Ultra-high performance liquid chromatographic determination of aflatoxin M1 in urine

The development of analytical methods to detect aflatoxin B1 (AFB1) in foodstuffs and its metabolites in human biological samples is useful for risk assessment. The latter methodology, i.e. the measurement of AFB1 biomarkers, has become important to assess human aflatoxin exposure. AFB1-lysine adduct, AFB1-DNA adduct and urinary aflatoxin M1 (AFM1) are some of the AFB1 biomarkers that can be measured by several analytical methods, such as enzyme-linked immunosorbent assay, radioimmunoassay, and high performance liquid chromatography (HPLC). HPLC coupled to a fluorescence detector is useful and preferable due to its high degree of sensitivity, but the analysis may take time and consume large amount of solvents. Therefore, the present study extrapolated the HPLC method to ultra-HPLC for the determination of urinary AFM1. After the extraction procedure with an immunoaffinity column, chromatographic separation was done using a high performance 1.8 μm microparticulate C18 column. The mean recovery from urine samples spiked with 0.5, 1.0 and 2.0 ng/ml AFM1 was 84.4±4.0%, with acceptable recovery values, interday (6.0±5.3%) and intraday (2.6±0.6%) coefficients of variation. The retention time was 5.7 min. This method was used to measure urinary AFM1 in 71 subjects, of which 13 had AFM1 levels above the limit of detection (0.018 ng/ml). The mean urinary AFM1 level of the positive samples was 18.8±28.6 pg/ml, ranging from 2.4 to 100.4 pg/ml. As this is one of the few studies investigating the occurrence of aflatoxin biomarkers in human biological samples in Malaysia, a study with a larger sample size is necessary to investigate the magnitude of aflatoxin exposure among the population

Quantitative image analysis of polyhydroxyalkanoates inclusions from microbial mixed cultures under different SBR operation strategies

Polyhydroxyalkanoates (PHAs) produced from mixed microbial cultures (MMC), regarded as potential substitutes of petrochemical plastics, can be found as intracellular granules in various microorganisms under limited nutrient conditions and excess of carbon source. PHA is traditionally quantified by laborious and time-consuming chromatography analysis, and a simpler and faster method to assess PHA contents from MMC, such as quantitative image analysis (QIA), is of great interest. The main purpose of the present work was to upgrade a previously developed QIA methodology (Mesquita et al., 2013a, 2015) for MMC intracellular PHA contents quantification, increase the studied intracellular PHA concentration range and extend to different sequencing batch reactor (SBR) operation strategies. Therefore, the operation of a new aerobic dynamic feeding (ADF) SBR allowed further extending the studied operating conditions, dataset, and range of the MMC intracellular PHA contents from the previously reported anaerobic/aerobic cycle SBR. Nile Blue A (NBA) staining was employed for epifluorescence microscope visualization and image acquisition, further fed to a custom developed QIA. Data from each of the feast and famine cycles of both SBR were individually processed using chemometrics analysis, obtaining the correspondent partial least squares (PLS) models. The PHA concentrations determined from PLS models were further plotted against the results obtained in the standard chromatographic method. For both SBR the predicted ability was higher at the end of the feast stage than for the famine stage. Indeed, an independent feast and famine QIA data treatment was found to be fundamental to obtain the best prediction abilities. Furthermore, a promising overall correlation (R2 of 0.83) could be found combining the overall QIA data regarding the PHA prediction up to a concentration of 1785.1 mgL-1 (37.3 wt%). Thus, the results confirm that the presented QIA methodology can be seen as promising for estimating higher intracellular PHA concentrations for a larger reactors operation systems and further extending the prediction range of previous studies.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE01-0145-FEDER-000004) funded by European Regional Development Fundunder the scope ofNorte2020 - ProgramaOperacional Regional do Norte.The authors also acknowledge the financial support to Cristiano S. Leal (PTDC/EBB-EBI/103147/2008, FCOMP-01-0124-FEDER009704) and Daniela P. Mesquita through the FCT postdoctoral grant (SFRH/BPD/82558/2011).info:eu-repo/semantics/publishedVersio

Geo-referencing the Satellite Image from Google Earth by Relative and Absolute Positioning

Introduction of geo-visualisation tools over the internet such as Google Earth (GE) has cut down the cost of data acquisition. This study is undertaken to validate the geo-information provided by GE that could be used for geospatial work. Satellite images and latitude-longitude coordinates (X-Y) for the campus of the University of Malaya has been downloaded from the internet. Geo-referencing of the satellite image was carried out using the relative positioning (RP) and absolute positioning (AP) within the geographic information system environment. Sources of X-Y for AP were obtained from GE and a topography map provided by the Malaysian Survey and Mapping Department. For absolute positioning, the data was obtained using GPS equipment. Comparison of these sources was undetaken with the total residual mean square error (RMSE) of X-Y in the map and at the source. All sources of X-Y had produced the total RMSE within 0.00014 degree. Considering the total RMSE as standard deviation (SD), the resulting range of error for geo-referencing of the satellite image was within 15 m. Thus, it can be concluded that geo-information from GE can be used as the source of base map

An overview of cathode material and catalysts suitable for generating hydrogen in microbial electrolysis cell

Bio-electrohydrogenesis through Microbial Electrolysis Cell (MEC) is one of the promising technologies for generating hydrogen from wastewater through degradation of organic waste by microbes. While microbial activity occurs at anode, hydrogen gas is evolved at the cathode. Identifying a highly efficient and low cost cathode is very important for practical implication of MEC. In this review, we have summarized the efforts of different research groups to develop different types of efficient and low cost cathodes or cathode catalysts for hydrogen generation. Among all the materials used, stainless steel, Ni alloys Pd nanoparticle decorated cathode are worth mentioning and have very good efficiency. Industrial application of MEC should consider a balance of availability and efficiency of the cathode material

A Case Study on Bulking Problems in Paper Recycling Effluent Treatment Plant in Malaysia

This study was conducted to investigate the cause of bulking problem at the effluent treatment plant (ETP) of a paper recycling plant in Malaysia. Hypothetically, the effluent is lacking nutrients and could induce the overpopulation of filamentous bacteria, and further cause the bulking problem during the effluent treatment using activated sludge process. Experiment to simulate treatment operations had been set up at laboratory. The simulation showed that the bulking started to occur after the first cycle of the fed-batch operation with the typical effluent. To make up the lacking of nutrients in the effluent, urea (N) and phosphate (P) were added as supplements with the ratio of BOD:N:P equal to 100:1.0:0.7. The supplemented effluent was again tested by a simulation study and showed that the bulking problem started to take place after the third cycle of feeding regime. Bulking problem also periodically took place in the actual operation when the same supplemented formula was applied; however the frequency of occurrence was lesser. Therefore, this study has shown that other than the lack of nutrients, there are other factors that could cause bulking problem

Taguchi optimisation approach for chromium removal in a rotating packed bed contractor

Rotating packed bed (RPB) is a doughnut shaped bed, which is spun at high speed to generate centrifugal force to pass fluid through an adsorbent bed at a high velocity. The centrifugal force, which is much larger than the gravitational force reduces mass transfer resistance for transporting adsorbate molecules to the adsorbent. In this study, the optimum condition of the working parameters of a RPB contactor for removal of chromium by activated carbon was investigated with the aid of Taguchi method. Four parameters, namely, rotating speed (rpm), feed rate (L/h), packing density (kg/m(3)) and initial solution pH were chosen as the control factors while initial concentration of chromium was chosen as the external noise factor. The optimum condition for the adsorption was found to be rotating speed (rpm) of 1200 (level 3), feed rate (L/h) of 50 (level 4), packing density (kg/m(3)) of 179 (level 3), and initial solution pH of 2 (level 1). The experimental and predicted S/N ratios with values 39.26 and 39.20 were in very good agreement with each other at the optimum condition. A removal of 91% was obtained at the optimum condition. Pseudo second order kinetics described the adsorption rate satisfactorily while the mechanism could be described by the film diffusion model. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Assessment of heavy metal contamination at west and east coastal area of peninsular Malaysia

Five heavy metal elements [Pb(II), Cr(VI), Ni(II), Zn(II) and Cu(II)] in the sediment of the two coastal areas had been analysed of the mid-east and mid-west of Peninsular Malaysia in the year of 2012. This is to assess and monitor contamination of heavy metal at mangrove area in the state of Negeri Sembilan, Melaka and Pahang. Overall and individual analyses on the heavy metals showed the concentration of the named heavy metals were not at alarming stage. All analysed elements were found to be much lower than the international guideline provided by the Chinese (EPA-China), Canadian (CEPA) and American (US-EPA). Quantitative assessment using Enrichment Factor shows that all analysed elements were to found be within the degree of background concentration

Retracted: Adsorption of copper ions onto cellulose xanthogenate derived from cogon grass (Imperata cylindrica) leaf powder

This article was withdrawn and retracted by the Journal of Fundamental and Applied Sciences and has been removed from AJOL at the request of the journal Editor in Chief and the organisers of the conference at which the articles were presented (www.iccmit.net). Please address any queries to [email protected]

Optimisation of the process variables in production of activated carbon by microwave heating

This study aims to investigate the optimal operating conditions in order to obtain cost effective production of activated carbon (AC) from palm kernel shell (PKS) by microwave heating. Interactions among the independent variables, namely irradiation time (T), microwave power (W), impregnation ratio between impregnating substances and PKS, and the concentration of impregnating substance (sulphuric acid) were considered for optimising the process parameters during the production of AC, aided by Central Composite Design. The optimum conditions for the independent process variables were 11.02 minutes of irradiation time, microwave power of 676 W and impregnation ratio of 0.68. The AC produced in this work had a surface area of 1011 m < sup > 2 < /sup > g < sup > -1 < /sup > with high porosity as shown by scanning electron microscopy (SEM). Zinc was used to verify the potential of AC as an adsorbent. Zinc removal at the optimum conditions was found to be 13.72 mg g < sup > -1 < /sup > . Such a Zn removal value is comparable with the earlier work of other researchers who used a conventional way of producing the AC. It is believed that microwave technology can be used for the production of AC in a short time with high energy efficiency, e.g., 11 minutes against 2-5 hours of reactivation for conventional methods