A method for the analysis of aflatoxins in food samples was developed. The preliminary work focused on optimizing sample pretreatment conditions such as the extraction solvent; the type and amount of drying agents; the extraction time; and the solvent-sample ratio. A 60:40 methanol/acetonitrile (%, v/v) extraction mixture provided recoveries in the range of 71.8–107.7% at spike levels of 1.5–50.0 µg/kg with relative standard deviations (RSDs) lower than 15%. The separation of the four aflatoxin compounds with high selectivity and sensitivity, and within reasonable retention times, was performed by a C18 250 mm × 4.6 mm × 5 µm column (Nucleodur 250-5) at 45°C. The developed QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure, high performance liquid chromatography (HPLC) method was then compared with the fluorometric determination method. It was found that the fluorometric determination method had a poor precision and positive bias as compared to QuEChERS-HPLC method. A total of 669 domestic and imported food samples in Jordan were analyzed for their aflatoxins content. Peanut and peanut butter samples showed the highest incidence of contamination (10 contaminations) followed by pistachio nut samples (6 contaminations) and sesame seed samples (2 contaminations).
The need for clean, inexpensive and renewable energy has increasingly turned research attention towards polymer photovoltaic cells. However, the performance efficiency of these devices is still low in comparison with silicon-based devices. The recent introduction of new materials and processing techniques has resulted in a remarkable increase in power-conversion efficiency, with a value above 10%. Controlling the interpenetrating network morphology is a key factor in obtaining devices with improved performance. This review focuses on the influence of controlled nanoscale morphology on the overall performance of bulk-heterojunction (BHJ) photovoltaic cells. Strategies such as the use of solvents, solvent annealing, polymer nanowires (NWs), and donor–acceptor (D–A) blend ratios employed to control the active-layer morphologies are all discussed.