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)

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. Keywords: Chromatographic peak areas, Chemometrics RSM, LC-MS, Pesticide analytes, QuEChERS-dSP

Amilcar Cabral and the Development Paradigms in Mrica: Revisiting the Earlier Strategies for the Mrican Union

From OAU to AU, the embattled vision of the African continent has always been that of generating development for the 'people'. The quest for selfgovernment presupposed the need for development. This was copiously captured in the popular aphorism ofKwame Nkrumah (one of the leading elites of the Organization for Africa Unity) that reads: "Seek ye first the political kingdom, and all other things will be added". The implication of the above statement is that once the African continent successfully wrestled political power from the colonialist, the continent would be on the path to development. Political freedom was conceived as a prerequisite for development. Many years have passed; meaningful development still remains a quest of the African continent. This paper comes across as a theoretical interrogation of some indigenous development frameworks proposed for the continent. Importandy, Amilcar Cabral endogenous proposal for development is examined with the view of providing a viable theoretical platform for pursuing meaningful and sustainable development for the continen

Development of headspace solid-phase microextraction method for the analysis of pesticide residues in fruit and vegetable samples using OFAT design

A headspace solid-phase microextraction (HS-SPME) method was developed as a preliminary investigation using univariate approach for the analysis of 14 multiclass pesticide residues in fruits and vegetable samples. The gas chromatography mass spectrometry parameters (desorption temperature and time, column flow rate, interface temperature) and solid phase microextraction parameters (fiber coating type, extraction temperature and time, pH, salt addition, stirring rate, dilution factor, organic solvent type and amount) were all investigated and optimized. The optimum values for the optimized parameters are as follows: Injection Temperature, 270 °C; Interface temperature, 300 °C; Column flow rate, 1.3 mL/min; Fiber coating, PDMS/DVB; Extraction time, 30 mins; Extraction temperature, 60 °C; Stirring rate, 300 rpm; Salt addition, 10% (v/w) NaCl; pH, 7; Desorption time, 7 min; Desorption temperature, 270°C; Organic solvent 3 % (methanol/acetone, 21:79%). The optimization of the mixture of organic solvents was optimized using design of experiment (DOE) with simplex lattice, designed using Minitab Statistical Software®. The developed method was then applied to the analysis of samples of apple, tomato, broccoli, lettuce, grape, cucumber, cabbage and pear. The investigated pesticides were found to be below the maximum residue levels, while some were not found. This shows that the fruit and vegetable samples are safe for consumption and do not pose any health risk for consumers.Keywords: Univariate design, Simple lattice design, design of experiment, GC-MS, HS-SPM

Mobile Phase Selection by Optimization for the Determination of Multiple Pesticides Using Liquid Chromatography-Tandem Mass Spectrometry

The selection of the best mobile phase setup is one of the most important factors to be considered prior to quantitative instrumentation of multiple pesticides. Usually, mobile phases comprises of water (A) and an organic solvent (B) are the setup used in liquid chromatography instruments for the analysis of pesticide residues in various samples. Unfortunately, most of the analyses are being carried out without optimization and selection of the best mobile phase setup to improve the sensitivity of the instrument. For that reason, the comparative analysis of the reportedly used mobile phases and some few suggested ones was carried out on the multi-pesticide mixture of 0.1 mg/kg (100 μg/kg) standard solutions and quantified with liquid chromatography–tandem mass spectrometry (LC–MS/MS) instrument. Consequently, the best mobile phases setup that resulted in the sum of average total chromatographic peak areas (ATCPAs) and average total chromatographic peak heights (ATCPH) for the total ion chromatography (TIC) scans as an index that correspond to the concentration levels was selected [0.1% formic acid in H2O (A) and 0.1% formic acid in acetonitrile (ACN) (B)]. And further optimization was successfully carried out on the selected mobile phase-A and the resulted setup [1% ACN and 0.1% formic acid in Milli-Q-water (mobile phase A) coupled with 0.1% formic acid in ACN (mobile phase-B)] improved the instrumental sensitivity on the targeted analytes. Thus, this justify the potential benefits of optimizing setup of the mobile phases prior to LC–MS/MS instrumentation of multi-pesticide analytes

Influence of pendimethalin and hand weeding on mineral composition of maize, cowpea and their intercrop

Weed competition has been a major challenge limiting crop yield especially in intercropping systems. Information on the use of chemicals for weed control in intercropping systems appears scanty. The aim of this study was to investigate the efficacy of pendimethalin (P) at 1 kg active ingredient/ha, and hand weeding (HW) on mineral contents of the harvested grains and effects of various weed control treatments in maize, cowpea, and their intercrop. Field experiments were carried out during the 2017 and 2018 rainy seasons. The field layout followed complete randomized block design with three replicates. There were eight treatments: Sole Maize/Cowpea + P, Sole Maize/Cowpea + P + 1HW at 3 weeks after sowing (WAS), Sole Maize/Cowpea + P+ 2HW at 3 and 6 weeks after sowing (WAS), Sole Maize/Cowpea weedy check, Intercrop + P, Intercrop + P + 1HW at 3WAS, Intercrop + P + 2HW at 3 and 6 WAS and Intercrop weedy check. It was observed that, P+1HW and P+2HW in both cropping systems have significant effects (p<0.05) and effectively control weed and increase the mineral contents in maize, cowpea, and their respective intercrop. The study revealed that, the mineral composition of maize and cowpea grains were improved by using pendimethalin with supplementary hand weeding. The study recommends that farmers should adopt intercropping maize with cowpea using pendimethalin plus one supplementary hand weeding at 3 WAS

Feelings of Insecurity in Hotels and Host Communities, Ibadan, Nigeria

The study examines factors influencing the feelings of insecurity in Hotels and Host Communities of Ibadan, Nigeria. The results showed that theft, fraud, robbery sexual abuse, and burglary were the most frequently worried crime in the hotel industry while robbery, theft, fraud, burglary, and sexual abuse were highly worried among the residents of host communities. Using factor analysis, Mechanical/personal (42.7%), human (19.5%), economic (11.53%), and environmental factors (8.49%) were the factors influencing the feelings of insecurity among hotel staff while human/personal (49.30%), economic (11.261%), mechanical (7.49%), and environmental factor (6.52%) were the factors among residents of host communities. The study concluded that irrespective of the geographical area, feelings of insecurity is associated with different determinants and criminal activities vary based on several factors

Dispersive liquid-liquid microextraction/HPLC techniques for determination of oxytetracycline and doxycycline residues in beef samples: method developments and statistical analysis

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)

Low coverage of COVID-19 vaccines in Africa:current evidence and the way forward

Disparities in COVID-19 vaccine coverage across the globe have uncovered inequities in global healthcare. While more than half of the population of the developed countries have been fully vaccinated, only a small percentage of the African population has received one vaccine dose so far, a far cry from the global vaccination targets. Furthermore, several low and middle income (LMICs) African countries lack the competence, infrastructure, logistics, and financial resources to mass-vaccinate their populations. This paper highlights the causes and implications of the low COVID-19 vaccine coverage on Africa and the global community, and discusses strategies for restructuring and strengthening COVID-19 vaccination in Africa

Enhancing Germination and Seedling Growth in Salt Stressed Maize Lines through Chemical Priming

This study aimed to investigate the tolerance level and the use of primers (H2O, KNO3, ascorbic acid and salicylic acid), in mitigating stress in maize in the newly released cultivars (SWAN-LSR-Y, BR9928-OMR-SR-Y and OMR-LSR-SY). Activities of SOD, APX, CAT and GSH and lipid peroxidation were investigated, to measure the biochemical response of the primed maize seeds. Maize seeds primed with KNO3 and ascorbic acid improved germination and anti-oxidative potential against ROS in ameliorating the salinity stress, while salicylic acid slowed germination. The same trend was followed in the seed vigour index and radicle length of seeds primed with ascorbic acid, which recorded the highest values. The control was observed to have the highest seed vigour index, while seeds primed with salicylic acid showed the least vigour index in the maize seeds.  Increased salinity stress showed adverse effects on all growth parameters. Of the maize cultivars tested, SWAN-LSR-Y showed the most tolerance to salinity stress, in terms of germination. Significant high enzymatic activities and lipid peroxidation were recorded in seeds primed with ascorbic acid and KNO3 show their importance in plant metabolic activities