Browsing by Author "Abdulrauf, L. B."

Now showing 1 - 10 of 10
  • Thumbnail Image
    Item
    Aflatoxin - control, analysis, detection and health risks
    (InTech Open, 2017-09-01) Abdulrauf, L. B.
    Aflatoxins are a group of highly toxic and carcinogenic substances, which occur naturally, and can be found in food substances. Aflatoxins are secondary metabolites of certain strains of the fungi Aspergillus flavus and A. parasiticus and the less common A. nomius. Aflatoxins B1, B2, G1, and G2 are the most important members, which can be categorized into two groups according to the chemical structure, namely, difurocoumarocyclopentenone series and ifurocoumarolactone. Of the 20 aflatoxins identified so far, only aflatoxins B1, B2, G1, and G2 are known to occur naturally and B and G classes refer to the blue and green fluorescence emitted by their metabolites under ultraviolet (UV) light, and the subtype 1 and subtype 2 imply the major and minor compounds, respectively. Aflatoxins fluoresce strongly under UV radiation (ca. 365 nm). The most common food commodities affected by aflatoxins are cereals (corn, wheat, barley, maize, oats, and rye), nuts (hazelnut, peanut, and pistachio nut), dried fruits (fig), and spices (chili powder). Aflatoxins pose a potential threat to human and animal health through the consumption, contact, or inhalation of foodstuffs and feedstuffs prepared from these commodities. As a result of the adverse health effects of mycotoxins, their levels have been strictly regulated especially in food and feed samples. Therefore, their accurate identification and determination remain a Herculean task due to their presence in complex food matrices. The great public concern and the strict legislation incited the development of reliable, specific, selective, and sensitive analytical methods for mycotoxins monitoring that are discussed in this book. The book comprises 12 chapters. Chapters 1 to 4 discuss the control and prevention of aflatoxin contaminations in foods, and Chapters 5 to 10 discuss the health risk posed by aflatoxin contaminations in food, while Chapters 11 and 12 discuss the new development in the analysis and detection of aflatoxins in food samples. The book contains up-to-date publications of leading experts, and, therefore, it is hoped that the reference cited by various authors will be a starting point to acquire a deeper knowledge on the prevention, control, identification, and determination of aflatoxins in foods and feedstuffs. I gratefully acknowledge the efforts and expertise of the contributing authors for their time and efforts in preparing the chapters and for their interest in the book project. I am indebted to the vice chancellor of Kwara State University, Malete, Ilorin, Nigeria, Prof. Abdul Rasheed Na’Allah and all the academic staff of the Department of Chemistry for the support and encouragement. I also acknowledge the support of my wife (Mrs. Rihanat Abdulra’uf), my children, and my colleagues at the School of Basic and Remedial Studies, Kwara State College of Education, Ilorin, Nigeria, for their unwavering support and encouragement during the chapter review process. My special appreciation and thanks go to the editorial team and publishing manager of InTechOpen Publisher for their promptness, encouragement, and patience during the review and publication process. Dr. Lukman Bola Abdulra’uf Department of Chemistry, College of Pure and Applied Sciences, Kwara State University, Malete, Nigeria
  • Thumbnail Image
    Item
    APPLICATION OF FACTORIAL DESIGN TO THE STUDY OF PARAMETERS IN THE DETERMINATION OF PESTICIDE RESIDUES IN APPLE BY HEADSPACE SOLID PHASE MICROEXTRACTION COUPLED TO GAS CHROMATOGRAPHY-MASS SPECTROMETRY
    (PACCON International Conference, 2012) Abdulrauf, L. B.; Tan, G. GH.
    Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. SPME process involves two basic steps which are the partitioning of analytes between the polymeric fiber coating and the sample matrix, and desorption of the concentrated extracts into the analytical instrument, without any clean-up step. In this study, factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) were studied using a factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticides were evaluated using 23 factorial designs. A 10 g sample was weighed into 20 mL amber glass vial, fortified with the standard mixture at three concentration levels (10, 50 and 100 µg.L–1) and allowed to rest for 2 hrs. Optimum dilution was made with 10 mL of distilled water containing 10% NaCl and the mixture was shaken ultrasonically for 3 min. The analytes were then extracted with 100 µm PDMS fibers according to the factorial design matrix and desorbed into gas chromatography–mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limit of detections was between 0.01 and 0.2 µg.L–1, which were lower than the MRLs for apples. The relative standard deviations were between 0.1 and 13.37% with average recovery of 80 to 105%. The linearity ranges from 0.5 – 50 µg.L–1 with RSD greater than 0.99
  • Thumbnail Image
    Item
    Applications of Experimental Design to the Optimization of Microextraction Sample Preparation Parameters for the Analysis of Pesticide Residues in Fruits and Vegetables
    (J AOAC International, 2015) Abdulrauf, L. B.; Sirhan, A. Y.; Tan, G. H.
    Sample preparation has been identified as the most important step in analytical chemistry and has been tagged as the bottleneck of analytical methodology. The current trend is aimed at developing cost-effective, miniaturized, simplified, and environmentally friendly sample preparation techniques. The fundamentals and applications of multivariate statistical techniques for the optimization of microextraction sample preparation and chromatographic analysis of pesticide residues are described in this review. The use of PlacketBurman, Doehlert matrix, and Box-Behnken designs are discussed. As observed in this review, a number of analytical chemists have combined chemometrics and microextraction techniques, which has helped to streamline sample preparation and improve sample throughput.
  • Thumbnail Image
    Item
    CHEMOMETRIC APPROACH TO THE OPTIMIZATION OF HSSPME/GC-MS FOR THE DETERMINATION OF MULTICLASS PESTICIDE RESIDUES IN FRUITS AND VEGETABLES
    (FFTC-KU International Workshop on Risk Management on Agrochemical, 2015) Abdulrauf, L. B.; Tan, G. H.
    A Headspace Solid Phase Microextraction (HS-SPME) method was developed using multivariate experimental designs, which was conducted in two stages. The significance of each factor was estimated using the Plackett-Burman (P-B) design, for the identification of significant factors, followed by the optimization of the significant factors using central composite design (CCD). The multivariate experiment involved the use of Minitab® statistical software for the generation of a 27-4 P-B design and CCD matrices. The method performance evaluated with internal standard calibration method produced good analytical figures of merit with linearity ranging from 1 – 500 µg/kg with correlation coefficient greater than 0.99; limit of detection (LOD) and limit of quantification (LOQ) were found between 0.35 and 8.33 µg/kg and 1.15 and 27.76 µg/kg, respectively. The average recovery was between 73 % and 118 % with relative standard deviation (RSD = 1.5 – 14 %) for all the investigated pesticides. The multivariate method helps to reduce sampling time and improve analytical throughput.
  • Thumbnail Image
    Item
    Chemometrics approach to QuEChERS-dSPE for multi-standard determination of pesticides in blank samples of Milli-Q-water using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS)
    (Chemsearch Journal, 2020) Lawal, A.; Abdulrauf, L. B.
    The development of the best efficient technique for multi-pesticide determination in food samples is one of the best ways to address issues concerned with the use of pesticides in agricultural practices. Even though, several conventional techniques have been used earlier such as solid-phase extraction (SPE) and liquid phase microextraction (LPME), unfortunately, these treatment techniques possess poor sensitivity towards targeted analytes due to lack of modifications and optimization which provides an optimum condition for the analyses. In the present work however, chemometrics (multivariate) approach was used as response surface methodology (RSM) for optimising significant factors of quick, easy, cheap, effective, rugged and safe (QuEChERS) with the dispersive solid phase extraction (dSPE) technique. The Blanket-Burman (screening) and Box-Behnken (optimising) design generated by Minitab statistical software were used for the screening and optimisation of significant factors, respectively as well as quantification using total chromatographic peak areas (TCPA) responses of high-performance liquid chromatography-tandem mass spectrometry instrument. Eventually, the acquired average TCPA recovery (56%) for the RSM optimized QuEChERS-dSPE technique was favoured over that of default technique (44%) after comparative studies. This justifies the validity of the optimized method to play an important role in the determination of multi-pesticide residues in water and other food samples with higher matrix interferences.
  • Thumbnail Image
    Item
    Dispersive liquid-liquid microextraction/HPLC techniques for determination of oxytetracycline and doxycycline residues in beef samples: method developments and statistical analysis
    (Nigerian Society of Physical Sciences, 2023-04-10) Aliu, M. A.; Junaid, A. M.; Ibraheem, A.; Ishaq, A.; Lawal, A.; Ayeni, K. E.; Lawal, A. R.; Abdulrauf, L. B.
    A rapid, cost-effective and environment-friendly sample pre-treatment method involving dispersive liquid-liquid microextraction (DLLME) and high-performance liquid chromatography (HPLC) was developed and applied for the extraction of oxytetracycline and doxycycline residues in beef samples (liver, kidney and muscle). Several influencing factors associated with the extraction and separation of these antibiotics residues, such as sample size, type and volume of disperser and extraction solvents, centrifugation speed and time, were optimized using Plackett-Burman design and central composite design, while insignificant factors were fixed at values determined using univariate analysis. Figures of merit of the analytical methodology including the limit of detection (LOD), the limit of quantification (LOQ), accuracy (in terms of average recoveries), precision and calibration functions were established according to the European Union commission decision 2002/657/EC. Linearity, in the range of 5–500 µg/kg, was obtained with regression coefficients ranging from 0.9983 – 0.9999. Inter-day repeatability, intra-day precision, LODs and LOQs obtained were 3.81 – 14.90%, 3.80 – 8.70%, 4.21 – 4.69 µg/kg and 14.02 – 15.65 µg/kg respectively. Samples with detectable drug residues have oxytetracycline being the most commonly detected. The developed method was successfully established and the concentration levels of drug residues detected were lower than the European Union set maximum residue level (MRL).
  • Thumbnail Image
    Item
    Recent developments and applications of microextraction techniques for the analysis of pesticide residues in fruits and vegetables. In: Pesticides – Recent trends in pesticide residue assay
    (Intech Open, 2012) Tan, G. H.; Abdulrauf, L. B.
    Analysis of pesticide residues and other contaminants in fruit and vegetable samples is becoming increasingly important due to the health hazards caused by their accumulation in human tissue. The body requires some important nutrients which can be provided by the consumption of fruits and vegetables. The purpose of any analytical study is to obtain information about substances and analytes present in the sample. Analytical process involves several steps: sampling, sample preparation, separation, quantification and data analysis
  • Thumbnail Image
    Item
    Removal of arsenic from aqueous solution by synthetic hematite
    (Journal of Chemical Society of Nigeria, 2011) Adekola, F. A.; Abdus-Salam, N.; Abdulrauf, L. B.
    A sample of hematite has been prepared and characterized by determination of some physico-chemical parameters such as X- ray Diffraction analysis, specific gravity and point of zero charge measurement. The potential of synthesized hematite for the sorption of arsenic(III) aqueous solution was also investigated, and the sorption data were found to be fitted with Langmuir adsorption isotherm (type 2) as well as Freundlich and Temkin isotherms with corresponding correlation coefficient (R) of 0.96, 0.94 and 0.94 respectively. The adsorption capacity calculated from the Freundlich and Langmuir isotherms were 0.35 and 0.60 respectively. The sorption kinetics was also investigated and the equilibrium time determined to be 320mins. The kinetics was found to follow pseudo – first order kinetics. Desorption study was also carried out with concentrated HNO3 (1M), and was found to be effective for the stripping of 86% of pre – sorbed arsenic from the adsorbent after the first use
  • Thumbnail Image
    Item
    Removal of arsenic from aqueous solution by synthetic hematite
    (Journal of Chemical Society of Nigeria, 2011) Adekola, F. A.; Abdus-Salam, N.; Abdulrauf, L. B.
    An hematite was synthesized and subjected to batch equilibration ofarsenic and its desorption processess that control the mobility, toxicity and availability in the water environment
  • Thumbnail Image
    Item
    Safety evaluation of some ready-to use herbal concoctions sold within Ilorin metropolis
    (NSUK Journal of Science and Technology, 2020) Zakariyah, R. F.; Odebisi-Omokanye, M. B.; Saliu, B. K.; Abdulrauf, L. B.; Jimoh, F. A.; Adebiyi, O. A.
    Safety and quality of indigenous herbal concoctions in Nigeria is of public health concern as the consumption is on the increase. Hence, this study was conducted to evaluate microbial and heavy metals contaminants in selected ready –to- use herbal concoctions within Ilorin metropolis. The heterotrophic microbial counts using pour plate method were assessed and the contaminations of selected heavy metals were analyzed using Atomic Absorption spectrophotometer. The viable plate count for bacteria and fungi ranged between 2.0 ×104 - 10.5 ×105 CFU/ml and 2.0 ×104- 8.3×105 respectively. Bacteria and fungi isolated include Pseudomonas aeruginosa, Micrococcus luteus, Citrobacter freundii, Staphylococcus aureus, Klebsiellia pneumoniae, Corynebacterium kutscheri, Aeromonas hydrophilia, Staphylococcus epidermis, S. cerevisae, Gliocladium sp., Penicillum sp., A. alternata, Aspergillus niger, C. albicans, R. stolonifer, Geotrichum sp and A. flavus respectively. Pb and Cu level concentrations were found to be in the range of 0.1-0.3mg/L and 0.01- 074 mg/L respectively. The concentration of Pb and Cu were generally high and above the safe limits set by WHO/FAO while Cd was not detected in any of the samples. Generally, the consumers of these herbal products are unwittingly exposed to heavy metal poisoning and microbial contaminants. It is suggested that regulatory bodies should intensify efforts to minimize human exposure risk.