Current Analytical Chemistry - Volume 18, Issue 8, 2022

Background: Recently, the microwave has shown tremendous research interest and potential for the extraction of phytoconstituents from plant resources as there is a need for the advancement of performance in the extraction method. Extraction is the first basic step in the preparation of crude extract followed by isolation, and characterization of isolated components related to current analytical chemistry. The current use of microwaves implements green technology and satisfies the demand for getting the maximum yield of the target compound. Methods: Research articles related to the current research topics on Microwave-Assisted Extraction (MAE) were collected and reviewed. Results: MAE promises to be a novel extraction technique for the extraction of phytoconstituents from natural sources than other conventional extraction techniques. Conclusion: Microwave-assisted extraction is proved to be advantageous as this method permits specificity, higher yield, selectivity, and extraction efficiency over traditional methods such as Soxhlet extraction, maceration and others along with reduced time and solvent consumption, less environmental pollution, and reduced degradation of thermolabile constituents.

Background: BPA and its analogues are poisonous and hazardous and found in water, food and environmental samples. These are a dangerous class of endocrine-disrupting chemicals (EDCs) that drastically affect the environment and human health. BPA and its analogues, such as BPS, BPF, BPE, BPB, BPAF, and BPAP, are a serious threat to human beings. Methods: Numerous methods are available for separating bisphenols (BPs) from water, food and environmental samples. Molecularly imprinted polymers (MIPs) are a superior and eco-friendly technique that eliminates BPs due to cavities in the shape, size, and functionality complementary to the template molecule. MIPs are widely used to remove BPA and its analogues. The inexpensive MIPs are a more attractive choice for separating various BPs due to their unique properties and offer a satisfactory pathway to adsorb any BPs from water, food and environmental samples to overcome their hazardous effects on human health. Results: This review aims to analyze and assess the recent advancements of MIPs for the separation of bisphenols. Following a concise introduction for newcomers entering the field, a comprehensive critical review of developments of MIPs and their applications for BPA and its analogues has been presented. In this review, we have discussed the MIPs with the method and constituents of synthesis. Secondly, the development of the different types of MIPs (particle, monolithic, membrane) has been presented for the BPs. Finally, the use of MIP as a stationary phase in chromatography with an emphasis on BPs is described. This section is subdivided into high-performance liquid chromatography (HPLC), capillary liquid chromatography (CLC), and capillary electrochromatography (CEC). Conclusion: Molecular Imprinting technology (MIT) technology provides an attractive pathway for further research and improvement in more efficient MIPs, with higher adsorption capacity. The significance of applications allowed to separate the BPs and discharged from various samples, thus reducing health risks. Therefore, MIPs may contribute to future prospective water, food and environmental samples treatment processes.

Background: As pathogenic bacteria account for the leading cause of diabetes-related infections, sensitive detection of bacteria from clinical samples has attracted abundant attention. Methods: We propose an innovative DNA-AuNP-based sensing system that integrates low-speed centrifugal bacteria isolation, detection and protein analysis. In the method, RCA (rolling circle amplification) is utilized to produce a long-ssDNA (single-strand DNA), which can form a hairpin structure comprising repeats of functional domains, such as PBP2a aptamer. When aptamers bind to target bacteria, the hairpin structure in the RCA product changes its conformation, exposing the AuNP binding sequence. As a result, the probe on the surface of AuNP hybridizes with AuNP binding sequence in RCA product by strand displacement reaction, releasing the fluorescent-labeled complementary probe as the detection signal. The simultaneous formation of the bacteria-DNAAuNP satellite network enables the isolation of target bacteria by low-speed centrifugation. Results: Eventually, we applied the method for MRSA (methicillin-resistant Staphylococcus aureus) detection and obtained a favorable detection performance with a limit of detection of 275 cfu/μL. Conclusion: We believe the method has potential application in the early diagnosis of diabetesrelated infections.

Aims: A new basic research was conducted concerning the possibility of using a flow DCFC (Direct Catalytic Fuel Cell) for analytical purposes, checking ethanol and glucose. Also making considerations on the energy conversion aspect of these fuels. Background: There are a large number of studies concerning catalytic or microbial fuel cells, which allow to obtain electricity, both using liquid fuels, such as ethanol and methanol, or solid fuels, such as carbohydrates, biomass and so on. These systems are frequently characterized by high conversion efficiency but also high complexity and considerable costs. Objective: In the present research we investigated the possibility of using a very simple flow system to carry out measurement of ethanol concentration, or glucose analysis, using the same flow system associated with a small reactor containing yeast (Saccharomyces cerevisiae). Methods: The main operating conditions have been optimized and the concentration range where the flow system response shows a linear correlation with the fuel concentration was also identified. Results: The current delivered by the catalytic system operating in flow was determined and the calibration sensitivity values are higher than the sensitivity found in batch mode. It has also been shown that it is possible to realize a very simple system, which can be used to study and evaluate the conversion of chemical energy into electrical energy, using ethanol or glucose as fuel and the theoretical importance and analytical advantages have been emphasized, so that the use of carbohydrates, such as solid fuels, could represent. Conclusion: Present research has shown how, by operating in flow mode, rather than in batch, it is possible to have advantages from an analytical point of view, since a considerable increase in the sensitivity of the method can be obtained, probably attributable to a reduction in the effects of poisoning. Moreover, how it is possible to study and optimize the energy conversion conditions by means of a simple and inexpensive apparatus.

Background: Copper is one of several heavy metals. A low concentration of copper is vital for animals and plants, whereas it is highly toxic to aquatic plants and bacteria in a high concentration. Therefore, copper ions in water and food must be controlled, and as a result, the development of novel methods for the determination of copper in water samples is of interest. Objective: Different techniques have been proposed for copper ions extraction and determination. The magnetic solid-phase extraction method is considered superior to the other method for simplicity, its higher enrichment, and the need for lower quantities of solvents. The novel modified magnetite nanoparticles as the sorbent, along with the atomic absorption spectrometry analysis, can be a low-cost, simple and rapid method for this propose. Methods: Traces of Cu(II) in environmental samples were preconcentrated using a novel magnetic adsorbent developed based on 2,2´-((1E,1´E)-hydrazine-1,2-diylidenebis(methanylylidene)) diphenol coated magnetite nanoparticles. The influence of ligand concentration, amount of adsorbent, pH, type of eluent, sample volume, and effects of interfering ions were optimized. The adsorbed species were eluted for analysis through atomic absorption spectrometry. Results: A linear calibration curve was recorded from 2 to 40 μg ml^-1 (r²= 0.999) under optimal conditions, and the detection limit of the method was as low as 1.6 μg ml^-1. Also, good recoveries were obtained for the real sample analysis. Conclusion: The developed procedure constituted a rapid extraction, a low-cost and efficient method, and was used for the analysis of copper ions in the tap, river, and lake water.

Background: Microwave-assisted extraction (MAE) is a green extraction technology that saves both in energy and time and that bioactive compounds can be extracted without loss as much as in traditional extraction methods. Objectives: This study aims to optimize the MAE process for maximizing the recovery of antioxidant compounds of flavonoids and the activity of radical scavenging of DPPH (2,2-diphenyl-1-picrylhydrazyl) from citrus peels (CP). Methods: The modeling used Box-Behnken Design (BBD) experimental design for optimizing three extraction parameters of time (5, 15, and 25 min), ethanol concentration (50%, 70%, and 90%), and extraction temperature (55, 65, and 75°C). UHPLC-MS analysis was performed to identify the qualitative flavonoid content in the extract. Results: Our results showed that the optimum MAE conditions that maximize the total flavonoid content and antioxidant activity of the CP extract were extraction time of 16.87 min, 50% ethanol, and temperature at 75°C. The obtained CP extract had a TFC of 14.10 mg QE/g and antioxidant activity of 51.52%, which was in line with the predicted values. Flavonoids of neohesperidin, naringin, hesperidin, narirutin, and nobiletin were identified in the extract of CP. Conclusion: The ethanolic extract of CP was confirmed to have high flavonoids content with potent antioxidant activity.

A Book entitled Applications of Ion Exchange Materials in published by Chemical and Food Industries Edited by Inamuddin, Abdullah M. Asiri, and Tauseef Ahmad Rangreez, Springer, in 2019, (Print ISBN 978-3-030-06084-8, ISBN 978-3-030-06085-5, DOI: 10.1007/978-3-030-06085-5). This book provides an up-to-date, complete overview of various applications of ion exchange resins in the chemical and food industry. The chemistry of ion exchange resin materials towards its allied applications, including deionization, dealkalization, dehydration, hydrogenation, esterification, reactive separation, synthesis, separation, and purification of industrial products, were well addressed in this book, along with drawbacks and future scope to improve for better performance on the industrial scale. This book consists of nine chapters. Altogether, they discuss the applications of ion exchange resins in solid acid catalysis, reaction separation, removal, and recovery of metals in chemical reactions, and preparation of Ag-aggregated ion-exchanged silicates, specifically as it is not possible to discuss each and everything in detail. The chapters are presented effectively by reputed experts around the world. That makes this book an exceptionally significant and authentic source of information. It is valuable for a book to provide updated information, review the work done to date, do proper analysis, compare the pros and cons of comparable existing technologies, and guide the reader to research gaps and places where improvement is required. This book is an essential reference guide for students, researchers, engineers, professionals, and industrial research and development specialists in chemistry, chemical and biochemical technology, food chemistry, synthetic chemistry, and industrial chemistry.

Background: Polyaromatic hydrocarbons (PAHs) are a class of toxic compounds commonly found in edible vegetable oils as a result of contamination through food processing. Among the wide variety of PAHs existing in edible oils, benzo(a)pyrene (BAP), benzo(a)anthracene (BAA), benzo( b)fluoranthene (BBF), and chrysene (CHR) are commonly monitored due to their toxicity, carcinogenic and teratogenic properties. Materials and Methods: In this context, we described a combination of liquid-liquid extraction and dual cartridge solid-phase extraction (dSPE) system for the extraction of BAP, BAA, BBF, and CHR in palm oil derived tocotrienol rich fraction (T3RF), followed by their analysis using GC-MS operating in selected ion monitoring mode (SIM). Results: The separation was effected using a DB-5HT column (30 m × 0.25 mm × 0.25 μm) that can operate at a high temperature limit of 400 °C, which enables the separation of the PAHs in < 28 min. The calibration curves were correlated within the range of 1.5-25 μg/ L, with detection limits (S/N: 3.3) of 0.48-1.35 μg/L, and relative standard deviations of ≤ 0.07% and ≤ 6.85% were achieved for intra-day retention times and peak areas. Conclusion: The proposed sample preparation and GC-SIM workflow greatly reduces interference caused by tocotrienol homologues and enables the quantitative determination of BAP, BAA, BBF, and CHR in T3RF and palm fatty acid distillates.