Preparation, characterisation and application of molecularly imprinted polymers for the selective removal of sterols from water

Water quality of the existing freshwater bodies in many countries has declined due to day-to-day human activities which result into discharging different pollutants.  This study therefore, aimed at developing a selective technique based on Molecularly Imprinted Polymers (MIPs) for the removal of toxic sterols from water. Cholesterol-Molecularly imprinted polymers and their corresponding Non-imprinted Polymers (NIPs) were prepared using a non-covalent method and their physical morphologies were characterised using Scanning Electron Microscope (SEM), Fourier-Transform Infrared spectroscopy (FT-IR) and surface analyzer [Brunauer–Emmett–Teller (BET)].The surface area obtained after optimization of the necessary parameters was 180.26 m2/g for MIP and 132. 18 m2/g for the corresponding NIP at a 1:8 template to monomer ratio. The FT-IR spectra of MIP and NIP were similar indicating the similarity in the backbone structure. The TGA profiles of the imprinted and non-imprinted polymers showed that polymers were thermally stable up to about 250 ⁰C. However, thermal stability was observed to vary with monomer to template ratios. In terms of binding capacity, MIPs were observed to have higher binding capacity of sterols as compared to their corresponding NIPs, and they were able to remove more than 98% of sterols from aqueous solution prepared at an optimal initial concentration of 40 mg/L.Keywords: Molecularly imprinted polymers, Sterols, water quality, GCxGC-TOFMS. toxic plant extractive

Variations of Concentrations of Lead, Zinc, Iron, Copper and Cadmium in Urine of Primary School Pupils in Relation to Age, Sex and Academic Performance

This study was conducted in order to assess the variations and correlations in the concentrations of lead, zinc, iron, copper and cadmium metals in the urine samples of selected primary school pupils with respect to their sex, age and academic performance. Urine samples were collected from 240 pupils in Dar es Salaam, Tanzania and then digested in concentrated acids and analysed using atomic absorption spectrometry (AAS). Lead, zinc, iron and copper were detected in most of the urine samples. Cadmium was not detected in any of the samples. The mean concentrations of lead, zinc, iron and copper in the samples from different classes ranged between 0.27–0.90, 0.59–0.78, 1.56–2.32 and 0.005–0.01 mg/L, respectively in pupils with high academic performance, and 0.37–0.71, 0.56–0.81, 1.79–2.55 and 0.005–0.01 mg/L, respectively in pupils with low performance. The overall mean concentrations of the metals ranged between 0.01–2.04 and 0.01–2.17 mg/L in males and females, respectively. There were no significant differences in most of the concentrations of the heavy metals in pupils’ urine samples between the two sexes. The findings indicated some significant positive correlations between the pupils’ age and the concentrations of lead and iron in urine samples, while there were no significant correlations for zinc and copper. Some of the concentrations of the heavy metals showed significant negative or positive correlations with the academic performance of the pupils. Therefore, the concentrations of the heavy metals were correlated with age, sex and academic performance in some samples. The concentrations of lead were generally alarming. Keywords: Heavy metals; children urine; age; sex; academic performance; Tanzani

Occurrence of Aflatoxins in Maize and Maize Products from Selected Locations of Tanzania and the Effects of Cooking Preparation Processes on Toxin Levels

The production and storage of food crops in different countries is affected by aflatoxins contamination, which are known to be carcinogenic and mutagenic to human beings and domestic animals. This study investigated on the occurrence of aflatoxins in maize products and the effects of cooking preparation processes on their concentrations. The maize samples were collected from fields, farmers' stores and markets of selected locations in Tanzania (i.e., Kongwa and Njombe districts). Extracted samples were analyzed for aflatoxins using high performance liquid chromatography. The concentrations of aflatoxins in maize and maize products ranged from below detection limit to 9.99 ± 1.43 μg/kg and 9.99 ± 0.14 μg/kg for Njombe and Uwemba wards, respectively. Whereas those collected from Kibaigwa ward in Kongwa district ranged from 2.87 ± 0.02 μg/kg to 10.26 ± 0.46 μg/kg. The levels in cooked maize products were lower than the uncooked maize products. The mean concentrations of total aflatoxins in cooked maize products were 0.45 ± 0.05 μg/kg for stiff porridge prepared from dehulled maize flour, 1.39 ± 0.02 μg/kg for stiff porridge prepared from undehulled maize flour, and 0.584 ± 0.06 μg/kg for maize meal (kande). Generally, the levels of aflatoxins were below the maximum acceptable limits set by WHO except for some samples from Kibaigwa market which were slightly above the set limits. Keywords: Aflatoxins; High Performance Liquid Chromatography; Maize; Fung

Levels of heavy metals in urine samples of school children from selected industrial and non-industrial areas in Dar es Salaam, Tanzania

Objectives: The levels of lead, zinc, iron, copper and cadmium metals in the urine samples of selected school children in industrial and non-industrial areas in Dar es Salaam were investigated. Methods: Urine samples were collected from 120 children in industrial areas and 120 children in non-industrial areas then digested in concentrated acids and analysed using atomic absorption spectrophotometry (AAS). Results: The concentrations of the heavy metals in the urine samples ranged from below detection limit/non-detectable (ND) to 1.92 mg/L for lead, ND to 2.55 mg/L for zinc, ND to 8.98 mg/L for iron and ND to 0.05 mg/L for copper. Cadmium was not detected. Significant differences were found between the concentrations of heavy metals in urine of pupils from the industrial areas and those from non-industrial areas. The mean concentrations of lead and copper in samples from industrial areas were significantly higher than those found in non-industrial areas (p < 0.002), while the mean concentrations of zinc and iron found in samples from non-industrial areas were significantly higher than those found in industrial areas (p < 0.0001). Conclusion: The contamination levels were generally high in samples from both areas indicating exposure from various sources. The findings indicate public health risks