In this approach, a nonchromatographic method was developed for selective extraction and determination of Cr(III) concentration in isotonic and energy drinks by FAAS. This new method uses Luffa cylindrica fibers as the solid phase extraction and an off-line flow injection system. Cr(III) and Cr(VI) adsorption behavior onto Luffa fibers allowed the selective separation of Cr(III) in the pH range of 4 to 5. The system variables were optimized through full factorial and Doehlert designs. Under optimal conditions, the detection and quantification limit for Cr(III) was 19.2 µg·L−1 and 63.9 µg·L−1, respectively, with precision below 0.19%. A high tolerance toward interfering ions was observed for the proposed method. Recovery test results obtained for different isotonic and energy drinks samples were higher than 87.6%. The method’s accuracy was confirmed through analysis of certified reference materials, water and sediment river samples (APS-1071 and APS-1066).
Moringa oleifera seeds used for selective extraction of manganese in aqueous samples. Around 60% of the Mn(II) was removed at an initial pH of 3.0. The maximum adsorption capacity for Mn(II) was 10.35 mg g-1. The adsorption of manganese onto Moringa oleifera seeds was optimized as a function of pH, adsorbent mass, particle size and contact time in aqueous solutions in batch tests. The results show that the optimized conditions for manganese adsorption were: pH 3.0, particle size ≤ 180 µm, adsorbent mass 1.0 g and contact time 15 min. Varying the pH allowed the separation of the manganese species, the seeds selectively retained Mn(II) while Mn(VII) remained free in solution. Around 60% of the Mn(II) was removed at an initial pH of 3.0 with a manganese concentration of 4 mg L-1. The adsorption process was evaluated through adsorption isotherms and kinetics studies. The maximum adsorption capacity for Mn(II) was 10.35 mg g-1. The isotherm followed the Langmuir model and the adsorption kinetics followed a pseudo-second-order kinetic model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.