are usually analyzed with a preliminary step of sample preparation, because pesticide residues are present in low concentrations and embedded in complex matrixes. Solid phase microextraction (SPME) is a solvent-free extraction technique that is fast, relatively inexpensive, easily automated, and versatile with high sample throughput. Analyte extraction, pre-concentration, and introduction into the analytical instrument are achieved in a single uninterrupted process. SPME uses fibers coated with a polymeric stationary phase that can be either a solid, liquid, or a combination of both. The fiber coating extracts the target analytes from a complex food matrix by absorption in the case of liquid coatings or adsorption in the case of solid coatings. The SPME fiber is then transferred into the analytical instrument for desorption and analysis of the target analytes. The use of sol-gel technology in the production SPME coated fiber has helped to increase the range of pesticide residues that can be extracted with the SPME technique.
- ItemDetermination of pesticide residues in beans using QuEChERS technique coupled to gas chromatography-mass spectrometry: Multivariate optimization of CEN and AOAC methods(Elsevier, 2025) Abdulra’uf, L. B.; Junaid, A. M.; Lawal, A. R.; Ibrahim, H. B.; Tan, G. H.The use of pesticides has led to environmental pollution and posed a global health risk, since they remain as residues on foods. Beans one of the most widely cultivated crop in Africa, and susceptible to attack by insects both on field and during storage, leading to the application of pesticides to control pests’ infestation. However, misuse of these chemicals by farmers on beans has resulted in the rejection of beans exported to European countries, due to the presence of pesticide residues at concentrations higher than the maximum residues levels (MRLs). In this study, the effectiveness of the Association Official Analytical Chemists (AOAC) Official Method and the European Committee of Standardization (CEN) Standard Method, were determined using multivariate approach for the analysis of organochlorine pesticide residues in 6 varieties of beans samples. The significance of factors (mass of sample, volume of acetonitrile, mass of magnesium sulphate, sample pH, centrifugation time and speed) affecting the efficiency of extraction was estimated using Plackett-Burman design, while central composite design was used to optimize the significant factors. The following optimum factors were subsequently used for method validation, recovery tests, and real sample analysis: 4 g of sample sludge (1:1 v/v), 10 mL of acetonitrile, 4.45 g of MgSO4, and 5 min of centrifugation at 5000 rpm. The figure of merit of analytical methodology estimated using matrix-matched internal standard calibration method gave linearity ranging from 0.25 to 500 μg/kg, with correlation coefficient (R2) greater than 0.99, the recovery ranged from 75.55 to 110.41 (RSD = 0.70–16.65), with LOD and LOQ of 0.23–1.77 μg/kg and 0.76–5.88 μg/kg, respectively.
- ItemMIXED LIGANDS COMPLEXES OF METRONIDAZOLE: SYNTHESIS AND ANTIBACTERIAL STUDIES(MATERIALS SCIENCE AND TECHNOLOGY SOCIETY OF NIGERIA, 2019-11-22) Lawal, A.; Issa, A; Rajee, A.O; Mamman, A; Saadu, H.O.; Bamigboye, M.O,; Babamale, H.F,; Osunniran, W; Busari, H.KThe synthesis of some transition metal complexes of metronidazole with oxalic acid have been reported and characterized using conductivity measurement, melting point determination, elemental analysis, infrared and ultraviolet/visible spectroscopic methods. Both ligands were bidentate in their moe of coordination with the metal ions. The antibacterial studies were investigated against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Klebsiella pneumonia. Mn(MET)(OXA)Cl2 has the highest inhibition against Klebsiella pneumonia, while Cu(MET)(OXA)Cl2 has the lowest inhibition against Bacillus subtilis.
- ItemSOLVENT -FREE SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL STUDIES OF UREA AND THIOUREA-METAL COMPLEXES(Science Focus, 2016-07-19) Amudat LAWAL; G.Grace NNABUIKE; J.Ayoola OBALEYE; Misitura LAWAL; M.Oluwaseyi BAMIGBOYE; H. Ojuolape SA'ADSolvent - based synthesis as well as Liquid Assisted Grinding (LAG) synthesis of urea and thiourea complexes is described for comparison purposes. The resulting complexes of both methods of syntheses were characterized using melting points, conductivity values, spectroscopic data (IR, UV-Visible) and antibacterial activity study. Spectral data of the complexes synthesized by LAG method was found to be similar to those synthesized by conventional synthesis. All the ligands were found to be monodentate and all the complexes exhibited tetrahedral and square -planar geometry. The LAG method was carried out by introducing a few drops of solvent. The method is faster with a better yield compared to solvent-based method. The antimicrobial study of the ligands and the complexes was carried out against Gram-positive (Staphylococus aureus and Bacillus subtilis) and Gram -negative bacteria (Escherichia coli). The antibacterial activity study of the complexes showed that they possessed higher inhibitory activity than their parent ligands at concentration of 200gm-1.