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The goal of this work was to assess the competence of organic hydrophobic resin bound gold nanocomposites (OH/R-AuNCs) for detection of pymetrozine insecticide from vegetable samples employing surface-enhanced/attenuated total reflectance-Fourier transform infrared (SE/ATR-FTIR) spectroscopy. The adsorption isotherm models, including the Langmuir, Freundlich and Temkin, are tested to reveal the interactive behaviour between the OH/R-AuNCs and pesticide. The adsorption occurs principally by London–Van der Waals dispersion interactions and hydrogen bonding interactions between the surface of OH/R-AuNCs materials and the hydrophobic part of pesticide molecule. The characteristic absorption band obtained at 3019.94 cm−1 was utilized for the quantitative analysis of pymetrozine insecticide in vegetable samples. The method was found to be accurate and precise, with mean recovery values in the range of 94.5–110 %, correlation coefficient of 0.992 %, and detection limit of 2.65 μg mL−1. The adsorption efficiency of the designed OH/R-AuNCs significantly influences the SE/ATR-FTIR response of the pymetrozine around 90 %. The optimized and validated method was applied to determine the residual concentrations of the pymetrozine that had been applied to vegetable samples.

The present work reported a novel strategy to construct supported cationic-polystyrene-resin-bound silver nanocomposites for enhanced catalytic reduction of 4-nitrophenol in an aqueous medium. The Fourier transform infrared spectroscopy (FTIR) was used as a model instrument for the study of catalytic reduction of 4-nitrophenol using cationic-polystyrene-resin-bound silver nanocomposite materials. The mechanism is based on the reduction of 4-nitrophenol to 4-aminophenol due to the electron transfer process that occurred between donor borohydride (BH4−) and acceptor 4-nitrophenol. The polystyrene resin provides support and surface area to increase the catalytic activity of silver nanoparticles. The diffused reflectance-Fourier transform infrared spectroscopy revealed the binding of silver particles onto the surface of cationic polystyrene resin beads. Furthermore, the catalyst was easily separated by the filtration and drying process and was able to reuse. A quantitative analysis of this work has also been performed. The linearity range, the limit of detection, and the limit of quantification obtained for the present method were 0.1 × 10−4 to 1.0 M, 0.6 M, and 2.1 M, respectively. Moreover, a good catalytic efficiency was found to be 96.8%. The advantages of the current method are its simplicity, sensitivity, rapidity, low cost, ease of preparation, and excellent catalytic efficiency to reduce 4-nitrophenol from an aqueous solution.

N, S co-doped graphene (NSG) has been synthesized by using graphene oxide, cyanamide and sodium sulphide as a source of C, N and S respectively. Due to its excellent electronic properties and stability, NSG has been used as an adsorbent for methylene blue (MB) removal from aqueous solution. Adsorption efficiencies of Graphene, N-doped graphene, S-doped graphene and NSG were compared during the study and it was found that NSG was the most efficient material for the adsorption of MB. The study was carried out in the UV-visible region by observing the changes in absorbance. NSG has excellent properties to adsorb the MB dye with a removal efficiency of 93.76±0.2%. Additionally, desorption studies were also carried out using 0.1 M cetylpyridinium chloride as cationic surfactant and the desorption% was found to be 50.28±0.1%, signifying its reusability as an adsorbent. This indicates that NSG opens a new window for the design of heteroatom-doped carbon material as well as its application in the adsorption studies. Accordingly, the synthesized material will be employed for wastewater treatment as a reusable adsorbent of MB in the near future with high efficiency and appreciable stability. In addition, the material has several other future applications such as electrode material for supercapacitor battery, sensor, adsorbent for metal ions and biomolecules, etc.

Biophenols (BPs) are one of the natural phytochemical products, found majorly in fruits, cereals, vegetables and beverages. BPs has gotten a lot of press in recent years due to their abundance in nature as well as biological activities. Furthermore, they are potential targets for food and pharmaceutical industries. Many extraction techniques are presented in this paper. Among all the techniques presented in this paper, pressing and solvent extraction methods are considered as traditional techniques while supercritical fluid extraction, solid phase microextraction, microwave assisted extraction, and Enzyme assisted extraction are considered as advanced techniques. The fundamentals on analysis of BPs employing different analytical instrumental techniques for qualitative and quantitative determination in environmental samples are also discussed. Only a few specific polyphenolic chemicals have had their safety and health claims formally sanctioned, therefore recent international regulatory laws are examined. In addition to the health claims and marketing of polyphenols as a functional food, the effects of food processing on polyphenol bioavailability are investigated. A number of investigational agents or polyphenol-rich content like HQC/QC and honey, from photochemistry are being also explored for recent antiviral treatment of COVID-19 and their treatment strategies. The day-by-day advancement in the analytical methodologies for BPs detection provides the platform to find out the health favorable components. This review focuses on the various extraction techniques, structure identification of plant extracts and quantification of BPs.