The electrochemical sensing of new psychoactive substance(s) (NPSs), synthetic cathinone derivatives also termed "legal highs", are explored with the use of metallic modified screen-printed electrochemical sensors (SPES). It is found that no significant electrochemical enhancement is evident with the use of either in situ bismuth or mercury film modified SPES compared to the bare underlying electrode substrate. In fact, the direct electrochemical reduction of the cathinone derivatives mephedrone (4-methylmethcathinone; 4-MMC) and 4'-methyl-N-ethylcathinone (4-methylethcathinone; 4-MEC) is found to be possible for the first time, without heavy metal catalysis, giving rise to useful voltammetric electroanalytical signatures in model aqueous buffer solutions. This novel electroanalytical methodology is validated toward the determination of cathinone derivatives (4-MMC and 4-MEC) in three seized street samples that are independently analyzed with high-performance liquid chromatography (HPLC) wherein excellent agreement between the two analytical protocols is found. Such an approach provides a validated laboratory tool for the quantification of synthetic cathinone derivatives and holds potential for the basis of a portable analytical sensor for the determination of synthetic cathinone derivatives in seized street samples.
Acrylamide is a potential health hazardous compound occurring in baked and fried food as a result of excessive dry heating during the preparation and/or processing of foods. Exposure to a high level of acrylamide may cause cancer, neurotoxicity, and mutagenicity. In this study, an isocratic reversed-phase high-performance liquid chromatographic (HPLC) method using a C18 column was used for the determination of acrylamide in selected food. The mobile phase consisted of 0.1% formic acid in water: acetonitrile (98:02), and the flow rate was 1.0 mL min-1, elution was monitored at 200 nm. Validation in selected conditions showed that the chosen method is sensitive, selective, precise, and reproducible with a linear detector response for the determination of acrylamide. The limit of detection (LOD), and the limit of quantification (LOQ), were achieved at 0.41μg mL-1 and 1.25 μg mL-1respectively. The proposed method was also applied after validation to the most popular six brands of chips and French fries available in the Libyan market. Acrylamide was extracted by a simplified extraction method avoiding cleanup by solid-phase extraction (SPE), then analyzed by HPLC-UV. The highest level of acrylamide was found in one brand of chips with a concentration of 16.33 μg mL-1, whereas only one of the French fries products analyzed exhibited an acrylamide concentration of 10.26 μg mL-1.
The contamination by organochlorine pesticides (OCPs) of the selected sites in the eastern region of Libya was investigated to estimate the current status of pollution in surface and groundwater sources. This study was conducted to determine the concentrations of some OCPs residue in surface and groundwater samples collected from thirty different sites around Al-Jabal Al-Akhdar northeast of Libya during the summer, autumn, and winter seasons of 2016. A simple and rapid method based on the liquid-liquid extraction method followed by an HPLC with reversed-phase was developed to determine six OCPs in water samples simultaneously. An HPLC instrument was supplied with a C18 column (250 mm × 4 mm; 4.6 μm particle size) and a UV detector at 238 nm. The mobile phase was composed of 0.1% propanol in water and acetonitrile (25/75, v/v). The method was validated using reference standards of these six OPCs at different concentration levels and shows good linearity in the concentrations between 5.0 and 25 µg mL− 1. The LOD and LOQ ranged from 0.71 to 2.24 μg mL -1 and 2.16 to 6.79 μg mL-1, respectively. Relative standard deviation (%RSD) ranged from 0.026 to 0.673 %. The only OCP residue found in the area of study was 2, 4-D, with a variation of its residue levels during the seasons. The overall results showed that surface water was more polluted with 2, 4-D than groundwater, which was detected in the wide range of concentration of 0.037 to 0.385 μg mL-1, 0.003 to 0.047 μg mL -1 and 0.012 to 0.039 μg mL-1 during summer, autumn, and winter, respectively.
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