Search

In this study, a magnetically recoverable nano photocatalyst (Fe3O4/Fe2O3/TiO2/Ag) was prepared using Ag nanoparticles supported on anatase TiO2-coated Fe3O4/Fe2O3 nanoparticles. The photocatalyst was characterized by FT-IR, XRD, BET-BJH, ICP-AES, TEM, DLS, VSM, FESEM, and EDX and found to have excellent catalytic activity for synthesizing HMFCA (5-hydroxymethylfurfural-2-carboxylic acid) from HMF (5-hydroxymethylfurfural) in the presence of a deep eutectic solvent under white light irradiation. An appropriate HPLC method was established to obtain good separation of the possible metabolic substances. The advantages of this protocol consist of the use of a stable and safe light source, an environmentally friendly solvent, magnetic recyclability, and long-term stability of the catalyst for at least six consecutive runs. The synthesis of HMFCA using this method meets the requirements of green, sustainable synthetic chemistry and has potential applications in pharmaceutical chemistry and organic synthesis. Considering the yield of 98%, this novel protocol demonstrates a potential for one-pot synthesis of renewable HMFCA and a valuable product. Overall, this study showcases the advantages of green chemistry to make it a promising avenue for future research. [ABSTRACT FROM AUTHOR]

In this project, the in‐situ formation of magnetic nanoparticles modified with pectin and acetamide was presented and used as a sorbent in the magnetic solid‐phase extraction method. The synthesis of the magnetic sorbent was studied by various characterization methods. The sorbent was employed for the microextraction of four model analytes including methyl paraben, ethyl paraben, propyl paraben, and butyl paraben. The separation and measurement of the extracted compounds were done by high‐performance liquid chromatography‐ultraviolet detection. In order to achieve the best extraction condition, factors affecting the extraction efficiency were investigated and optimized using response surface methodology. In the obtained optimized condition, the following parameters were achieved: limits of detection: 0.16–0.28 µg/L, limits of quantification: 0.49–0.92 µg/L, and intra‐ and inter‐day relative standard deviations: 1.2%–6.6% and 1.6%–4.8%, respectively. The linear dynamic ranges of the method for methyl paraben, ethyl paraben, butyl paraben, and propyl paraben were 1–200, 0.5–500, 1–500, and 1–500 µg/L, respectively. In order to investigate the effectiveness of the method, the proposed magnetic nanosorbent was used to measure the desired parabens in cosmetic samples. The results showed good accuracy and precision of the developed method for the determination of trace amounts of target analytes. [ABSTRACT FROM AUTHOR]

In the current study, a new magnetic sorbent (Fe3O4@2,6‐diamino‐4‐(3,4‐dihydroxyphenyl) pyridine‐3,5‐dicarbonitrile) was prepared as a new and efficient sorbent to be used in the magnetic solid‐phase extraction method to extract tebuconazole and propiconazole as model compounds. In this regard, effective parameters such as pH of the sample solution, desorption volume, ionic strength, extraction time, desorption time, and amount of the magnetic sorbent were optimized using experimental design. In the optimal condition, the linear dynamic ranges for tebuconazole and propiconazole were between 0.5 and 200.0 µg/L. Also, the limits of detection, limits of quantification, and relative standard deviations were 0.21–0.14 µg/L, 0.49–0.45 µg/L, and 1.3%–4.6%, respectively. The estimated enrichment factors for tebuconazole and propiconazole were 22 and 28, respectively. The absolute recovery (AR%) values for tebuconazole and propiconazole were also 67% and 84%, respectively. Finally, the proposed method was used for determination of tebuconazole and propiconazole in cucumber, tomato, orange, and lemon fruits. The obtained result confirmed that the presented method is capable for the analysis of the selected analytes in complicated matrices. In addition, the ARs% were in the range of 67%–84%. The result proved that the presented method can be an alternative to the extraction process of various pesticides. [ABSTRACT FROM AUTHOR]

In this study, in situ electrodeposition of Zn─Al‐layered double hydroxides (Zn─Al‐LDHs) on the surface of pencil graphite substrate were practiced with interlayer modification by ibuprofen. The prepared composite increases the efficiency of the proposed method by increasing the level of interaction between the sorbent and the selected analytes including acetylsalicylic acid and naproxen (NAP) in real sample. Eventually, the extracted target analytes were injected into high‐performance liquid chromatography ultraviolet (HPLC‐UV) for their measurement. The experimental design including PBD and BBD was implemented to obtain the maximize efficiency and optimal condition for extraction of the target analytes. Therefore, in optimal conditions, limits of detection of 0.33–0.64 µg L−1, linear dynamic range (LDR) of 1–100 µg L−1 (with r2 > 0.9934), and limits of quantification (LOQs) of 1.1–2.1 µg L−1 were obtained for target analytes by SPME‐HPLC‐UV. The intra‐day relative standard deviation (RSD%) were found to range in 3.90%–5.30% (4.90%–6.80%) at concentration of 5–50 µg L−1 (2–10 µg L−1). According to obtained result, the relative recovery was calculated between 90% and 109%. Therefore, the obtained results showed that the selected method has a suitable performance for the preconcentration and extraction of acetylsalicylic acid and NAP in biological samples. [ABSTRACT FROM AUTHOR]

Graphite carbon nitride (g-C3N4) is a two-dimensional nano-sheet with electronic properties, which shows unique characteristics with high chemical and thermal stability in its structure. The functionalization of these compounds through covalent bonding is an important step towards significantly improving their properties and capabilities. To achieve this goal, a novel strategy for the covalent functionalization of Fe3O4@g-C3N4 with thiamine hydrochloride (vitamin B1) via cyanuric chloride (TCT), which is a divalent covalent linker, was presented. The efficiency of Fe3O4@gC3N4@Thiamine as a heterogeneous organic catalyst in the synthesis of spirooxindole-pyran derivatives and 2-amino-4H-pyran under solvent-free conditions was evaluated and the yields of high-purity products were presented. In addition, easy recycling and reuse for seven consecutive cycles without significant reduction in catalytic activity are other features of this catalyst. Moreover, the performance of the prepared sorbent in the microextraction technique (herein, magnetic solid phase extraction) was studied. The tebuconazole was selected as the target analyte. The target analyte was extracted and determined by HPLC–UV. Under the optimum condition, the linear range of the method (LDR) was estimated in the range of 0.2–100 μg L−1 (the coefficient of determination of 0.9962 for tebuconazole). The detection limit (LOD) of the method for tebuconazole was calculated to be 0.05 µg L−1. The limit of quantification (LOQ) of the method was also estimated to be 0.16 µg L−1. In order to check the precision of the proposed method, the intra-day and inter-day relative standard deviations (RSD%) were calculated, which were in the range of 1.5- 2.8%. The method was used for the successful extraction and determination of tebuconazole in tomato, cucumber, and carrot samples. [ABSTRACT FROM AUTHOR]